SAI I on ey hed oy ee rte ere SR an Te ee a aan Ro ar ae vis Te) Fares Rennes pred aera sers oe m Serer Rec ances aceww ns Mane leroenen ete hogs aN iets Jeremie tae iaPny oot Si os es Pe roan ea , = ; c P Z 7 - aS cs ees See es Rosier ee ‘ ‘ -, aaa Nae Dimentcweara we Rees s ee : e cage Sores cae terereeesss Ceeecrcme trations een rstnes 3 i = = ae 7 : eae toon stro ae e ne ; ; z ; ; os mrss. See teesoone Pana sae : % a a ; 7 = See mene arewieeertne. Serkan parecer = : , opr va nso: , r an nos Some pean pore aae eet eee ee eG _ Sacer ‘ pea aes meresee. Z 2 = 4 4 Lane ieee ne nent Sean ane e a eN eeT 2 : nner wenn! > epee oT eco ra aneeshatti ¢ Lecobienst co eameeey = oes oe ipower ee : Pct lr yee lorena reese s neni - Bitoe te rev sen care a idee’, 4 SNe eRe ri eee Sect : oe SSD oot Nate ewer vote tors comes ; é ac Fanaa ann narra EES Be 2 tnatetacesseeniseemen eee = Ba Sree een pi eae ass : ~ Sais enisterenpe ale 7 r See ove : spread me s is ; : Se Ss ; oe eerie : ; Rebmwcer neon cone oe eros ; y Sate ccoe eee Gera eeea See Rater : ; : ; eset SS No ea soon Z i Ras : Seon Ieee eee Sacer sere ee ' , ras : eee eae Ssrire eos : : : : . re, re : err een ae ee po cooeemee eer one ese res osenawer = es = Sesice renner eerie or snes wage tae Poas erratic ome eee eee Saloons nde or arpa Say ooreew som nares neat amerr, pevsetracnr stern tertaeeneres ene 4 ; ig't a Let Ad wt ; SMITHSONIAN INSTITUTION _~~ UNITED STATES NATIONAL MUSEUM Bulletin 131 THE MINERALS OF IDAHO BY EARL V. SHANNON Assistant Curator of Geology, United States National Museum WASHINGTON GOVERNMENT PRINTING OFFICE 1926 } ho ; a 1a Re SMITHSONIAN INSTITUTION UNITED STATES NATIONAL MUSEUM Bulletin 131 THE MINERALS OF IDAHO BY EARL V. SHANNON Assistant Curator of Geology, United States National Museum WASHINGTON GOVERNMENT PRINTING OFFICE 1926 ADVERTISEMENT The scientific publications of the National Museum include two series, known, respectively, as ‘Proceedings and Bulletin. The Proceedings, begun in 1878, is intended primarily as a medium for the publication of original papers, based on the collections of the National Museum, that set forth newly acquired facts in biology, anthropology, and geology, with descriptions of new forms and revi- sions of limited groups. Copies of each paper, in pamphlet form, are distributed as published to libraries and scientific organizations and to specialists and others interested in the different subjects. The dates at which these separate papers are published are recorded in the table of contents of each of the volumes. The Bulletin, the first of which was issued in 1875, consists of a series of separate publications comprising monographs of large zoological groups and other general systematic treatises (occasion- ally in several volumes), faunal works, reports of expeditions, catalogues of type-specimens, special collections, and other material of similar nature. The majority of the volumes are octavo in size, but a quarto size has been adopted in a few instances in which large plates were regarded as indispensable. In the Bulletin series appear volumes under the heading Contributions from the United States National Herbarium, in octavo form, published by the National Museum since 1902, which contain papers relating to the botanical collections of the Museum. The present work forms No. 131 of the Bulletin series. ALEXANDER WETMORE, Assistant Secretary, Smithsonian Institution. Wasuineton, D. C., February 23, 1926, II TABLE OF CONTENTS Page RTRGRO GUC HI ON sett seen eRe ser Sse en epee Se es nt 1 Geologic summary of the occurrence of metalliferous ores in Idaho__-_-___-_ 2 Meta production of ldahos- isa lo 22 si s20c2 2 Sess et 4 Metal production for 1918 by counties_.=-=:22-2-2-22--+-2-222-2f Ltt 8 earache PER MNEERTOHESUNLG Geom eter takin nee Sat ern ss Be NE ee 11 Classification of the valuable minerals__—.---2-2--.-.----.-2-2222¢ 2% 42 WESCHIPtONS OT IMIneralse = ee shee oes sess care ee 46 BID) sy era Cl ees Sw SR Fe le ot ge de ie ce ee eh EN 46 Crea ar cere a ae oe ek nee eo ee at ese es IN RE 47 RSMo) oN De SS ra ec AA 48 PTS @ TNT Cig Mi Rene one Se yok oh ee ret ei Sie neo ht ee one te AIEEE AeA 50 IBS Tan ab nee ate sy Se na Re ee ee oe Se fe IO 50 NGO ee ee OE eS ra oe oe ees oe SE 50 EL CG UT eet eee Ss sn es 9 Se Se er BSE 70 Misi omnite: <2. po Sat es er ee oe ee STS 71 Goldedimalgam 2 ee See eb A SOL Pe 292 Ey ae eee ere ae oe ne © 8 en ee Birr nn Rote ona en US 293 imcinchivesSpCscariteyseries” = 25° 55s oe sas <= errors sce See 295 Andragdite-Grossiuuarivesserlesa == s22 6" } a 525 sens ae ute 300 HOTS teri tee aerate ete wwe Fie a Seb eben nin ae en 307 Sea es eee eee ere ee Se Be ete oe een ee See 310 SPY OPO SOP ROLE b) o Sepke eagale yclsg fia ee ae t e 311 BESS TS AL EN ae i aeons pee Ne Me npn ae Puree Neer ENE Te Se 314 VARA ONE ens cag SN Ne Ll gn het nd fe aa ease maa SPaAOREY 316 BIN CSO IZ ary Seen pe es Se aphan Pn ar Va rr a arom ee 319 PASTY GL sail C1 si tics ae meee rae ea atest apis baby See Mire Ser Ae een ae eae 320 gS Eb ee eee ee Ge Se er ee eo ee ee Serene nn cas ee 321 VI TABLE OF CONTENTS Descriptions of minerals—Continued. Page Gaol irae eas Fe EUs ne a Spee eet oY eee gn oe et A nag ea 321 ZOYSIL Gi ihe al ei ha apa IRN LN Lae Ce ie RO Oey See Done pea oes 322 (TIM OZOISU HE sesh ey ee ae ge Eee ARR YEO epee Symes Syne 324 EG IRUEA GO eo 2s ad Jr a Sa vee ci ue te) eae aa 324 PETG PATA NG Goes os ie ot eyes a TRI ae I ae PEG ae Ss Se at eae ip aie 329 RES GET Oost ee aL sale oy er aN en ay ee ee id 331 OH OMG OCIGE See oa Se a eee en A ee tp Ee at 2s nh ee 333° AD iyp ihe Sac nanan eine ae nae gene Aen tea pee acetate ele 334 @alamimee ich Se RE eS: GCOS re rma a reap panne cay ee ipa Na 337 MBOMPMA a IME yee NN ANE ae Lala appa gure ealoyeed als 341 Steevie 3 oS ica Me oe UNH Ae Re ae en ere lp eg 344 TE GaN pe ere cy aa Nee as ST eae Stan ie ete oleae pkey 346 DWord raat i Nei Ss A all aceon nay eats L 346 Te trl Se The I eR wee 22 PU ES Tat ce LY oli ag pe ATR LE a lcs a ne 349 BSS UEL LOE ee eeet aeons eae ie ape Ue cy a ete CaaS Rue Sec NS 353 ADGA UETYD OTH G age ac a ake Et a aL Nea Oe 357 Ga baa it ee ee a Ne a a Ge aA Nea la 357 Airy aT 1G ee i es ea Sie RCL Ce ae rg coe Los OS ep 360 ERHOMSONIGE | 2k oe ge Pal be Sli sc eget a 362 INEUSC OVALE aie ee ely See eh BT Ss TE rn a a NTA a ey ery = eS 365 INVeir pero ibe x ie 2 eyes a Ss AT Sg SN ec 367 MS TECHEG Sessa a pe ee St gat se 367 Bi Gibe aa ke SA a LVS pe ee ees 376 C@hloritoid:2 S23 see a a To Sea epee a aa 377 Serpentine: (228 8 a he oe AC ae eee 383 Grarmnrerithe es a Pa Up ek 8 Ry en ep a 384 Vale sn. 32 ee ep aes = pa ee gt are ee eel Sh Seas he pepe oP 384 Gelerc omit ee ee Ne rs a i pee Ze hr a 384 VCROMMI Gos he Se ee Be aes aC le lanes av EL nto ta oe 385 Montmorillonite and Jueverrierites = - 22s Oe 386 Montmorillonite: . 023.0223 eee eet 387 TG VERFICTIG@ oo 355 oh pie) oy Wi a 6 sn aM pen ae Sane 388 FR AML Gry Sut sia le ea IR a ee pe ps A eet cn Seale SO ne 390 Wranophane ston ae a ne Ps Sue reap oy aE a ee 390 Chrysocolls cc. 4c\ 72S nS Ws \ cee AD eg UR a 391 Copper pitch: ore. a). 25.) kU eta Sn ee 395 @hiloropiall size fer Aa RI ee a a a 397 MEL sir Ors te ac I i a ell a et ed 398 Telingsitie ese os a a eh eee eae Ree 399 VERSUS SREY UGG es apo pues La a a PSEA ert Dl og 400 EST. TN TR TUG os settee I i I hes ce a ne 401 “Lhe Niobates- amb alatese ceo oes 0 2 ey ae cee 404 OGRE US OMI CS se ease es a ee ne a 405 Are burr bya tea ee he SN a hee 405 Samiarskite c= 25 2 ss aa ey et ee ae ho gee ee emu ere 408 ERT Uva Gee es aaa Se ae ge a: ye 409 POS CN yan ais aap ae NS ang nee a ep 409 GIR ETT GS Seta NO LY On Cas ie eta ee 410 POLY CHASE sions a ae cee et a OS CERI RE lp Ae ee 410 IVEQ TUR ZAGC Eee ee ce a oer RE ey CN aa ke 411 AD ATITG se = Sie ae MO ey Aiea pl 1S ge ee Se Se Sa 415 Wollaphaniite.. <2. 5! a0 52) otis et ha eI cat ake cat ee 416 IPyromGrp ite: 21> ayes Se lah ee 50 Lee ea ay Sage ies 2 ee 418 TABLE OF CONTENTS Vil Descriptions of minerals —Continued. Page Viren Ge eee ene eee ne ee eer ee ye eS ee ee a So Se 423 Vier STCITNL GC epee ees Se ree ee Ne Me LE cee ee 424 Oliviecribe meee wee ek oye: 10y Ra eee ee ea ee = 424 iniehial cite seen akan open ie See eT sa ae ae wee 425 Sins Aas ee nc ae att te I re ge eee ee sane ed ett aes 427 es besiege eee ae See ee 429 em apennite 6. = 4 as et i. A eee eo oe eee 431 TO CLL eae er a ee ke ee ee et et Sale 431 Bayldonite.