Document wDNax441gq8nmDdm2MDOgmKYd

FILE NAME: Railroads (RR) DATE: 1970 DOC#: RR075 DOCUMENT DESCRIPTION: Published Report from MT Bureau of Mines STATE OF MONTANA BUREAU OF MINES AND GEOLOGY U. M. Sahinen, Director BULLETIN 79 Geology and Mineral Deposits of Lincoln and Flathead Counties, Montana by Willis M. Johns Montana Bureau of Mines and Geology This report has been prepared by the Montana Bureau of Mines and Geology under a cooperative agreement with the Great Northern Railway Company and the Pacific Power & Light Company j ij MONTANA COLLEGE OF MINERAL SCIENCE AND TECHNOLOGY Butte, Montana 1970 BNSFP 00000313 IGNEOUS ROCKS--M ESOZOIC B A SIC STOCKS 57 QUARTZ LATHE PORPHYRY AND DIORITE DIKES Several quartz latite porphyry dikes north and southwest of the Rainy Creek intrusive are ex* posed, fo ^ d istan ce^ -^ reat-a^ .k alf j l mile, and they range in width from 50 to 75 feet. Specimens are characterized by light-gray to white phenocrysts in a dark-yellowish-green to brown or black groundmass, which weathers dark gray to rusty orange brown. The phenocrysts range from 3 to 25 mm in length; rectangular phenocrysts attain a width of 7 mm. In thin section most of the phenocrysts can be identified as plagioclase, but a few are quartz. Feldspar phenocrysts exhibit Carlsbad, albite, and pericline twinning, and most are strongly sericitized. The most abundant feldspar is albite, which occurs in grains 0.35 to 0.7 rom in width and 1.0 to 2.35 mm in length. The very fine grained groundmass contains slightly ..more plagioclase than orthoclase; ferromagnesian minerals are also ' abundant, and iron oxides and moderately abun dant quartz are disseminated throughout. Iro n . oxide grains (hematite and limonite) range from 0.10 to 0.42 mm; angular to subrounded quartz grains range from 0.05 to 0.43 mm. Two diorite dikes south and southwest of the Rainy Creek pluton strike eastward (Beer, I960). In surface exposure the rocks are light yellowish orange to light gray, are medium grained, and weather bright yellowish orange. Needles and grains of pyroxene are disseminated unevenly throughout the groundmass. The most abundant mineral seen in thin sec tions is plagioclase; the grains range from 0.80 to 2.25 mm. Next most abundant are crystals and grains of pyroxene (probably diopside) ranging from 0.05 to 1.45 mm. Quartz is minor, and the grains range from 0.12 to 0.15 mm. Magnetite is also sparse; the grains range from 0.10 to slightly more than 2 mm. age of dikes . Granitic dikes are closely related to acidic stocks, and it seems reasonable to assume that the ages of the two kinds of rock are similar, that is, late Mesozoic. BASIC STOCKS RAINY CREEK STOCK The Rainy Creek stock is west of the Koote nai River about 8 miles northeast of Libby. This large complex stock of pyroxenite and syenite underlies part of the valley of Rainy Creek and extends east beneath Vermiculite Mountain. The irregular outcrop area of the stock is about 7% square miles. Aegirite pyroxenite and aegirite-diopside py roxenite, syenite, and some pegmatite have in truded strata of the Wallace Formation. Pyroxe nite is probably the oldest intrusive rock in the stock-and-constitutes about two-thirds of ..the stock. Almost all of the other one-third is syenite. Quartz veins containing small amounts of chalcopyrite, sphalerite, and galena are postsyenite in age, as they intrude pyroxenite and syenite. A small amount of opaline material associated with quartz veins was observed localty in the Zonolite Company's open p it The border phase of the pyroxenite intrusive mass is rich in magnaHta An analysis of a magnetic concentrate of this material gave 83.80 percent iron, 0.60 percent titanium oxide, 2.40 percent silica, and 0.50 per cent phosphorus. Pyroxenite within the Zonolite pit is lightgray to yellowish-green coarse-grained friable rock composed of vermiculite, aegirite, aegiritediopside, soft fibrous tremolite, apatite, magnetite, garnet biotite, and