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TALC AND TALLAPOOSA ANTHOPHYLUTEDEPOSITS IN AND CH ALABAMA By Thornton L. Neathery ^% V LIBRARY m c^ GEOLOGICAL SURVEY OF ALABAMA BULLETIN 90 PLAINTIFFS EXHIBIT WCD-35 i GEOLOGICAL SURVEY OF ALABAMA Philip E. LaMoreaux State Geologist DIVISION OF ECONOMIC GEOLOGY W. Everett Smith Chief Geologist BULLETIN 90 TALC AND ANTHOPHYLLITE ASBESTOS DEPOSITS IN TALLAPOOSA AND CHAMBERS COUNTIES, ALABAMA By Thornton L. Neathery UNIVERSITY, ALABAMA 1868 S TATE OF ALABAMA Honorable Albert P. Brewer, Governor G EO LO G ICA L SURVEY OF ALABAMA AND O IL AND GAS BOARD OF ALABAMA Philip E. LaMoreaux, State Geologist and Oil and Gas Supervisor A. J . Harris, Attorney Katherine L. Fraker, Secretary O IL AND GAS BOARD OF ALABAMA E. K. Hanby, Chairman C. D. Glaze, Member E. O. Eddins. Member Philip E. LaMoreaux., Secretary ADMINISTRATION George W. Swindel, Jr., Assistant to State Geologist (Administration) Thomas A. Simpson, Assistant to State Geologist (Programs and Plans) Virginia Q. Shanner, Accountant Adna S> Howard, Librarian Dorothy L. Brady, Librarian William H. Btirkes, Duplicating Equipment Operator Thomas V. Stone, Photography Specialist Gene A. Clements, Scientific Aide Fendley L. Frazier, Scientific Aide Samuel L. Coleman, Scientific Aide Melvin A. Grinstead, Carpenter John C. Price, Laborer Roy W. Thomas, Utility Laborer Mavourneen J . Dean, Receptionist Clarice Booth, Secretary Annette W. Green, Secretary WATER RESOURCES Doyle B. Knowles, Chief Hydraulic Engineer Stanley L. Graves, Hydraulic Engineer Jesse S. Ellard, Geologist Philip C. Reed, Geologist Victor M. Shamburger, Jr., Geologist John L . Sonderegger, Geologist James D. Turner, Geologist Anthony M. Malatino, Chemist Jaoelle D. Davenport, Scientific Aide Julia M. Leatherwood, Secretary Boyd L. Bailey, Petroleum Geologist T. L . Slay, Field Agent R. C. Wood, Field Agent Anna K. Collins, Secretary Monzula G. Sherry, Secretary M. Jean Smith, Secretary GEOPHYSICS Thomas J . Joiner, Chief Geophysicist Thomas H. Clements, Geophysicist William L. Scarbrough, Geophysicist Robert C. MacElvain, Petroleum Specialist Donald B. Moore, Geologist Robert E. Kidd, Geologist Gary V. Wilson, Scientific Aide Joe C. Beasley, Scientific Aide Nickole L . Moore, Key-Punch Operator Audrey T. Hartley, Secretary PALEONTOLOGY-STRATIGRAPHY Charles W. Copeland, Jr., Chief Geologist James A. Drahovzal, Geologist James C. Kelley, Geologist ECONOMIC GEOLOGY William E. Smith, Chief Geologist Otis M, Clarks, Jr., Geologist T. W. Daniel, Jr., Geologist Thornton L. Neathery, Geologist Michael W. Szabo, Geologist Paul H. Moser, Geologist Herbert S. Chaffin, Jr., Geologist Merla W. Elliott, Secretary OIL AND GAS H. Gene White, Chief Petroleum Engineer William E. Tucker, Petroleum Engineer SPECIAL CONSULTANTS "'Walter B. Jones, State Geologist Emeritus "Winnie McGlamery, Paleontologist Emeritus COOPERATIVE STUDIES WITH U.S. GEOLOGICAL SURVEY WATER RESOURCES DIVISION William L. Broadhurst, District Chief William J . Powell, Hydrologist Charles F. Hains, Hydrologist James R. Avrett, Hydrologist Lawson V. Causey, Hydrologist Robert J . Faust, Hydrologist Joe R. Harkins, Hydrologist John G. Newton, Hydrologist Marvin E. Davis, ji^drologist John C. Scott, Hydrologist "Lyman D. Toulmin, Jr., Geologist Patrick 0 . Jefferson, Hydraulic Engineer Alfred L. Knight, Hydraulic Engineer Jerald F. McCain, Hydraulic Engineer Charles 0. Ming, Hydraulic Engineer Samuel C> Moore, Hydraulic Engineer Joe R. WillrooD, Hydraulic Engineer Hiley H. Cobb, Hydraulic Engineering Technician Paul W. Cole, Hydraulic Engineering Technician Tommy R. Duvall, Hydraulic Engineering Technician Franklin D. King, Hydraulic Engineering Technician Clifford L . Marshall, Hydraulic Engineering Technician Ernest G. Ming, Jr., Hydraulic Engineering Technician George H. Nelson, Jr., Hydraulic Engineering Technician David M. O' Rear, Hydraulic Engineering Technician Fletcher C. Sedberry, Hydraulic Engineering Technician Vickie L . Welch, Hydraulic Engineering Technician Ira A. Giles, Physical Science Technician Wiley F. Harris, Jr., Physical Science Technician Douglas D. Batemon, Engineering Aid Jonathan D. Hayes, Engineering Aid Reba S. McHenry, Hydraulic Engineering Aid Bobby G. Byrd, Engineering Aid Willard W. Livingston, Jr., Engineering Aid Jerry A. Daniel, Cartographic Technician Alma J . Roberts, Administrative Assistant Bernice L. McCraw, Editorial Clerk Sandra B. Simpson, Clerk-Stenographer Madeleine R. Powell, Clerk-Dictating Machine Transcriber COOPERATIVE STUDIES WITH U.S. BUREAU OF MINES TUSCALOOSA' METALLURGY RESEARCH LABORATORY John P. Hansen, Director James 5. Browning I. L. Feld AREA II MINERAL RESOURCE OFFICE Robert D. Thomson, Administrator Ronald P. Hollenbeck James F. O'Neill COOPERATIVE RESEARCH ACTIVITIES WITH UNIVERSITIES AND COLLEGES University of Alabama Arizona State University Birmingham Southern College Florida State University University of Houston University of Illinois University of Chattanooga Yale University University of Iowa Louisiana State University Memphis State University University of North Carolina Auburn University Interm ittent employment only- i Honorable Albert P. Brewer Governor of Alabama Montgomery, Alabama Dear Governor Brewer: University, Alabama June 3, 1968 I have the honor to transmit herewith the report " Talc and Anthophyllite Asbestos Deposits in Tallapoosa and Chambers Counties, Alabama," by Thornton L. Neathery, which has been published as Bulletin 90 of the Geological Survey of Alabama. Anthophyllite asbestos is an important industrial mineral for which there are few substitutes. The demand for this acid resis tant material has been increasing for many years and should in crease more rapidly in the future. In view of the expanding market and anticipated growth of the asbestos industry, an appraisal of Alabama's anthophyllite and talc resources was considered neces sary. The present report indicates that significant quantities of talc and asbestos are available for economic development. Philip E. LaMoreaux State Geologist CONTENTS Description of properties--Continued Prather property ..................................................... ............. Clema Smith property................................................................... Garfield Heard property............................................................... George Sims property .................................................................. Clem Vines property ..................................................................... Clem Vines property, northa r e a .......................................... Clem Vines property, south area .......................... ............ Clarence Ware property ............................................................... Pettus Harris property................................................................. Camp Hill Road properties ........................................................ E stes property ............................................................................. Coosa River News Print property............................................... Jennings -Satterwhite properties ............................................... . History of mining and production....................................................... Mining methods ................................................................................... Reserves ......................................................................................... R eferences.............................................................................................. Page 71 75 75 77 79 79 81 85 85 88 88 90 90 92 93 94 97 ILLUSTRATIONS Figure 1. Index map of study a r e a .................. ................ 2. Geologic rock-type map of the Dadeville a r e a ............ 3. Pyroxenite inclusions in well banded hornblende g n e is s ...................................................... 4. A typical outcrop of pyroxenite ................................... 5. Typical "buckshot" soil derived from the * decomposition of pyroxenite-amphiboliterock................... 6. Antbophyllite veins crisscrossing the face of a pyroxenite boulder .......................................................... 7. Pyroxenite boulders released by the weathering of hornblende gneiss .............................................................. 8. Road cut exposure showing shell-like rims of talc os e-pyroxenite surrounding decomposed pyroxenite ........................................................................... 9. Compositional diagram showingseveral phases in the system Mg0-Si02-H20 ................................................ 10. Pressure-temperature curves ofunivariant equilibrium for several phases in the system Mg0-Si02-H20 ........................................................................ 3 11 16 17 18 24 25 30 33 ii 15 CONTENTS Abstract ................................................................................................. Introduction ........................................................................................... Location and distribution............................................................. Purpose and scope......................................................................... Previous w ork............................................................................... Present investigation................................................................... Acknowledgments ......................................................................... Geography ............................................ Geology ................................................................................................. G e n e r a l.......................... Structure and metamorphism ....................................................... Pyroxenite and related mafic rocks ................................................... D istribution................................................................................... C h aracter....................................................................................... O rigin .............................................................................................. Alteration p ro cesse s............................................................. Serpentinization ........................................................... Steatitization ............................................................... Amphibolization............................................................. Chloritization ............................................................... Physicochemical conditions of alteration ..................................... Asbestos ................................................................................................ M in e ra lo g y ...................................................................................... Chrysotile asbestos ............................................................. Amphibole asbestos ............................................................. Tremolite-actinolite ..................................................... Anthophyllite ............................................................... Cross-fiber veins ................................................. Slip-fiber veins ..................................................... Mass-fiber dep osits............................................... Occurrence of anthophyllite ....................................................... Talc ........................................................................................................ M in e ra lo g y ...................................................................................... Character and classificatio n ....................................................... Talc ................ S te a tite ................................................................................... S o a p s t o n e ............................................................................... O c c u rre n c e ..................................................................................... Description of properties..................................................................... Perry Wise-Sanders properties..................................................... W. B. Railey property................................................................... Sorrell Estate property................................................................. Fargarson property........................................................................ Knight property................................ Walker property............................................................................. Page 1 2 2 2 4 5 5 6 7 7 10 12 13 15 16 23 24 26 27 29 30 38 38 38 39 39 40 40 43 44 46 48 48 48 48 49 49 49 51 57 62 65 68 68 70 TALC AND ANTHOPHYLLITE ASBESTOS DEPOSITS IN TALLAPOOSA AND CHAMBERS COUNTIES, ALABAMA By Thornton L. Neathery ABSTRACT Talc and anthophyllite asbestos deposits in Tallapoosa and Chambers Counties, Alabama, are associated with a complex group of calcic-magnesium mafic and ultramafic rocks. These rocks are a part of a discontinuous belt of mafic and ultramafic rocks which occur within the crystalline gneiss and schist of eastern North America and extend from east-central Alabama to western New foundland. In Tallapoosa County, these rocks crop out in narrow, arcuate bands which extend from the vicinity east of Dudleyville westward to the southwestern part of the county, a distance of approximately 20 miles. The mafic rocks consist chiefly of amphibolite, gabbro diorite, and horn blende gneiss. The ultramafic rocks are predominantly pyroxenites composed of heterogeneous aggregates of enstatite, hypersthene, olivine, and bronzite. The enclosing paraschist and gneiss are moderately folded and have a well developed foliation usually parallel to their compositional layering. The rock sequence strikes northeasterly concordant with regional trends. An occasional divergence in strike suggests minor cross folding. Field mapping indicates that the regional structure is a broad synform trending northeastward from south of Dadevillq to a prominent granite outcrop in Chambers County. Amphibolite zones are extensive and numerous. Their outcrop area tends to be elongate with the regional strike, and often exceeds 6 miles in length. The outcrops vary in width from 100 feet to over a mile. Exposures of amphibolite are few, and outcrop boundaries are difficult to map. The mafic and ultramafic rocks represent a wide variety of distinct but related rock types which have been involved in one or more periods of regional metamorphism. Four processes of alteration are recognized in the amphibolites and pyroxenites. These are (1) serpentinization, (2) steatitization, (3) amphibolization, and (4) chloritization; steatitization and amphiboliza;tion predominate. Most occurrences of asbestos are found in the eastern part of the maficultramafic belt. Three types of anthophyllite asbestos are recognized on the basis of fiber orientation: cross-fiber, slip-fiber, and mass-fiber. The talc is predominantly a " talc-rich" soapstone which occurs a s shell like entities in the saprolite overlying the mafic-ultramafic rock complex. Talc appears to be far more abundant than anthophyllite. Calculations, based on evaluation of three talc samples and five significant talc-bearing properties, i2 T A LC AND ANTH O PH YLLITE A SBESTO S DEPOSITS indicate the potential availability of approximately 8 million tons of talc. Con siderable tonnages of anthophyllite asbestos could conceivably be derived as a primary product or as a secondary product from talc mining. INTRODUCTION LOCATION AND DISTRIBUTION Talc and anthophyllite asbestos deposits in Alabama are associated with a complex group of mafic and ultramafic calcicmagnesian rocks. They are considered to be part of the discontin uous belt of mafic and ultramafic rocks that extends from eastcentral Alabama to western Newfoundland, a distance of more than 2,000 miles (Pratt and Lewis, 1905, p. 34). The belt is well de veloped in the Piedmont region of Alabama, especially in Talla poosa County, isolated mafic and ultramafic rock occurs in other divisions of the Alabama Piedmont, especially in Coosa, Chilton, Clay, and Cleburne Counties. Various types and quantities of asbestos and talc are found in the area of mafic and ultramafic rock. The significant deposits of asbestos occur in the eastern part of the county near Dudleyville. The talc deposits are le ss restricted in distribution and crop out more or le ss continuously from Dadeville to Dudleyville (fig. 1 ). The area of the present study is bounded on the east by the Pleasant Grove granite outcrop in Chambers County; on the north and west by the Brevard zone; and on the south by an arbitrary line 10 ter 12 miles south of and parallel to the strike of the Brevard zone. PURPOSE AND SCOPE Anthophyllite asbestos is an important industrial mineral for which there are few substitutes. The demand for anthophyllite asbestos has increased for many years and is expected to increase more rapidly in the future. Research continues to develop new uses for all varieties of asbestos, especially the acid resistant variety, anthophyllite. Anthophyllite is presently used for acid resistant filter material, asbestos cement, and insulating material. In view of the expanding market and anticipated growth of the Figure 1.