- 2-2... + Bote ened ee ge Sk ee pte eae ea 2 2 ae 433 TE ens eee eae Nein ee Se kee ee ee eS oe eye eS 433 RinGuelmlt Cm ae we Bee el eee ee eee eae ee SSeS 435 Sy CL STIG fs 2 Tee alee et ee rn = 438 Nic eee EO eer Geen oe es eee eee eee 439 inrdwiglee = ses el eee ole eee aes ke cee See eset 440 aritc meee eeene ie ee yh AEN Oa eee Ee et 442 Wmglesiter sc suis S20 (oe oct L oe gee eS ees 444 BUDS CR Talat @ ee epes eae p ye ook eg ee ee a 450 MO echo Tni meen eee ee ee ee ae et es 453 BER OVC LIAN THe epee ae pans Ce anny te ee Oe et See 454 eirvarit eee ee ee ee ee ee ee hea ee eS 455 1), Bar Ses oy lt ree ts ed a Po Ee yt seo pe BO gy a Po 459 Gross eee on ES ee BEL S eee eet sisse ees eee e= 459 PSOMMUB== a= beh es Soest seen eens sce esas 461 Melanterite 25. 225 soak pene esse Hane ---55544-Fee= 461 G@lraloaniiinitemeteas< os oy ee neee ne A eae en BS A eS 462 MOOS TN Ome eee Sirk tre he ee es ee ie ee eee a Se a 463 CAINE Cte ete ed ee ee bake te eNotes 463 INiendozit cusste et sete Pal Se 2 iat eh = Re eee ee ete 464 ickermigite@ne: tee. LOGE MA ae ode oes cetera pan esta eees a5 464 Pets Cee eee el coe ant Sa NE oe Be a ee 465 IBMT BOIATOSIGG 5c 325652 25 Se eee nen ase 5=-s Ss seesepessa2 466 Mice WOULAMILS. PrOUD! 2 o>. oe oe FL ak ea eS 466 RVOlGeAITitemeeentae me ke een mimes Oa Piel ret ae Se ete See 467 En enter et oan Se so a ee ee Se 467 TG EN Grit @ eee ee ec ee Ae See oe ae ae 468 STEEL Ge See es ara PL tg eee tell ae 469 Pow cliite samen ore ke 2 ee ee en eee eee 472 SFL tit ee ae ee rae Seah PN Tien aa SA ne oe oleae 474 Wnlienitemetrer ert ec uter eh ot Se en eo oie oe a eget 474 Miner alacOs letter Me betew se 9 ovate otis Spree ee eS 478 NinnG oxen a ane we be ise, ee er eee 481 So athde reas eel she Aaisraddee esi pice aoe pore - + Si oven ~ ene se > Riser leniadtate aie cradle. BbOk a «seg OF RO, are A soc Ae ie a a Rpennrat item 3 aun y he i es wea eA Ai eM sen ; ie Wiatebe data oss SSTEAG HSS RuMG A soon ehien MA RE Plata Theos tei a sie yan rn op 5 Scns TNE ui phan date nt oe ay singe 5? Rn tt Bera THE MINERALS OF IDAHO By Earu V. SHANNON Assistant Curator of Geology, United States National Museum INTRODUCTION The present volume contains the results of a comparatively large amount of detailed work, principally upon the specimens of Idaho ores and minerals in the United States National Museum. To- gether with these original observations is given a very complete compilation of such literature as pertains to the mineralogy of the State. No such work on the minerals of a geographic area can be complete and there are doubless many occurrences of unusual minerals in the State, of which the writer has no knowledge. New discoveries will doubtless be made with increasing number from year to year and the present manuscript, however carefully compiled, can serve only as a nucleus around which to assemble new facts. No visits to the state on observation or collecting trips have been possible since the work was begun. The writer spent many years as a collector in the Coeur d’Alene district and the statements regard- ing the occurrence of the minerals of that district are based upon personal observation. It has not been possible to visit this region within the past several years or at any time since training was acquired in the recognition of obscure or unusual minerals. The specimens preserved in the National Museum have, for the most part, been random selections of typical ores or specimens selected to illustrate some geologic phenomenon without particular reference to the mineralogy and such unusual minerals as they contain are nearly wholly accidental. In cases where mineral occurrences have not been mentioned, the excuse must be that no specimen was available for examination. Many remarkably fine specimens have been lost through smelting or otherwise and the occurrence of many minerals in abundance in rich ores is now established only by fragmentary records substan- tiated by a single specimen accidentally preserved. It is hoped that one purpose of this publication will be accomplished by arousing interest of persons possessing a latent interest in mineralogy in the preservation of unusual mineral specimens. It has not been possible, during the preparation of this report, to establish connections with a 54347—267—_2 1 2 BULLETIN 131, UNITED STATES NATIONAL MUSEUM single resident mineralogist or mineral collector in the State nor to locate a mining man or prospector having an active interest in min- eralogy.' The National Museum is in a position at all times to carefully identify any mineral which may be sent in for examination free of charge and any specimen of merit which may be donated is assured _ of careful and permanent preservation in the Museum collections. It is to be hoped that in the not distant future there may be established, as a part of the excellent educational system of the State of Idaho, a State museum devoted to the adequate care and preservation of the minerals and other natural history material of the area. Many mineralogic problems which have developed during the course of the work have had to be left more or less in the air because of inadequate material, but each investigation has been pursued as far as the specimens at hand permitted. The general properties, beyond the mere statement of the com- position and crystallization of the minerals, could not be given, and for these reference must be had to a standard textbook. For the more common minerals Ford’s revision of Dana’s Textbook of Min- eralogy is recommended, while for details regarding the rarer species the standard reference work, Dana’s System of Mineralogy, must be consulted. It has not been possible to revise the arrangement of the text, which is alphabetical, by counties, in accord with the recent sub- division and creation of new counties, and the locality references are, with a few exceptions, based upon the county map of 1914. The districts mentioned are essentially as defined in Hill’s Mining Dis- tricts of the Western United States, United States Geological Survey Bulletin 507. The Idaho section of this valuable work is reprinted below, with some additions to the bibliography. GEOLOGIC SUMMARY OF THE OCCURRENCE OF METALLIFEROUS ORES IN IDAHO, Ore deposits are irregularly distributed in Idaho. The extreme southern and eastern parts of the State are almost barren. The mining districts are most abundantly clustered in a region extending from the vicinity of Boise in a northeasterly direction to Lemhi County and the Salmon River Valley. The most important output is that of lead and silver from the Coeur d’Alene district, in the northern part of the State. Gold and silver are derived from the belt mentioned and from veins in Owyhee County, in the southwest corner of the State. 1Since the above was written a number of men, including Dean Francis A. Thomson, of the Idaho State School of Mines, and Stewart Campbell, State mine inspector of Idaho, have assisted by sending unusual minerals from the State tothe United States National Museum for identification. 2 By Waldemar Lindgren. Reprinted without change from U.S. Geol. Survey Bulletin 507, pp. 24-26, 1912. THE MINERALS OF IDAHO 3 The most prominent geologic feature is the great central mountain mass bordering Montana and continued on the north by the Clear- water and Coeur d’Alene Mountains. The eastern part of this mountain mass consists of pre-Cambrian and Paleozoic strata, the extreme western part of Triassic sediments. Between these two lies a great intrusive mass of granitic rocks, principally quartz monzonite, continued on the north and east by smaller intrusive areas. The northern or panhandle part of the State is mainly built up of the steeply inclined sedimentary strata of a thick pre-Cambrian complex known as the Belt series. ‘The southern and southwestern parts of the State are covered by thick volcanic flows of Tertiary age, and this area connects on the east with the lavas of the Yellowstone Park region and Utah. Toward the Nevada line rise a number of short ranges of the type of the Basin Ranges of that State, and the extreme southeastern part of Idaho is occupied by north-south ranges built up of folded and faulted Paleozoic and Mesozoic rocks which may be considered as a northward extension of the Wasatch Mountain system. Pre-Cambrian deposits are not present in Idaho, except possibly in some of the less important districts in the northern part of the State, where mineralization seems to have accompanied intrusion of diabase sills in the Belt series. Here as elsewhere two important kinds of deposits may be recognized—those which were formed shortly after the intrusion of the great central batholith of Jurassic rocks, probably in late Cretaceous time, and those of late Tertiary age which developed after the outburst of the Tertiary lavas in the southern and central parts of the State. The latter are confined to the gold and silver veins of Owyhee County and to a belt of lavas in the central part of the State, including such deposits as the Custer, in Custer County; the Singiser veins in Lemhi County; and the Thunder Mountain deposits in Idaho County. A few unimportant deposits of copper and lead ores of uncertain age occur in the Paleozoic limestones of the ranges in the extreme southeast corner of the State. The upper parts of the late Cretaceous ore deposits have to a considerable extent been removed by erosion and the parts now exposed contain ores formed at considerable depths. They are mainly fissure veins, but in places, as in southern Lemhi County and at the Wood River (Hailey) district, these merge into replacement deposits of galena in limestone. Contact-metamorphic deposits containing copper ores are developed on a rather extensive scale at Seven Devils, near the Oregon boundary line, and at White Knob, in the southeastern part of Custer County, but neither place has proved a large or steady producer. 