Document VJnX2dRNdkDEyDOe0OmMkNLQg

FILE NAME: Railroads (RR) DATE: 1929 Feb DOC#: RR071 DOCUMENT DESCRIPTION: Govt Report - Deposits of Vermiculite and Other Materials in the Rainy Creek District Near Libby, MT _r\ i r\ rs G to VS fr ( 2 i Y V tT Please do not destroy or throw away this publication. If you have no further use for it write to the Geological Survey at Washington and ask for a frank to return it % D epa rtm en t o p t h e I nterior Rar 0 . West, Secretary P K C SlO E N T '3 riF~IOE U. S. GEOLOGICA!. SUEYET Georje Otte Smith, Director MAY 2 2 1929 G N. ft Ali. WAY Bulletin 805--B DEPOSITS OP YEEMIULITE I K ) OTHER M n rom .s IS TEE. RAINY CREEK DISTRICT SEAR LIBBY, MOSTASA BY J. T. PARDEE a n d E. S. LARSEN i>: Contributions to economic ecology, 1928, P a r ti (Pages 17-28) Published February 28, 1922 united states GOVERNMENT PRINTING WASHINGTON 1329 OFFICE I CONTENTS i fags Summary----- ----------------------------- ... -- ---------- IT Introduction__. . . -- - - - ------------------------ 13 Geography . - ................. -- --------- ------ -------- 18 G e o lo g y -......... . . . ------- . . ------- 19 Holt scriPii------------ ---------------- ------------ 30 Porphyry-.. . . . , . . . . . - --. -- --------- 20 Intrusive stuck . . --------------- ---------- - 20 ryroxonltc______ - . `1 - ...........................- 20 i S y en ite................ . - -- ............... 21 ' Granite and monxonlt----------------------------- 22 Uydrmtiprmnl niflinmiriiliisin-.-------------. . . 22 tlturnil deposits . . -- ....... ............. 22 > Vormlculity___ . . . _________ _______ - 22 Ckaruelor. . _ ___ _ _______ 22 General omirrence_______ -- _____ 22 Occurrence In thp Rainy Greek dlstrlct. 2 3 . Production und uses--------------------------- 24 Fibrous arnphibolcs________________ _____ 24 I Feldspar___ 27 Copper, lead, due, and vanadium 27 H,LUSTRATION Pose I'ni'ra 1. Geologic mup of Gin Italny Greek district, T. SI N., 'n. 30 TV., Montana__________ __ _________________________________ 18 ) Ill'* ' DEPOSITS OF VERMICULITE AND OTHER MINERALS IN THE RAINY CREEK DISTRICT, NEAR LIBBY, MONT. By J. T. P abdee and E . S. L ames flmnusr The deposits described are in an easily accessible area about 7 miles north east oE Libby, Host. They occur in a Block of alkaline rocks that is Intrusive Intoargillile and quartzite of the AlgoukUn Belt series. About two-thirds of the stock consists of a coarse-grained pyroxenito that ranges from, nearly un mixed pyroxene h nearly unmixed biotlte or Its alteration product vcradcuUte and generally' contains an unusual amount (7 to 10 per cent) of fluorine-rich apatite. In addition, -the analysis of a representative simple shows'the pres ence of more vanadium, (0.12 per cent Y,0) than occurs in Igneous rocks generally. , ... Tho remainder,of the stock Is coarsc-gralncd syenite composed clitefly of intergrown potash and soda feldspars (mlerocline mlcroperth'tte) and altered nephdine syenite composed chiefly of mlcroperthlte and nests of secondary, muscovite- Near the main Igneous body Is a lkd of fresh nepheline syenite. 'Widespread, and unusual changes in the stock hnve bepn ,caused by hydro thermal action. The principal minerals thus produced nre white mica, aegtrtte and oeglritedlopslde (both locally vanacHferons),' vermlculite, and fibrous amphiboles. Locally titanlte and feldspars are developed and also vein's con taining a variety of minerals, A large body of the vermlculite is being developed commercially by the Zonollte Co. In addition several smaller bodies are bring explored, by the Vormicullt & Asbestos) Co., and in soma of ttese bodies the mineral makes up from 30 to B4 per cent of- the pyrorenlte country rock. ` 'Vermlculite is com paratively new to commerce. I t is' a mlctillke minral 'containing a large amount of water. Upon being heated it expands enormously and hssumes golden or silvery lusters. The expanded material is so light that It floats on water. It appears to have a low heat conductivity and to resist high tempera ture. Tho Zonollte Oo. reports 1,500,000 pounds mined and sold under the trade neme "Zonolite.1' Tho uses of zonollte include fireproof rooting, wall board, and similar material, packing for refrigerators`sound-deadening plas ters, bollor covering, electrical insulation, and wall-paper decoration. ' On the spur north of Kearnoy OreK much of the pyroxene of the large liyroxenite body has been altered to amphibole of a fibrous habit that Is known commercially as amphibole asbestos. Bodies of a dikcllke form 14 feet or less in width consist of nearly Unrobced amphibole asbestos (near .tremollte),- and in several