--Index map of study area INTRODUCTION CO 4 TA LC AND ANTHOPHYLLITE ASBESTO S DEPOSITS asbestos industry, an appraisal of Alabama's anthophyllite re sources was considered necessary. The associated talc deposits, although somewhat inferior in grade to other talc deposits of the eastern United States, occur in significant quantities to be con sidered a primary resource. The purpose of this report is to present the basic geology, and an appraisal of the talc and anthophyllite asbestos resources in Tallapoosa and Chambers Counties, it is hoped that the data in this report will be the basis for future investigation and develop ment of these resources. PREVIOUS WORK The occurrence of talc and anthophyllite asbestos in the Dadeville area of Tallapoosa County was noted by Eugene A. Smith in 1873 at several prospects opened in search of corundum. It is reported that from 1939 to 1940 extensive prospecting for chromite took place in the Easton and Buttson communities of the central Dadeville ultramafic rock outcrop area. Numerous shallow cuts and pits were excavated in the pyroxenite, many of which are still open for examination. in 1953, the Red Hawk Mining Co., Montgomery, Ala., con ducted exploration activities in the western end of the Dadeville area. They opened 7 or 8 large bulldozer trenches and possibly several smaller ones. It is not known if the company removed any sample material for testing. In 1963, the American Talc Co., Alpine, Ala., leased several hundred acres of land in the east-central part of the district along the Dadeville-Dudleyville road. Twelve diamond core holes were completed during their investigation. The Geological Survey of Alabama furnished technical assistance in interpreting the drill hole data. Also, in 1963, the Tallapoosa Mining Co., Camp Hill, Ala., was organized and acquired the mineral rights to several thousand acres of land. The company opened several small bulldozer pits and one large pit in the eastern end of the area, and recovered 20 to 25 tons of material which was subsequently used for product testing in 1965. In 1965, the Tallapoosa Mining Co. lands were conveyed to the Black Warrior Petroleum Co. INTRODUCTION 5 In 1965, the Powhattan Mining Co., Baltimore, Md., obtained a mineral lease on 140 acres of land in the Oziah Church area, and began sampling for anthophyllite. They conducted extensive exploration activities on the property, excavating numerous pits and trenches. Sampling continued during 1966-67, and several carloads of crude material were shipped from Dadeville for test purposes. PRESENT INVESTIGATION The present geologic study of the talc and anthophyllite asbestos deposits was begun in the spring of 1965. The original purpose of the investigation was to obtain as much information as possible on the distribution, character, origin and potential re serves of anthophyllite asbestos in Alabama. As the investigation continued it became apparent that the associated talc was of sufficient quantity to warrant expanding the original scope of the project. As the project progressed and additional deposits were located, regional reconnaissance studies were incorporated into the program. Although the outcrop area of the mafic and ultramafic rocks is extensive, the area containing talc and anthophyllite was found to be largely restricted to the original area of study. The area of mafic and ultramafic rock between Dadeville and Dudleyville was mapped in detail. Attempts were made to locate, examine, and delineate all of the previously prospected asbestos deposits and establish the general limits of the talc-bearing rock. Particular attention was given to several deposits that were cur rently being prospected. A geologic rock-type map of the talcanthophyllite area was prepared. ACKNOWLEDGMENTS Many persons contributed to this investigation, and without their assistance many phases of the study would not have been completed. Particularly helpful were W. H. Barnes, Probate Judge, Tallapoosa County; J. C. Pritchard, Road Commissioner, District 3, Tallapoosa County; L. A. Abrams, Mayor, Dadeville; Mrs. Marian Tucker, Dadeville; Claude T. Bartlette, Camp Hill; and Donald G. Ferrell, President, Black Warrior Petroleum Co., Mobile, Ala. 6 T A LC AND ANTH O PH YLLITE A SBESTO S DEPO SITS Acknowledgment is also made to Mr. Fred A. Mett, President, and Mr. Frank Burleson, Mine Foreman, Powhattan Mining Co., for their courtesies and suggestions. Local residents and land owners in the principal area of study were most helpful in supplying back ground data and directions to outcrops. Mr. James F. O'Neill, Supervising Mining Engineer, U.S. Bureau of Mines, visited the area and made helpful suggestions as to how to sample the talc and asbestos outcrops for mineral dressing studies (Neathery and others, 1967). The cooperation and advice of other personnel of the U.S. Bureau of Mines is also appreciated. GEOGRAPHY The Dadeville area is located in east-central Alabama in parts of Tallapoosa and Chambers Counties (fig. 1). The area lies within the Piedmont region of Alabama which coincides with the Opelika Plateau physiographic division of Adams (1926, p. 26) and is equivalent to the Greenville Plateau in Georgia (LaForge and others, 1925, p. 77-80). The Opelika Plateau is considered to be an ancient peneplaned upland surface. Elevations range from 800 to 900 feet above mean sea level with occasional hills rising above the general surface. The Dadeville area is underlain by an alternating sequence of resistant and nonresistant weathered metamorphic rock; the strike and,., dip of this rock influences the topography. Streams generally follow the trend of softer rocks. Near the Tallapoosa River valley the topography becomes irregular. Mostof the land has been under cultivation in previous years. Now, however, most of the land has been given over to pulpwood and dairy farming. Some acreage is still natural forest; it is in these areas that most of the ultramafic rock outcrops are found. The area is readily accessible by numerous State and County roads, both hard surfaced and graded. Numerous logging roads have been constructed into many of the larger timber tracts. Most of the roads can be traveled by car or truck; a few are passable only with 4-wheel drive vehicles. GEOGRAPHY 7 Dadeville, the county seat of Tallapoosa County, is the prin cipal railroad loading and serviceing facility for the area. The Central of Georgia Railroad operates north from Dadeville to Birmingham and connecting railroads, and southeast to Opelika, Ala., and Columbus, Ga. Another branch of the Central of Georgia Railroad passes through the eastern end of the area of Lafayette, county seat of Chambers County. GEOLOGY GENERAL The rocks of the Dadeville area consist of a series of paraschists and paragneisses, all of high metamorphic rank, extrusive and intrusive mafic and ultramafic rock, and plutons of granite and granodiorite. Diabase dikes, tentatively dated as being of Triassic age, cut across the area in Chambers County. Adams (1933, p. 168), in a report on reconnaissance mapping of the Ala bama Piedmont, tentatively designated this series as the Dadeville Belt. The belt extends from southeastern Tallapoosa County, across Chambers County and parts of Lee and Randolph Counties northwestward through Georgia (Crickmay, 1952, p. 6-22). The rocks of the Dadeville Belt are correlative with those of the inner Piedmont Belt of North Carolina (King, 1955, p. 352-356) and South Carolina (Overstreet and Bell, 1965, p. 43-70). Paraschists and paragneisses are the principal rock types underlying the Dadeville area. These rocks vary considerably in bulk composition and include many rock types of the amphibolite facies of regional metamorphism, including: muscovite-biotite gneiss, biotite gneiss, biotite schist, mica schist, quartz-mica schist, quartzite, and garnet-kyanite mica gneiss and schist. The biotite gneiss and schist are folded and contorted and enclose pegmatite veinlets and lenses. The quartzite is usually white to dark gray, and grades from a massive quartzite to a quartz-mica schist. It is usually present as thin layers associated with the muscovite-biotite gneiss and mica schist, although quartzite is not restricted to this group. The garnet-kyanite mica gneiss and schist have been found only on the southeastern side of the Dade ville mafic zone. 8 TA LC AND ANTHOPHYLLITE ASBESTOS DEPOSITS Many observed contacts between the gneiss and schist are gradational. The gneiss grades into mica schist with an increase in the quartz and mica, and possibly a decrease in feldspar con tent. Originally, these rocks may have been sedimentary rocks of eugeosynclinal affinity--graywacke, shale, siltstone, etc. The mafic rocks consist of hornblende schist or gneiss of variable thickness and are interlayered with the more felsic or micaceous rocks. The hornblende gneiss and schist are commonly dark gray, dark green, or black, fine to coarse grained, gneissic, schistose, or massive. The various rock types include garnet bearing and garnet-free hornblende gneiss and schist, diopsidehornblende gneiss and schist, diopside-biotite-hornblende gneiss and schist, diopside-labradorite-hornblende gneiss and schist, hornblende-biotite-oligoclase gneiss and schist, actinolite schist, and chlorite schist. The diopside-labradorite-hornblende-bearing rocks are the most common calcic-magnesian rocks in the Talla poosa County mafic-ultramafic area. Included in the mafic rock series are small masses of hornblende gabbro, pyroxenite, and soapstone. Many of the mafic rocks probably originated either as intrusive or extrusive volcanic flows of intermediate to basic composition. Some may have been impure calcareous sediments interbedded with the original sedimentary material. Within the area of study, three large areas are underlain by granitic rocks of varying textural and structural composition. A granite exposed at Rock Mill, Randolph County, is a medium- to coarse-gr&i'ned gneiss containing porphyritic phases composed essentially of biotite, plagioclase, orthoclase, and quartz, with garnet, zircon, and rutile as accessory minerals. At the Pleasant Grove community, northwestern Chambers County (T. 23 N., R. 25 E.), granitic gneiss crops out over an area of several square miles. The granite is medium to coarse grained and displays banding of the mafic constituents. The granite weathers to retilinear exfoliated blocks which are used locally as building stone. The essential minerals are biotite, orthoclase and plagioclase feldspar, and quartz, with rutile and zircon as acces sory minerals. The third prominent granite area is located in southeastern GEOLOGY 9 Tallapoosa County and parts of Lee and Elmore Counties. A badly weathered biotite granite is exposed throughout several townships. The granite consists of biotite, orthoclase and plagioclase feld spar, and quartz, with apatite, garnet, zircon, and rutile as minor accessory minerals. Gneissic banding of the major constituents is visible near the perimeter of the granite mass. In the Dadeville area a number of pegmatites strike generally N. 30 W., across the regional strike. These pegmatites are for the most part mica-bearing, although several are only quartzfeldspar in composition. They show no evidence of metamorphism, and are interpreted as products of the last period of metamorphism. Several pegmatites, which have been mapped in detail, are com plete entities with no off-shoots or leader veins; most are less than 150 feet in length, although two are known that are more than 300 feet long. The pegmatites are zoned elipsoid-shaped entities with a quartz core, feldspar zone, feldspar-mica zone, and selvage zone. Most of the pegmatites lie south of and adjacent to the eastern mafic and ultramafic zones. Several small thin pegmatites appear to cut across the mafic and ultramafic zones. On the south eastern border of the Dadeville Belt, several scattered pegmatites are known but they are small and may represent large segregations in a granite complex. The Inner Piedmont of Alabama is cut by at least four promi nent diabase dikes, presumably of Triassic age, which strike N. 3-15 W. The largest dike, the Auburn Dike (Adams, 1933, p. 172), extends from south of Auburn, Lee County, to the valley of the Tallapoosa River in northwestern Chambers County. This dike has been traced for approximately 33 miles from near the Upper Cretaceous overlap to the valley of the Tallapoosa River. Its width averages about 50 feet. A second dike, designated the Marcott by Adams (1933, p. 172), lies approximately 3.5 miles east of the Auburn Dike. It has been traced for approximately 26 miles, its width averaging le ss than 20 feet. Two smaller dikes, the Snapper and Danway (Adams, 1933, p. 173), lie east of the Marcott. These are 3 and 6 miles long; they average 8 to 10 feet in width. R. W. Deininger (personal communication, 1965, Memphis State University) states that the 10 TA LC AND ANTHOPHYLLITE ASBESTOS DEPOSITS dikes may be easily traced and that the two largest dikes, Auburn and Marcott, may be dike systems in which several dikes are spaced closely en echelon along strike. STRUCTURE AND METAMORPHISM Except for diabase dikes of T riassic age in the southwestern part of Chambers County and the mica-bearing pegmatites, the rocks of the inner Piedmont of Alabama have been subjected to several successive cycles of deformation and metamorphism. Resulting structural and metamorphic features are complex and only a general outline as related to the ultramafic occurrence is given here. The metamorphic rocks of the Inner Piedmont of Alabama have a northeast regional strike, are moderately folded, and have a well developed foliation that is usually parallel to the compositional layering of the gneiss and schist. Local divergences from regional strike are attributed to minor cross folding, possibly reflecting strike-slip movement along the Brevard zone (fig. 2). Reconnais sance mapping in the Dadeville area indicates that the local struc ture is a synform, possibly complicated on the northwestern flank by isoclinal or overturned asymmetrical folding of high amplitude and short wave length. The synform is bounded on the north and south by thrust faults. Strike and dip measurements show that on the northwestern flank, c|ips are to the southeast, and on the southeast, the dips are to the northwest. The axis of the synform trends northeastward from south of Dadeville, Tallapoosa County, to at least as far as the granite outcrops in Chambers County. The inner Piedmont of Alabama is bounded on the north by the projection of the Brevard zone. This zone is a narrow belt of low-grade metamorphic rocks (Reed and Bryant, 1964), which in cludes phyllonite, phyllonite schist with lenses of blasto-mylonite, etc. The rocks of the Brevard were classified by Adams (1926, p. 36) as altered Wedowee Formation. To the southeast, the Dade ville Belt of the Inner Piedmont is mapped separately from its companion, the Opelika Belt, because of the absence of hornblende gneiss in the Opelika Belt (Adams, 1933, p. 169). Crickmay (1952, p. 6-22), however, did not recognize the Opelika Belt as a separate GEOLOGY T 22 12 TA LC AND ANTHOPHYLLITE ASBESTOS DEPOSITS identity and grouped it with the Dadeville. The present reconnais sance study concurs with Crickmay; no separation of the Dadeville and Opelika Belts appears justified. Comparisons of rock units within the Inner Piedmont do not support separation of the Opelika from the Dadeville. Berquist (1960) described many of the rocks of the Opelika Belt as being intensely shattered. This suggests the possibility that the zone may represent the sole of an over thrust, supporting Clarke's (1952, p. 78-80) hypothesis of tectonic emplacement. Structural interpretations by Clarke (1952, p. 78) on the rela tionships of the three principal faults of the Inner Piedmont, the Brevard, Towaliga, and Goat Rock, suggest that they may be tectonically related. He proposed that all three faults may repre sent a plane of a large overthrust fault upon which is superimposed contemporaneous or later folding. The degree of metamorphism varies considerably within the area. Metamorphic grade increases from northeast to southwest and from northwest to southeast. Outcrops of higher grade meta morphic rocks are scattered throughout the area, representing either residual thermal centers or retrograde resistant areas. Detailed study of the various rock units was not within the scope of the present investigation. Cursory examination of com posite mineral assemblages of the various rock types suggests that the metamorphic grade may be represented by the cordieriteamphibolite facies of Abukuma-type regional metamorphism; for example, products of high temperatures and moderate to low pres sures, or the almandine-amphibolite facies of Barrovian-type regional metamorphism (Winkler, 1965, p. 69-107). PYRGXENITE AND RELATED MAFIC ROCKS The talc and anthophyllite deposits in the Dadeville area are associated with a complex group of calcic-magnesian mafic and ultramafic rocks which range in composition from hornblende gneiss and enstatite-pyroxenite to soapstone. These rocks crop out in two prominent narrow arcuate rock-unit bands which extend from the vicinity of Dudleyville westward to the southwestern part of Tallapoosa County, a distance of approximately 20 miles (fig. 2). PYRO XEN ITE AND R E LA TE D MAFIC ROCKS 13 in the following discussion the term " amphibolite" is used to describe all schistose mafic rocks which are composed essen tially of amphibolite minerals (hornblende, actinolite, tremolite, etc.). Those rocks which are designated as mafic rocks are com posed of 50 percent or more ferromagnesian minerals (hornblende, pyroxene, and olivine). With an increase in the dark mineral con tent the mafic rocks may grade into ultramafic rocks. The pyroxenites are ultramafic rocks composed of heterogeneous aggregates of enstatite, hypersthene, and bronzite. DISTMBUTIQN Amphibolite, mafic and ultramafic rock outcrops are extensive and numerous. Outcrop areas tend to be elongate with regional trends, generally exceeding 6 miles in length and ranging from 100 feet to over 1 mile in width. Exposures are few and outcrop bound aries of the individual zones cannot be mapped accurately. An extensive amphibolite zone has been traced from Georgia into Alabama north of the granite outcrop at Rock Mills, Ala. This zone is cut off before it reaches the town of Roanoke in Randolph County. Between Roanoke and the Pleasant Grove community, Chambers County, only thin bands of hornblende gneiss occur. West of Pleasant Grove an amphibolite-mafic-ultramafic complex crops out and is exposed more or le ss continuously along the regional strike for 15 miles. Near Jacksons Gap, two distinct amphibolite zones, spaced approximately 0.5 mile apart, crop out and extend southward for an additional 5 miles. For the purpose of description, the district is divided into four parts: (1) the area west of Alabama Highway 49 and west of U.S. Highway 280; (2) the area in the vicinity of Red Ridge and Agricola; (3) the area south of the North Fork of Sandy Creek and east of U.S. Highway 280; and (4) the area east of Alabama High way 49 and north of the North Fork of Sandy Creek. (1) West of Alabama Highway 49, amphibolite rock crops out as two large, distinct, and separate rock units. Several small amphibolite outcrops, which have not been delineated, are also present. They are essentially greenstones containing small m asses of meta-ultramafic rock and zones of soapstone. The greenstones 1 4 TA LC AND ANTH O PHYLLITE A SBESTO S DEPOSITS are composed chiefly of green hornblende (possibly edenite), epidote, actinolite, chlorite, and talc. The meta-ultramafic rocks appear as massive aggregates of epidote, diopside, and hornblende. (2) Near Red Ridge west of Agricola, a zone of soapstone crops out. Rocks of hornblende gabbro composition have also been found in this area. (3) In the vicinity of the North Fork of Sandy Creek, north and east of Camp Hill, a major zone of ultramafic rock crops out. Its longitudinal limits are concealed by saprolite and dense vege tation. Most of the ultramafic rock is essentially enstatite with disseminated talc and anthophyllite, although one pyroxenite body does have a high percentage of talc and anthophyllite. Contacts are not visible and continuity between outcrops have not been established. Additional mafic and ultramafic bodies may occur within the area. (4) East of Alabama Highway 49, a prominent zone of mafic and ultramafic rock has been mapped. The two bands of amphibo lite which occur west of Alabama Highway 49 (see item 1) appear to converge into a single irregular mass east of the highway. This mass is a complex assemblage of various mafic and ultramafic rock composed predominantly of pyroxenite-bearing amphibolites, pyroxenite bodies, serpentine zones, and hornblende gneiss. In cluded within this assemblage are scattered occurrences of horn blende, actinolite, chlorite schist, hornblende gabbro, and horn blende diojrite. The talc and anthophyllite deposits are associated with the pyroxenite and pyroxenite-bearing amphibolite rock. In the central part of the zone, near Easton, outcrops suggest over folds. A striking feature of the eastern ultramafic complex is horn blende gneiss enclosing lenticular masses of ultramafic rock (fig. 3). These ultramafic rocks are essentially pyroxenite composed of massive crystalline aggregates of enstatite and hypersthene with olivine and bronzite as occasional accessory minerals. The amphibolite matrix is a prominently banded hornblende gneiss composed of green hornblende, albite-bytownite feldspar, quartz, chlorite, talc, and magnetite. PYRO XEN ITE AND RELA TED MAFIC ROCKS 15 Figure 3.