4 BULLETIN 131, UNITED STATES NATIONAL MUSEUM The veins are contained in a great number of districts situated in and around the borders of the central granitic mass. Most of them carry gold and silver in a quartz gangue with abundant sulphides. Among the best known districts are those of the Idaho Basin and the vicinity of Boise, adjoined on the east by the Sawtooth, Atlanta, and Rocky Bar districts. To the northeast are a number of minor dis- tricts in Lemhi County. To the north are those of Warren, Florence, Buffalo Hump, Dixie, Elk City, and Pierce. Still farther north, surrounding a smaller granitic intrusive mass, cluster the lead-silver bearing veins of the Coeur d’Alene district. The late Cretaceous gold-bearing veins have usually yielded placer deposits of importance, many of which are still producing. The placer districts of greatest present importance are in the Idaho Basin, along the eastern bound- ary of Lemhi County, and at Pierce. The now largely exhausted placers of Warren, Florence, Elk City, and the Coeur d’Alene region should also be mentioned. The fine gold occurring in the sands of Snake River has been described trequently, but the actual production from these deposits is very small. Placers of diminishing importance are situated along Salmon and Boise Rivers. Among the Tertiary veins those near Silver City and De Lamar, in Owyhee County, have been and are still important producers. These veins cut through early Tertiary rhyolites and basalt and bear clear evidence of having been formed within short distances of the present surface. Less well known are the veins at Custer, and also those ot a few districts like Singiser, in Lemhi County, which occur under similar conditions. Low-grade gold ores have been mined at Thunder Mountain, in Idaho County, and are said to form disseminations in rhyolitic tuffs. The Tertiary veins carry gold and silver with a very small amount of sulphides and no important amount of base metals. Idaho contains few deposits of iron, and none of them is mined at present. Iron Mountain, in Washington County, near Snake River, is the principal locality. No rare-metal deposits cf importance occur in Idaho. METAL PRODUCTION OF IDAHO It is deemed appropriate to here give a few figures on the amount and value of the metal production of the State in order to convey some idea of the importance of the mining industry which, after all, is concerned entirely with obtaining and marketing minerals. The following figures are taken from State Mine Inspector Robert N. Bell’s annual report for 1918. Estimated total value of metals mined previous to 1898, $381,315,312. THE MINERALS OF IDAHO CGol@eimetoitices, 91,698. .......2-22ns20-s2---- 2 ebede Bilver fame ounces, 5,206,700... = -<2222ss-2. hol PEls2 at Messe porns 224 70,00 02-22 25222522 ses522lsescut eshte PGS VEU GoS eee os ea we ee Oe Gold#finevounces,, 75,054... 22.222. coe anes Silver, fine ounces, 4,480,174__...._.____----_-------__----_- headssponnds, 86,499 506._.....2.222c2essseenscee ene igi. Woppersqpoundseee 02 Se eee ever e eck oo ll DIME SN BR OmIRVAIMGS: foo a ee es aE ek By direct shipment: Pog mime ounces, LOZ. (52200 2235.62 on else eae Silver; fine*ounces; 4,324 133_..2-- 222.2 25 eco bead, pounds; 96;425,500_5.2 2 Ni ne VOD ee ae ee oe atl an ae Se uke apt 3 otalevalWesas ns ea Oh i eens Through the United States assay office___..._..____.-_-._-_- iHstimated-from: other sources: 22-20 = 2 ee ne eee ee Total value t aa re fh notte SE REL 2, 166, 351. 90 = Sab R eos. sess ana Se ee oS 1, 255, 619. 00 PCE RIE rOuNUES, 12,050,010.) a2 27 “see h ons be aves. elt eee 6, 426, 715. 00 MeneenoundasG0t242 000-8 Hs <= 4 2 eon eee ee a eee 1, 278, 483. 78 Sotal: value for 1918.2 225 se eem eke ae nee s = eee 37, 320, 082. 43 otal value for 191 72< |: 22 S355 See ee eae eee Se 56, 292, 210. 00 Decreases ene iS. 5552 5 et. eae eae 18, 972, 127. 57 THE MINERALS OF IDAHO tl IDAHO MINING DISTRICTS The following section has in large part been taken from Hill’s Mining Districts of the Western United States (James M. Hill, United States Geological Survey Bulletin 507, 1912), from which the Idaho portion has been reprinted without change except for additions to the bibliography. Such additions have been of titles of papers which have come under the present writers notice which are believed to have some interest, either mineralogically or as related to the metalliferous mines. By no means all of the geologic literature relating to the State is mentioned. As previously mentioned this classification of the districts has been followed in the body of this manuscript and it has not been possible to revise the text to conform with recent creation of new counties, since it is often difficult to determine, without tedious research and correspondence, just where a given mine or district lies with reference to the changed geographic boundaries. For references to papers on Idaho geology not mentioned here the reader is referred to John M. Nichols’ bibliographies published as bulletins of the United States Geological Survey, particularly to Bulletins 746 and 747, which are complete for the period from 1785 to 1918, and to subsequent bulletins by the same author. Bulletin of the United States Bureau of Mines, No. 166, A Preliminary Report on the Mining Districts of Idaho, Washington, 1919, should also be consulted. Many references not found in this section will be found in footnotes in the body of the present work. References to pub- lished descriptions, in the following tabulation of mining districts are, unless otherwise stated, to publications of the United States Geological Survey. The abbreviations used in stating these are as follows: M 20 BOneiG Y Monograph. eee Dee ee ea es = Professional Paper. BUS Se cee Bulletin. NARS op Water Supply Paper. Min; Res. 2. Mineral Resources. Hollos= == 22.2% Folio of Geologic Atlas of the United States. Top. sheet____- Topographic map sheet of the topo- graphic Atlas of the United States. The data given for the Black Hornet district may be taken and explained to give a key to the meaning of the abbreviations, etc., used for the other districts. 12 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Apa County 1. Black Hornet (Highland Valley, Shaw Mtn.) Au, Ag (D., Pl.). 8 miles east of Boise, O. 8. L. R. R. Granite cut by granite-porphyry. Veins. Lindgren, W., The mining districts of Idaho Basin and Boise Ridge, Idaho. 18th Ann. Rept., pt. 3, 1898, pp. 703, 705, 707. Min. Res. 1905, pp. 224-225. 1906, pp. 249-250. 1907, pp. 288-289, pt. 1. 1908, pp. 414, pt. 1. 1909, pp. 431, pt. 1. Top sheet Boise. Folio 45, 1898. In the first line are given the three names by which the district is known. The abbreviations Au and Ag are chemical symbols indi- cating that gold and silver are the metals mined in the district, gold, mentioned first, being the more important. The abbreviations D and PI. in parenthesis indicate that both deep mines and placers are worked, the deep mines, mentioned first, being the most important. The second line gives the location of the district with reference to the nearest railroad point—8 miles east of Boise station on the Oregon Short Line Railroad. The next line states that the inclosing rocks are granite cut by granite porphyry and the fourth line that the deposits of the deep mines are veins. The references are to the third part of the Annual Report of the United States Geological Survey for 1898 and to several volumes of the series of reports of the United States Geological Survey on the Mineral Resources of the United States. Finally the last two lines indicate that the district is within the area covered by the topographic map of the Boise quad- rangle and by geologic folio No. 45, both published by the United States Geological Survey. The abbreviations used for the metals mined are as follows: Au Gold. Ti Titanium. Bi Bismuth. Ag Silver. Mn Manganese. U_ Uranium. Cu Copper Ni_ Nickel. VY Vanadium. Pb Lead. Co Cobalt. Sn. Lin. Zn Zine. W_ Tungsten. Mo Molybdenum. Hg Mercury. Sb Antimony. Pt Platinum. Fe _ Iron. As Arsenic. Pd Palladium. Cr Chromium. IDAHO Apa County 1. Black Hornet (Highland Valley, Shaw Mountain). Au, Ag (D, PIl.), 8 miles east of Boise, O. 8S. L. R. R. Granite cut by granite porphyry. Veins. THE MINERALS OF IDAHO 138 Lindgren, W., The mining districts of Idaho Basin and Boise Ridge, Idaho. 