places tills substance composes from 50 to 75 per cent of the country rock. A small amount baa been mined for experimental purposes, but no com mercial production Is reported. The material near the surface Is rather easily 17 ) i ) ) 18 ('ON'i'unui'nuNn to koonomic mooum-?, m a s, part i separuteil. or lUierlsod. Tliii libers nro week and inelastic, blit they compose a fluffy muss tlml to ult appearances Is slmllur to the ordinary run of umphlhole mass lllicr. is ' The ycnllo tonly cnntulus large lunsnc of nearly immlxcd nlknline feldspar, but whotliur Its quality Is each as Is required In the ceramic or other Industries lias not boon (lulunnlnetl. ' ` Veins Hint occur In the pyroxenlte mass oontuln--in addition to quarts-- chalwipyrllo, (pileun, sphalerite, iluoritc, strontlnnlto, colesttfe, neglrlte, aeglrite- dlopstde, mid oilier minerals. Samples of the ueglrltcs showed the presence, respectively, of nearly 4 tier cent and nearly a per cent of vanadium Oxide (ViOi). A. wimple; ef n imrt of one vein contained about 2 per cent of copper. IN U 'K O P U C T IO N Tho deposits described herein have been visited by the writers at different times between 1911 and 1927. D uring the earlier p a rt of th at period quart lades along Rainy Creek were being developed by .15. M. Thomas, since deceased, whom the writers hold in grateful recollection for aid and courtesies extended to them in the field. The specimens collected a t that time included several unusuul and inter esting hinds of locks and minerals. Analyses of some of them in tho laboratory o the United States Geological Survey showed, among oUior tilings, tho presence of considerable vanadium, on which a report was published.1 A ftor the death of Mr. Thomas several years ago dovolopmont work oeased for a time. D uring tho W orld W ar the demand for steel-hardening metals directed the attention of E . N. Alloy, of Libby, to the area as a possible source of vanadium. W hile searching a small tunnel for ores of th a t metal he observed th at the Unites of a coarse mica!ike mineral in the walls swelled enor mously when heated by the flame of bis candle. The flaky mineral proved to be vermiculito, and further examination showed it to be present in great quantities. Since then Mr. Alley and others, incor porated as the Zonolito Co., have developed this unique deposit and built a plant at Libby to convert the crude vermiculito into the prod uct which thoy call " xonolito." More recently several companies have been formed to exploit, other deposits in the same area. QEOGUAXHY Tlio area undor consideration is the lower p a rt of tlio basin of Rainy Creek, about 7 miles northeast of Libby, Mont. (Soe pi. 1.) I t in easily reached from the main automobile highway along the north bank of tlic Kootenai Itiver by a short branch road up Rainy Greek. The Groat Northern Railway approaches within 2 miles, but it lies on tho opposite bank of the rivor. A few miles below Rainy Mvoratm, Jfi. H,, null lim it, W. l\, Two vnmullieroua tiyglritcH from Mbby, M<mU: Aifl. Jtm r. Kcl., *UU atr. v<>). , ]>!. m 21)0, 1013. V . . QBOLOOICAL flURVUT BULLETIN SM PLATS 1 EXPLANATION Biotite rock (Altered to Vermiculite) Syenite !/_w- A Pyroken ite Bel-t series (Aregnidlliltiem,qeusatorntzei)te, Strike and dip Adit Prospect Contour Interval 100 feet Datum mean sea fcvel GKOLOQIC M A P O t 'T l U i ItA lN Y CIlISIiK M STK1CT, T . 31 N ., R . 30 W., M ONTANA VERMIGHLirE IN' RAINY OBESE DISTRICT, MONT, 19 Creek, however, a logging railroad crosses to the north bank. The name- Rainy Creek is said to be a corruption of Rennie Creek, the s t r ^ m having originally been named after a prospector, John Rennie, who explored its basin about 40 years ago. F o r a mile above its mouth the valley of Rainy Creek is narrow and steep-sided. Farther up it is wider and its bordering slopes gentle. This upper stretch, together with several small branch val leys, form s a basinlike depression surrounded by mountains 1,000 feet or more high. W ithin it the local relief ranges from 500 to 1,000 feet. The altitude at the mouth of Rainy Creek is somewhat less than 2.100 feet, and the ridges surrounding the basin reach 4,500 feet or more. GEOLOGY BEET SERIES The R ainy Creek basin is underlain chiefly by argillite and quartz ite th a t apparently are the equivalents of the rocks exposed along the Kootenai River west of Libby described by Calkins * as follows: Summary o f section in gorge of Kootenai River between Troy and Libby, l[ont. rs Argillite, greenish gray and dark bine, finely laminated, not continuously exposed________________________________ Quartzite and indurated sandstone and