--Pyroxenite inclusions in well banded hornblende gneiss; W. B. Railey property, NE% sec. 15, T. 22 N., R. 23 E. CHAKACTEK Pyroxenite outcrops exhibit distinct and easily distinguished, characteristics unrelated to the enclosing gneiss and schist. The contact between the mafic and ultramafic zone and the surrounding gneiss and schist is usually sharp. Often the pyroxenite masses form prominent knobs and peaks (fig. 4) and near streams may form moderate cliffs or spurs. The pyroxenite is massive and more resistant to weathering than the foliated gneiss and schist and stands above the surface as rounded, solution-pitted, boulderlike masses. The pyroxenite outcrops are barren or have a thin soil zone covered by sparse vegetation. The soil contains abundant small boulders, cobbles, and nodules of greenish-gray to yellowish-green weathered pyroxenite. Such soil is known locally as " buckshot 16 T A L C AND A N TH O PH Y LLIT E A SB EST O S D EP O SIT S Figure 4.--A typical outcrop of pyroxenite; W. B. Railey property, NE% sec. 15, T. 22 N., R. 23 E. so il" (fig. 5). The fragments of weathered pyroxenite often have an ocherpus crust which grades into yellowish-green centers of coarsely crystalline pyroxenite. Some fragments may have a hard oxide shell enclosing talc, with or without anthophyllite. Several outcrops consist of massive boulders displaying thin anthophyllite veins in raised relief against a matrix of pyroxene (fig. 6). OSIGIN The mode of origin, emplacement, and alteration of ultramafic rock and volcanic amphibolite has been of interest to geologists for many years. Considerable controversy has existed regarding the formation and emplacement of ultramafic rock and it was not until the early part of the 1900ss that they were generally accepted as being of igneous origin.Most geologists now consider ultramafic PYRO XEN ITE AND R E LA T E D MAFIC ROCKS 17 Figure 5.--Typical " buckshot" soil derived from the" decomposition of pyroxenite-amphibolite rock. rock to be the result of direct crystallization from primary magmas of their composition. The mechanics of emplacement, however, remain^ conjectural. In recent years experimental work supported by field observation has suggested that certain forms of ultramafic rocks can be produced by metamorphic processes acting upon less basic rocks. Field observations suggest that the mafic and ultramafic rocks of the inner Piedmont of Alabama may be products of one or more of the following modes of origin: (1) metamorphosed equiva lents of lava flows or sills associated with tuffs and volcanic detrital material; (2) ultramafic segregation in a basalt flow; (3) gabbro intrusions with partially crystalline xenoliths of pyroxenite; or (4) an alpine-type peridotite-pyroxenite intrusion associated with earlier deformation. The uniqueness of the Dadeville mafic Figure 6.--Anthophyllite veins crisscrossing the face of a pyroxenite boulder. and ultramafic rocks lies in the areal distribution of the amphibo lites and the unusual relationship of the pyroxenites to the am phibolites. It is difficult to account for all the variations in texture and mineralogy of the ultramafic-mafic rock complex with a single hypothesis of origin. The following section discusses briefly the concepts of origin and mechanism of emplacement for various occurrences of ultramafic rock. The discussion is presented as an aid in understanding the rock relationship within the Dadeville area. Early proponents of igneous origin of the ultramafic rock proposed that the material making up the ultramafic mass was injected as a liquid into the enclosing rock from magmatic cham bers below the outer crust. In 1915, Bowen (p. 79-80) suggested that an ultramafic magma consisting almost entirely of olivine (a peridotite) could not exist in a liquid state below the melting point of olivine (1800 C). The lack of evidence to support emplacement of peridotite at this high temperature led him to conclude that olivine peridotites were PYRO XEN ITE AND R E LA TE D MAFIC ROCKS 19 formed by accumulation of early crystallizing olivine from a com plex magma. He then suggested (Bowen, 1917, p. 237) that if the mass of olivine crystals was subjected to stress forces, the mass could then be intruded into other rocks as a solid or near solid mass with little or no liquid addition. Later, Hess (1938, p. 326-341) postulated that ultramafic magmas of peridotite composition were the result of partial fusion of a peridotite substratum, injected synkinematically into the overlying rock. These magmas would have approximately the com position of serpentine, and the presence of as little as 5 percent water would sufficiently lower the temperature of the mass, facili tating migration and further assimilation. Hess further contended that the water necessary for melting and migration would be taken up by the cooling mass to form serpentine. Hess (1938, p. 329) suggested also that basaltic magmas were products of partial fusion of mafic norite, or equivalent, from a zone above the peridotite substratum. He reasoned that the mafic rock would become more Ca-rich upon rising above the peridotite substratum, producing norite, olivine basalts, gabbros, etc. In comparing serpentine and other ultramafic occurrences, Hess (1938, p. 331) observed that ultramafics intruded at shallow depths into water-bearing sediments suffered a much greater degree of serpentinization than did ultramafics intruded at great depths into relatively anhydrous gneiss. Two processes were postulated for this association: (1) magmatic differentiation of the ultramafic magma, and (2) the acquisition of additional water by the ultra mafic magma from the wall rock. Bowen and Tuttle (1949) studied the ternary system Mg0-Si02HjO at temperatures up to 1000 C, and pressures as great as 40,000 pounds per square inch. The results of their investigation supported Bowen's earlier work and indicated that peridotite magmas could exist only at temperatures well above 1000 C, even if the water content was in excess of 10 percent. Thus they con cluded (Bowen and Tuttle, 1949, p. 455) that the formation of peridotite from a liquid magma intruded at low temperatures was not feasible. Bowen and Tuttle (1949, p. 355-456) postulated, however, that under certain conditions of crustal deformation, 2 2 TA LC AND ANTHOPHYLLITE ASBESTO S DEPOSITS They (Engel and Engel, 1962) concluded that the Adirondack amphibolites are metamorphic in origin and indicative of reduction, dehydration, and incipient basification of a basaltic system at temperatures between 550 C to 625 C and at pressures near those that occur at a minimum depth of 7 miles. Petrographic studies have led some workers to postulate amphibolite origin as the result of basification of magnesium-rich sedimentary rock. Sprenson (1953), reporting on the distribution of ultramafic bands in an amphibolite in west Greenland, considered the association to be a product of metamorphic processes acting upon impure calcareous sediments. He argued that the ultramafic rock could not be considered a magmatic secretion in the amphib olite, nor could the amphibolites be considered as being derived from an original ultramafic rock. He (Sprenson, 1953, p. 33) sug gested that the ultramafic pyroxenite had been formed as a band of ultramafic schlieren in the amphibolite by metamorphic differen tiation combined with metasomatic processes. The ultramafic schlieren were localized along internal zones of potential shear. The kinetic energy required for the creation of the potential shear zone was assumed to have been converted into some other form of energy inasmuch as shearing apparently did not take place. Sprenson (1953, p. 35) concluded that this energy transformation was responsible for the formation of the ultramafic bands, provided that a state of tension was maintained over a sufficient duration to permit equilibration under the imposed physicochemical conditions. Amphibolites of like bulk composition may thus be derived from rocks of diverse parentage by different metamorphic process es. The true origin of most amphibolites, therefore, remains conjectural, largely because there are few, if any, relict textures, minerals, or field relations clearly indicative of the parent rock. Areal relationships of structure and distribution of ultramafic and mafic rock types in the Dadeville area follow closely the described occurrences of Benson (1926, p. 68-76). The association of alpine peridotites with geosynclinal sediments is nearly univer sal. The location of the Brevard fault zone, elongate amphibolite zones on one side of a regional synform structure, and random ultramafic bodies on the other, indicate this mode of origin. The PYROXENITE AND RELA TED MAFIC ROCKS 23 emplacement of the ultramafic bodies is considered to have occur red during the early stages of deformation and the ultramafic rocks may become completely altered to magnesium schist if deformation is severe. However, the wide occurrence of rocks of gabbro com position and the pyroxenite boulders which are seen enclosed within the amphibolite matrix at many localities in the Dadeville area could represent ultramafic differentiates of gabbroic intrusives, preserved or accentuated by polymetamorphism. The rocks of the Inner Piedmont of Alabama are similar to the metamorphic facies of the Abukuma-type series of regional meta morphism. It is assumed that the intercalated volcanics would also be products of high temperature, low pressure metamorphic envi ronment. The experimental work reported by Holmes and Harwood (1932), Bowen (1915-1917), Bowen and Tuttle (1949), and data obtained on the formation boundaries of enstatite-forsterite equi librium, suggest that the ultramafic rocks of the southeastern Piedmont may reflect material of common origin differentiated under different environmental conditions. Most of the associated hornblende gneiss and gabbroic rocks weather rapidly, forming clayey soils. These soils are generally reddish black to greenish black, often containing irregular frag ments of quartz. Some of the more massive hornblende gneiss and metagabbro bodies are resistant to weathering and form blocky outcrops with large fragments scattered throughout the soil cover (fig. 7). The soil derived from these rocks is generally light greenish gray to greenish yellow. ALTERATION PROCESSES The mafic and ultramafic rocks represent a wide variety of distinct but related rock types which have been involved in one or more cycles of regional metamorphism, structural dislocation, and pervasion by emanations mobilized from the country rock. Four processes of alteration are recognized in the Alabama mafic and ultramafic rocks: (1) serpentinization; (2) steatitization; (3) amphibolization; and (4) chloritization. All these processes occurred more or le ss concurrently throughout the mafic-ultramafic belt; however, one mode of altera tion generally predominated over the other three at a given locality 2 4 TA LC AND ANTHOPHYLLITE A SBESTO S DEPOSITS F igure 7 .--Pyroxenite boulders re le a se d by the w eathering of hornblende g n eiss (see a lso figure 3). (fig. 8). The processes of amphibolization and steatitization were most widespread. Serpentinization and chloritization were more localized. SEBPENTIMZATIOM Serpentinization is the process of alteration by which the ferromagnesian minerals, or rocks, are converted to serpentine minerals or serpentinite rock. The process is best illustrated by L ...V M M W W W PYRO XEN ITE AND RELA TED MAFIC ROCKS 25 Figure 8.--Road cut exposure showing shell-like rims of talcose-pyroxenite surrounding decomposed pyroxenite. Thin veinlets of anthophyllite may be seen in the lower center of the cut. the alteration of olivine, a constituent of many mafic and ultramafic rocks. The alteration of olivine to serpentine involves essentially the process of hydration, if the olivine is iron rich, magnetite may form as a secondary product. A typical reaction is: (1) 6 (Mg3Fe)(SiO,,)2 + 12 H20 + 0 2 = 3 M g^C U O H le + 2 F e 30 4 Olivine Serpentine Magnetite Serpentinization begins along the periphery of the olivine grain and progresses toward the center. In many cases the serpen tinization is so complete that only a small remnant or skeleton of the original olivine crystal may be observed under the microscope. Many large olivine bodies contain a core of unaltered olivine sur rounded by a sheath of serpentine olivine. ! r m m w rtT O w rY 'r 2 6 T A LC AND ANTH OPHYLLITE ASBESTO S DEPO SITS The following mechanisms of serpentinization have been postulated: (1) deuteric alteration of peridotites during crystalli zation, by hydrous components of the original magma; (2) direct crystallization of the serpentine from hydrous ultramafic magma; (3) alteration of peridotites by hydrothermal solutions derived from the surrounding country rock during later metamorphism; and (4) serpentinization of the ultramafic rock during tectonic transport, with water supplied from the enclosing rocks. Recent experimental work by Bowen and Tuttle (1949) on the system Mg0-Si02-H20 seems to preclude the acceptance of the first two theories. Serpentinization by tectonic transport is partic ularly advocated by Bowen and Tuttle (1949, p. 454-457). STEATITIZATION Steatitization is the alteration of mafic and ultramafic rocks resulting in the formation of talc. Talc is a comman-to-major con stituent of the Dadeville deposits. It appears to have been derived by the alteration of olivine, pyroxene, and amphibole in the pres ence of water, carbon dioxide, and silica. Chidester (1962, p. 94) concluded from a detailed study of some selected talc-bearing ultramafic rocks in Vermont that " . . . steatitization took place contemporaneously with and at essentially the same temperature as regional metamorphism. " He further suggested that the additive components were derived mainly from adjacent rocks of sedimen tary origin during progressive metamorphism. Field observations and microscopic studies made during the investigation for this report favor this mode of alteration. Steatitization of hornblende rock derived from gabbros pro duced massive, often schistose rocks, referred to as soapstone. Metasomatism of aluminous hornblende usually produces chlorite; however, under certain conditions of temperature and pressure the aluminum is mobilized and removed from the system and talc is formed. (2) 3 Ca2(Mg, Fe)4Al(OH)2(Al, Si70 22) + H20 + 6 0 2 = Hornblende 4 Mg3(Si40,o)(OH)2 + 6 CaO + 12 FeO + 3 A120 3 + 5 S i0 2 PYROXENITE AND R ELA TED MAFIC ROCKS 27 The alteration of olivine to talc involves the addition of water and the loss of iron and magnesium. (3) 4 (Mg, Fe)2SiO< + H20 = Mg3(Si40,,,)(0H)2 + 5 (Mg, Fe)0 Olivine Talc The iron and magnesium may be deposited as magnetite or magne site or removed by solution. Iron is often deposited as limonite. The alteration of enstatite is very common, and involves the addition of water and silica. (4) 3 MgSiOj + H20 + S i0 2 = Mg3(Si4O,0)(OH)2 Enstatite Talc Talc may develop on olivine or enstatite along cleavage cracks or within the mineral grain. The talc growth may develop until the original host mineral is totally replaced. Anthophyllite may also alter to talc, which usually develops parallel to the cleavage of the anthophyllite crystal. At many localities, steatitization has progressed to the stage where the amphibolite, mafic, or ultramafic body is more or le ss a talcose rock, or soapstone. Faint lineations of schistosity are often observed in the replaced rock. Generally, the texture is of randomly oriented and interlocking talc laminae. In some talc occurrences, thin flakes and layers of pure, apple-green talc have been developed along what maybe cleavage planes or shear planes. Several anthophyllite occurrences show talc, anthophyllite, and enstatlfe in apparent equilibrium. AMPBHBOOZATION Amphibolization is the alteration of pyroxenes (enstatite, hypersthene, olivine, etc.) to amphibole minerals (anthophyllite, hornblende, actinolite, tremolite, etc.). Alteration of pyroxene to an amphibole takes place with a decrease in specific gravity and an increase in volume. The reverse is true in the alteration of olivine. The formation of hornblende from augite and basic plagioclase in gabbro or diorite is a common metamorphic alteration process, By the introduction of magnesium and iron, the basic plagioclase may reform to various ferromagnesian silicates, but more commonly 28 T A L C AND A N TH O PH Y LLITE A SBEST O S D EPO SITS to hornblende of the actinolite series. Other silicates often asso ciated with this reconstitution are zoisite, epidote, and chlorite. The alteration of olivine to amphibole in Appalachian amphi boles is commonly observed and reported. The needles of amphi bole penetrate the olivine crystals without regard to boundaries, cleavages, or cracks. The needles are usually straight, oriented in all directions, and may penetrate several individual olivine crystals. Continued formation of amphibole needles leads to the conversion of a pyroxenite orperidotite to an amphibolite composed of a mass of crossed and interlocking amphibole minerals. The amphibole thus formed, especially in the Dadeville area, is the orthorhombic variety, anthophyllite. The monoclinic variety, cummingtonite, which is difficult to distinguish from tremolite and actinolite, has not been identified in Alabama. The alteration of olivine to anthophyllite involves the elimination of a part of the magnesium and iron or an addition of silica. (5) 7 (Mg, Fe)2S i0 4.