18th Ann. Rept., pt. 3, 1898, pp. 703, 705, 707. Min. Res. 1905, pp. 224-225. 1906, pp. 249-250. 1907, pp. 288-289, pt. 1. 1908, pt. 1, p. 414. 1909, pt. 1, p. 341. Top. sheet Boise. Folio, 45, 1898. . Boise (McIntyre). Au, Ag, 3 to 5 miles east of Boise, O. S. L. R. R. Granite cut by granite porphyry and lamprophyre dikes. Veins. Lindgren, W., The mining districts of Idaho Basin and Boise Ridge, Idaho. 18th Ann. Rept., pt. 3, 1898, p. 705. Min. Res. 1907, pt. 1, p. 288. 1908, pt. 1, p. 414. 1909, pt. 1, p. 341. . Snake River placers. Au (Pl.). Stream gravels. Min. Res. 1905, p. 224. 1907, pt. 1, p. 289. Top. sheet Bisuka. Hill, J. M., Notes on the fine gold of Snake River, Idaho. U. S. Geol. Surv., Bull. 620, pp. 271-294, 1915. Bell, R. N., The origin of the fine gold of Snake River. Eng. Mining Journ., vol. 73, pp. 143-144, 1902. Irvine, C. D., Fine gold of Snake River, Idaho. Mining World, vol. 29, p. 917, 1908. Maguire, Don., Snake River gold fields of Idaho. Mines and Minerals, vol. 20, pp. 56-58, 1899. Washburn, W. H., Gold in Snake River bars. Mining Scientific Press, vol. 81, pp. 610, 1900. Cross, C. Whitman, Gold sand from Snake River, Idaho, Colo. Sci. Soc., Proc., vol. 1, pp. 36-87, 1885. The above references apply generally to Snake River placer sand. Apams County. (See Washington.) Bannock County . Fort Hall. Cu, Ag, Au, Pb., 9 miles east of Pocatello, 1144 miles west of Portneuf, O. 8. L. R. R. Paleozoic sediments and diabase. Veins. Weed, W. H., Copper mines in the United States in 1905. Bull. 285, 1906, pp. 107-108. Weeks, F. B., and Heikes, V. C., Notes on the Fort Hall mining district, Idaho. Bull. 340, 1908, pp. 175-183. Min. Res. 1905, p. 225. 1906, p. 250. 1907, pt. 1, p. 289. 1908, pt. 1, p. 414. 1909, pt. 1, p. 341. 14 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Breger, C. L., The salt resources of the Idaho-Wyoming border, with notes on the geology. U.S. Geol. Surv., Bull. 430, pp. 555-569, 1910 Richards, R. W., and Bridges, J. H., Sulphur deposits near Soda Springs, Idaho. U.S. Geol. Survey, Bull. 470, pp. 499-503, 1911. Bear Lake Country 5. Bear Lake. Cu., 4 miles east of Montpelier, O. 8. L. R. R. Triassic ‘‘Red Beds.” Disseminations. Gale, H. S., Geology of the copper deposits near Montpelier, Idaho. Bull. 430, 1910, pp. 112-121. Weeks, F. B., and Ferrier, W. F., Phosphate deposits in the western United States. Bull. 315, 1907, pp. 460-461. Weeks, F. B., Phosphate deposits in the western United States. Bull. 340, 1908, pp. 441-444. Min. Res. 1905, p. 225. 1906, p. 250. 1907, pt. 1, pp. 289-290. (Phosphate and Coal) Schultz, A. R., A geologic reconnaissance for phosphate and coal in southeastern Idaho, ete. U.S. Geol. Survey, Bull. 680, 1918. 6. St. Charles. Pb, Ag, Cu. 5 miles south of Paris, O. S. L. R. R. Paleozoic sediments. Veins and replacements. Richards, R. W., Notes on lead and copper deposits in the Bear River Range, Idaho and Utah. Bull. 470, 1911, pp. 177-187. BineuamM County Mansfield, G. R. and Larsen, E. S. Nepheline basalt in the Fort Hall Indian Reservation, Idaho. Journ. Wash. Acad. Sci., vol. 5, pp. 463-468, 1915. BINGHAM AND BONNEVILLE CoUNTIES 7. Mount Pisgah (Caribou). Cu, Au, Ag. (Pl, D.). 42 miles NNE. Soda Springs, O. S. L. R. R. Min. Res. 1905, p. 225. 1906, p. 250. 1907, pt. 1, p. 290. 1908, pt. 1, p. 415. 1909, pt. 1, p. 342. 8. Snake River placers. Au (PIl.). Steam gravels. Min. Res. 1905, p. 225. 1906, p. 250. 1907, pt. 1, p. 290. 1908, pt. 1, p. 415. 1909, pt. 1,-p. 342. BuaInr County Lakes, Arthur, The Dollarhide Mine [Wood River region] Idaho. Mining World, vol. 24, p. 437, 1906. Umpleby, J. B., Ore deposits in the Sawtooth quadrangle, Blaine and Custer Counties, Idaho. U.S. Geol. Surv., Bull. 580, pp. 221-249, 1914. THE MINERALS OF IDAHO 15 Blake, W. P., Wood River, Idaho, Silver-lead mines. Eng. Mining Journ., vol. 4, pp. 2-3, 1887. Lakes, Arthur, Some of the veins of ore deposits of the Wood River district, Idaho. Mining World, vol. 23, pp. 696-697, 1905. The Wood River mining district of Idaho. Mining World, vol. 34, pp. 307-308, 1911. Shannon, Earl V., Boulangerite, bismutoplagionite, nammaunite, and a silver- bearing variety of jamesonite. Proc. U. 8. Nat. Mus., vol. 58, pp. 589-607, 1920. Additional notes on the crystallography and composition of boulangerite. Amer. Journ. Sci., vol. 1, pp. 423-426, 1921. 9. Antelope. Ag, Pb. 17 miles SW. Darlington, O. S. L. R. R. Min. Res. 1908, pt. 1, p. 416. Prof. Paper 97, p. 119, pp. 1138-114. 10. Camas. Au. 20 miles SW. Hailey, O. 8S. L. R. R. Granite and diorite. Veins. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, p. 208. 11. Dome. Pb, Ag, Cu, Au. 28 miles NE. Arco, O. S. L. R. R. Paleozoic sediments and granite. Veins and replacements. Eldridge, G. H., A geological reconnaissance across Idaho. Sixteenth Ann. Rept., pt. 2, 1895, pp. 264-271. Min. Res. 1906, p: 251. 1907, pt. 1, p. 291. 1908, pt. 1, p. 416. 1909, pt. 1, pp. 342-343. Umpleby, P. P., U. S. Geol. Surv., No. 97, pp. 1138-115. U. S. Bureau of Mines, Buil. 166, p. 68. 12. Elkhorn (Ketchum). Pb, Ag. Station O. S. L. R. R. Paleozoic sediments. Veins. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, pp. 209-211. Min. Res. 1882, pp. 311-312. 1883, 1884, pp. 424-425. 1885, p. 258. Top. sheet Hailey. Jenney, W. P., Graphitic anthracite in the Parker Mine, Wood River, Idaho. Sch. of Mines Quarterly, vol. 10, pp. 813-315, 1889. Era District P. P. 97, pp. 120-122. 16 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 13. Galena. Pb, Ag. 26 miles NW. Ketchum, O. 8S. L. R. R. Min. Res. 1882, pp. 311-312. 1883-84, pp. 424-425. 1885, p. 258. 1886, p. 146. Top. sheet Sawtooth. 14. Hamilton (Clyde). Cu, Pb, Ag, Au. 28 miles NE. Mackay, O.S. L. R. R. Paleozoic sediments. Veins. Min. Res. 1907, pt. 1, p. 291. 1908, pt. 1, p. 416. Umpleby, P. P. 97, p. 113. 15. Lava Creek (Martin). Ag, Cu, Pb. 24 miles SW. Arco, O. S. L. R. R. Paleozoic sediments, granite. Veins and replacements. Eldridge, G. H., A geological reconnaissance across Idaho. Sixteenth Ann. Rept., pt. 2, 1895, pp. 264-271. Min. Res. 1906, p. 251. 1907, pts 1, p. 29 1908, pt. 1, p. 416. Umpleby, P. P. 97, pp. 122-123. 16. Little Smoky. Au, Pb, Ag. 28 miles west of Hailey, O. S. L. R. R. Paleozoic sediments cut by granite. Veins and replacements. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, p. 209. Min. Res. 1908, pt. 1, p. 416. 1909, pt. 1, p. 348. Top. sheet Sawtooth. 17. Little Wood River (Muldoon). Pb, Ag. 20 miles east of Bellevue, O. S. L. R. R. Paleozoic sediments. Veins and replacements. Min. Res. 1882, pp. 311-312. 1883-84, pp. 424-425. 1885, p. 258. 1908, pt. 1, p. 416. 1909, pt. 1, p. 343. Finch, Elmer H. Muldoon district, Idaho. U.S. Geol. Surv., 1917, Prof. paper 97, pp. 106-109. 18. Mineral Hill (Hailey). Pb, Ag, Zn, Cu, Au. Station O. 8. L. R. R. Paleozoic sediments cut by granitic rocks. Veins. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, pp. 190-209. THE MINERALS OF IDAHO 17 Min. Res. 1882, pp. 311-312. 1883-84, pp. 424-425. 1887, p. 107. 1905, pp. 226-227. 1906, pp. 251-252. 1907, pt. 1, pp. 291-292. 1908, pt. 1, pp. 416-417. 1909, pt. 1, p. 343. Top. sheet Hailey. 19. Rosetta. Au, Ag, Pb, Zn. 30 miles west of Ketchum, O. 8. L. R. R. Paleozoic sediments cut by granitic rocks Veins. Min. Res. 1905, p. 227. 1906, p. 252. 1907, pt. 1, p. 292. 1909, pt. 1, p. 335. Top. sheet Sawtooth. 20. Sawtooth. Ag. 40 miles NW. Ketchum, O. 8. L. R. R Granite. Veins. Min. Res. 1885, p. 258. Top. sheet Sawtooth. 21. Snake River placer (Neeley). Au (PI). Neeley Station, O. 8S. L. R. R. Stream gravels. Min. Res. 1905, p. 227. 1906, p. 252. Hill, J. M., Notes on the fine gold of Snake River, Idaho, U.S. Geol. Surv. Bull. 62, p. 292, etc., 1915. 22. Soldier. Au (Pl). 33 miles north of Gooding, O. S. L. R. R. Stream gravels. Min. Res. 1908, pt. 1, p. 417. 1909, pt. 1, p. 343. 23. Warm Springs. Ag, Pb, Zn, Au. 12 miles west of Ketchum, O. 8. L. R. R. Min. Res. 1882, pp. 311-312. 1883-84, pp. 424-425. 1905, p. 227. 1906, p. 253. 1907, pt. 1, p. 292. 1908, pt. 1, p. 417. 