shale, reddish purple and green___ , _________________________________ 'J___ Argillite grading into sericitic quartzite, mainiy___green, but with purple strata interbedded- Argillite, siliceous, greenish gray, in part somewhat calca reous and weathering to a yellow color; dip flat, about___ Limestone, cream-colored, weathering somewhat yellow, with some partings of green argillite, exposed near Kootenai F a l l s ____ ._________________________________________ Shale, indurated, and shaly limestone and quartzite, purple and gray-green, with some calcareous bands____________ Argillite, mostly greenish gray, weathering yellow as if cal careous, sun-cracked and ripple-marked_____________ Argillite, purple___________________________________ Argillite, gray-green_______________________________ Fcety <300 1,250 1,400 1,000 30 600 3,200 5 100 11,285 No detailed examination of these rocks was made in the Rainy Creek area, but in general they exhibit moderately steep dips and open folds that trend northwestward Near the borders of the intru sive stock described farther on the argillite is altered to a faintly banded hornstone; elsewhere the rocks show the effects of regional metamorphism only. They doubtless belong to the Algonkian Belt series. =Calkins, P. C.. A gcolosical reconnaissance in northern Idaho and northwestern Montana: r . S. Goo!. Survey Bull. 3S4, p. 70, 1909. \ z r i lf 2 0 ' J UTIONS TO ECONOMIC GEOLOGY, 1088, PART I PORPHYRY Small dikes of a rather- dark gray rock th a t is classified as qy krtz hvtito porphyry arc apparently the oldest intrusive rocks present. They penetrate the Belt series in m any places, hut none were seen, cutting the other igneous rocks. They consist of phenocrysts of whits feldspar (plagioolase) in a fine-grained groundtnass made up of quartz, feldspars (orthoekse, plagioclase), and alteration products, including upidolu, serieite, chlorite, caleite, and. biotite. INTRUSIVE STOCK A slock of alkaline rocks intrusive into the Belt series underlies an area of about 6 square miles in the basin of Itainy Creek, (See pi. 1.) I t is composed of pyroxenite and syenite and their alteration products; the pyroxenite is the older of the two. These rocks, espe cially the pyroxenite, are much less resistant to weathering and ero sion than the surrounding Belt rocks, and a basin has, therefore, developed in them. Pyroxmtte.--A coarse-grained pyroxenite composes about twothirds of the stock. I t is a soft darlc-green rock that forms the gentler slopes and offers few natural outcrops. In most places the rock is so friiible that it can be crushed to a sand by squeezing in the hund. In mining operations holes for blasting commonly can be made in this rock with an ordinary anger. Tn mineral composition the rock ranges from nearly unmixed pyroxene to nearly unmixed biotite or its alteration product vermiculitc. Apatite high in fluorine commonly makes up 1 to 10 per cent of the rock, which therefore is the richest in apatite among all the largo bodies o f rock known to the writers. Feldspar (microcline mieropcrlhile) occurs in amounts as much as 15 per cent of the mass. The accessory minerals are chiefly magnetite (or ilmenite) with rarely titanito and garnet. As shown by the analysis of a representative sample taken from a tunnel on the Napoleon claim, the pyroxenite is composed chiefly of the silicates of iron, calcium, and magnesium. The rock contains proportionately less silica and magnesia, and more iron and lime than most pyroxenites, I t is high in phosphorus and fluorine; these ele ments together with much of the excess of lime are contained in the apatite previously mentioned. An unusually interesting feature is the presence of a noteworthy amount of vanadium.3 The complete analysis follows: 3 J.ucaeu, IS. S., uutj Hum, W. 1'., up cl t., p. 203. ^ y- VERMIOULITE IN RAINY CREEK DISTRICT, MONT. / 21 Analysts of pyroxm ite from Rainy CreeTc, Mont. CAuelyzud by George Steiger In tbe laboratory of tbo IT. S. Geological Survey. Nickel tpt tested for. Specific gravity, 3.417, measured on a full-sized band atieclmenl Per cent ........ . . ______ 37.47 m , .......... ............ Pat cent a a AIjO-i,______________ - _______ 2.86 J?=0__________________ __ .1.33 _______________________ 11-77 S............ ................................................. 04 FeO________________________ 7.83 F ---------------------- ------------------ .36 MgO............................................... 10.12 V=0>------------------------------------- . 12 run ______ _ ______ 21. ns M u m ___________ __ , ig Na=0----------------------------------- -47 BaO_____________ _________ . 