hydroblotite. Fluorine-rich apatite makes up 7 to 10 percent of the rock. Aegirite and aegirite-diopside both are locally vanadiferous. Boettcher (1963) described two major types of pyroxenite; the more abundant type (common pyroxenite) consists of pyroxene, vermiculite, and apatite. Another, finer grained type of pyroxenite consists of pyroxene and con tains smaller proportions of vermiculite, apatite, garnet, magnetite, and sphene. Near the center of the pyroxenite mass is a biotite-rich (biotitite) area consisting of 90 per cent biotite, the rest being feldspar, pyrite, and cal cite. Tremolite (amphibole asbestos) forms at the expense of pyroxenite in altered zones bordering syenite apophyses and quartz veins th at cut the pyroxenite mass (Boettcher, 1963). Aegirite-diopside and vermiculite crystals within the pyroxenite are as large as 4 cm. Some pale-green prismatic crystals of apatite are as much as 10 cm in length but average crystals are 1 or 2 cm long. The rest of the rock comprises about 5 percent orthoclase, less than 5 percent quartz, less than 1 percent plagioclase, and smaller amounts of sphene, carbonate, zircon, garnet, and biotite. The southwestern part of the Rainy Creek stock consists of medium- and coarse-grained yellowish-green and gray syenite containing mus covite and iron oxides. Composition of the syenite is diverse; the main body is composed of potash feldspar and mica, whereas a small body of nephe line syenite southwest of the main syenite intru sive body is composed of nepheline, microcline, albite, and aegirine. B N SFP_00000377 Figure S2.--Claim m ap of litt le D arling (5358) and Jea n e tte (5354) lodes, southeastern Flathead County, it is notjmown whether this work-was eyericem- pleted. ' . . -. . An open cut adjacent to the Forest Service trail to Baptiste Lookout and a mile northwest of Mt. Baptiste exposes a 3-inch vertical quartz vein striking N, 84 E. Hie vein contains milky quartz and small masses of chalcocite and hematite. The cut is in the Grinnell.Formation, which strikes N. 5 W. and dips 10 E. A t the head of Silver basin (upper South Fork Logan Creek) between Baptiste Lookout and Mt. Baptiste, a 20-foot timbered shaft was sunk in the basal unit of the Piegan Group. No ore was found on the dump, and no veins were visible from the collar of the caved shaft. On the Truman Creek-Blacktail Mountain road 0.4 mile south of Kerr Mountain, a 4 by 6- foot pit at the base of a cliff exposes a 17-inch quartz vein striking east and dipping 74 S. The massive white quartz vein contains vugs filled with hematite. Specular hematite is found as un altered masses in quartz. A fault, indicated by 2 inches of shattered rock and gouge, parallels the hanging wall of the vein. Country rock is purple- gray finely banded quartzite of the Ravalli Group, which strikes N. 47 W. and dips 25p NE. Three intersecting (?) quartz veins are ex posed in a road cut at the head of Truman Creek 3 miles north of Lake Mary Ronan. Small limonitefilled vugs in shattered quartz were noted in 3%- and 1V^-inch veins striking northeast and east respectively. White massive vuggy quartz, con taining siderite and iron oxides, is poorly exposed in a plus 6-inch vein believed to strike northwest. Traces of copper and silver are associated with the quartz veins. Two claims, Old Dominion No. I and 2, were located by Gary L, Vollmer of Kalis pell on October 8, I960.' _ .j highway- cut near Swan Lake i- mlle - northwest of Swan Lake campground, a Vi-inch veinlet of earthy malachite follows bedding in Grinnell argillite. A sample of the mineral zone assayed 1.16 percent copper and 0.55 ounce silver a ton. Locally at other outcrops east of Swan Lake, malachite was found as blebs, many of which have a chalcopyrite nucleus. A piece of lead-zinc float was reported found in 1926 during trail construction on the Helen Creek trail about 1 mile southwest of Helen Moun tain, a t a point where the trail turns from a north easterly to a southerly