+ 9 (S i0 2 + 2SH20 = 2 (Mg, Fe)7(Si60 22)(0H)2 Olivine _ Anthophyllite (6) 8 (Mg, Fe)2S i0 ,^ H 2P = (Mg, Fe)7(Si80 22)(0H)2 + 9 FeMgO Olivine Anthophyllite The alteration of olivine to tremolite or actinolite is not as simple; it involves the addition of both silica and lime. (7) 5 (Mg, Fe)2S i0 4 + 11 S i0 2 + 4 CaO + 2 H20 = : Olivine 2 Ca2(Mg, Fe)s(Si80 22)(0H)2 Tremolite The alteration of enstatite to anthophyllite involves the addi tion of silica and water and often the secondary anthophyllite may take the form of the original enstatite grain. This type of alteration evidently results in the formation of the mass-fiber asbestos boul ders often observed scattered in the surface of the amphibolite rock. The amphibole needles may penetrate the enstatite in all (8) 7 MgSi03 + S i0 2 + H20 = Mg7Si80 22(0H)2 Enstatite Anthophyllite directions or they may develop parallel to the long dimension of the enstatite crystal. PYROXENITE AND R ELATED MAFIC ROCKS 29 CH LO ltm ZA TiO N Chloritization of basic igneous rock involves hydration, car bonation, and oxidation; processes characteristic of dynamic metamorphism. The formation of chlorite from augite or hornblende requires only the addition of water and a reconstitution of the components. Chlorite formed from olivine or enstatite requires the addition of aluminum and water, and the loss of magnesium and iron. The formation of chlorite from enstatite involves the lo ss of silica. Chloritization of rocks of hornblende composition, such as gabbros, requires the addition of water and the separation of lime, iron, and silica. The following reaction represents a possible alteration: (9) 5 Ca2(Mg, Fe)4Al(0H)j(Al, Si70 ,, ) + 7 0 S + 11 H20 = Hornblende 4 Mgs Al(OH)8AlSi3O,0 + 23 S i0 2 + 10 CaO + 20 FeO + A120 3 Chlorite (typical) The reaction favors the formation of chlorite rather than talc be cause of the presence of the more immobile aluminum ion and the absence of sufficient magnesium. If the composition of the original rock was typical of gabbro, the basic plagioclase may also alter to chlorite. The resulting rock derived from a gabbro may assume the texture of the original material or if stress was a catalytic parameter, the resulting chloritic rock may assume a schistose structure. The alteration of olivine to chlorite requires the addition of alumina and water. A typical chemical reaction is represented by equation 10: (10) 3 (Mg, Fe)2S i0 4 + A120 , + 4 H20 = Olivine Alumina (Mg, F e)sAl(OH)BA1Si 30 ,0 * (Mg, Fe)0 Chlorite 30 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS The alteration of enstatite to chlorite is similar: (11) 5 (Mg, Fe)SiO, A120 3 + 4 H20 = Enstatite Alumina (Mg, F e)s Al(OH)sAlSi30,o + 2 S i0 2 Chlorite The chlorite generally develops as flakes or laminae enclosing the olivine or enstatite grain, and as narrow veinlets penetrating the grains in all directions. The alteration of olivine often pro duces magnitite which is disseminated in the chlorite mass. PHYSICOCHEMICAL CONDITIONS OF ALTERATION The physicochemical conditions involved in the formation and alteration of the talc and anthophyllite are discussed in the follow ing pages. This discussion should aid in understanding the occur rence of talc and anthophyllite in the ultramafic rocks. The physicochemical relationships of enstatite, talc, antho phyllite, and various other members of the ternary system MgOSi0j-H20 (fig. 9), have been studied by Bowen and Tuttle (1949), Figure 9.--Compositional diagram showing several phases in the system M g0-Si02-H20 . PHYSICOCHEM ICAL CONDITIONS O F ALTERATIO N 31 Yoder (1952), Roy and Roy (1955), Fyfe (1962), Greenwood (1963), and Kitahara and others (1966). The binary system Mg0-Si02 was studied by Bowen and Anderson (1914). Based on the results of a series of experiments performed at temperatures up to 1,000 C and pressures up to 40,000 psi (pounds per square inch), Bowen and Tuttle (1949, p. 447) constructed a series of pressure-temperature curves for univariant equilibrium between four phases of the system Mg0-Si02-H20. These curves define the boundaries of divariant regions where three of the vari ous phases are in equilibrium. A significant part of Bowen and Tuttle's studies (1949) dealt with the interrelations of the phases talc, anthophyllite, and enstatite. Stable phase relationships of anthophyllite with other members of the Mg0-Si02-H20 system could not be determined in the presence of excess water; however, Bowen and Tuttle reported that small amounts of anthophyllite were obtained together with the other equilibrated phases under a wide variety of conditions. A hydration-dehydration sequence illustrating the basic relation ship of talc-anthophyllite-enstatite is given below': (12) 7 MgSi03 + S i0 2 + H20 = Mg7Si80 22(0H)2 Enstatite Anthophyllite and (13) 3 Mg7Si80 22(0H)2 + 4 S i0 2 + 4 H20 = 7 Mg3Si40 7(0H)2 ' : Anthophyllite Talc Bowen and Tuttle (1949) were able to produce anthophyllite in the presence of water vapor only as a metastable phase by heating talc at 800 C at 15,000 psi for an hour; continued heating pro duced enstatite and silica. They concluded that anthophyllite formed only a transient phase in the presence of water vapor in the alteration of enstatite to talc. Talc was found to form readily below 800 C at water pres sures between 6,000 and 30,000 psi. At temperatures above 800 C talc appeared as a metastable product with forsterite (magnesium olivine) and enstatite. Below 800 C in water deficient systems where talc is a stable product, anthophyllite occurred but was found to be always partially altered to talc. 3 2 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS Bowen and Tuttle (1949, p. 450) concluded that anthophyllite will develop as an intermediate phase in the formation of talc from anhydrous material. They surmised that a stable field of existence for anthophyllite could be found under the physicochemical param eters bounded by the field to the left of curve I (fig. 10). Above curve II, enstatite, talc, and water vapor are in equilibrium with each other. Anthophyllite cannot exist as a stable phase in this region since it is a simple binary compound between enstatite and talc. Anthophyllite might exist, however, as a stable phase imme diately above curve I for its region of divariant stability would then be bounded by the univariant curve II. Curve II would repre sent the binary equilibrium enstatite + talc = anthophyllite Bowen and Tuttle (1949) speculated that anthophyllite would form under conditions where total composition of the rock mass and the parameters of the induced components was such that there would be sufficient water to convert the mineral assemblage to talc and (or) serpentine. A stable equilibrium between anthophyllite and serpentine is not possible because of the more hydrous character of the serpentine. Yoder (1952) and Roy and Roy (1955) also concluded that anthophyllite was a stable phase of the system Mg0-Si02-H20 only in water deficient regions. Yoder (1952, p. 599) concluded, on the basis of experimental data, that the upper limit of talc stability , ' enstatite + quartz + vapor = talc lies near an invariant point at 795 C. He also determined that the equilibrium reaction talc + forsterite = enstatite + vapor takes place at approximately 660 C at 15,000 psi. Above 660 C enstatite is stable in the presence of excess water. Yoder (1952, p. 612) surmised that anthophyllite would remain stable at temper atures below 660 C in water deficient systems. Fyfe (1962), in a study of the relative stability of talc, antho phyllite, and enstatite, experimentally showed that anthophyllite was not a transient phase but that the reactions involving the formation and dehydration of anthophyllite were " sluggish." He experimented over a limited range of conditions between 670 C at PHYSICOCHEMICAL CONDITIONS OF ALTERATION 33 C U R V E I - Maximum limit of existence of serpentine in systems con taining excess H 20 (Bowen and Tuttle, 1949) C U R V E II - Maximum limit of anthophyllite stability in systems having a deficiency in H,0. (Inferred from Bowen and Tuttle, 1949) C U R V E III - Maximum limit of existence of talc in systems containing excess H20. Also, lower limit of region of stability of anthophyllite under conditions of excess H20 (Greenwood, 1963) C U R V E IV - Maximum limit of stability of anthophyllite in systems con taining excess H 20 (Greenwood, 1963) Figure 10.--Pressure-temperature curves of univariant equilibrium for several phases in the system Mg0-Si02-H20. 3 4 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS 2,000 bars 1 pressure and found it possible to convert talc to anthophyllite + quartz in the presence of water and enstatite + quartz to anthophyllite in the presence of water. Complete conversion of talc to anthophyllite and enstatite to anthophyllite was achieved at temperatures near 760 C in the presence of excess water. Enstatite and quartz heated to 775 5 C at 2,000 bars pressure yielded only a small amount of anthophyllite. Enstatite and quartz heated to 755 5 C at 2,000 bars pressure formed only antho phyllite. Greenwood (1963) experimentally determined the stability limit of anthophyllite at low water pressures and concluded that the curve for the reaction talc + enstatite = anthophyllite should pass through 727 C at 22.5 kilobars 2 water pressure with a slope of 12.5 bars per degree. He further showed that the re actions forsterite + talc = 5 enstatite + H20; and enstatite + quartz + H20 = talc were transient reactions up to nearly 30 kilobars pressure and 900 C. The stable reactions were 4 forsterite + 9 talc = 5 anthophyllite + 4 H20 ; and 7 enstatite + quartz + H20 = anthophyllite at approximately 690 C at 10 kilobars pressure. Kitahara and others (1966) studied the phase relations of the system Mg0-Si02-H20 at high temperatures and pressures and agreed generally with the results of Greenwood (1963). They found that the reaction forsterite + talc = anthophyllite was a transient phase to temperatures of approximately 730 C before enstatite appeared. They further supported conclusions of Bowen and Tuttle (1949) that primary serpentine magmas cannot exist at low temperatures and high water pressures. The results ' 1 bar equals approximately 14.5 lb s/in 2; 2,000 bars equal approximately 29,000 lb s/in 2. 2 1 kilobar equals 1,000 bars. PHYSICOCHEMICAL CONDITIONS OF ALTERATION 35 of their work showed that the water pressure could be increased to at least 30 kilobars without the formation of serpentine liquid. The preceding experimental data indicated that the relation ship between talc-anthophyllite and talc-anthophyllite-enstatite (pyroxene) is dependent upon the nature of the hydrothermal com ponents. It has been shown that in order to maintain equilibrium between talc and anthophyllite, the hydrothermal emanations must be low temperature and water deficient, or high temperature with excess water. In addition, the hydrothermal alterations must begin at sufficiently high temperatures to produce talc-anthophylliteenstatite instead of talc-enstatite. Based on the above discussion the significant parameter of metamorphic alteration is considered to have been water deficient environment. Field evidence indicates that the ultramafic bodies in theDadeville area have a mineral zonation typical of that shown in figure 11. A thin discontinuous zone of serpentine (zone I) forms the periphery of the ultramafic body. Stable mineral phases existing in zone I are shown in figure 11. Zone I may grade gradually or sharply into zone II, which is composed primarily of talc, talcoseanthophyllite, talcose-enstatite, and enstatite. Veins of antho phyllite are common in zone II and vary in width from microveinlets to as much as 18 inches. Stable phases which are common to zone II are shown in figure 11. Zone II grades gradually into zone III, the central core. In some of the ultramafic bodies the central core appears to be missing or is represented by an abundance of ensta tite crystals having incipient talc and anthophyllite alteration. Anthophyllite veins are common in zone III, but they are usually le ss than 2 inches in width. The stable mineral phases indicative of zone III are shown in figure 11. The ultramafic mass is commonly surrounded or enclosed by a hornblende gneiss, gabbro, or diorite, although biotite gneiss has been recovered from core samples. The existence of a low water vapor parameter is supported by the configuration of the mineral zones, their mineral composition, and a scarcity of serpentine. The gradual transition from a hydrous border zone assemblage to a relatively anhydrous internal mineral assemblage indicates one of two basic variations in the metamor phic history of these deposits. Replacement of the enstatite by E X P L A N A T IO N CO ON TA LC AND ANTHOPHYLLITE ASBESTO S DEPOSITS NOTE: T - TALC A - A N T H O P H Y LLIT E E - ENSTAT1TE S - SER P E N T IN E F - F O R ST E R IT E B - B R U C IT E Figure 11.--Principal zones of a typical talc-anthophyllite-bearing ultramafic body, and diagrams of stable mineral phases in the principal zones. (Modified from Bowen and Tuttle, 1949, p. 447.) PHYSICOCHEMICAL CONDITIONS OF ALTERATION 37 anthophyllite indicates either high temperature metamorphism under conditions of sufficient water vapor or low temperature metamorphism under conditions of insufficient water. Replacement of anthophyllite by talc indicates either a decrease in temperature while the equilibrium pressure of the H20 remained equal to the total pressure, or that of the activity of H20 increased while the temperature remained constant. A combination of both conditions would produce the same resultant effect. The amount of anthophyllite present in a given mineral a s semblage must vary inversely with the amount of serpentine be cause of the equilibrium conditions (fig. 10). A water deficient system would restrict the formation of the more hydrous phases such as serpentine and tend to redistribute the available water to form more partial hydrated minerals such as talc or anthophyllite. The lack of serpentine in the Dadeville area suggests that the excess water was not available to hydrate the ultramafic m asses. The incipient alteration observed in the interior part of the ultramafic bodies reflects the decrease in the amount of water vapor permeating to the central part of the mass. The influence of internal stress forces has not been consid ered. It is assumed that under the influence of high internal stress, the parameters of alteration would be affected, resulting in a low ering of the kinetic energy necessary to activate alteration pro cesses, in ..summation, it is postulated that the last metamorphic parameters affecting the ultramafic bodies were most probably low temperature (500 to 550 C), low pressure (less than 2,000 bars), with a deficiency in the available water. The divariant field lying between curve 1 and II in figure 10 would reflect the most probable general compositional variation in the ultramafic assemblage in the Dadeville area. 38 T A L C AND A N TH O P H Y LLIT E A SB EST O S D EPO SITS ASBESTOS MINERALOGY Asbestos is a commercial term applied to a family of fibrous minerals that are resistant to heat and acid. The fibrous nature of some of the asbestos minerals allows them to be woven into fabric. Chrysotile asbestos, a variety of serpentine, is the most important commercial variety of asbestos and constitutes about 95 percent of the total world's asbestos production. Two divisions of the asbestos family are recognized: chrysotile asbestos and amphibole asbestos. Chrysotile asbestos has been reported at several localities in the Dadeville area, but the presence of this mineral could not be confirmed. Amphibole asbestos includes the fibrous varieties of anthophyllite, actinolite, tremolite, crocidolite, and amosite. These minerals vary in chemical and physical properties. Anthophyllite is the principal mineral in the Dadeville area. Small amounts of nonfibrous tremolite and actinolite occur with the anthophyllite and mafic and ultramafic rocks. CHRYSOTILE ASBESTOS Chrysotile asbestos is a fibrous form of the mineral serpen tine, a hydrous magnesium silicate, Mg3(Si20 5)(0H)4. It has fine, silky, flexible fibers that range in color from light green to shades of brown. Often trace quantities of iron, nickel, manganese, or aluminum may substitute for the magnesium and modify the physi cal properties. Chrysotile generally occurs as cross-fiber veins ranging in width from a fraction of an inch to over 6 inches. Most of the commercially valuable deposits occur as crosscutting dis continuous veins in massive serpentine bodies, which have been derived by the alteration of peridotites, Chrysotile may also occur in thin alteration zones in dolomite or dolomitic limestone which has been intruded by basic igneous rock. Approximately half of the world's annual production of chrys otile comes from a relatively small district in the province of Quebec, Canada. This district contains numerous rich chrysotile deposits associated with a northeastward-trending belt of serpen tine peridotite bodies. A small amount of high-grade chrysotile has been produced in Arizona from dolomitic limestone which has ASBESTOS 39 been altered by diabase igneous intrusion (Stewart, 1955, p. 5-12). AMPHIBOLE ASBESTOS The amphibole asbestiform minerals are a series of complex silicates characterized by perfect prismatic cleavage. Tremolite, actinolite, crocidolite, amosite, and anthophyllite are the only amphibole minerals which occur in asbestiform masses. All the asbestiform amphiboles contain iron, and, with the exception of crocidolite, magnesium. Anthophyllite is distinguished from tremolite and actinolite by the absence of calcium. Crocido lite is distinguished from the other amphibole minerals by the presence of sodium, and amosite is distinguished by its high iron content (up to 40 percent). Actinolite and tremolite form a contin uous Fe-Mg molecular substitution series, with tremolite contain ing little or no iron. The replacement of one element by another is a common characteristic in amphibole asbestos minerals. This substitution of elements and the resulting change in the physical properties of the amphibole asbestos produces erratic and unpredictable physi cal characteristics in some deposits. TEEMOLITE-ACTSNOL1TE Tremolite and actinolite are commonly associated with the ultramafic rocks in the Dadeville area. These amphibole minerals often oodur in asbestiform. They form a continuous Fe-Mg molecu lar substitution series; tremolite, Ca2Mg5(Si80 22)(0H)2, being the low iron (less than 2 percent) or iron free member, and actinolite, Ca2(Mg, F e)5(Si80 22)(0H)2, being the iron-bearing member. Large crystals of each have been found along the periphery of the ultramafic-mafic rock complex in the Dadeville area. These minerals may appear white or grayish green to green, and occur in slender prismatic crystals often arranged in a radial pattern. Tremolite fibers are generally coarser and weaker than chrysotile, but fibers of exceptional strength and flexibility occur. Tremolite asbestos most commonly occurs as slip-fiber veins in shear zones, it has been found in metamorphosed dolomite and dolomitic limestone, but more often in metaultramafic rocks. 