1909, pt. 1, p. 343. Top sheet Sawtooth. BotsrE County Jones, E. L., jr., Lode mining in the Quartzburg and Grimes Pass belt, Boise Basin, Idaho. - U. 8. Geol. Surv., Bull. 640, pp. 83-111, 1916. Lindgren, W., Monazite from Idaho. Amer. Journ. Sci., vol. 4, pp. 63-64, 1897. Mining Scientific Press, vol. 75, pp. 168, 1897. 18 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Shannon, Earl V., On galenobismutite from a gold quartz vein in Boise County, Idaho. Wash. Acad. Sci., Journ., vol. 11 pp. 298-300, 1921. Notes on Anglesite, anthophyllite, calcite datolite, sillimanite, stil- pnomelane, tetrahedrite and triplite. Proc. U. S. Nat. Mus., vol. 58, pp. 437- 453, 1920. Mineralogy of some black sands from Idaho with a description of the methods used for their study. Proc. U. S. Nat. Mus., vol. 60, art. 3, 33 pp., 1921. Notes on the mineralogy of three gouge clays from precious metal veins. Proc. U.S. Nat. Mus., vol. 62, art. 9, 1922. 24. Banner. Ag. 76 miles NE. Boise, O. S. L. R. R. Granite. Veins. Top. sheet Bear Valley. (Coal). Bowen, C. F., Coal at Horseshoe Bend and Jerusalem Valley, Boise County, Idaho, U. S. Geol. Surv., Bull. 531, pp. 245-251, 1913. 25. Moore Creek. Au, monazite (Pl.). . Stream gravels. Top. sheet Idaho Basin. 26. Centerville (Idaho Basin). Au (D, Pl.). 44 miles NE. Boise, O. S. L. R. R. Granite cut by aplite and lamprophyres. Veins, stream gravels. Lindgren, W., The mining districts of Idaho Basin and Boise Ridge, Idaho. Eighteenth Ann. Rept., pt. 3, 1898, pp. 617-744. Min. Res. 1905, pp. 228-229. 1906, p. 253-254. 1907, pt. 1, p. 293. 1908, pt. 1, pp. 418-419. 1909, pt. 1, p. 344. Top. sheet Idaho Basin. Hastings, John B., The Boise Basin in Idaho. Eng. Mining Journ., vol. 58, p. 560, 1894, Scientific Amer. Supplement, vol. 38, pp. 15540-15541, 1894. Nye, Robert, The Boise Basin mining district. Mining and Scientific Press, vol. 81, p. 400, 1900. 27. Deadwood. Au (PIl.). 80 miles NE. Boise, O. 8S. L. R. R. Stream gravels. Min. Res. 1907, pt. 1, p. 293. 1908, pt. 1, p. 419. 1909, pt. 1, p. 345. Hill, W. H., The Deadwood placer claims, Idaho. Eng. Mining Journal, vol. 60, pp. 225-226, 1895. Top. sheet Bear Valley. 28. Gold Fork (Roseberry). Au (PIl.). 41 miles SE. Evergreen, P. & I. N. R. R. Tertiary gravels. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. 20th Ann. Rept., pt. 3, 1900, p. 242. THE MINERALS OF IDAHO 19 29. Highland Valley. Au (D, Pl.). 18 miles ESE. Boise, O. 8S. L. R. R. Granite cut by granite porphyry. Veins. Min. Res. 1908, pt. 1, p. 414. 1909, pt. 1, p. 345. Top. sheet Boise. Folio 45, 1898. 30. Idaho City (Idaho Basin). Au, monazite (D, Pl.). 36 miles NE. Boise, O. 8S. L. R. R. Granite cut by aplite and lamprophyres. Veins, stream gravels. Lindgren, W., The mining districts of Idaho Basin and Boise Ridge, Idaho. Eighteenth Ann. Rept., pt. 3, 1898, pp. 617-744. Min. Res. 1905, pp. 228-229. 1906, pp. 253-254. 1907, pt. 1, p. 293. 1909, pt. 1, p. 344. Top. sheet Idaho Basin. Moore Creek. (See No. 25.) 31. Payette River placers (Jacobs Gulch). Au (PIl.). Stream gravels. Min. Res. 1908, pt. 1, p. 419. 1909, pt. 1, p. 345. Top. sheets Garden Valley, Squaw Creek. 32. Quartzburg (Idaho Basin). Au, monazite (D, Pl.). 51 miles NNE. Boise, O. 8S. L. R. R. Granite cut by diorite porphyry. Veins, stream gravels. Lindgren, W., The Mining districts of Idaho Basin and Boise Ridge, Idaho. 18th Ann. Rept., pt. 3, 1898, pp. 617-744. Min. Res. 1905, pp. 228-229. 1906, pp. 253-254. 1907, pt. 1, p. 293. 1908, pt. 1, pp. 418-419. 1909, pt. 1, p. 344. Top. sheet Idaho Basin. 33. Summit Flat (Pioneerville). Au, Ag. 50 miles NNE. Boise, O. 8. L. R. R. Granite cut by aplite and lamprophyre. Veins. Lindgren, W., The mining districts of Idaho Basin and Boise Ridge, Idaho. 18th Ann. Rept., pt. 3, 1898, pp. 617-744, p. 695. Min. Res. 1907, pt. 1, p. 294. 1908, pt. 1, p. 420. 1909, pt. 1, p. 345. Top. sheets Idaho Basin, Garden Valley. 34. Twin Springs. Au (PI). 41 miles East of Boise, S. L. R. R. . Stream gravels. Top. sheet Twin Springs. 20 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 35. Westview (Willow Creek, Pearl, Rock Creek). Au, Ag, Pb. 8 miles NE. Emmett, P. & I. N. R. R., 15 miles north of Eagle, O. S. L. R.R. Granite cut by granite and diorite porphyry dikes. Veins. Lindgren, W., The mining districts of Idaho Basin and Boise Ridge, Idaho. 18th Ann. Rept., pt. 3, 1898, p. 707. Min. Res. 1905, p. 229. 1906, p. 255. 1907, pt. 1, p. 294. 1908, pt. 1, p. 420. 1909, pt. 1, p. 345. Top. sheet Boise. Folio 45, 1898. BonNER CouUNTY (Includes Boundary County) Curtis, W. M., The Priest Lake mining district, Idaho. Engineering & Mining Jour., vol. 82, p. 866, 1906. Soper, E. K., The mining districts of northern Idaho. Mining & Sci. Press, vol. 116, pp. 121-127, 1918. Lancaster, Joseph, The Priest Lake district, Idaho. Mining World, vol. 32, p. 100, 1910. Daly, Reginald A., Geology of the North American Cordillera at the Forty-ninth Parallel. Canada Dept. Interior, Report of Chief Astronomer for 1910, vols. 2 and 8, pp. 1-799, map, 1918. Also issued as Memoir 38 of Canada Geol. Survey, Ottawa, 1915. Daly, Reginald A., The differentiation of a secondary magma through gravita- tive adjustment. (Moyie sill in the Purcell Mountain Range, Idaho-Mon- tana). Festschrift Harry Rosenbusch, pp. 203-233, Stuttgart, 1906. 36. East Shore (Clark Fork). Cu, Au, Ag, Pb. Clark Fork and Hope stations, N. P. R. R. Algonkian sediments (Belt Series). Veins. Calkins, F. C., and MacDonald, D. F., A geological reconnaissance in northern Idaho and northwestern Montana. Bull. 384, 1909, pp. 95-97. MacDonald, D. F., Economic features of northern Idaho and _ north- western Montana. Bull. 285, 1906, pp. 47-48. Min. Res. 1907, pt. 1, p. 294. 1908, pt. 1, p. 420. 1909, pt. 1, p. 345. U.S. Bureau of Mines Bull. 166, pp. 14 and 16-17, 1919. 37. Kootenai. Ag. Pb. 40 miles NW. of Iola, G. N. R. R. 38. Mooyie Yaak. Au, Pb, Ag. (Now Boundary County:) 19 miles NE. Bonners Ferry, G. N. R. R. Calkins, F. C., and MacDonald, D. F., A geological reconnaissance in northern Idaho and Northwestern Montana. Bull. 384, 1909, pp. 107-108. U.S. Bureau of Mines Bull. 166, p. 14, 1919. 39. Pend Orielle (Blacktail). Au, Ag, Cu, Pb. 5 miles east of Westbound, N. P. R. R. Pre Cambrian (Belt?) sediments cut by monzonites. Veins. THE MINERALS OF IDAHO 91 Calkins, F. C., and MacDonald, D. F., A geological reconnaissance in northern Idaho and Northwestern Montana. Bull, 384, pp. 97-99, 1909. MacDonald, D. F., Economic features of western Idaho and Northwestern Montana. Bull. 285, 1906, pp. 46-47. Min. Res. 1907, pt. 1, p. 294. 1908, pt. 1, pp. 240, 421. 1909, pt. 1, p. 345. Top. sheet Sandpoint. U.S. Bureau of Mines Bull. 166, pp. 15-16, 1909. 40. Pine Creek. Au, Ag, Pb, Zn. 12 miles NNW. Priest River, G. N. R. R. Veins. MacDonald, D. F., Economic features of northern Idaho and northwestern Montana. Bull. 285, 1906, pp. 45-46. Top. sheet, Sandpoint. 41. Priest Lake (Coolin). Pb, Ag, Cu. Au. (Now Boundary County.) 25 miles north of Priest River, G. N. R. R. Pre Cambrian sediments, granite. Veins. Min. Res. 1908, pt. 1, p. 420. 1909, pt. 1, p. 345. U.S. Bureau of Mines, Bull. 166, pp. 13-14, 1919. Top. sheet, Sandpoint. BONNEVILLE COUNTY (See Bingham County) Cassia COUNTY Black Pine (Quicksilver). See E. S. Larsen, University of Idaho School of Mines Bull. 2, pp. 65-67, 1920. 42. Connor Creek (Cumora, Stokes). Au, Ag, Pb, Cu. 38 miles SSE. Burley, O. S. L. R. R. Veins. Min. Res. 1905, pp. 229-230. 1906, p. 255. 1907, pt: 1, p. 295: 1908, pt. 1, p. 421. Goose Creek (Coal). See C. F. Bowen, Lignite in the Goose Creek district, Cassia County, Idaho. U.S. Geol. Survey Bull. 531, pp. 252-262, 1913. 43. Snake River Placers. Au. (PI.) Stream gravels. Min. Res. 1905, pp. 229-230. 1906, p. 255. 1907, pt. 1, p. 295. CLEARWATER COUNTY (Formerly part of Nez Perce County) Shannon, Earl V., Description of vivianite incrusting a fossil tusk from gold placers of Clearwater County, Idaho. U.S. National Museum, Proceedings vol. 59, pp. 415-417, 1921. gS BULLETIN 131, UNITED STATES NATIONAL MUSEUM 103. Burnt Creek. Au (Pl.), 35 miles NE. Ahsahka, N. P. R. R. Stream gravels. Min. Res. 1905, p. 237. 1906, p. 261. 1907, pt. 1, p. 304. 1908, pt. 1, p. 429. 1909, pt. 1, p. 351. 104. Moose City. Au (PI.), 80 miles NE. Ahsahka, N. P. R. R. Stream gravels. 105. Musselshell Creek (Weippe). Au, monazite (D, Pl.), 25 miles East of Greer, N. P. R. R. Granite, gneiss, and schist. Veins, stream gravels. Lindgren, W., A geological reconnaissance across the Bitterroot Range and Clearwater Mountains. P. P. 27, 1904, p. 105. Schrader, F. C., An occurrence of monazite in northern Idaho. Bull. 430, 1910, pp. 184-190. Orofino (coal). See Chas. T. Lupton. The Orofino coal field, Clearwater, Lewis and Idaho Counties, Idaho. U.S. Geol. Survey Bull. 621, pp. 99-108, 1915. 