direction. The float may have come from the divide south of Helen Moun tain.,. . U. S. Forest Service personnel report that a --sluice box was observed about 1925 near the mouth of Hodag Creek, about a mile north of Blackbear Guard Station. The sluices have now disappeared, and no tailings were noted there. Barren quartz veins and veinlets striking about N. 75 W. and dipping 11 NE are exposed by three or more shallow pits on the north side of Soldier Creek north of Soldier Lake about 6% miles northwest of Spotted Bear Ranger Station. ' NONMETALLIC DEPOSITS VERMICULITE Rainy Creek mineral deposits were first pros pected in the 1880's when base metals in quartz veins were discovered at the north end of the1 Rainy Creek pluton, but the presence of vermicu lite was first determined by E. N. Alley of Libby while prospecting for vanadium in 1915. Smallscale vermiculite production commenced in 1925, and in 1939 several independent operations were BNSFP 00000466 * NONM ETAIXIC DEPOSITS--VERM ICULITE M7 combined under the name Universal Zonolite Insulation Company, the name was changed to Zonolite Company in 1848. In 1864 the company became the Zonolite Division of the W. R. Grace Company. . . . . . . . . . . ... ' A 1,000-ton mill eirected in 1848 produced 350 to 400 tons of concentrate a day. Production has been increased to 500 tons a day, and the present facilities are to be expanded. Since the middle 1820's, about 35,000,000 tons of ore and waste have been moved, a t an ore-to-waste ratio of ,1:1.4 (Boettcher, 1863, Pj_7). .... ,, Open-pit mining .methodsTare used, and the ore is selectively mined and loaded by power lu Mine waste and mill tailings S3 Blotitite (H Nepheline syenite H I Pyroxenite I S Syenite CU Belt Series Figure S3.--G eologic m ap of Rainy Creek pluton, Rainy C reek d istrict, Lincoln C ounty (A. L. B oettcher, 1943). BNSFP 00000469 GEOLOGY AND MINERAL D EPO SITS, LINCOLN AND FLATHEAD COUNTIES shovels. Waste is trucked to a dump at the south west end of the mine area. Milling is done by a combination of wet and dry processes, including Some opalized rock was uncovered at the west end of a lower bench in 1964. . The Rainy Creek pluton has many minerals of gravity methods, flotation, and screening. The vermiculite. concentrate is dried and screened to various size ranges. The Rainy Creek intrusive body is an elon gate composite stock of blotlte-magnetite-pyroxenite and syenite (Fig. 53) intruding strata of the Wallace Formation within the trough of a north west-trending syncline. An alteration,halo reported to be 300 feet wide (Boettcher, 1983) consists of potential value, besides the vermiculite, which is being marketed at~present.J Amphibole asbestos (tremolite), the nearly pure feldspar in the syenite dikes, biotite in the jjiotite mass, and apatite, as sociated with vermiculite, pyroxene, and the mag netite-rich border phase of the biotite-magnetite pyroxenite intrusive body, may be profitable by products if separation can be achieved economical ly and if markets can be developed for these min recrystallized and sericitlzed metasedimentary erals. rocks surounding the magnetite pyroxenite; the Origin of th vermiculite is still debatable, intensity of alteration decreases outward from the contact of magnetite pyroxenite with sedimentary rocks. A border phase of the magnetite pyroxenite is magnetite rich, a grab sample of the material although some investigators have concluded that it is derived from biotite through hydrothermal al teration or alteration by weathering and surface water. Boettcher (1963, p. 59) stated: assaying about 16 percent magnetite. , . Boettcher (1963, p. lg),^described, twp .tPAjor, ,'pyrbxhte rock types; the mre abundant type is. very coarse grained pyroxenite composed of py roxene (probably diopride), mixed vermiculite and hydrobiotite, and accessory fluorpatite; it con tains all .of the economic vermiculite in the stock. The grain size of the pyroxenite ranges from 1 cm to 2 meters