06 V in ...................... . sw SrO________________________ .14 H =0~---------- --------------------- H a O + ______________________ 'T'to- ...... ........ . -27 100.77 1..0773 Less O ____________________ .02 Z rO ________________________ None. 100,75 Syenite.--About one-third of the Rainy Creek stock consists of syenite, the main body of -which occupies an area of about 2 square miles in the south-western part. In addition many small bodies of syenite cut the pyroxenite, only the larger of "which are indicated on the map. Much of the syenite is variable in texture, and the mass is probably made up of several separate but related intrusive bodies. The rock of the main body is medium to coarse grained, nearly white where fresh but iron stained on weathered surfaces. I t is composed chiefly of intergrown potash and soda feldspars (micro line micropertliite), with about 15 per cent of secondary muscovite in coarse plates. Accessory and secondary minerals, which as a rule are present in small amounts, include dark hornblende, fluorite, apa tite, titanite, rutile, biotite, and garnet. The dikelike body that projects into the ridge north of Kearney Creek is a medium-grained greenish-gray to nearly white rock with numerous streaks and bunches of a darker color. I t is also made up chiefly of micropertliite. The darker parts are rich in pyroxene and. titanite. A dike of syenite at the northern extremity of the stock is opened for nearly 100 feet by a tunnel. This rock is giant grained and composed mostly of intergrown potash and soda feldspars (perthite) cut by very numerous veinlets of green pyroxene (diop- sidic aegirite). South of the stock in the Belt rocks, on the ridge north, of Thomas Creek, is a small dike of nepheline syenite. This rock varies irregu larly from fine to coarse grained, and the coarser grains have diam eters as great as 7 inches. I t is composed chiefly of the soda feldspar albito, the closely related mineral nepheline, and the potash feldspar microclino in nearly equal amounts. In addition there are small amounts of aegirite, apatite, and magnetite and secondary fluorite 22 { JUTIONS TO ECONOMIC OEOt.OOY, 1028, 1'AItT I and zenlifo. In (ho hand specimen the rock is seen to consist mainly of wluto feldspar. 'Hie nephditie occurs in crystals several inches across, which on account of their brown tin t and greasy duster how plainly in contrast with tho porcelain-lilcc feldspar. G itA NOTE AND MONZONITE A few mull dike of nearly white granite cut the Belt rocks, and one sucit dike a few inches wido was observed to penetrate the syenite. Tin* rock is composed mainly of feldspar and quart'/ with small amounts of pyroxene., apatite, titanile, Uuorite, and magnetite. On (he Ada claim a small dike that cuts the pyroxenito shows smull porphyriiic crystals of feldspar and green hornblende in a fine groundmass. It is to bo classified as quartz monzonite porphyry. HYDBOTHEBMAL METAMOBPHISM Changes in the stock by the action of hot solutions have been so widespread and so unusual in character as to deserve special notice. The principal minerals produced by these changes are white mica, aegiritc, aegirito-cliopside (both locally vanadiferous), vermiculite, and fibrous amphiboles. Locally titanite and feldspars axe de veloped, and also quartz veins containing chalcopyrite, pyrite, galena, sphalerite, slroiitianitc, and other minerals. In the following pages the present or prospective economic value of several of the minerals is discussed. m in e r a l d e p o s it s VEBMICTJ1OTE nhwttctc)'.--'['lie vermiculiles are micalike minerals that give off much water when heated nnd therefore exhibit the physical character of exfoliation. Some kinds are described as slowly opening out into long wormlike threads, hence the group name. Dana'-1 lists more than a dozen varieties of vermiculite from different places. The variety from West Chester, Pa., called jefferisite resembles the vermiculito from Kainy Creole more closely perhaps than any of the others. Dana describes it as'occurring In broad crystals or crystalline plates. Surface o f plates often Irlangalarly marked liy tins crossing o f lin e s a t angles o f 00" nml 120. C leavage: Basal, eminent, flexib le, alm ost brittle. 11. =3.11. O. - 2.30. Luster pearly on cleav age surfilce, Color dark yellowish brown anil brownish yellow ; light yellow by transmitted light.; also greenish yellow. ifeneral omem/ieet.