106. Pierce. Au (D, Pl.), 28 miles NE. Greer, N. P. R. R. Granite, gneiss, and schist. Veins, bench gravels. Lindgren, W., Mineral deposits of the Bitterroot Range and Clearwater Mountains. Bull 213, 1903, pp. 66-70. A geological reconnaissance across the Bitterroot range and Clearwater Mountains. P. P. 27, 1904, pp. 102-105. Russell, I. C., Geology and water resources of Nez Perce County, Idaho, ~ pt. 2. W.S. P. 54, 1901. Min. Res. 1905, p. 237. 1906, pp. 261-262. 1907, pt. 1, p. 304. 1908, pt. 1, p. 429. 1909, pt. 1, p. 351. CusTER County Jennings, E. P., The Lost Packer copper gold mine. Canada Mining Institute Journal, vol. 9, pp. 54-57, 1906 and Mining & Scientific Press, vol. 92, pp. 435-436, 1906. Kemp, J. F., and Gunther, C. G., The White Knob copper deposits at Mackay» Idaho. American Inst. Mining Engrs. Bulletin, vol. 14, pp. 301-328, (1907) and Transactions, vol. 38, pp. 269-296, 1908. Bell, Robert N., An outline of Idaho geology and of the principal ore deposits of Lemhi and Custer Counties. Fourth International Mining Congress, Pro- ceedings, pp. 64-80, 1901. The Ramshorn mine at Bayhorse, Idaho. Mines and Minerals, vol. 21, pp. 174-176, 1900. Ross, Clarence S., and Shannon, Earl V., Mordenite and associated minerals from near Challis, Custer Co., Idaho. U.S. National Museum, Proceedings vol. 64, art. 19, 1924. Shannon, Earl V., An iron amphibole similar to hudsonite from Custer County, Idaho. Amer. Journ. Sci., vol. 8, pp. 323-324, 1924. THE MINERALS OF IDAHO ; 23 Koch, Louis A., A new occurrence of ptilolite. Amer. ‘Mineralogist, vol. 2, pp. 143-144, 1917. Julien, Alexis A., The volcanic tuffs of Challis, Idaho. (Abstract). New York Academy of Sciences, Trans. vol. 1, pp. 49-56, 1882, Science, vol. 2, pp. 606-609, 1881. 44, 45. 46. 47. Alder Creek (Lost River, White Knob). Cu, Au, Ag, Pb. Mackay Station, Ooo kin RR. Paleozoic sediments, granite and porphyry. Contact metamorphic. Weed, W. H., the copper mines of the United States in 1905, Bull. 285, 1906, p. 108. Umpleby, J. B., Geology and ore deposits of the Mackay region, Idaho. Prof. Paper 97, 1917. The genesis of the Mackay copper deposits, Idaho. Economic Geology, vol. 9, pp. 307-358, 593-594, 1914. Crystallized chrysocolla from Mackay, Ida. Wash. Acad. Sci. Journ., vol. 4, pp. 181-183, 1914. Schaller, W. T., and Larsen, E. 8., Custerite, a new contact meta- morphic mineral. Amer. Journ. Sci., vol. 36, pp. 385-394, 1913. Min. Res. 1905, p. 230. 1906, p. 255. 1907, pt. 1, p. 295. 1908, pt. 1, p. 422. 1909, pt. 1, p. 346. Bay Horse. Ag, Pb, Cu, Au., 76 miles NW. of Mackay, O.S. L. R. R. Paleozoic sediments cut by granite. Veins and replacements. Min. Res. 1887, p. 107. 1905, p. 230. 1906, p. 256. 1908, pt. 1, p. 422. 1909, pt. 1, p. 346. Umpleby, J. B., Ore deposits of northwestern Custer County, Idaho. Bull. 539, pp. 59-76, 1913. Bell, Robert N., The Ramshorn mine at Bayhorse. Mines and Minerals, vol. 21, pp. 174-176, 1900. East Fork. Pb, Ag, 24 miles west of Mackay, O. 8. L. R. R. Min. Res. 1908, pt. 1, p. 422. Umpleby, J. B., P. P. 97, pp. 103-106, 1917. Loon Creek (Casto, Lost Packer). Au, Ag, Cu. 125 miles NW. Mackay, Woolas he. kv. Precambrian sediments cut by granite and capped by rhyolite. Veins. Umpleby, J. B., A preliminary account of the ore deposits of the Loon Creek district, Idaho. Bull. 530, 1912. Weed, W.H., The copper mines of the United States in 1905. Bull. 285, 1906, p. 108. Umpleby, J. B., Some ore deposits of NW. Custer Co., Idaho. Bull. 539, p. 94, 1913. Min. Res. 1906, p. 256. 1907, pt. 1, p. 295. 1908, pt. 1, p. 422. 1909, pt. 1, p. 346. 24 BULLETIN 1381, UNITED STATES NATIONAL MUSEUM 48. Seafoam. Au, Ag, 109 miles NW. Ketchum, O. 8. L. R. R. Min. Res. 1905, p. 230. 1908, pt. 1, p. 422. 1909, pt. 1, p. 346. Ida. Bur. Geology & Mines, Bull. 3, 1920. Top. sheet, Bear Valley. 49. Sheep Mountian. Ag, Pb. 131 miles NW. Ketchum, O. 8. L. R. R. Granite and schist cut by diorite and quartz porphyry. Replacements. Eldridge, G. H., A geological reconnaissance across Idaho. Sixteenth Ann. Rept., pt. 2, 1895, p. 258. Idaho Bureau Mines & Geology, Bull. 3, pp. 18-17, 1920. Top. sheet Bear Valley. 50. Stanley Basin. Au, Ag (D. PI.). 89 miles NW. of Ketchum, O. 8. L. R. R. Granite and porphyry. Veins, stream gravels. Min. Res. 1905, p. 230. 1906, p. 256. 1907, pt. 1, p. 296. 1908, pt. 1, p. 422. 1909, pt. 1, p. 346. Idaho Bureau of Geology and Mines, Bull. 3, pp. 138-17, 1920. Hess, F. L., and Wells, R. C., Brannerite, a new mineral. Journal Franklin Institute, vol. 189, pp. 225-237, 1920. Top. sheet Bear Valley. 51. Washington Basin. Au, Ag. 48 miles NW. of Ketchum, O. 8. L. R. R. Umpleby, J. B., Ore deposits in the Sawtooth quadrangle, Blaine and Cus- ter Counties, Idaho. Bull. 580, pp. 244-246, 1915. 52. Yankee Fork (Custer). Au, Ag. 114 miles NW. of Mackay, O. S. L. R. R. Tertiary volcanics. Veins. Min. Res. 1905, p. 231. 1906, p. 256. 1907, pt. 1, p. 296. 1908, pt. 1, pp. 421-422. 1909, pt. 1, p. 346. Umpleby, J. B., Some ore deposits in Northwestern Custer County, Idaho. Bull. 539, pp. 80-89, 1913. ELMorRE CouUNTY 53. Atlanta. Au, Ag (D. Pl). 89 miles NE. Mountain Home, O. 8. L. R. R. Granite cut by quartz porphyry. Veins, stream gravels. Eldridge, G. H., A geological reconnaissance across Idaho. Sixteenth Ann. Rept., pt. 2, 1895, pp. 253-257. Min. Res. 1905, p. 231. 1906, p. 257. 1907, pt. 1, p. 297. THE MINERALS OF IDAHO 95 53. Atlanta—Continued Min. Res. 1908, pt. 1, pp. 423-424. 1909, pt. 1, p. 347. Thomson, James. The geology of the territory of Idaho, U. S., and the silver lode of Atlanta (Abstract). Geol. Society of Glasgow, Scotland, Transactions, vol. 8, pp. 173-177, 1886. Clayton, Joshua E., Atlanta district. Amer. Inst. Mining Engineers, Transac- tions, vol. 5, pp. 468-473, 1877, and Engineering and Mining Journal, vol. 23, pp. 374-375, 1877. Hastings, John B., The Atlanta Lode, Idaho. Engineering and Mining Journal, vol. 59, p. 28, 1895. Bell, Robert N., Atlanta gold district, Idaho. Engineering and Mining Journal, vol. 86, pp. 176-177, 1908. Rich gold ore found in Idaho. Engineering and Mining Journal, vol. 102, pp. 783-785, 1916. Top. sheet Rocky Bar. 54. Black Warrior. Au, Ag. 99 miles NE. Mountain Home, O. 8. L. Granite cut by quartz porphyry. Veins. Min. Res. 1906, p. 256. 1907, pt. 1, p. 297. 1908, pt. 1, p. 4238. 1909, pt. 1, p. 347. Top. sheet Rocky Bar. 55. Highland Valley. Au, Ag (PI.). 25 miles ESE. Boise, O. 8. L. R. R. Stream gravels. Min. Res. 1907, pt. 1, p. 297. 1908, pt. 1, p. 423. 1909, pt. 1, p. 347. Top. sheet Idaho Basin. 56. Neal. Au, Ag. 25 miles SE. Boise, O. S. L. R. R. Granite cut by granite- and syenite-porphyry and lamprophyre. Veins. Lindgren, W., The mining districts of Idaho Basin and Boise Ridge, Idaho. Eighteenth Ann. Rept., pt. 3, 1898, pp. 699-703. Min. Res. 1905, p. 225. 1906, p. 250. 1907, pt. 1, p. 297. 1908, pt. 1, p. 424. 1909, pt. 1, p. 347. Top. sheet Idaho Basin. 57. Pine Grove. Au, Ag. 45 miles NE. Mountain Home, O. 8. L. R. R. Veins (?). Min. Res. 1905, p. 231. 1906, p. 257. 1907, pt. 1, pp. 297-298. 1908, pt. 1, p. 424. 1909, pt. 1, p. 347. Top. sheet Camas Prairie. 54347—267}——3 26 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 58. Rocky Bar (Bear Creek). Au, Ag. 65 miles NE. Mountain Home, O.S. L. R. R. Granite cut by diorite, diabase, and quartz porphyry. Veins. Eldridge, G. R., A geological reconnaissance across Idaho. Sixteenth Ann. Rept., pt. 2, 1895, pp. 250-253. Min. Res. 1907, pt. 1, p. 297. 1908, pt. 1, p. 423. 1909, pt. 1, p. 347. Top. sheet Rocky Bar. FREMONT CouNTY Horseshoe Creek (coal). See Woodruff, E. G., The Horseshoe Creek district of the Teton Basin coal field, Fremont County, Idaho. U.S. Geol. Survey Bull. 541, pp. 379-388, 1914. 59. Little Lost River (How). Pb, Ag. 25 miles NE. of Arco, O. 8. L. R. R. Min. Res. 1908, pt. 1, p. 424. 1909, pt. 1, p. 347. 60. Skull Canyon (Kaufman). Cu, Pb, Ag, Au. 50 miles West of Dubois, O. 8S. L. R. R. Paleozoic sediments. Replacements. Weed, W. H., The copper mines of the United States,in 1905: Bull. 285, 1906, p. 108. Umpleby, J. B., Prof. Paper 97, pp. 110-112, 1917. Min. Res. 1905, p. 231. 1906, p. 257. 1907, pt. 1, p. 298. 1908, pt. 1, p. 424. IpaHo County Jellum, S. P., Central Idaho gold districts (including Lolo, Pardee, Pierce, New- some, Elk City, Orogrande-Fourmile, Buffalo Hump, Dixie, etc.). Northwest Mining News, vol. 3, pp. 83-91, 107-114, 134-139; vol. 4, pp. 2-6, 31-37, 66- 73, (1908-9). Reprinted, 84 pp., Spokane, Wash., 1909. Maguire, Don, Central Idaho gold field. Mines and Minerals, vol. 19, pp. 289-291, 1899. Schrader, F. C., An occurrence of monazite in Northern Idaho. U. 8S. Geol. Survey, Bull. 430, pp. 184-190, 1910. Silliman, Benjaman, jr., On an association of gold with scheelite in Idaho. Amer. Journ. Sci., vol. 13, pp. 451-452, 1877. Thomson, Francis A., Gold veins of sundry areas in the Idaho batholith. Eng. and Mining Journ., vol. 118, No. 14, pp. 533-540, 1924. 