4 0 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS Actinolite asbestos is commonly green to grayish green, it is of poor quality and has limited use in industry because the fibers are weak and brittle. Actinolite asbestos is commonly found in slip-fiber veins in metaultramafic rocks of the southeastern Pied mont as alteration products of pyroxene minerals, it has been tentatively identified from several samples collected in the Dadeville area; however, it does not occur in significant amounts to be considered a potential asbestos mineral. ANTHOPHYLLITE Anthophyllite asbestos, (Mg, Fe)7Si80 2*(0H)a, is the fibrous form of the orthorhombic amphibole, anthophyllite. It is greenish gray to gray in fresh unweathered specimens, but weathers to a characteristic clove brown. The fibers are generally short, slightly flexible, and have a low tensile strength, unsuited for spinning purposes. Members of the anthophyllite series have been shown to be three component minerals of limited substitution involving chiefly magnesium, iron, and aluminum; calcium, sodium, and potassium may also occur in small amounts (Rabbitt, 1948). Chemical analy se s of three samples of anthophyllite taken from various prospects in the Dadeville area are given in table 1. The identification of anthophyllite, especially the asbestiform varieties, is dependent on X ray. An electron micrograph (fig. 12) shows the fibrous characteristics of anthophyllite from the Dade ville area. The sample was treated with a dilute solution of sulfu ric acid prior to electron analysis to remove any surface contami nation. Anthophyllite asbestos occurs in magnesium-rich mediumgrade metamorphic rock. Commercial deposits of anthophyllite asbestos occur as mass-fiber aggregates associated with altered mafic and ultramafic rock and in lesser quantities of cross-fiber and slip-fiber veins. CROSS-FIBER VEINS Cross-fiber anthophyllite occurs in veins, with the fibers arranged parallel to each other and perpendicular to the walls of the vein. The veins may vary from a fraction of an inch up to 12 ASBESTOS 41 Table 1.--Chem ical a n a ly se s of anthophyllite sam p les, Dadeville, Alabama (in percent) Assay 1 Assay 2 Magnesian oxide, MgO Iron oxide, FeO Silica, Si02 Calcium oxide, CaO Sodium and potassium oxide, Na20 + K20 Alumina, A120 3 Loss on ignition, L.O.I. 31.12 10.58 54.22 .26 .87 .19 1.89 34.09 11.31 48.73 N.D. .93 .34 N.D. N.D . - Not determ ined. A s s a y s 1 and 2 by L . B . Adam s C o., Birm ingham , A la. A s s a y 3 by B la c k Warrior P etroleum C o ., M obile, A la. Assay 3 26.16 10.75 57.84 .72 .43 1.21 2.89 to 14 inches in width, but average 1 to 4 inches. They cut through the enclosing rock in all directions, often intersecting one another at various angles. Vein length is erratic, extending from several inches to several tens of feet with many cross-fiber veins fading into mass-fiber anthophyllite bodies (fig. 13). Many cross-fiber veins are composed of practically pure anthophyllite with lesser quantities of talc, quartz, and enstatite. In the more altered ultramafic rocks, talc is commonly associated with the anthophyllite and often has almost completely replaced the anthophyllite. Contacts between the vein material and the enclosing rock are usually quite sharp. Veins stand out in both saprolite material and in partially decomposed pyroxenite. Often the wall rock mate rial is removed by weathering leaving the anthophyllite veins in positive relief (fig. 6). The cross-fiber material probably represents products of early hydrothermal solutions reacting on the wall surfaces of tension fractures produced by dislocation forces accompanying metamor phism. Many of the cross-fiber veins fade into mass-fiber asbestos, suggesting that the processes of hydrothermal alteration continued after cessation of early dislocation. Figure 12.--Electron micrograph of randomly oriented anthophyllite fibers, magnification 4,400. (Photograph by U.S. Bureau of Mines, 1965.) ASBESTOS 43 Figure 13.--Specimen of mass-fiber anthophyllite containing small veins of cross-fiber anthophyllite. SLIP-FIBE R VEINS When the asbestos fibers are arranged parallel to the enclos ing wall rock, it is designated slip-fiber asbestos. There are all gradations in orientation of fiber arrangement between cross-fiber and slip-fiber veins. Generally, it is interpreted that slip-fiber asbestos is derived from cross-fiber by movement of the wall rock with respect to the vein material. Except for the orientation of the fibers, slip-fiber anthophyllite is similar to cross-fiber in charac ter and chemical composition. Slip-fiber veins are not as common as cross-fiber veins. In the Dadeville area most of the slip-fiber anthophyllite is short, rarely exceeding 2 inches in length, and generally averaging le ss than an inch. 4 4 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS MASS-FIBER DEPOSITS Mass-fiber asbestos differs from cross-and slip-fiber asbestos in that it forms the body of the rock mass. Much of the mass-fiber anthophyllite is very coarsely crystalline, composed of interlock ing bundles of fibers. Other mass-fiber anthophyllite is less coarsely crystalline and often the fibers are arranged in a distinct radial form around a central core of anthophyllite-enstatite. Two types of mass-fiber anthophyllite asbestos have been recognized in the Dadeville area: (1) peripheral zone anthophyllite; and (2), massive individual bodies composed almost entirely of anthophyl lite. A peripheral zone of schistose rock is characteristic of many of the ultramafic rocks; the well developed zone of mass-fiber anthophyllite is much le ss common. Where present, the zone of mass-fiber anthophyllite lies adjacent to the ultramafic rock mass and is separated from the country rock by a thin layer of schistose talc and vermiculite. The peripheral zone of asbestos is generally uniform in width, although the zone may vary rapidly in width along the strike or with depth. The peripheral zone mass-fiber asbestos ranges in color from grayish white to various shades of mottled buff and light brown. Anthophyllite, which lies on or nearthe surface, is usually stained by iron oxide and is often quite soft. The unweathered asbestos is more compact, but the fibers can be easily separated. The peripheral zpiie of mass-fiber asbestos is usually composed of 75 to 85 percent anthophyllite and 15 to 25 percent talc. Trace amounts of chlorite, magnesium oxide, and magnetite are often present. Altered ultramafic rock may occur as irregular masses com posed predominantly of varying percentages of anthophyllite, talc, and enstatite. The enstatite usually occurs as large, bladed, interlocking crystals oriented in all directions in respect to each other. In some outcrops 50 percent or more of the rock is composed of partially altered enstatite. Generally, the enstatite has under gone extensive alteration, and consists chiefly of anthophyllite with lesser amounts of talc and traces of chlorite. It is the com pletely altered enstatite pyroxenite rock that contains the greatest ASBESTOS 45 percentage of anthophyllite. The degree of alteration of the enstatite varies considerably within each rock and from one rock to another. Significant interpretation cannot be placed upon the variation in alteration or completeness of alteration in one rock and the adjacent rock. The most common form of anthophyllite in the massive asbes tos is that in which the anthophyllite fiber has developed parallel to the long direction of the enstatite crystal and is pseudomorphic after the original crystalline structure of the rock. Thus, the antho phyllite fiber occurs as wide flat interlocking bundles having diverse orientation. Fresh unweathered anthophyllite is bluish gray to greenish gray, massive, and hard. In unweathered expo sures, the fibrous character of mass-fiber anthophyllite is not readily apparent; however, if crushed the fibrous character is observed. A le ss common form not readily observed in Alabama is the variety of mass-fiber anthophyllite in which the fibers occur as a mass of interlocking cones. Conrad and others (1963, p. 19) de scribed a typical occurrence .. the fibers radiate from a common center and vary from a lA inch up to about 1 inch in length. In some cases, the apex of an individual cone is as much as % inch higher than the perimeter, and in others the cones are almost flat. Individual well shaped cones are not common because of mutual interference during development, but the tendency toward radial and cqqe structure is quite evident . . . " Massive anthophyllite varies from light bluish or greenish gray to mottled buff to grayish yellow. It is massive, compact, and tough. The individual fibers are generally short; the individual bundles splintering on impact. Talc is the most common accessory mineral, often occurring as apple-green flakes between the antho phyllite bundles and as interstitial filling material around and between the radial cones. A pseudobanding of talc and anthophyl lite was observed in several rock specimens found in the vicinity of Oziah Church. (See section " Description of Properties," Clem Vines property, north area.) 46 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS QCCUBRENCE OF ANTHOPHYLLITE The alteration of pyroxene to anthophyllite is a common process in rocks composed of olivine and (or) enstatite. Thin sections prepared from the Dadeville pyroxenite-anthophyllite rock show slender needles of anthophyllite scattered throughout the groundmass of pyroxene. The anthophyllite needles are usually straight, show no preferred orientation, and often may penetrate several pyroxene grains. Anthophyllite forming from enstatite often takes the crystal form of the enstatite crystal with needles lying parallel to the major axes of the enstatite crystal. As alteration increases and the ratio of anthophyllite to pyroxene becomes greater, large areas of the rock may be composed of crossed and interlocking anthophyllite crystals enclosing small remnant pyrox ene grains. Cross- and slip-fiber anthophyllite veins are products of secondary mineralization. Rarely do they show any evidence of having been derived from the wall rock as is so often shown by the mass-fiber varieties. Many theories have been proposed and discarded in an effort to explain the origin, character, and relation of vein asbestos. The theory most generally accepted today and the one which appears to be most applicable to the Dadeville area is aptly illus trated by Cooke (1936, p. 362) and summarized by Paige (1937, p. 109): " In my opinion, all important phenomena of asbestos veins, . . . ace explainable on the hypothesis that gradual opening of fissures in response to tensional strain was accompanied by contemporaneous deposition of asbestos." In explaining his hypothesis Paige cited the following: (a) The gradual opening of the vein was an adjustment to tensional strain carried out beyond the elastic limit of the peridotite mass. (b) If the expansion was induced by hydration of the rock mass (serpentinization), the increase would have been taken up in the increased volume of the affected block. (c) The relatively constant ratio of width to wall rock altera tion to width of vein would be a natural accompanying process. ASBESTOS 47 (d) The narrow width veins meet the requirement for a gradual widespread structural adjustment throughout the area. (e) The attitude of the crystal fiber to the walls would reflect differential movement of the walls during formation. (f) Where no asbestos veins exist, the absence could reflect the absence of suitable host openings during permeations. The fact that anthophyllite is present in various forms in rocks which range from peridotite to soapstone in composition and occur in a similar manner throughout the entire length of the Appa lachian peridotite belt, indicates a probable metamorphic deriva tion. The development of fibrous asbestiform anthophyllite has been considered to be partly related to physical phenomena direct ly related to weathering. The softest and most fibrous anthophyl lite in the Dadeville area occurs generally near the weathered surface of the deposit, and, with increasing depth, the anthophyl lite fiber is harder, more brittle, and less easily worked. Chalcedony quartz occurs with surface and near surface fibrous anthophyllite as boxwork, irregular nodules, and massive fragments (fig. 14). Such secondary quartz may be a product of Figure 14.--Fragment of chalcedony boxwork. 48 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS leaching from the anthophyllite. it is common practice to allow anthophyllite ore, especially mass-fiber varieties, to remain in a stockpile exposed to the weather for a year or more prior to milling, TALC MINERALOGY Talc is an inclusive term used to describe': (1) the pure min eral in the form of aggregates of flakes or fibers; (2) steatite, the compact cryptocrystalline variety; and (3) soapstone, a soft impure talcose rock (Wells, 1965). The mineral talc, Mg3Si<0,o(OH)j, is a hydrous magnesium silicate. The theoretical formula corresponds to 63.5 percent S i0 2, 31.7 percent MgO, and 4.8 percent H20 . Experimental work has shown that these components may vary within wide limits--the magnesium to silica ratio ranges from 1.1 to 4.3 and the water content ranges from 3 to 7 percent (Spence, 1940). Most talc (Chidester, 1962, p. 48) contains small amounts of F e+i (gener ally about 0.x percent) and lesser amounts of A1 (generally about O.Ox percent). The F e +2 substitutes directly for the Mg+I, whereas the Al+S may substitute for both the Mg+1 and S i*4. A few other elements may occur in trace amounts. CHARACTER AND CLASSIFICATION Three varieties of talc or talc rock are recognized, based on the purity ofltie talc-bearing rock. In the Dadeville area all vari eties may be observed but soapstone is the most common. TALC Talc commonly occurs as a foliated or micaceous mineral which can be easily scratched with a fingernail. It has a greasy feel, pearly luster, and when pure, ranges in color from light green to white. The color is dependent on the processes by which it has been formed and the nature of the original magnesium rock. Talc derived from dolomite rock is generally pure white to cream col ored, whereas talc derived from magnesium and ferromagnesian silicate minerals is commonly pale greenish gray. Talc pseudomorphs after diopside, enstatite, and tremolite are often buff to TALC 49 brown, depending upon the iron content of the original mineral and the degree of iron oxidation. On weathering, talc becomes white and lusterless. Thin light-green leaves of talc are often observed dispersed throughout anthophyllite masses. The leaves are generally orien ted parallel to the long axis of the asbestos fiber and may repre sent alteration of the asbestos to talc. STEATITE Steatite is a massive compact cryptocrystalline variety of talc which has no visible grain and is usually pale cream to off white in color. It is most often a metasomatic alteration product of carbonate rock, such as dolomite. Some steatite, however, may be produced by hydrothermal alteration of low iron magnesium rocks and pyroxene (diopside and enstatite), amphibole, and often mica. SOAPSTONE Soapstone is generally defined as massive talc mixed with varying proportions of chlorite, amphibole, pyroxene, and mica, as well as lesser amounts of quartz, carbonate minerals, and sulfide minerals. Soapstone is frequently found as bands or lenses either bordering or enclosed in bodies of altered ultramafic rock, such as peridotites and pyroxenites, or mafic rocks, such as a gabbro, whiph have been transformed wholly or in part into soapstone. In such occurrences, the formation of talc constitutes a high degree of alteration of the original rock. If the alteration has proceeded to the point where 75 to 95 percent of the rock is composed of talc, this material is often designated talc instead of soapstone. OCCURRENCE Talc is a secondary mineral, usually formed by hydrothermal alteration of original magnesium-rich carbonate or silicate rocks or minerals, such as dolomite, pyroxene, amphibole, or chlorite. Pseudomorphs of talc after a variety of minerals are known, partic ularly in zones of intense metamorphism. Transient phases are Jr*.-W . r r m w r m w , w 5 0 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS common and the paragenetic sequence is often difficult to deciph ;r. The formation of talc on a major scale is considered to take place under one or more of the following conditions: (1) Intense dynamic metamorphism, where the magnesian host rock has been subjected to severe deformation together with ac companying differential changes in heat and pressure. (2) Contact metamorphism, where the magnesian-rich host rock has been intruded by igneous rock. (3) Hydrothermal alteration contemporaneous with regional metamorphism where the magnesian host rock has been subjected to pervasive emanations mobilized from the adjacent country rock. Where the host rock is an ultramafic ferromagnesian rock, as found in the Dadeville area, the first stage in the alteration se quence from the pyroxenite, peridotite, or serpentine is usually to a chlorite, which in turn alters to talc. If the'alteration is only partially complete, the soft talcose-chlorite rock, soapstone, is formed. However, if the conditions of alteration lie above the stability limits of the chlorite mineral, intermediate compounds and minerals may form instead. In the Dadeville area, talc is observed as a secondary alteration product after anthophyllite rather than chlorite. Talc occurs as solid massive blocks and as irregular shell like bodies in, the saprolite overlying the mafic and ultramafic rock. These Bodies are known to exist in the saprolite cover to depths of at least 30 feet. Material exposed in road cuts shows a characteristic oblate to circular peripheral shell of talc similar to that observed around mass-fiber anthophyllite, and identical in shape to the outline of the ultramafic inclusions in the hornblende gneiss (fig. 3). It is probable that the talc rings represent an alteration product from the anthophyllite, which in turn formed from the pyroxene minerals of the ultramafic component. Many of the talc boulders have solid centers. Residual accumulations in sev eral areas completely cover the ground surface with talc boulders and cobbles (fig. 15). The most abundant form of talc appears to be the soapstone variety. Zones of soapstone and several large bodies of soapstone Figure 15.