or more in length, the average grain size being about 5 cm. The secondi finer grained type described by Boettcher forms zones within the coarse-grained pyroxenite. It consists almost entirely of pyroxene and contains only small quan tities of mixed vermiculite and hydrobiotite, apa tite, garnet, magnetite, ilmenite, and sphene. " There is.no eyidenge in the,,fieldJ it, in thin section' to indlcaie that the ver miculite (or biotite if tfe vermiculite was originally biotite) or the biotitite* core are alteration products of the pyroxene. Furthermore, field relationships suggest that the vermiculite (or biotite) and bio titite are older than the veins, syenite dikes, and pegmatites, and could not be alteration products associated with their emplacement . . . It is concluded that biotite is a primary constituent of the pyroxenite. The problem is to determine if the vermiculite is an alteration product A mass of blotite, 600 by 1,000 feet, near the center of the biotite-magnetite pyroxenite intrusive body was described by Boettcher (1963, *B iotitlte is a term used by G runer (1934) and -B oettcher to describe a rock com posed m ainly of biotite, b u t con taining feldspar, pyrite, and calclte. _ ,,p. 13) as consisting of 90 percent biotite and the other 10 percent feldspar, pyrite, and calcite. The contact between biotite and pyroxenite is sharp. Syenitie pegmatite bodies as much as 10 feet wide intrude both biotite pyroxenite and biotite. Bordering the biotite-magnetite pyroxenite in trusive body on the southwest (Fig. 53) is a syenite body, from which an apophysis extends . into the pyroxenite. The main syenite body is coarse-grained microcline microperthite containing 20 to 30 percent muscovite. Bordering the syenite apophysis and related syenite dikes in the pyroxe nite are alteration halos of tremolile after pyrox enite, which are of potential economic import ance as a source of brittle asbestos. Southwest of the syenite mass is a coarse-grained nepheline syenite intrusive body containing nepheline, albite, aegirine, and microdine-perthite (Boettcher, 1963). Post-syenite quartz veins contain uneconomic amounts of chalcopyrite, bornite, sphalerite, fluo F igure 54.--C taim m ap of Poston property, Rainy Creek rite, pyrite, aegirine, rutile, and accessory calcite. district. BNSFP_00000470 NONM ETALUC DEPOSITS--BARITE 149 of blotite and, if so, to determine the nature of the alteration . . . the w riter favors the hypothesis that the vermicu lite has been derived from biotite by the . actiQn qf fluWs. of.magmatic .origin," ....... . Another vermiculite deposit of undertermined extent is north of Fleetwood Creek toward the northern part of the Rainy Creek stock. (Fig. 54). Eight unpatented claims, the Last Chance and Last Chance No. 1 to 7, were staked by George Ottoway and Mr. Fleetwood in 1925. The property was acquired by H. J,, H. L., and U. L. Poston of Kalispell in 1932. During the 1950's the property was leased and optioned by the F. &. S. Construction Company of Butte. Prior to 1964, H. J. Poston assumed complete ownership of the group. A small irregular stock composed of porphyritic syenite and some pyroxenite intrudes the Wallace Formation ,east of Bobtail Creek about 10'M es north of E lb b ^ ^ e ^ i j s m t o n private land and National' Forest land. A t the southwest end of the stock, an exposure in a cut on the east side of the road exposes tremollte, biotite, magnetite, and pyroxene minerals. Some vermiculite has been reported in the cut. Develop ment work consists of some pits in soil-covered areas near the south end of the stock. map) strikes N. 15 W. and dips 60 NE, crossing the Windjammer claim. The cross veto a t the southwest ends of the Windjammer and Tungsten King claims (No. 3 on map) is 4% feet wide, strikes.N. 60QW, and dlps 47 It is well ex-., posed in a 35-foot drift, where its width averages 30 inches. Some sulfides occur in this vein. The Tungsten King vein (No. 4 on map) trends N. 50 E. and