61. Big Creek. Au, Ag, Pb, Cu. 60 miles west of Kooskia, N. P. R. R. Veins. Min. Res. 1907, pt. 1, p. 299. 1908, pt. 1, p. 425. 1909, pt. 1, p. 348. Livingston, D. C., and Umpleby, J. B., A reconnaissance in south central Idaho. Ida. Bureau Mines and Geology, Bull. 3, pp. 7-12, 1920. THE MINERALS OF IDAHO oF 62. Camp Howard (White Bird). Cu, Au, Ag. 12 miles SSW. Grangeville, N. P. R. R. Paleozoic sediments cut by diorite. Veins. Lindgren, W., A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in Montana and Idaho. P. P. 27, 1904, p. 107. Min. Res. 1907, pt. 1, p. 299. 1908, pt. 1, p. 425. 63. Cottonwood Buttes. Au, Ag, Cu. Cottonwood station, N. P. R. R. Pretertiary sediments. Veins. Lindgren, W. P. P. 27, 1904, pp. 106-107. 64. Crooks Corral. Au, Ag (PIl.). 65 66 51 miles north of Evergreen, P. & I. N. R. R. Bench gravels. Min. Res. 1907, pt. 1, p. 299. 1908, pt. 1, p. 425. . Dewey (Harpster). Au, Cu. 7 miles west of Grangeville, N. P. R. R. Slates and schist cut by diorite. Veins. Lindgren, W., P. P. 27, 1904, pp. 105-106. . Dixie. Au, Ag. 78 miles southeast of Grangeville, N. P. R. R. Granite. Veins. Lindgren, W., Mineral deposits of the Bitterroot Range and Clearwater Mountains, Montana. Bull. 2138, 1903, pp. 66-70. A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in Idaho and Montana. P. P. 27, 1904, pp. 91-96. Min. Res. 1905, p. 232. 1906, p. 258. 1907, pt. 1, p. 299. 1908, pt. 1, p. 425. 1909, pt. 1, p. 348. U. 8S. Bureau of Mines Bull. 166, p. 41, 1919. Livingston, D. C., and Stewart, C. A., The geology and ore deposits of the Dixie district, Idaho. Idaho University Bulletin 9, No. 2, 1914. 67. Elk City. Au, Ag (D. Pl). 52 miles SE. of Grangeville, N. P. R. R. Pre-Cambrian gneiss cut by granite. Veins, stream gravels. Lindgren, W., Mineral deposits of the Bitterroot Range and Clearwater Mountains, Montana. Bull. 213, pp. 66—70. A geological reconnaissance across the Bitterroot Range and Clearwater Mountains, in Montana and Idaho. P. P. 27, 1904, pp. 91—96. Min. Res. 1905, p. 232. 1906, p. 258. 1907, pt. 1, p. 299. 1908, pt. 1, p. 425. 1909, pt. 1, p. 348. 28 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 67. Elk City—Continued. Flagg, Arthur L., The Elk City mining district, Idaho. Amer. Inst. Mining Eng., Bull., vol. 76, pp. 571-580; Trans., vol. 45, pp. 113-122, map, 1914. 68. Florence. Au (D, Pi.). 42 miles SSE. of Grangeville, N. P. R. R. Granite. Veins, stream gravels. Lindgren, W., Mineral deposits of the Bitterroot Range and Clearwater Mountains, Montana and Idaho. Bull. 213, pp. 66-70, 1905. The gold and silver veins of Silver City, De Lamar and other Mining districts of Idaho. Twentieth Ann. Rept., pt. 3, 1900, pp. 232- 237. Min. Res. 1905, p. 232. 1906, p. 258. 1907, pt. 1, p. 299. 1909, pt. 1, p. 348. 69. Maggie. Au (PIl.). 8 miles east of Kooskia, N. P. R. R. Stream gravels. Min. Res. 1906, p. 258. 70. Marshall (Resort). Au. Ag (D. Pl.). 50 miles NE. of Evergreen, P. & I. N. R. R. Granite. Viens, stream gravels. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, p. 277. Min. Res. 1905. p. 252. 1907, pt. 1, p. 300. 1908, pt. 1, p. 425. 1909, pt. 1, p. 348. 71. Newsome. Au (D. Pl.). 31 miles east of Grangeville, N. P. R. R. Pre-Cambrian gneiss, cut by granite. Veins, terrace gravels. Lindgren, W., Mineral deposits of the Bitterroot Range and Clearwater Mountains, Montana. Bull. 213, 1903, pp. 66-70. Min. Res. 1905, p. 233. 1906. p. 258. 1907, pt. 1, p. 300. 1908, pt. 1, p. 425. 1909, pt. 1, p. 348. 72. Orogrande. Au, Ag (D. Pl.). 61 miles SE. of Grangeville, N. P. R. R. Pre-Cambrian gneiss cut by granite. Veins, stream gravels. Lindgren, W., A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in Montana and Idaho. P. P. 27, 1904, pp. 94-98. Min. Res. 1905, p. 233. 1906, pp. 425-426. 1909, pt. 1, p. 349. THE MINERALS OF IDAHO 29 73. Profile. Au. 151 miles NE. of Emmett, P. & I. N. R. R. Tertiary volcanics. Veins and impregnations. 74. Robbins (Buffalo Hump). Au, Ag. 50 miles SE. of Grangeville, N. P. R. R. Granite schist cut by granite dikes. Veins. Lindgren, W., Mineral deposits of the Bitterroot Range and Clearwater Mountains, Montana. Bull. 213, 1903, pp. 66—70. A geological reconnaissance across the Bitterroot Range and Clearwater Mountains in Idaho and Montana. P.P. 27, 1904, pp. 99-102. Min. Res. 1995, p. 2383. 1906, pp. 258-259. 1907, pt. 1, p. 300. 1908, pt. 1, p. 426. 1909, pt. 1, p. 349. Flagg, Arthur L., Buffalo Hump mining district, Idaho. Mining World, vol. 38, pp. 813-814, 1913. Whittle, C. L., The Buffalo Hump mining camp, Idaho. Eng. and Mining Journ., vol. 68, pp. 215-216, 1899. 75. Salmon River placers (Simpson). Au, Ag (PI.). Stream gravels. Min. Res. 1905, pp. 233-234. 1906, p. 259. 1907, pt. 1, p. 300. 1908, pt. 1, p. 426. 1909, pt. 1, p. 349. 76. Thunder Mountain. Au, Ag. 139 miles NE. Emmett, P. & I. N. R. R. Tertiary volcanics. Veins and impregnations. Min. Res. 1905, p. 234. 1906, p. 259. 1907, pt. 1, p. 300. 1908, pt. 1, p. 426. 1909, pt. 1, p. 349. L’Hame, Wm. E., Thunder Mountain, Idaho. Mines and Minerals, vol. 21, p. 558, 1901. Thunder Mountain district, Idaho. Mines and Minerals, vol. 24, pp. 207-209, 1903. Umpleby, J. B., and Livingston, D. C., A reconnaissance in south central Idaho. Idaho Bureau Mines and Geology, Bull. 3, pp. 3-6, 1920. 77. Warren. Au, Ag, Cu (D. PIl.). 67 miles NE. of Evergreen, P. & I. N. R. R. Granite cut by lamprophyre dikes. Veins. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept. pt. 3, 1900, pp. 237-249. Min. Res. 1905, p. 234. 1906, p. 259. 1907, pt. 1, pp. 300-301. 80 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 77. Warren—Continued. Min. Res. 1908, pt. 1, p. 426. 1909, pt. 1, p. 349. Hill, W. H., The Little Giant mine at Warren, Idaho. Eng. and Mining Journ., vol. 62, p. 417, 1896. KootTenal County 78. Camas Cove (Tyson). Au (PI.). 18 miles SSE. of St. Maries, C. M. & St. P. R. R. Stream gravels. Min. Res. 1905, p. 234. 1907, pt. 1, p. 301. 1908, pt. 1, p. 426. U.S. Bureau of mines, Bull. 166, pp. 17-18. 79. Lakeview. Ag, Pb. 15 miles east of Athol, N. P. R. R. Pre-Cambrian sediments. Veins. Calkins, F. C., and MacDonald, D. F., A geological reconnaissance in western Idaho and northwestern Montana. Bull. 384, 1909, pp. 43, 60, 62, 95-96. Min. Res. 1905, p. 234. 1906, p. 259. U. S. Bureau of mines, Bull. 166, pp. 14-15, 1919. Top. sheet, Rathdrum. 80. Medimont. Ag. Cataldo and Dudley stations, O. W. R. & N. R. R. Algonkian sediments. Veins. Min. Res. 1905, p. 234. LatTaH County Kunz, George F., On the occurrence of opal in northern Nevada and Idaho. Annals New York Acad. Sci., vol. 21, pp. 214-215, 1912. Sterrett, D. B., Mica in Idaho and New Mexico and Colorado. U.S. Geol. Survey Bull. 530, pp. 375-390, 1913. Shannon, Earl V., Note on a garnet from a pegmatite in Idaho. Amer. Mineral- ogist, vol. 7, pp. 171-173, 1922. 81. Gold Creek (Potlatch). Au (PIL.). Station, W. I. & M. R. R. Stream gravels. Min. Res. 1905, p. 234. 1907, pt. 1, p. 301. 1908, pt. 1, p. 426. U.S. Bureau of mines, Bull. 166, p. 34, 1919. 82. Hoodoo (Blackbird). Au, Cu (D. PIl.). 8 to 12 miles NNE. of Harvard, W. I. & M. R. R. Min. Res. 1905, p. 234. 1907, pt. 1, p. 301. 1908, pt. 1, p. 426. Livingston, D. C. and Laney, F. B., Idaho Bureau of Geology and Mines, Bull. 1, pp. 92-97, 1920. THE MINERALS OF IDAHO 31 83. Moscow. Au (PI. D.). Station, N. P. R. R. Stream gravels. Min. Res. 1905, p. 234. 1906, p. 259. 1907, pt. 1, p. 301. Top. sheet, Pullman. Lemui County Hidden, Wm. Earl., The Hayden Creek, Idaho, meteorite. Amer. Journ. Sci., vol. 9, pp. 367-368, 1900. Ross, Clyde P., A new copper district near Salmon, Idaho. Eng. and Mining Jour., vol. 118, pp. 205-208, 1924. 84. Blackbird. Cu, Au, Ag, Ni, Co. 25 miles west of Noble, C. & P. R. R. Pre-Cambrian schist cut by basic dikes and granite. Veins and replacements. Umpleby, J. B., Ore deposits of Lemhi County, Idaho. Bull. 528, pp. 159-165, 1913. 85. Bluewing (Patterson Creek). Ag, W. 80 miles north of Mackay, O. 8S. L. R. R. Granite. Veins. Umpleby, J. B., Bull. 528, pp. 109-112, 1913. 86. Carmen Creek, Au, Cu. Station G. & P. R. R. Pre-Cambrian schists. Veins. Min. Res. 1907, pt. 1, p. 320. Umpleby, J. B., Bull. 528, pp. 126-127, 1913. 87. Eldorado (Geertson). Au. 10 miles NE. of Baker, G. & P. R. R. Pre-Cambrian schists cut by basic dikes. Veins. Min. Res. 1905, p. 236. 1908, pt. 1, p. 427. 