--Surface accumulation of talc along access road on the Clem Vines property, north area. are found in the Dadeville area. Bands of soapstone occur as lenses or irregular shaped bodies in and along the margins of the ultramafic and mafic rock, and often grade into these rocks. Large massive bodies of soapstone occur along the strike of the Dade ville ultramafic belt. They average 2 miles in length and half a mile in width. The limits of these original bodies are poorly de fined and may grade into partially altered gabbroic rock. DESCRIPTION OF PROPERTIES Many occurrences of talc and anthophyllite have been noted in the Dadeville area. This report describes all the deposits and occurrences that were investigated by the Geological Survey of Alabama (fig. 16). Included with the following descriptions (Neathery and others, 1967) are eight deposits that were jointly investi- T. 22 N. TA LC AND ANTHOPHYLLITE ASBESTOS DEPOSITS ct.on 11. Clem V in e s Property 12. C larence Ware Property 13. Pethis H arris Property 14. C a m p H ill Road Properties 15. E ste s Property 16. C oosa R ive r New s Print Property 17. Jennings-Satterw hlto Property | | | | | | T o lc and antho phyltite area Inferred talc deposits Figure 16.--Index map of talc and anthophyllite properties in the Dadeville area. DESCRIPTION OF PROPERTIES 53 gated by the U.S. Bureau of Mines and the Geological Survey (fig, 17). None of the deposits have been mined commercially. In 19t>3-66, more than 175 tons of anthophyllite material were taken from two of the properties for sampling and testing purposes. Talc has not been produced from the area, although research sam ples have been collected from many localities. To obtain information on the quantity and quality of the talc and anthophyllite material, the Survey excavated six prospect trenches on five significant properties distributed along the strike of the talc-anthophyllite zone. The trench sites were chosen on the basis of exposures or outcrops of talc or anthophyllite and earlier favorable prospecting sites. The trench sites were first cleaned or denuded of any forest or field cover. The soil and saprolite clay was either scraped off or excavated until the remnant structure of the pyroxenite-amphibolite could be seen in the walls or floor of the trench. At three locations the depth of weathering was extremely variable and only a partial removal of the overburden could be made using a bull dozer. At these locations auger holes were used to supplement the information obtained by trenching methods. Representative samples were obtained from the cleared trench sites by the use of a small gasoline-powered trenching machine. This machine cut a ditch approximately 8 inches wide to a depth of between 16 and 18 inches (fig. 18). Material excavated from the ditch yfes passed through a sample splitter with 4-inch splitter slots until approximately 800 pounds of material remained (fig. 19). This material was stored in airtight and watertight drums and delivered to the U.S. Bureau of Mines, Tuscaloosa Metallurgy Research Center, for testing (Neathery and others, 1967). Trench logs were recorded for each trench excavated. These logs accompany the description of the prospect on which the ex ploration was performed. Table 9 is a summary of the trenching activity. T A LC AND ANTHOPHYLLITE ASBESTOS DEPOSITS Figure 17.--index map of talc and anthophyllite deposits investigated by the Geological Survey of Alabama and the U.S. Bureau of Mines. (From Neathery and others, 1967.) DESCRIPTION OF PROPERTIES 55 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS Figure 19.--Sample material being quartered prior to final recovery DESCRIPTION OF PROPERTIES 57 P E E E Y WISE-SANBE8 S F E O P SB T Y The Perry Wise-Sanders property (No. 1, fig. 16) is 4 miles north of Dadeville, in parts of secs. 15 and 16, T. 22 N., R. 23 E. (fig. 20). This prospect includes the Perry Wise and Sanders prop erties and those adjacent to them, and represents the westernmost part of the Dadeville mafic-ultramafic belt. The mafic and ultramafic rocks occur as isolated outcrops of amphibolite, serpentinite, and pyroxenite. Serpentinite is exposed in three shallow trenches approximately 700 yards northeast of the Wise house and in a road cut in front of the Sanders house. Pyroxenite float is scattered over the land surface, especially in the wooded areas, on and surrounding the Wise property. The rock is an interlocking aggregate of enstatite crystals with minor amounts of hypersthene. Both of these minerals show alteration to talc and commonly to anthophyllite. Near the mafic rock boundaries the talcose material becomes hard and has a texture similar to the enstatite rock or radial massfiber anthophyllite. Veins of talcose-anthophyllite, Ve to 1 inch wide, crisscross the face of several of the pyroxenite outcrops. Thick zones of chlorite and vermiculite suggest internal shearing within the ultramafic mass. Hard anthophyllite, talcose-anthophyl lite, talcose-enstatite, and massive talc boulders are scattered over much of the surface. This land has been under cultivation for many years and much of the larger float material has been removed. The: largest exposures of talc are visible in the road cuts along the section-line road east of the Sanders house. Peripheral shell like structures of talc ranging from lA to 10 inches in thickness and up to 3 feet in diameter are distributed through the saprolite for approximately 400 feet along the road right-of-way (fig. 21). In 1953, the Red Hawk Mining Co., in an effort to develop an anthophyllite deposit, excavated three large trenches on the Perry Wise property and two on the adjacent Scroggins property. Two trenches across the road from the Perry Wise house are reported to have uncovered considerable talc, probably similar to that visible along the section-line road. The remaining three trenches exposed serpentinite and enstatite rock containing small veins of anthophyllite and talcose-anthophyllite. T 22 N 58 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS Figure 20.--Sketch map of Perry Wise-Sanders and adjoining properties. (From Neathery and others, 1967) DESCRIPTION OF PROPERTIES 59 Figure 21.--Road cut in the NE% sec. 21, T. 22 N., R. 23 E. showing peripheral shell talc boulders in saprolite. The talc zone exposed along the road right-of-way east of the Sanders house (fig. 22) was bulk sampled by the Survey (table 2). A narrow trench 16 inches deep was cut parallel to the road on the shoulder after removal of superficial material. Talc, talcoseanthophyllite and several small veins of anthophyllite were cut. Two thin small quartz mica pegmatites were cut, one at the east ern end of the trench and one at the western edge. 60 T A L C AND A N TH O PH Y LLITE A SB EST O S D EPO SITS Figure 22.--Typical sampling trench cut by the Geological Survey of Alabama on the Perry Wise-Scroggins properties. Humps in trench are massive talc boul ders later removed by pick and axe. DESCRIPTION OF PROPERTIES 61 T ab le 2 .--Trench log, P etty W ise-Sanders properties L o catio n : Perry W ise-Sanders properties, in road cut on north sid e of road in the SE% se c . 16, T. 22 N., R. 23 E . Top 6 inches of road b ase removed. Azimuth, 270. Sample: Beginning at e a st end of trench, 8 inches wide x 16 inches deep x 340 feet long. Interval (in feet) Description 0-3 3-12 12-30 30-212 212-225 225-229 229-239 239-242 242-251 251-255 255-259 259-267 267-283 283-28f 285-340 Yellowish-tan clay saprolite. Yellowish-buff saprolite. Reddish-gray to maroon saprolite. Buff-tan saprolite with hard greenish-gray ta lc boulders at 34, 37, 41, 48, 54, 59, 72, 76, 81, and 84 feet; at 95 feet, hard green talc; hard greenish-gray talc boulders at 100, 112, 121, 133-140, 145, 176, 184, and 200-212 feet; scattered anthophyllite fibers between 125-212 feet. Pink-tan saprolite with occasion al talc boulders. Hard gray-white talc. Brown saprolite. Hard, partly altered talc o se hornblendite, tremolite cry stals. Orange-brown to pink saprolite, few talc boulders. Hard gray-white talc. B lack hornblende, talco se , limonite crusts. Brownish-tan to pink saprolite with occasion al talc boulders, mostly feldspar pegmatite. Yellow-tan saprolite, talc saprolite with thin stringers of pegma tite; at 280 feet, large talc boulders. P egm atite, in je cted betw een ta lc se a m s; strik e N. 33 W., dip 33 N E; not sampled. Brown to tan saprolite and so il; not sam pled. 6 2 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS W. B . B A IL E Y P B O P E B T Y The Railey property (No. 2, fig. 16) is in the N%NEM sec. 15, T. 21 N., R. 23 E., about half a mile northeast of the Perry Wise property (fig. 23). The soil zone has been removed by bull dozer stripping from a number of acres of previously cultivated land, and subsequent erosion has exposed the underlying bedrock at many localities. The bedrock is a well banded hornblende-gneiss-amphibolite, which encloses irregularly shaped and random sized inclusions of ultramafic rock (fig. 3). Occasional fragments of hornblende gabbro and hornblende diorite are found scattered over the extreme east ern part of the property. The soil is a typical example of " buckshot" soil. It contains numerous pyroxenite fragments and has a buff-green to yellow-green color. The pyroxenite fragments range from V8 inch to 24 inches in diameter and comprise over 50 percent of the upper level of the exposed saprolite zone. In 1953, the Red Hawk Mining Co. cut two large trenches, one normal to the strike and one parallel to the strike of the ultramafic belt. The trench nearest the Railey house cut through several thin veins of anthophyllite and scattered masses of apple-green talc. Mr. Railey reported that during the sinking of a well adjacent to the house, a thick zone of material which resembled anthophyllite was penetrated at a depth of approximately 100 feet. During this investigation, one small trench was cut approxi mately normal to the strike in a field 250 feet south of the Railey house. The material exposed consisted of saprolite, chlorite, vermiculite, thin-vein anthophyllite, apple-green talc, and alluvium (table 3). 22 N F igure 23.--Sketch map of W. B. R ailey property. (From Neathery and others, 1967) DESCRIPTION OF PROPERTIES o\ CO / a * / w a i 'A ,w w ry?*' 64 T A L C AND A N TH O PH Y LLITE A SB EST O S D EPO SITS T a b le 3 .-T re n ch log, W. B . R a ile y property Location: W. B. Railey property; trench 300 feet long and 2 to 4 feet deep cut using bulldozer. Azimuth, 165. Sample: Beginning at north end of trench, 8 inches wide x 16 inches deep x 270 feet long. Interval (in feet) Description 0-29 29-33 33-42 42-68 68-110 110-132 132-150 150-175 175-192 192-200 200-270 Reddish-brown saprolite; at 0 feet, talc boulders; at 9 feet, talc boulders; at 10 feet, dark weathered hornblendite fragm ents; at 25 feet, talc boulders. Large talc boulders, dark-gray-green talc, greasy, some iron stain inclusions. Reddish-brown saprolite, occasion al talc boulders. Greenish-black to green-brown sap rolite, occasion al talc frag ments at 47, 52, and 56 feet. Green-brown saprolite, occasion al fragments of hard hornblendite; a t 77 feet, firm to hard rock with thin se am s of ta lc ; at 90 feet, talc o se hornblendite cobbles; at 96 feet, hard hornblendite; at 100-105 feet, hard rock; at 106 feet, seam of talc 1 foot thick. Buff- to grayish-tan saprolite, talc cobbles, iron-manganese nodules in top 3 inches of cut. Buff-tan saprolite, very talcose, no boulders; at 139-143 feet, zone of silver-gray vermiculite mixed with chlorite. Buff-tan to whitish-tan talc and anthophyllite, soft to hard; hard boulders at 155 to 160-164 feet. Gray saprolite; fragments of talc, anthophyllite, actinolite-schist, hornblendite, quartz, mica, and chlorite. Reddish-brown top so il saprolite, few fragments of talc. ,,Reddish-brown alluvium containing ta lc and anthophyllite frag ments, nodules of weathered pyroxenite, and hornblende gn eiss. f r k 1-------------- -- ~ -- ............................... ........ ........ DESCRIPTION OF PROPERTIES 65 SORRELL ESTATE PROPERTY The Sorrell Estate property (No. 3, fig. 16) is on a large tract of timberland in parts of secs. 1 and 12, T. 22 N., R. 24 E., in the vicinity of Easton (fig. 24). Numerous outcrops of mafic and ultramafic rock occur through out the property. Mafic rock types include hornblende gabbro, hornblende gneiss, and hornblende diorite. Actinolite schist was found as surface rock at several places. The ultramafic rock is a pyroxenite composed of stubby interlocking crystals of enstatite and hypersthene with traces of bronzite. Black magnesium-oxide stains are common along cleavage faces. Altered material retains the crystalline structure of the pyroxenite, but includes talc and anthophyllite as transformation products. Corundum crystals were found on this property during the latter part of the 19th century. Talc, talcose-anthophyllite, and talcose-pyroxenite occur mostly as surface material and a talcose mass-fiber anthophyllite was found in an outcrop. Along the Germany Ferry Road, beginning at its junction with Tallapoosa County Road 44 and extending northeasterly for approximately 1,000 yards, massive peripheral shell-like talc bodies, chalcedony boxwork, anthophyllite veinlets, and hornblende gneiss with ultramafic inclusions are exposed along the right-of-way. The rocks are weathered to variable depths and display continuous alteration from amphibolite-pyroxenite to talc-anthophyllite. 4 20-foot shaft on the west side of the road, approximately 300 yards from the road junction, exposed spheroidal boulders of talc and talcose enstatite throughout its depth. A large pit is located approximately 550 yards north of the shaft. There is massfiber anthophyllite and talcose mass-fiber anthophyllite on the dump. The original depth of this pit is unknown. Several other prospect trenches are in the area south of the pit; each has ma terial similar to that found in the large pit. A narrow trench, approximately 650 feet in length, was cut along the Germany Ferry Road right-of-way, beginning at the junc tion of the Germany Ferry Road and County Road 44. The trenchcut materia] is shown in the trench log (table 4). T A LC AND ANTH O PHYLLITE A SBESTO S DEPOSITS Figure 24.--Sketch map of Sorrell Estate and adjoining properties. (From Neathery and others, 1967) DESCRIPTION OF PROPERTIES 67 T ab le 4 _Trench log, Sorrell E s ta te property Location: Sorrell Estate property, Germany Ferry Road right-of-way; trench cut 1200 feet long and 1 foot deep using bulldozer. Azimuth, 65 at 0-815 feet, 56 at 815-900 feet, 50 at 900-1000 feet, and 45 at 1000-1100 feet. Sample: Beginning at southwest end of trench, 8 inches wide x 16 inches deep x 650 feet long. Interval (in feet) D escription 0-8 8-220 220-231 231-383 383-420 420-432 432-452 452-479 479-483 483-650 650-716 716-815 815-900 900-1140 Large talc boulders, hard, fractured, filled with clay seam s, partly altered pyroxenite fragments. Tan saprolite containing boulders and cobbles of talc of variab le s i z e s , very firm, some hard zon es; large ta lc boulders at 42-52, 57, 97, 118, and 139 feet. Dark-brown saprolite, iron-manganese rich nodules. Tan saprolite, talc boulders increasing in number and s iz e ; at 276 feet, large hard talc boulders; hard talc at 322-324, 334-338, and 378-383 feet. Soil and talc , saprolite, so il, black loam saprolite, with boulders of talc. Tan to reddish-tan saprolite, abundant talc blebs, cobbles, and boulders. B lack loam, little saprolite, large cobbles and boulders of hard talc. Red-brown to gray saprolite, some talc, high-iron nodules; hard silic a g o ssan at 450, 455, and 461 feet. Green to silver-gray talc zone, chlorite, vermiculite, talc, tremolite, boulders of silic a gossan and limonite. Red-tan saprolite, talco se , few blebs of talc, talc cobbles, and silic a gossan ; hard talc boulders at 508, 512, 521-526, 531-533, 550-553, 569-571, and 650 feet. B lack loam overlying talc and talc saprolite exposed in lower 4 in ch es of trench; scattered boulders of hard white ta lc ; not sam pled . Reddish-tan talcose, saprolite; talc boulders at 747, 767, 803, and 856 feet; not sampled. Reddish-tan saprolite; talc boulders at 837, 845-851, and 855861 feet; at 874 feet, anthophyllite seam ; not sam pled. Reddish-brown saprolite, talc cobbles, some anthophyllite at 974 feet, high iron, very clayey; not sam pled. 68 T A LC AND ANTHOPHYLLITE A SBESTO S DEPOSITS FARGARSON PROPERTY The Fargarson property (No. 4, fig. 16) is in the SE% sec. 6, T. 22 N., R. 24 E., approximately half a mile north of the Sorrell Estate property on the Germany Ferry Road. Pyroxenite, amphibolite, and hornblende gabbro occur as surface float material and in isolated outcrops. Pyroxenite crops out to form low bluffs along the banks of a small stream which p asses through the property. Vegetation and soil cover conceal the rock-type boundaries. The residual soil type is the typical ` 'buckshot" variety found throughout the district. On the Germany Ferry Road, north of the old Fargarson house, a road cut exposed talcose pyroxenite and chloritic amphibolite. Irregular shaped lenses of talcose-chloritic amphibolite are encased in zones of green-black chlorite and thin sheaths of talc. Physically, the lenses are similar to those observed in the area of the Perry WiseSanders property. Cross-fiber and mass-fiber anthophyllite, talcose-anthophyllite, and chalcedonic anthophyllite are found as surface material in the wooded area in the eastern part of the property. In a road cut on the Germany Ferry Road just south of the old Fargarson house, cross-fiber anthophyllite, talcose-pyroxenite, and chalced ony boxwork occurs scattered throughout dark-red saprolite. Evidence of former prospecting was not found during a cursory examination qf the property. KNIGHT PROPERTY The Knight property (No. 5, fig. 16) is in the N%NW% sec. 5; N'ANE'A and SEKNEK sec. 5, T. 22 N., R. 24 E. (fig. 25). A large body of pyroxenite crops out 100 yards northeast of the Knight house. It is an ellipsoidal-shaped exposure, approxi mately 1,000 feet long, the major axis of which trends east-west. The pyroxenite body is composed chiefly of large interlocking crystals of enstatite and hypersthene with minor olivine. Incipient talc alteration along crystal boundaries can be observed in thin sections. To the south, amphibolite, hornblende gneiss, and horn blende gabbro are present as scattered surface rock. A large area is littered with quartz fragments and may represent the location of L Figure 25.