--Vennicnlite is a constituent of some altered igneous rodcs, and it goncnilly occurs mixed with other mituTals and .T. ii , TIw nyrfU*m of uilitt*raIotfy, DuBerluttvo tiilnuruloyy, tilli ) New York ' *}iti W'llvy Si tjonsi, JLDOD. yy. UC1-UU8, } V VEKM1CTJUT15 IN TtAIttY CHEEK. EISTtUCT, MONT. ' 2 S thus distributed through the rock mass. In a few places, however, it is\found in almost clean or nnmixetl bodies large enough to line. Bodies that have a diltelikc form and range from 1 to C feet in width are reported from North Carolina. So far as known no commercial use has keen made of them. A deposit in Chaffee County, Colo., is described by S terrctt5 as follows: A hydrated form of bloUte mica found about 5 miles Koutheaslwaril of Hecla, iu the I 'urret lining district, has been used 5 the industries during (lie last few years. The material is ruined and handled under the name of tnng ash. by th e Denver Mining & Manufacturing Co. by calcining the micu ns it conies from Uio mines mid then crushing and sizing, a ground product with a rich golden-bronze to sliver color mid metallic luster is olduinod. This is suitable fo r various decorative purposes. Because of the expansion and exfoliation the mica undergoes when culcined a little of the crude product will make a large quantity of the calcined product. The finished tang ash is light, and a small quantity will spread over a large surface. According to Mr. W. W. Kirby, secretary of the company, the mica is found In veins th a t lie between gray granite and hard black schist and th a t reach in places a thickness of 4 fe e t I t occurs in shoots about 40 feet long, very much like ores in metalliferous veins, and forms solid masses of crystals, the largest 2 or 3 inches in diameter, bunched together at different angles. In the parts between the ore shoots a sim ilar variety of mica forms about 50 per cent of the filling. The mica is greenish to brownish black. Tile folia are flexible and inelastic. When heated- they swell and exfoliate v ary much like vermiculite. The laminae of Uio calcined product are sufficiently separated and brittle to break down into a line scaly product, which exhibits the colors und luster already meulioned. Deposits of vermiculite in the T urret district, 14 miles north of Salida, 9 miles from lola, Gunnison County, and at Westcliffe, Custer County, Colo., are described, briefly by Alderson.0 The largest of these deposits, the one at Westcliffe, has a maximum width of more than l'i feet mid is more than 30 feet long. Oticvn'V&nce in the Iiainnj Oreeh district.---A body of vermiculite in the ituiny Creek district that is being developed by the Zonolite Co. on the spur north of Kearney Creek is much larger than any deposit' heretofore known. I t presents no natural exposures, but its outcrop and the slopes below are mantled with a yielding slippery soil com posed chiefly of micalike flakes. As incompletely shown by the work ings so for made, this body appears to be of dikelilce form and at least 100 feet wide and 1,000 feet long. I t extends to a depth of more than 100 feet, its lower lim it not being shown. Several smaller bodies of vermiculite occur in the ground of the Vermiculite & Asbestos Co. on the northwest slope o f the same spur. There a ' Sterrutt, D. 13., Mica deposits of the United States: U. S. Qeol. Survey Bull 740 u go J!>23. ' "MOi-rsun, V. ('., .leiferlsiie, Colorado School of Mines, no date. > 111027--29---- 1 ) 9A JftOtiS TO ECONOMIC OKOI.OOV, 1025, PAKT I iuimcl penetrates six bodies that range from 1 to 4 feet in width. They are of Hat lenslilce or tabular form, and most of them are defi nitely sepa ralutl from the wall rock by fault or slip planes, Tn<>din- plete oxpoMitvs of several oilier similar bodies ere made by smaller workings. Tbu vermiciilite is an aUorntion product of biotile and locally is one. of the main constituents of the pyroxenite mass. In open cuts ami funnels that arc scattered over the upper p a rt of the spur north of Kearney Creek it appears generally to make up SO per cent or more of the rock. Samples representing areas of several square feet at different places in the workings of the Vennicnlite & Asbestos Co. contained from 30 to 84- per cent of venniculile. Apparently there is a huge amount of such mixed material. No analyses showing the chemical composition of the vermiculite from Rainy Creek arc available. Specimens from different places described by Dana7 are all hydrated silicates of magnesium and alu minum containing more or less iron. Production and uses.