dips 40 SE, It is a split off vein No. 1 and is 2 to 5 feet wide. Other veins crop out on the Buckskin and Windy Pass claims. The Buckskin vein is 3% feet wide, strikes N. 80 W., and dips 85 N. On the Rising Sun fraction, the vertical vein (No. 1) is about 3 feet wide. All veins are in the Wallace Formation, which trends about N. 30 W. and dips 60 to 65 S. Tom Schessler (personal communication) re ported that a 3%-foot vein on the Buckskin claim contains 8 inches of quartz and barite on the hanging wail, 14 inches of yellow crystalline bar .. ..ite iip the center, and 20_4nches of brecciatpd bar*, ite, ankerite, and siderite on the footwall. Schess ler estimated the barite content of sections of veins as ranging from 40 to 60 percent. High-grade parts of the veins may assay 85 to 95 percent barium sulfate. KENELTV BARITE BARITE KOTSCHEVAR The Kotschevar or Copper Mountain group is on Copper Mountain 5 raUes south of Troy in the Troy district. The property consists' of nine un patented lode claims and three, milisites (Fig. 55). The group was purchased in lPJ^frona. James B. Robinson of Spokane, Washington, by Donald and Lendal Kotschevar of Sandpoint, Idaho, and Mis soula, Montana. No production has been ,reported. The property is developed by an 80-foot adit (accessible) on Vein No. 1, a 35-foot adit on Vein No. 3, and several pits and cuts on the other veins. Three branching fracture-filling veins and one cross vein ranging from 1 to 5 feet in width strike northwest to northeast (DeMunck and Ack erman, 1958). The three branch veins dip east and the cross vein dips southwest. The barite vein on the Julia K. claim (No. 1 on map, Fig. 55) strikes about N. 20 W. and dips 44 NE, but swings to strike about N. 30 E. on the Tungsten King, Rising Sun, and Nina K. claims. It is well exposed in an 80-foot adit, where it is 30 to 40 inches wide and is composed of dense white barite, which assays 92.1 percent barium sulfate and 0.35 percent silica. A split from this vein (No. 2 on The Kenelty barite lease is about 2 miles south of Loon Lake on the south side of a tribu tary of the Fisher River, in Lincoln County. Ger ald Kenelty of Libby discovered the vein during logging operations in 1960 and leased the property from The Anaconda Company in 1961. The proper ty has been inactive for several years. Three trenches and a strip pit 175 by 18 by 5y% feet expose a barite vein along a probable strike length of about 600 feet. Width of the vein ranges from 10 to 18 feet. The vein strikes N. 65 to 75 W. and is vertical or nearly vertical at the center c u t The massive white and reddish-white taarite contains minor white quartz, hematite, and sericite. South of the stripped area (Fig. 56) is a fourth cut exposing a 2%- to 3-foot vein, which strikes N. 30 E. and is vertical. The barite con tains some quartz and small masses of purplishmaroon hematite and sericite. Country rock is serlcitic light-gray, yellow-gray, and yellow-brown noncalcareous siltstone and argillite of the Libby Formation. Samples of barite from surface cuts have specific gravities of 4.15 to 4.20. In 1962 about 400 tonsrpf barite was mined and shipped by Great Northern Railway to Cal-Bar a t Clear Lake, Washington. Most of the ore was broken by jackhammer and loaded by front-end loader from the northwest trench. Chunks of high- BNSFP 00000467 NONM ETIAIC DEPOSITS--STONE 163 and green-gray sericitic talc containing dissemin W O LLA STO NITE ated pyrite, iron oxides, and some quart!. ' Two bodies of wollastonite (CaSi08) on the The deposit may have been formed by hydro thermal alteration of favorable Striped Peak strata;'" ' ' '.... ' ' ' ' "" "" ' "" south side of Kennedy Gulch, 5% miles east of Libby, strike N. 30 W. They are poorly exposed and unexplored, but each is at least 2 feet wide, and they are about a quarter of a mfle 'apart. Coun TREMOLITE In the Rainy Creek stock, mass-fiber trem olite of contact-metamorphic origin borders syenite dikes and quartz veins. The