--Sketch map of Knight-Walker properties, DESCRIPTION O F PROPERTIES ON VO r 70 T A L C AND A N TH O PH YLLITE A SB E ST O S D EPO SITS a quartz body. The boundary limits between the mafic and ultramafic rocks and surrounding gneiss are obscured by dense under growth but changes in soil color and the presence of the surface rock tend to follow the contacts. Talc and talcose anthophyllite are exposed as surface accu mulations in the stream southwest of the Knight house and in the fields to the west of the stream. Several thin veins of soapstone crop out in the roadbed near the northern boundary of the property. Major prospecting has not been done on the property. WALKER PROPERTY The Walker property (No. 6, fig. 16) is in the SWAX sec. 33, T. 23 N., R. 24 E. The principal prospects are located on a narrow northeastward-trending ridge, approximately 650 yards N. 22 E. from the Knight house. These workings can be reached only by foot (fig. 25). From the pyroxenite outcrop on the Knight property, northward to the creek, ultramafic rock occurs as surface material. Beyond the creek, a narrow ridge rises to the northeast. The rock exposed along the crest of the ridge is predominantly a pyroxenite but scattered boulders of serpentinite are present. Hornblende gneiss and hornblende gabbro occur as surface rock material on the east ern part of the property. A series of shallow prospect pits and trenches have been excavated along the crest of the ridge for a distance of approxi mately 550 yirds. Material exposed in the dumps consists of minor amounts of green flaky talc, talcose-anthophyllite, and talcosepyroxenite. On the southwest nose of the ridge, a large prospect trench, cut in the form of a " T " , exposes talcose-pyroxenite, pyroxenite, and serpentinite. Just north of the fence line between the Knight and Walker properties several smaller prospect pits have been excavated along the northern face of the hill. Dump material is a talcose pyroxenite similar to that found on the Knight property. The date of the prospecting work is uncertain, it is reported that most of the work was done during 1939-40. It was also reported that the excavations were done searching for corundum and chro mite. No recent work has been done. DESCRIPTION OF PROPERTIES 71 PBATSEE PROPERTY The Prather property (No. 7, fig. 16) is in the SE% sec. 4, T. 22 N., R. 23 E., north of Tallapoosa County Road 44 (fig. 26). Pyroxenite and amphibolite constitute the country rock over most of this property. Biotite gneiss crops out along the southern part of the property, and scattered masses of hornblende-diorite occur north of the property. The pyroxenite is a mixture of enstatite and hypersthene, showing incipient talc alteration along many crystal faces. Some pyroxenite material may be bronzite. Small talcose pyroxenite cobbles and quartz fragments occur as surface material over much of the cultivated area. Anthophyllite-bearing zones are indicated in the pyroxeniteamphibolite zones by sharp changes in soil color. The soil derived from the amphibolite is usually gray to greenish gray, whereas the soil derived from the pyroxenite and anthophyllite is yellow to ocher in color. At a tenant house in the NE%SE% sec. 4, an exca vation for a storm cellar uncovered a thick vein of cross-fiber anthophyllite in one of the lighter-colored soil areas. Talc, soap stone, and talcose-chalcedonic anthophyllite occur scattered as surface accumulations through the cotton field (fig. 27). Several corundum crystals have been found on the property. In 1963, the American Talc Co. explored parts of the property. Twelve drill holes were completed to an average depth of 65 feet. Three bot tomed in talc and the remainder penetrated the mafic-ultramafic rock complex and bottomed in a biotite gneiss or diorite. A typical ,core log-is given in table 5. 72 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS Figure 26.--Sketch map of Prather and adjoining properties (From Neathery and others, 1967) HOOTEN im m m iw i DESCRIPTION OF PRO PERTIES 73 Figure 27.--Surface accumulation of talc and anthophyllite in cotton field on the Prather property. r 7 4 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS T a b le 5 .--T y p ical core log, Prather property Depth (iri feet) Interval Core recovered Description O.Q to 5.0 5.0 to 11.6 11.6 to 18.8 18.8 to 25.5 25.5 to 35.7 35.7 to 37.9 37.9 to 45.7 45.7 to 60.4 60.4 to 65.8 65.8 to 75.5 5.0 No core Overburden. 6.6 2.0 Gray soft saprolite, granitic texture; top contact dip 80; sc h ist plan es dip 40. .5 Brown mud (core ground up). .4 T alc fragments, light-gray (original th ick n ess unknown). .4 Gray granitic saprolite. 7.2 .9 Gray granitic saprolite. 1.5 Gray granitic rock altered to talc. 1.1 T alc, light-gray. 6.7 1.6 T alc. 10.2 .4 T alc, containing mica fragments. .1 M ica-sch ist sap ro lite, dip 30. 1.7 T alc. 1.0 M ica-schist saprolite. .7 Fragm ents, m ica-schist and ta lc . 1 ;7 T a lc. 2.2 2.2 T alc. 7.8 .3 M ica-schist and talc fragments. 1.0 T alc vein, dip 30. .6 M ica-schist saprolite. .7 T alc, soft. .2 M ica-schist saprolite. .3 T alc. .2 Mica sc h ist. .7 T alc. 7 14.7 No core Unknown. 5.4 .2 Weathered mica sch ist. 5.2 Biotite sch ist to gn eiss, hard; dip at top of unweathered gn eiss, 35. 9.7 9.3 Banded biotite gn eiss, dip 35. Bottom of hole 75.5 feet DESCRIPTION OF PROPERTIES 75 GLEMA SMITH PROPERTY The Clema Smith property (No. 8, fig. 16) is in the NW%SW% sec. 3, T. 22 N., R. 24 E., adjacent to the Prather property (fig. 26). Pyroxenite float and hornblende gneiss are scattered over much of the property. Fragments of soapstone, talc, and talcoseanthophyllite were found as surface float in a small cotton field. Prospecting has not been done on the property but its location relative to the Prather property suggests that material similar to that found on the Prather property should occur on this property. GARFIELD HEARD PROPERTY The Garfield Heard property (No. 9, fig. 16) is in the EKSWJ4 sec. 2, and in the NE%NWM sec. 10, T. 22 N., R. 24 E., south of Tallapoosa County Road 44, approximately half a mile west of Oziah Church (fig. 28). The mafic-ultramafic rock forms an irregular outcrop pattern, the limits of which are difficult to map because of the saprolite cover. The rock type is predominantly pyroxenite with minor oc currences of actinolite-hornblende amphibolite, irregular zones of chlorite and vermiculite cut the mafic rock body. Two small north westward-trending quartz-mica pegmatites have been located adja cent to the mafic body, but evidence is not available to indicate whether they cut the mafic rock complex. The anthophyllite occurs as veins, in widths up to 14 inches and as mass-fiber bodies. Cross-fiber veins are exposed in the ditches along the timber road near the Heard house. Talc and talcose enstatite boulders were found along the southern and southwestern limits of the mafic body. The anthophyllite occurrence is irregular and varied. Pockets ranging in weight from 1 ton to over 8 tons have been extracted. Veins vary widely in width and often terminate abruptly at a small nonmineralized cross joint. The anthophyllite is buff tan to cream color, but individual fibers are generally light cream to white when separated from the mass. Small flakes of chlorite and talc have developed parallel to some of the anthophyllite fibers and often constitute more than 50 percent of the rock. wi-wwiif.V'rtrrtvjwy 76 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS Figure 28.--Sketch map of Garfield Heard property. (From Neathery and others, 1967) DESCRIPTION OF PROPERTIES 77 Prior to 1964, several individuals, including Mr. Heard, opened small prospect pits at several places on the property. In 1965, the Powhattan Mining Co. prospected the property and it is reported that approximately 100 tons of anthophyllite were shipped to their Baltimore processing plant. Most of the excavations were refilled by contract agreement after termination of prospecting activities and little evidence remains to indicate the subsurface conditions. GEOSGE SIMS PROPERTY The George Sims property (No. 10, fig. 16) is in the NW%SW% sec. 2, T. 22 N., R. 24 E., between the Garfield Heard and the Clem Vines properties, south of Tallapoosa County Road 44 (fig. 29). Pyroxenite and some actinolite-hornblende schist crop out on a small hill south of the road, adjacent to the east boundary of the Heard property. The pyroxenite is a composite mixture of inter locking crystals of enstatite and hypersthene with talc and antho phyllite alteration rims. Thin veinlets of cross-fiber anthophyllite, Ve to \ inch wide, crisscross the surface of many of the outcrop boulders. The boulders are often composed of talcose mass-fiber anthophyllite which may have a chalcedonic zone or rim. The soil is the characteristic " buckshot" type, containing pyroxenite nodules and irregular fragments of talc. Several large boulders of talc were found embedded in the saprolite. Prospecting work has been limited to a small pit located 100 yards sputh of the road, adjacent to an old field. Fragments of cross-fiber anthophyllite are found on the dumps as residual mate rial. Tallapoosa Mining Co, opened this pit during exploration activities on adjacent properties. South of the pit, scattered frag ments of talc and hard talcose anthophyllite occur as surface float. Several large boulders of black hornblende gneiss were found on the field-rock dump. 7 8 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS F igu re 2 9 .--Sketch map of Clem Vines and adjoin ing p roperties. (From Neathery and others, 1967) DESCRIPTION OF PRO PERTIES 79 CLEM VINES PSOPEETY The Clem Vines property (No. 11, fig. 16) is in the E AX sec. 2, T. 22 N., R. 24 E,, north and south of Tallapoosa County Road 44 (fig. 29). For purposes of description the property has been divided into the north and south areas. CLEM VINES PROPERTY, NORTH AREA The north area (No. 11A, fig. 16) is accessible by a well graded timber road which leaves the county road directly across from Oziah Church. Approximately 300 yards north of the church, the timber road junctions; the left fork veers to the northwest and the right fork continues north for a short distance and then turns east. Both roads cross a small stream about 150 yards north of their junction. This stream exposes black to green-black amphib olite along much of its course and represents the northern boundary of the mafic-ultramafic complex in this area. North of the stream, mica schist, biotite gneiss, and quartz bodies crop out and sepa rate this mafic-ultramafic area from another about 0.5 mile to the north. To the west of the timber road, on a parcel of land belonging to the Sorrell Estate, a large mass of altered pyroxeniteis exposed. The material grades from talcose pyroxenite to talcose-chalcedonic mass-fiber anthophyllite. Talcose pyroxenite also occurs in a few scattered outcrops and surface float. In the vicinity of the timber road junction, surface accumula tions of' talc and talcose anthophyllite are common (fig. 15). Nu merous boulders, cobbles, and fragments of peripheral shell talc are found along the stream course south of the black amphibolite zone. A 300-foot north-south oriented trench excavated during this investigation exposed massive boulders and peripheral shell-like bodies of talc embedded in the saprolite (table 6). For completeness in sampling and to avoid the necessity of excavating the entire trench to fresh rock material, three 4-inch diameter auger holes were drilled into the floor of the trench on 100-foot centers. Each hole bottomed at a depth of 15 feet in fresh unweathered talcose material. Two of the holes contain cross-fiber anthophyllite in the auger cuttings, A smaller prospect pit had been opened earlier near the northern end of the large trench, it 80 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS T a b le 6 . --Trench log, Clem Vines property, north area Location: Clem Vines property, north area; trench cut 300 feet long and 4 feet deep using bulldozer. Azimuth, 340. Sample: Beginning at south end of trench, 8 inches wide x 1 foot deep x 267 feet long. Interval (in feet) D escription General 0-30 30-40 40-79 79-96 96-109 109-111 111-123 123-145 145-156 156-169 169-179 179-186 186-199 199-209 209-226 226-257 257-267 Reddish-tan saprolite with abundant boulders of talc. Reddish-tan sap rolite with many talc boulders. White to gray-white ta lc ; 1.1 foot of c la y at 53 fee t; thin seam of anthophyllite. Reddish-tan saprolite with many ta lc boulders. White to gray-white ta lc , som e stain in g, little c la y , t a lc m assiv e, hard. Reddish-tan saprolite with occasion al talc boulders. T alc boulder zone; talc, white to gray-white, hard, m assive. Reddish-tan saprolite with talc boulders. T alc zone, gray to gray-white talc, seam of reddish-tan saprolite, talc stained, gritty, hard. Reddish-tan saprolite, talcose. T alc zone, numerous zon es of m assive talc interspersed with thin seam s of reddish-tan saprolite; talc, hard, gritty, white to gray-white to greenish-white. Reddish-tan saprolite, talc boulders. T alc boulders, m assive hard talc, gray to gray-greenish-white; 1.5 foot seam of saprolite. Reddish-tan saprolite, few sm all talc pebbles. T alc zone, m assive talc boulder, hard, white to gray-greenishwhite, some grit; reddish-tan saprolite seam , some iron staining. Reddish-tan saprolite, few cobbles and pebbles of white to graywhite talc, iron stained. T alc zone, white to greenish-white, hard, m assive, some grit, iron stain in g erratic; reddish-brown saprolite seam s. Reddish-brown saprolite, high percentage of talc o se cobbles and pebbles. DESCRIPTION OF PROPERTIES 81 was excavated by the Tallapoosa Mining Co. during their pros pecting activities in 1964. Some cross-fiber material was obtained. The pit site is now covered by material removed from the larger trench. CLEM VINES PROPERTY, SOUTH AREA The south area (No. 11B, fig. 16) is accessible by a field service road, beginning immediately behind Oziah Church. Included with the south area are the road cut exposures along Tallapoosa County Road 44. An outcrop of pyroxenite is exposed on a small hill approxi mately 125 yards southeast of the church, it is composed of large stubby interlocking crystals of enstatite and hypersthene which have been altered to talc and mass-fiber anthophyllite. The pyrox enite body grades southward into more highly altered material. Throughout the area the soil is of the " buckshot" variety and often contains large boulders of pyroxenite. In a road cut on Tallapoosa County Road 44 (100 to 200 yards east of the church), cross-fiber anthophyllite, talc, and chalcedony boxwork may be seen in the deep-red saprolite. The anthophyllite veins are badly weathered and stained. The asbestos fiber is soft and ranges from 4 to 6 inches in length. A pyroxenite intrusion is suggested by the presence of a discordant zone of weathered biotite gneiss separating two zones of weathered mafic rock. Above^the road cut in the adjoining woods, pyroxenite and gneiss are found as float material. Boundaries between the two rock types are covered by vegetation and soil. A small pit, approximately 100 yards southeast of the church and adjacent to the field service road, was opened by the Talla poosa Mining Co. in 1963. A small quantity of anthophyllite was recovered prior to its being backfilled. Short cross-fiber anthophyl lite remains scattered about the rim, a residual product from the leaching of the excavated material. A cemetery adjacent to the churchyard and immediately north of the pit described above, is situated on several large pockets of mass-fiber anthophyllite. Many of the grave sites were excavated in the mass-fiber and cross-fiber anthophyllite, which was dumped along the southern fence line. 8 4 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS T ab le 7 .