--As an economic product vermiculite is com paratively new. An unknown but probably small amount has been mined in Colorado. I n the Rainy Creek area near Libby, M ont, the Zonolite Co. reports 1,500,000 pounds mined and converted into the heat-expanded product zonolite and 100 tons sold in the crude form. Prices range from $10 or less a ton for the crude vernriculilc to $20 or m o re a Ion for zonolite. The most striking features of the ver- miculito from Rainy Creek are its properties of expanding enor mously when heated and at the same time assuming golden or silvery lusters. The expanded material floats on water ancl is nearly as light as cork. I t appears to have a very low heat conductivity and to be capable of resisting high temperature. These qualities a t once sug gest it to be useful for heat and cold insulation and sim ilar purposes. Uses repented by the Zonolite Co. include fireproof roofing, plaster, and wall board, packing for safes and refrigerators, acoustic and sound-deadening plasters, pipe and boiler covering, electrical insula tion, and wall-paper decoration. EIBROTTS AMPHIBOLES Locally the pyroxene (diopside) of the large pyroxenite mass has been changed by hydrothermal metamorphism to an amphibole offibrous habit, related to tremolite. The minerals known commer cially us amphibole asbestos are more or less useful, their value depending on their quality and the relative location o f the deposits. Amphibole asbestos is found in many places in the Appalachian and * Dana, J. I)., op. dt,, p. 005. 4 > VEUJIXOUUTIO IN ItAINY CHEEK DISTRICT, MO. 25 western mountain regions. Usually it is associated with igneous rocks and occurs as veins and bodies of dikelilce form. The princi- paisVodies th a t have been worked are in Georgia. I n recent years small amounts have been mined in North Carolina, Virginia, and Maryland. L ittle is known of the deposits in the Western States, except one near ICamiah, Idaho, which is described bj H ille r8 as including h alf a dozen ledges within a few square miles, The lni'gest of these ledges is lenticular in form, about 200 feet long and 40 feet wide. In the R ainy Creek district in Montana the workings of the Ver- njicnlite & Asbestos Co. expose several bodies of amphil ole asbestos which are of dikelike or tabular form and of different v ridths. The largest, as exposed by open cuts, appears to be 100 feet <r m ore long and from a few feet to 14 feet wide. A body 4 feet o more wide exposed in the face of a tunnel at a depth of 150 feet may be the downward continuation of the same deposit. Several smaller bodies are exposed in other workings. Samples representing the different bodies show the amphibole to be mixed with 1 to 10 per cent of other minerals, chiefly vcrmiculite and unaltered pyroxencl I n other places the country rock is particularly rich in amphibole. A sample across a w idth of 16 feet of the rock as exposed by a [short tunnel contains, in round figures, 75 per cent of amphibole, 15 per cent of pyroxenite and apatite, and 10 per cent of vcrmiculite1. A sample representing another body 50 feet wide consists of 50j per cent of amphibole, 30 per cent of pyroxenite, and 20 per cent o i vermiculite. In several places elsewhere on the spur north of Kearney Creek the pyroxenite appears to be comparably rich in. fibrous amphibole. Doubtless, i f necessity arose, the fibrous mineral could jbe separated from the other rock constituents, and in that event the richer parts of the pyroxenite mass might be the source of a very large amount of the fibrous mineral. [ As commonly understood, the term asbestos embraces the fibrous varieties of several minerals, including anthophyllite, tremolite, acti- nolite, and erocidolite, which belong to tire amphibole group, and chrysotile, a variety of serpentine. The usefulness of tnese minerals depends on th eir resistance to heat and the strength alnd flexibility of their fibers. A ll the varieties mentioned except clocidolite are about equally resistant to heat. I The tremolite and anthophyllite asbestos are more resistant to acids than chrysotile and erocidolite, but in flexibility Iand strength of fiber chrysotile and erocidolite are far superior to the; others. The Dffler, a. S,, U. S, Geol. Survey Bull, 4T0, pp, [519, C29, 1911. 26 l Jim O N S TO KOONOMTO OISOUKJY, li)28, PART X asbostiform minerals arc classified also as cross fiber ancl slip fiber, according to whether the libers n,ra crosswise or parallel to the -rolls of (he body. Muss fiber is the name applied (o material in >fhich (lie fibers or groups of libers stand a t various angles. Most of the elu-ysotile and the better or more valuable grades of amphibole asbestos occur as cross fiber in narrow veins that compose but a, small part of tile rode removed in mining. The cheapest grades of asbestos are mass liber amphibole, which, however, is commonly found in bodies of fairly large siy.e. Thu annual production of amphibole asbeslos in the United States from 