tremolite has formed from pyroxenite. Tremolite asbestos has economic potential for use in many applications, such as roofing, where the spinning qualities of the higher grade chrysottle is not needed. The deposit has been discussed under Vermiculite. Asbestos try rock is the Wallace Formation. A sample from the outcrop assayed 42 per cent CaO, 45.80 percent silica, 3,90 percent AljOg, 5 percent C 02, 1.20 percent ferric oxide, and 0.50 percent ferrous oxide. Magnesium oxide was nil. W ollastonite is used in the ceramic industry, the chemical industry, in high-grade electrical in sulators, and as a nonmetalic filler. (tremolite, a cross-fiber variety) also occurs at CLAY the Esther May and Larue-Cripe prospects in the Yaak River area, Lincoln County. The Esther May claims, about half a mile northwest of Yaak in the northwest comer of. Lincoln County, were staked by Romeo and Vir ginia Garrison in 1946. The group comprises two unpatented claims, the Esther May No. 1 and 2. In 1948 the claims were leased to Hough and Love^ land of Spokane, Washington, for a period of 10 years. The lessees drilled twelve to fifteen holes near a small asbestos vein exposed on a bluff. All holes were reported to have intersected tremolite at depths of 20 to 30 feet. In 1958, H. P. Reins hagen, Sr., and H. P. Reinshagen, Jr., of Libby, Clay is widespread in Lincoln and Flathead Counties; varieties include laminated glacial-lake lay, alluvieLplay^nd. clay.,formedby. hydrother mal alteration- of igneous rock. No special study of clays was made for this report; but samples of clay from the area have been included In a con tinuing Bureau study of all Montana clay and shale. Samples from selected areas have been examined for their suitability as (ramie raw ma terials, as a source of alumina for aluminum re covery, and as possible expandable material for lightweight aggregate. Clays that have been ex amined, are tabulated (p, 154). The results of test ing are given in the publications listed, to which the reader is referred for details, leased the property for one year, with option to buy, but dropped the option. ' STONE A vertical vein of tremolite about 3 inches TUFA wide, trending N. 10 W., is exposed at'fife baste A deposit of calcareous tufa on the D. A. of a bluff. Wallace country rock also strikes N. 10 W. and dips 75 NE. A second vein, 6 inches wide, has been explored by a shallow pit, in which Sheffler ranch near the mouth of a small tributary of the Kootenai River, about 2 miles southeast of Leonia, is approximately half a mile from the the vein trends N. 70 W. and dips 60" SW. Great Northern railroad. It is estimated to be Autunite, a calcium'uranium phosphate mineral, 1,200 feet long, 50 feet wide, and +12 feet deep, was reported found associated with a 3-inch syen ite dikelet in a small pit at the face of a bluff. The and assays show 85 to 90 percent CaCOa. Three other deposits of tufa are on the Marlon Fisher dikelet strikes N. 70 E. and dips 70 SE. Wallace argillite has been hydrothermally altered; silica has been introduced into the surrounding country rock. A metadiorite body whose trend was not de termined crops out in the area. ' ranch 3% miles southeast of Leonia. Another body of calcareous tufa is poorly ex posed 3 miles northeast of Loon Lake, along the road on the east side of Pipe Creek in Lincoln County. It contains about 88 percent calcium car LARUE-CRIPE u.,.- The Larue-Cripe prospect, about 1 mile south ` of Roderick Butte, consists of a harrow trem olite asbestos vein exposed in two small surface pits. The vein is 3 to 6 inches thick, strikes N. 70 E., and dips 55 NW. The country rock is ripple-mark ed and mud-cracked Wallace argillite. bonate and was deposited by a spring. Calcareous tufa near the Jack Garrison ranch on the J. Neil haul road on Callahqji .Creek south of Troy assayed about 90 percent cfil#um carbon ate. These deposits of tufa are possible sources of rock for the manufacture of quicklime. BNSFP 00000473