--Trench log, Clem Vines property, south area Location: Clem Vines property, south area; trench 325 feet long and 6 to 10 feet deep cut using bulldozer. Azimuth, 160. Sample: Beginning at south end of trench, 8 inches wide x 18 inches deep x 296 feet long. Interval (in feet) Description General 0-32 32-74 74-220 220-235 235-255 255-258 258-296 Reddish-brown sap rolite with stringers of anthophyllite; talc boulders; vermiculite zones; and partially altered pyroxenite. Reddish-brown saprolite, talc cobbles; 6- to 8-inch wide antho phyllite vein at 23 feet. Gray to buff-tan altered pyroxenite; abundant vermiculite; gray to gray-green talc cobbles and boulders; thin veins of anthophyb lite; reddish-brown saprolite seam s and iron stain s. Reddish-brown saprolite containing boulders of gray talc; vein and sh ells of anthophyllite; few seam s of vermiculite and chlorite at 153 feet. M assive anthophyllite vein with clay seam s. Fiber, buff-tan to reddish-brown; som e 2% to 3 inches long, m ost short, c r o s s fiber, little m ass-fiber. Reddish-brown saprolite with random anthophyllite b leb s and sm all veinlets. Thick vein of cross-fiber anthophyllite, buff-tan, 4 to 6 inches long. Reddish-brown saprolite; thin veinlets of short cross-fiber anthophyllite, little talc, some vermiculite and chlorite. DESCRIPTION OF PROPERTIES 85 CLARENCE WARE PROPERTY The Clarence Ware property (No, 12, fig. 16) is in the NEMSWM and part of the SE^SW^ sec. 1, T. 22 N., R. 24 E., east of the Clem Vines property and west of the Pettus Harris property (fig. 31). The property is accessible by a number of logging and field roads. Ultramafic and mafic rocks occur in badly weathered and altered pyroxenite and amphibolite outcrops and some altered pyroxenite and amphibolite occur as occasional scattered surface float. The soil is green to greenish black and contains abundant small nodular concretions of pyroxenite. The pyroxenite is essentially a composite mixture of inter locking bundles of short stubby enstatite crystals with incipient talc alteration. Anthophyllite and chalcedonic-anthophyllite occur in cross-fiber veins and mass-fiber bodies. Soapstone is common; it is found in outcrop and as surface accumulations, particularly in the fields adjacent to the Ware house. Prospecting has not been attempted on the property. PETTUS HARRIS PROPERTY The Pettus Harris property (No. 13, fig. 16) is in the SW^NE^ sec. 1, T. 22 N., R. 24 E., approximately half a mile north of the Dudleyville community (fig. 31). Outcrops of mafic and ultramafic rock are,scarce and few were found during a cursory examination of the property. Some amphibolite and pyroxenite were found as occasional surface material along the western property boundary. Mica schist and quartz occur as float and in rock dumps in the eastern part of the property. Faint shadows and coarse textured zones in the saprolite on a wall of a 10-foot deep trench suggest that the country rock is a hornblende gneiss (with pyroxenite in clusions) similar to that seen on the Railey property and the Sor rell estate. Well-banded gneiss and schist are exposed in the floor of a large trench. Talcose and chalcedonic mass-fiber anthophyl lite and talcose-pyroxenite occur as surface material in the area of exploration activity. Chalcedony boxwork fragments occur also as surface material in the immediate area of the prospect. Exploration consists of two trenches; one cut by the Talla poosa Mining Co. parallel to the regional strike of the country 8 8 TA LC AND ANTH O PH YLLITE A SBESTO S DEPO SITS CAMP HILL HOAD PROPERTIES These properties (No. 14, fig. 16) are located along the rightof-way of the Dudleyville-Camp Hill Road, in the NE% sec. 26, T. 22 N., R. 24 E. (fig. 32) on the Ragsdell, Vines, and Burnett properties. The pyroxenite occurs as a lens-shaped mass approxi mately 600 yards long and 200 yards wide. Tallapoosa County Road 87 dissects the mass for approximately 0.8 mile, parallel to a northeastward-trending major axis. Road cut exposures show irregularly shaped pyroxenite boulders enclosed in a matrix of amphibolite and chlorite. The pyroxenite is an aggregate of inter locking talcose enstatite crystals. All the material is badly weath ered and identification is often difficult. The exact dimensions of the material is not defined because of soil and vegetation cover, and the deposit may be larger or smaller than indicated. Cross-fiber veins, 2 to 3 inches wide, peripheral shell, and mass-fiber anthophyllite were found in the altered part of the ultramafic body. Chalcedony boxwork and concretions are scattered over the surface. Soapstone fragments were found in the drainage ditches bordering the road, but the property has not been pros pected. ESTES PROPERTY The Estes property (No. 15, fig. 16) is in the E%NW/4SE/4 sec. 34, T. 23 N., R. 24 E., about half a mile south of the Buttson community.,, Large isolated boulders of pyroxenite are scattered through the wooded sections of the property. The pyroxenite is an enstatite-hypersthene assemblage typical of the district. All the specimens examined show alteration along the crystal boundaries to talc and anthophyllite. Mass-fiber anthophyllite occurs as surface accumulations in an abandoned field. Soapstone fragments were found along the northern flank of the ridge which crosses through the property. Several excellent specimens of actinolite and chlorite were col lected from boulders in a field-rock dump, but exploration work was not carried out on this property. .aa F igure 32.--Sketch map of Camp H ill Road properties DESCRIPTION OF PROPERTIES \CoO 90 T A L C AND AN TH O PH YLLITE ASBESTOS DEPOSITS I COOSA. EW ER NEWS PRINT PROPERTY The Coosa River News Print property (No. 16, fig. 16) lies to the east along the strike from the Estes property and is in the NWM and part of the SAl sec. 35, T. 23 N., R. 24 E. Pyroxenite 1 crops out along the northern flank of the eastward-trending ridge and forms small prominent bluffs along an adjacent stream. The | bluffs mark the approximate northern boundary of the mafic-ultra[ mafic rock complex in this area. To the north, mica schist and f gneiss occur as surface material. Along the crest of the ridge and I to the south, abundant pyroxenite and altered pyroxenite occur as l scattered float. In several areas abundant surface accumulations of pyroxenite occur. The pyroxenite is a mixture of enstatite and | hypersthene with traces of bronzite. Incipient alterations of the pyroxene minerals have formed talc and anthophyllite. Some ser pentine occurs at several localities. An old abandoned road trace crosses the property. Just before \ it crosses a small stream, the first of a series of small pyroxenite bluffs crop out. Extending eastward from the trace, a series of shallow pits, trenches, and cuts have been opened. The material exposed from these excavations is a talcose pyroxenite. Tourma\ line occurs with the pyroxenite approximately half a mile east of the road in an area of dense surface accumulations of pyroxenite. To the east of the Coosa River News Print property, an outcrop of soapstone occurs. To the south of the ridge, amphibolite, pyrox enite, and,, talcose pyroxenite make up the larger part of the sur face matrial. Dense vegetation and heavy soil cover mask the limits of the various rock units. Several boulders of mass-fiber talcose-anthophyllite occur near the site of an old home on the prospect. The prospecting j work along the northern bluffs is tentatively dated as 1939-40. J! JENNMGS-SATTEBWHITE PROPERTIES t The jennings-Satterwhite properties (No. 17, fig. 16) are in I the SE%NWJ4 and the SW%NE% sec. 36, T. 23 N., R. 24 E., approx! imately a quarter of a mile east along the strike from the Coosa I River News Print property, and approximately a mile north of the I Pettus Harris property. DESCRIPTION OF PROPERTIES 91 Serpentine and pyroxenite are exposed in a road cut just north of the Jennings house. Thin veins of asbestos VBinch to 3 inches in width crisscross the outcrop surface. Boulders and fragments of pyroxenite occur near the upper part of the cut. The boundary of the mafic-ultramafic rock complex is represented by a narrow northeastward-trending ridge which passes through both properties. To the north and south, biotite schist and gneiss crop out. The southern boundary is also marked by an outcrop of black horn blende gneiss. In a cotton field, along the crest of the ridge, boulders and fragments of talc, talcose-anthophyllite, and talcose-pyroxenite occur scattered across the surface. Chalcedonic anthophyllite is present toward the center of the field. The surface material extends from the vicinity of the Jennings house northeastward to the Satterwhite house, a distance of about 2,000 yards. There are several shallow overgrown depressions in the woods west of the Jennings house, but it is not known if they represent old prospect pits. T a b le 9. --Summary o f trenching activ ity Property name and number' Length Depth of Length of Length of of cut overburden sample trench sample (feet) (feet) (feet) (feet) (1) Perry Wise-Sanders 340 340 283 (2) W. B. Railey 300 2-4 270 200 (3) Srirrell Estate 1200 1-10 1140 650 (11A) Clem Vines, north area 300 0-4 2 267 267 (1 IB) Clem Vines, south area 325 6-102 296 296 (13) Pettus Harris 300 6-102 274 202 1 P roperty num ber given by the G e ological Survey of A labam a (fig. 16). 2 Supplem ental auger h o les u sed for verification of m aterial and overburden estim ate. 9 2 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS HISTORY OF MINING ANO PRODUCTION Since 1873, a number of mining companies and individuals have taken small to moderate amounts of anthophyllite asbestos from the Dadeville area. Most of the early prospecting efforts were for evaluation tests. Several tons of material would be removed from a surface or near-surface occurrence and either stockpiled in hopes of attracting larger mining interest or shipped to laboratories and producers for evaluation studies. In 1965, the Powhattan Mining Co. began small-scale mining activities on the Garfield Heard property, near the eastern end of the anthophyllite district (fig. 33). The property was worked inter mittently during the following year and several carloads of antho phyllite were shipped to a Baltimore processing plant. At present no other mining company is active. Figure 3 3 .--E xcavation of sm all open pit on the Garfield Heard property, 1965. HISTORY OF MINING AND PRODUCTION 93 In 1963, the American Talc Co. did preliminary exploration drilling for talc on the Prather property. The results of their work were inconclusive. Over the years several attempts have been made to interest various talc producers to develop the material but without success. MINING METHODS Simple mining methods are employed in the extracting and recovery of anthophyllite asbestos because of the size, shape, and occurrence of the deposits. Open-cut methods are generally used. In many instances, the ore is recovered entirely by hand labor using picks, shovels, and wheelbarrows. Auxiliary equipment may include bulldozers, front-end loaders, draglines, and pneumatic drilling equipment (fig. 34). j j | F igu re 3 4 .--Hand loadin g of anthophyllite m aterial after excavation . 94 T A L C AND ANTH OPH YLLITE ASBESTOS DEPOSITS Most of the anthophyllite mined to date in Alabama has been from shallow deposits. Both vein and mass-fiber material have been recovered. Ore near the surface is usually quite soft and can be removed by hand methods. With depth, the anthophyllite be comes harder and more compact and hammers and dynamite are employed to break up the larger m asses. Open cuts are limited in depth by hard rock but often groundwater seepage makes continued excavation difficult. Also, the saprolite wall rock tends to become unstable when wet making deep excavation hazardous. It should be noted that many of the early prospect shafts and trenches, which are entirely within the amphibolite-pyroxenite boundaries, have stood open without shor ing for several decades. The recovery of talc has not been attempted in the Dadeville area. Mining methods would by necessity take the form of largescale open-pit operations. Primary recovery would consist princi pally of the separation of the large nodules and boulders of mas sive talc and talcose-anthophyllite from the associated saprolite by a log washer operation. Bulldozers, scraper pans, front-end loaders, and draglines would constitute the principal items of earth-moving equipment required. Mining depth would be limited by depth to hard rock, but observations indicate that depths to 30 feet are feasible. RESERVES The nature and occurrence of the anthophyllite and talc de posits makes it difficult to formulate an estimate of the potential total reserves of these materials in the Dadeville area. The occur rence of talc appears to be far greater than the available antho phyllite but insufficient exploration, a saprolite zone of varying depth, and limited outcrop information foreshadow any estimate. Market requirements for lower grade mass-fiber asbestos would dictate the quantity of anthophyllite that might be minable. Re serve estimates of the vein-type asbestos cannot be computed. Based on past exploration and observations during this study, it is possible that a considerable tonnage of anthophyllite asbestos of all varieties may be derived as a primary product, or as an indirect secondary recovery product from talc production. RESERVES 95 The total potential talc-anthophyllite-bearing zone of the Dadeville amphibolite belt may encompass as much as 6,800 acres of timberland and farmland. Based on field observations, it is possible that 25 percent or 1,700 acres of the land could contain talc or talcose material. Prospect pits and road cuts indicate that the talc occurs to depths of at least 30 feet. The crude talc is mixed with varying parts of saprolite clay, thin seams of anthophyllite, pyroxene alteration products, and unaltered pyroxene. The amount of talc in the crude ore ranges from 3 to 26 percent. In preparing tonnage estimates for this report only material yielding more than 15 per cent talc was considered. A large-scale recovery test would more accurately establish a finite recovery and percentage figure. Ore estimate data for five properties are given in table 10. Although little data are available to substantiate the tonnage estimates, it is believed that the results are within the limits of error for the investigation. A tonnage factor of 3,700 tons per acre-foot was used to estimate the potential talc ore in the Dade ville area. Tonnage factor calculations are as follows: 43.560 sq ft/a ere _____1 ft thickness Estimated wt. 1 ft' 43.560 ft3/acre-foot 170 lb s/ft3______ ' (5>2,000 lb/ton 7,405,200 lbs/acre 3,700 tons/acre-foot .( TALC AND ANTHOPHYLLITE ASBESTOS DEPOSITS V0O\ Property name and number (1) Perry Wise-Sanders (3) Sorrell Estate (5) Knight (11A) Clem Vines, north area (12) Clarence Ware Total acres represented Average grade Total tons of talc Total talc-anthophyllite area (acres) Potential talc-bearing acres Area (acres) 80 108 50 86 36 360 Table 10.--Ore reserve estim ates Expected depth (feet) Tonnage factor (ions/acre-foot) 30 3,700 30 3,700 30 3,700 30 3,700 30 3,700 Crude material (tons) ' 8,900,000 12,000,000 5,550,000 9,950,000 4,000,000 6,800 1,700 4 15 3,700 94,500,000 Talc (percent)2 16.1 17.4 3(19.7) 25.9 3(19.7) 19.7 19.7 Talc (tons) ' 1,400,000 2,100,000 1,090,000 2,580,000 790.000 7,960,000 18,620,000 1 A ll num bers rounded. 2 B ase d on beneficiation stu d ies. 3 Not in clu d ed in c a lc u la tio n s for av erage grade. 4 Minimum a v e ra g e depth. -- REFERENCES 97 REFERENCES Adams, G. I., 1933, General geology of the crystallines of Alabama: Jour. Geology, v. 41, p. 159-173. Adams, G. I., Butts, Charles, Stephenson, L. W., and Cooke, C. Wythe, 1926, Geology of Alabama: Alabama Geol. Survey Spec. Rept. 14, 312 p. Benson, W. N., 1926, The tectonic conditions accompanying the intrusion of basic and ultrabasic plutonic rocks: Natl. Acad. Sci. First Mem., v. 19, 90 p. Berquist, H. R., 1960, Petrographic study of the crystalline rocks from the Opelika quadrangle, Alabama: Alabama Geol. Survey Bull. 69, 44 p. Bowen, N. L ., 1915, The later stages of the evolution of igneous rocks: Jour. Geology, v. 23, no. 8, Supp., 91 p. _____ 1917, The problem of anorthosites: Jour. Geology, v. 25, p. 209-243. Bowen, N .L.,an d Anderson, Olaf, 1914, The binary system MgO-Si02: Am. Jour. Sci., v. 37, p. 487-500. Bowen, N. L ., and Tuttle, 0. F ., 1949, the system MgO-SiOj-HjO: Geol. Soc. America Bull., v. 60, p. 439-460. Bowles, Oliver, 1955, The asbestos industry: U.S. Bur. Mines Bull. 552, 122 p. Chidester, Alfred H., 1962, Petrology and geochemistry of selected talc-bearing ultramafie rocks and adjacent country rocks in north-central Vermont: U.S. Geol. Survey Prof. Paper 345, 207 p. Clarke, J. W., 1952, Geology and mineral resources of the Thomaston quadrangle, Georgia: Georgia Geol. Survey Bull. 59, 99 p. Conrad, S. G., Wilson, W. F., Allen, E .P ., and Wright, T. J., 1963, Anthophyllite asbestos in North Carolina: North Carolina Dept. Gonserv. and Devel. Bull. 77, 61 p. Cooke, H. C., 1936, Asbestos deposits of Thetford district, Quebec: Econ. Geology, v. 31, p. 355-376. Grickmay, G. W., 1952, Geology of the crystalline rocks of Georgia: Georgia Dept. Mines, Mining, and Geology, Bull. 58, 54 p. Engel, 'A'. E. J., and Engel, C. C., 1962, Progressive metamorphism of amphib olite, northwest Adirondack Mountains, in Petrologic studies--a volume in honor of A. F. Buddington: New York, Geol. Soc. America, p. 37-82. Fyfe, W. S., 1962, On the stability of talc, anthophyllite, and enstatite: Am. Jour. Sci., v. 260, p. 460-466. Greenwood, H. J ., 1963, The synthesis and stability of anthophyllite: Jour. Petrology, v. 4, p. 317-344. Hess, H. H., 1938, A primary peridotite magma: Am. Jour. Sci., 5th ser., v. 35, p. 321-344. Holmes, Arthur, and Harwood, H. F., 1932, Petrology of the volcanic fields east and southeast of Ruwenzori, Uganda: Geol. Soc. London Quart. Jour., v. 88, p. 370-442. Hopkins, Oliver B., 1914, A report on the asbestos, talc, and soapstone deposits of Georgia: Georgia Geol. Survey Bull. 29, 319 p. 9 8 T A L C AND AN TH OPH YLLITE ASBESTOS DEPOSITS King, Philip E., 1955, A geologic section across the southern Appalachians--an outline of the geology in the segment in Tennessee, North Carolina, and South Carolina, in Russell, R. J.,e d ., Guides to southeastern geology: Geol. Soc. America, p. 332-373. Kitahara, S., Takenouchi, S., and Kennedy, G. C., 1966, Phase relations in the system Mg0-Si02-H20 at high temperatures and pressures: Am. Jour. Sci., v. 264, p. 223-233. LaForge, Laurence, Cooke, C. Wythe, Keitn, Arthur, and Campbell, M. R., 1925, Physical geography of Georgia: Georgia Geol. Survey Bull. 42, 189 p. Neathery, Thornton L., LeVann, Herbert P., Ahrenholz, H. William, and O'Neill, James F., 1967, Talc and asbestos, Dadeville, Alabama: U.S. Bur. Mines Rept. Inv. 7045, 57 p. Overstreet, W. S., and Bell, Henry, 1965, The crystalline rocks of South Carolina: U.S. Geol. Survey Bull. 1183, 126 p. Paige, Sidney, 1937, Asbestos deposits of Thetford district, Quebec, a discus sion: Econ. Geology, v. 32, p. 108-109. Pratt, J. H., and Lewis, J . V., 1905, Corundum and the peridotites of western North Carolina: North Carolina Geol. Survey, v. 1, 464 p. Rabbitt, J . C., 1948, A new study of the anthophyllite series: Am. Mineralogist, v. 33, p. 263-323. Reed, John C., and Bryant, Bruce, 1964, Evidence of strike-slip faulting along the Brevard zone in North Carolina: Geol. Soc. America Bull., v. 75, no. 12, p. 1177-1196. Roy, D. M., and Roy, Rustum, 1955, Synthesis and stability of minerals in the system Mg0-Al20 3-Si02-H20 : Am. Mineralogist, v. 40, p. 147-178. Sorensen, Henning, 1953, The ultrabasic rocks of Tovqussaq, West Greenland, a contribution to the peridotite problem: Meddel. om Gr^nland, bind 136, no. 4, 86 p. Spence, H. S., 1940, Talc, steatite, and soapstone; pyrophillite: Canada Dept. Mines, Mines Br. Pub. 803, 146 p. Stewart, L . A^ 1955, Chrysotile asbestos deposits of Arizona: U.S. Bur. Mines Inf. Circ. 7706, 124 p. Tilly, C. E., 1957, Paragenesis of anthophyllite and hornblende from the Ban croft area, Ontario: Am. Mineralogist, v. 42, p. 412-416. Turner, F. J., and Verhoogen, John, 1951, Igneous and metamorphic petrology: New York, McGraw-Hill, 1st ed., 602 p. Yoder, H. S., Jr., 1952, The Mg0-Al20 3-Si02-H20 system and the related meta morphic facies: Am. Jour. Sci., Bowen vol., p. 569-627. Wells, J. R., 1965, Talc, soapstone, and pyrophyllite, in Minerals facts and problems: U.S. Bur. Mines Bull. 630, p. 919-927. Winkler, H. G. F ., 1965, Petrogenesis of metamorphic rocks: New York, Springer-Verlag, 220 p.