1015 to 1025, as reported in the volumes of Mineral Resources, lias ranged from 42 to 1,415 tons. The average price during the same period ranged from $8 to $1GQ a ton. In 1922, when the lastmentioned price was attained, the amount produced was only 42 tons, most if not all of which was a high-grade cross fiber from Pylesville, Md. The years of low price were years in which the produc tion increased and was made up chiefly of mass-fiber anthophyllite. As some of the more valuable cross fiber is included in the total amounts reported, the price of mass fiber in 1925, for example, must have been somewhat less than $9 a ion. The bulk of the amphibole asbestos produced in recent years in the United States has come from Georgia. Small amounts have born reported from Maryland, Virginia, North Carolina, California, anti Washington. The deposit near ICumiah, Idaho, previously men tioned, Inis been operated intermittently since 1916, small shipments being made in 1017 and 1025. Most of the product reported has been used us a constituent in millboards, roofing, flooring-, plasters, cements, paint filler, pipe coverings, and similar articles. A small part has hern used for making chemical fillers, for which, as already explained, the amphibole varieties, because of their resistance to acids, are particularly well suited. However, material for this pur pose must be exceptionally clean, and free from impurities of any sort, and in general its value for any purpose varies according to the strength and separability of its fibers. A small amount of mnphibolo asbestos 1ms been mined in (he Rainy Greek district for experi mental purposes, but no commercial production is reported. The asbestos from Rainy Creek is related to tremolite, hut the pres ence in it of considerable soda nod ferric iron suggests th at it will be less resistant to heat than the true variety of tremolite. Near the surface the asbestos is rather soft and easily separated or iiberized. The libers are weak and inelastic and break into short pieces, but they compose a fluffy mass that to all appearances is similar to the general ) VERMIOULITE IN RAINY CREEK DISTRICT, MONl / 2 7 run of amphibole mass fiber. Samples from places not affected by vvgatbering consist of rather harsh fibers th a t are not easily sepa rated ns those in the weathered material. To obtain a ^suable prod uct more or less impurities would need to be separated Ifrom all the bodies th at were seen. The value of the Rainy Cicek deposits ap_.p...a. r..e..mnti1l<y>> d.I neMpennn d/ins on the /dI e>v..e1lo__p__m___e_nit. o. _ffl n. .e. a. r_-t_b_y_ m ar1I.cetts.. E E I/D S P A R Most of the large mass of syenite in the Rainy Creekldistrict is o f fairly uniform composition. I t is made up chiefly of alkaline (pot ash-soda) feldspars with about 15 per cent of white mica! (muscovite) in aggregates of coarse plates. Ferromagnesian minerals are almost entirely absent, but some magnesia is present in the mica, and a little iron is indicated by the characteristic stain. In the United States considerable alkaline feldspar is used in m ak ing pottery, chinaware, porcelain, and other ceramic products. Most of the quarries are near the eastern seaboard, where feld'spar deposits are locally abundant and where the ceramic Industrie! are concen trated. A few are in California. The value of any deposit depends on its accessibility, nearness to markets, size, and quality. The body a t Rainy Creek is of large size, but whether its quality will meet economic requirements has not been determined. I t is] easily accessible, but it is rather distant from established markets. COPPER, READ, ZINC, AND VANAKITJM Veins that are found chiefly in the pyroxenite area were partly ex plored several years ago, as mentioned on page 18, in ja search for metalliferous minerals. One of the veins, which is develpped by some short tunnels and shafts on the Napoleon and Copper Antler claims, is about 10 feet wide. The middle p art is chiefly quartz with scat tered grains of galena and chalcopyrite. N ext to the walls are zones a few inches wide made up chiefly of vanadium-bearing aegirite, microcline, strontianite, celestite, pyrite, and chalcipyrite w ith smaller amounts of quartz, fluorite, galena, and sphalerite. A repre sentative sample of one of the zones,.analyzed by R. C.jWells in the laboratory of the United States Geological Survey, contained 1,92 per cent of copper. 1 The vanadiferous aegirite is the most conspicuous mineral of the zones. I t occurs as black needles as much as h a lf an inch long that project from the walls and also form radiating nodules or spherulites embedded in the other minerals. An aegirite-augite (dionside) occurs 28 co. J T I O N S TO E C O N O M IC G E O LO G Y , 1 0 2 8 , 3?A R T I also in vein lets in the form o nodules itn inch or less in diameter composed of line radiating fibers. The composition of these iv/o pyroxenes is ns follows: t .In//,'.7 of ruiHuUferous acylrite and aiujirUe-amjito from- the, ltaintf OreeJo dU triot, M ontana {An.tly.toil hy W. 1\ Until In tho lohorolory tif tlio 11. S. Ueological HiirvoyJ AuBttUu AuKlritouugilo Augiritu Aeglrltc* ouglie SIOi.. TVIeO>0i.,. V,0,, AliOj. CaO,, MgO. MI'-onOO... 6J.M M 21.7 'S.oa .as 3.06 J.46 .56 A3.32 .36 J2.3H ` 2. BO 1.40 12. IB 7.01 3.70 .48 KttaO......................, ................ x o ......................................... CirjOi .................................... 1I>0~..................... ............... IIjO+...................................... s .................. .......................... nrw 10.40 ,n .00 None. .13 100.81 0.26 .20 Twee, .07 .13 100.40 A dupllcato sample gave 3.SI per oonl. *A duplicate sample gave 2.82 per cent. For a few inches on both, sides of the veins the pyroxene of the . wall rock is changed to a fibrous amphibole related to actinolite and glaucophane. Some calcite, pyrite, and chalcopyrite are present in the altered rock, and locally there are sulphides and large amounts of quarts. On the Joseph claim a small vein that cuts the syenite consists of quartz and a little chalcopyrite and its oxidation products. 'Hie ncphelitie syenite dike south of the main syenite body is also cut by a quartz vein that shows a little pyrite and galena, several small quartz lodes occur in the belt, of slightly metamor phosed sedimentary rocks surrounding the intrusive stock. One of these lodes near the nepheline syenite dike on the divide north of Thomas Crook consists chiefly of quartz and fluorite th at are stained green with topper carbonates. Others farther northwest, near Biiiny Creek, show copper-stained quartz. A few that were observed west and north of the intrusive mass showed quartz only. Although they are of unusual interest for their mineralogy, the veins are probably not rich enough in materials of economic value to be worked under present conditions. INDEX Vago M ay, K. N., development by....................... l8 Amphiboles, fibrous,...occurrenceand utili zation of.. . . . . . . . . . . . 24-27 Asbestos, amphibole,...occurrence.and..utili zation of . --- 24-27 Black sand, composition o f ........................ 14-15 occurrence of, in Washington,-- -------- 11-13 in Oregon and California-- ............ 13 Calkins, V. c.fquoted........................ 10 Collier, A. J., q u o ted ................................. 11 Cypress Island, Wash., platinum od,, . . . . . . . 0-10 Dana, J. IX, quoted-........................... . 22 KeWspur, occurrence of, lb tho Itoiny Creek district, Mont-..---------- . . . . . . . 27 Vaga Motamorphisca, hydrothermal, effects of, In the Rainy Crook district, M ont.. 22 Ocean Beach, Wash., mining o n ...__ 3-4 occurrence of platinum and gold o n ..... 4-4 Olympic Peninsula, Wash,, geography and geology o f ................. ............ . . . 4 Platinum, earlier production of, on Ocean Beach, W ash..____. . . . . ___ ___ i~$ occtirrenceof, In W ash in gton .........__ l - n Pyiosenite, nature and occurrence of, In the Hainy Creek district, Mont___,, 20-21 Bainy Creekdistrict, Mont,, geologic map of. 18 Igneous rocks of........................................ 20-22 location of.............,,................................. is-tf) mineral deposits in........ ............ .......... . . 2a-?a stratified rocks of..................................... w Gold, oarly production of, on Ocean Beach, Steiger, George, analysis b y .- .--. . . . . . . . . . . . 21 Wash................. ......................... 1, Stptratt, X), D., quoted______________ 23 Syenito, irnluro uad occurrence of, in the Hornor, H, 31, quoted....-------------------- - 13 Jtolny Creek district, Mont....... 21-22 Hunt, IV. y ., analysis by..........................-- 2 Thomas, 3 , M., acknowledgment to______ 18 Kumlah, Idaho, jisbeslos produced at-- ---- 25,25 Kootenai Hiver, Mont,,sectionon--....... - 10 Lewis Hiver, South Pork of, geography ami geology of basin of..._______ _ 7*8 mining on.............-- . . . . . -- -- -------- 6-7 occurrence of platinum nod gold on____ 8-0 Vcrmiculite, nature nnd occurronco of, In the Rainy Creek district, Mont. 22,23-24 occurrence of, In Colorado and North Carolina........ . . . . . . . . . . . . . . . . . 23 VonnicutUo & Asbestos Co., operations of. 23-24,25 Zonolito Co., operations of................. 29 28,23