1909, pt. 1, p. 350. Umpleby, J. B., Bull. 528, pp. 123-124, 1913. 88. Eureka. Au, Ag. 8 miles NW. of Salmon, G. & P. R. R. Pre-Cambrian schist cut by granite. Veins. Min. Res. 1907, pt. 1, p. 320. 1908, pt. 1, p. 427. Umpleby, J. B., Bull. 528, pp. 157-158, 1918. 89. Forney (Gravel Range). Au, Ag (D, Pl.). 46 miles SW. of Salmon, G. & P. R. R. Tertiary volcanics. Veins. Min. Res. 1905, p. 236. 1907, pt. 1, p. 320. 1908, pt. 1, p. 427. 1909, pt. 1, p. 350. a2 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 89. Forney—Continued. Umpleby, J. B., Bull. 528, pp. 174-175, 1913. Carr, H. C., Vein structure in the Monument mine. Mining Scientific Press, vol. 98, pp. 557-558, 1909. 90. McDevitt. Au (D, Pl.). Sunfield station, G. & P. R. R. Pre-Cambrian schists. Veins, stream gravels. Min. Res. 1905, p. 236. 1909, pt. 1, p. 351. Umpleby, J. B., Bull. 528, pp. 118-119, 1913. 91. Gibbonsville. Au, Ag (D, Pl.). Station, G. & P. R. R. Pre-Cambrian slates. Veins. Lindgren, W., Bull. 213, pp. 66—70, 1903. P. P. 27, p. 90, 1904. Bacorn, H. C., A complicated Fault system. Eng. & Mining Journ., vol 79, p. 324, 1905. Lincoln, F. C., Gold deposits of Gibbonsville, Idaho. Mining Sci. Press., vol. 105, pp. 47-49, 1912. Umpleby, J. B., Bull. 528, 1913. 92. Indian Creek (Ulysses). Au, Ag, Cu. 17 miles WNW. of Noble, G. & P. R. R. Pre-Cambrian schist cut by granitic dikes. Veins. Min. Res. 1905, p. 236. 1906, pp. 260-261. 1907, pt. 1, p. 320. 1908, pt. 1, p. 427. 1909, pt. 1, p. 350. Umpleby, Bull. 528, pp. 187-138, 1913. 93. Junction. Pb, Ag. Station, G. & P. R. R. Paleozoic sediments cut by acidic intrusions. Veins. Min. Res. 1907, pt. 1, p. 302. 1908, pt. 1, p. 428. 1909, pt. 1, p. 350. Umpleby, J. B., Bull. 528, pp. 114-115, 1913. 94. Kirtley Creek. Au (PI, D.). 10 miles East of Sunfield, G. & P. R. R. Pre-Cambrian shists cut by basic dikes. Veins, stream gravels. Min. Res. 1907, pt. 1, pp. 302-303. 1908, pt. 1, p. 428. Umpleby, J. B., Bull. 528, pp. 124-125, 1913. 95. Leesburg (Arnett Creek). Au (Pl. D.). 16 miles west of Salmon, G. & P. R. R. Pre-Cambrian schists cut by granite. Veins, stream gravels. Min. Res. 1905, p. 236. 1907, pt. 1, p. 303. 1908, pt. 1, p. 428. Umpleby, J. B., Bull. 528, p. 148, 1913. THE MINERALS OF IDAHO 88 96. Mackinaw. Au, Ag (Pl. D.). 20 miles NW. of Salmon, G. & P. R. R. Pre-Cambrian complex cut by granite. Veins, stream gravels. Min. Res. 1907, pt. 1, p. 303. 1908, pt. 1, p. 428. 1909, pt. 1, p. 350. Umpleby, J. B., Bull. 528, pp. 150-152, 1913. 97. Mineral Hill (Shoup). Au (D, Pl.). 13 miles west of Noble, G. & P. R. R. Gneiss cut by granite porphyry and diorite. Veins, stream gravels. Lindgren, W., P. P. 27, pp. 66, 89-90, 1904. Min. Res. 1905, p. 236. 1906, p. 261. 1907, pt. 1, p. 303. 1908, pt. 1, p. 428. 1909, pt. 1, p. 351. Umpleby, J. B., Bull. 528, pp. 140, 141, 1913. 98. Parker Mountain. Ag, Au. 75 miles SW. of Salmon. G. & P. R. R. Tertiary volcanics. Veins. Min. Res. 1905, p. 236. 1906, p. 261. 1907, pt. 1, pp. 303-304. 1908, pt. 1, p. 428. Umpleby, J. B., Bull. 528, pp. 177-178, 1913 99. Pratt Creek. Au, Ag, Pb (Pl, D.). 10 miles east of Baker, G. & P. R. R. Pre-Cambrian schist. Veins, stream gravels. Min. Res. 1908, pt. 1, p. 428. Umpleby, J. B., Bull. 528, p. 121, 1913. 100. Spring Mountain. Pb, Ag, Cu, Au. 38 miles SSE. Junction. G. & P. R. R., 60 miles NE. of Mackey, O.S:.b..K. FR. Paleozoic sediments, cut by diorite. Veins and replacements. Min. Res. 1887, p. 107. 1907, pt. 1, p. 303. 1908, pt. 1, p. 428. 1909, pt. 1, p. 351. Umpleby, J. B., Bull. 528, pp. 86-87, 1913. 101. Texas Creek (Gilmore). Pb, Ag, Au. 19 miles south of Junction, G. & P. R. R., 80 miles NNW. Dubois, Ons. Le Ren: Paleozoic sediments cut by basic dikes. Veins and replacements. Min. Res. 1905, pp. 235-236. 1906, pp. 261, 446. 1907, pt. 1, p. 303. 54347—26}—4 34 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 101. Texas Creek—Continued. Min. Res. 1908, pt. 1, p. 428. 1909, pt. 1, p. 351. Umpleby, J. B., Bull. 528, pp. 104-110, 1913. Nichols, Ralph, Lead-silver mines of Gilmore, Lemhi Co., Idaho. Amer. Inst. Mining. Eng., Bull., vol. 83, pp. 2625-2627, 1913, Trans., vol. 46, pp. 937-939, 1914. Shannon, Earl V., Ludwigites from Idaho and Korea. Proc. U. 8S. Nat. Museum, vol. 59, pp. 667-676, 1921. 102. Yellowjacket. Au (D. Pl). 58 miles WSW. of Salmon, G. & P. R. R. Schist (Precambrian?) cut by rhyolite and andesite-porphyry and minette. Veins. Eldridge, G. H., Sixteenth Ann. Rept., pt. 2, pp. 259-264, 1895. Min. Res. 1905, p. 236. 1906, p. 261. 1907, pt. 1, p. 304. 1908, pt. 1, p. 428. 1909, pt. 1, p. 351. OwYHEE CouUNTY Brown, H. 8., and Mudgett, F. G., The De Lamar mine of Southwestern Idaho. Calif. Journ. Technology, vol. 12, pp.£35—41, 1908. Gale, Hoyt 8., Nitrate deposits. U. 8.fGeol. Survey, Bull."523, p. 36,%1912. Mansfield, G. R., Nitrate deposits in southern Idaho and eastern Oregon. Bull. 620, pp. 19-44, 1915. Shannon, Earl V., On the occurrence of ilvaite in the South Mountain district, Owyhee County, Idaho. Amer. Journ. Sci., vol. 45, pp. 118-125, 1918. The occurrence of bindheimite as an ore mineral. Economic Geology, vol. 15, pp. 88-93, 1920. Boulangerite, bismutoplagionite, naumannite, and, 'a silver-bearing variety of jamesonite. Proc. U. 8. Nat. Museum, vol. 58, pp. 589-607, 1920. An occurrence of naumannite in Idaho. Amer. Journ. Sci., vol. 50, pp. 589-607, 1920. Owyheeite. Amer. Mineralogist, vol. 6, pp. 82-83, 1921. Notes on the mineralogy of three gouge clays from precious metal veins. Proc. U. S. Nat. Museum, vol. 62, art. 15, 1922. 107. Carson (War Eagle, Silver City, Florida Mountain). Ag, Au. 23 miles SSW. of Murphy, I. N. R. R. Granite and Tertiary volcanics. Veins. Lindgren, W., The Gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, pp. 146-157, 1900. Min. Res. 1905, pp. 237-238. 1906, pp. 262-264. 1907, pt. 1, p. 305. 1908, pt. 1, pp. 429-430. 1909, pt. 1, p. 352. Top. sheet Silver City. Folio, 104, 1904. THE MINERALS OF IDAHO 85 108. De Lamar. Au, Ag. 31 miles SSW. Murphy, I. N. R. R. Tertiary volcanics. Veins. Eldridge, G. H., A geological reconnaissance across Idaho. Sixteenth Ann. Rept., pt. 2, 1895, pp. 271-274. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, pp. 106-147. Min. Res., 1907, pt. 1, p. 305. 1908, pt. 1, pp. 429-430. Top. sheet Silver City. Folio 104, 1904. 109. Flint. Ag, Au. 40 miles SSW. of Murphy, I. N. R. R. Granite and diorite. Veins. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, pp. 187-199. Min. Res. 1909, pt. 1, p. 352. 110. Mammoth. Au, Ag. 33 miles SSW. of Murphy, I. N. R. R. Granite. Veins. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, p. 188. 111. Snake River Placers. Au (PI.). Stream gravels. Min. Res., 1907, pt. 1, p. 306. 1908, pt. 1, p. 430. Top. sheet Bisuka, Silver City. Folio 104, 1904. 112. South Mountain. Pb, Ag, Cu. 46 miles SSW. of Murphy, I. N. R. R. Schist, diorite, and limestone. contact metamorphic, veins. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts of Idaho. Twentieth Ann. Rept., p. 3, 1900, p. 188. Min. Res., 1906, p. 446. 1907, pt. 1, pp. 305-306. Bell, R. N., South Mountain, Idaho: Eng. & Mining Journ., vol. 83, pp. 283-284, 1907. SHOSHONE CoUNTY The ore deposits of Shoshone County are nearly all in what is popularly known as the Coeur d’Alene Region or district, which has, for administrative and other purposes, been subdivided into the Beaver, Eagle, Evolution, Hunter, Leland, Pine Creek, Placer Center, St. Regis, Summit, Yreka, and other subdistricts. The following papers apply to several or all of these. 36 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Auerbach, Herbert S., The North Side of the Coeur d’Alene district. Eng. and Mining Journ., vol. 86, pp. 65-70, 1908. Tungsten ore deposits of the Coeur d’Alene. Eng. and Mining Journ., vol. 86, pp. 1146-1148, 1908. Calkins, F. C., Geology and ore deposits of the Coeur d’Alene (discussion). Econ. Geology, vol. 4, pp. 258-261, 1909. Finlay, J. R., The mining industry of the Coeur d’Alenes, Idaho. Amer. Inst. Mining Eng., Trans., vol. 33, pp. 235-271, 1903. Huston, George, Notes on the geology of the Snowstorm mine, Idaho. Eng. and Mining Journ., vol. 90, pp. 1109-1110, 1910. Pritchard formation rocks. Mining World, vol. 36, p. 305, 1912. The copper beds of the Coeur d’Alene. Mining and Sci. Press, vol. 110, pp. 145-147, 1915. Ingalsbe, F. R., The Coeur d’ Alene mining district, Idaho. Eng. Mining Journ., vol. 96, pp. 156-159, 19138. Ransome, F. L., The Coeur d’ Alene district. Mining Mag., vol. 12, pp. 26-32; 1905. Rowe, J. P., Mining in the Coeur d’ Alene district, Idaho. Mines and Minerals, vol. 28, pp. 549, 551, 1908. The Coeur d’Alene mining district, Idaho. Mining World, vol. 29, pp. 739-740, 777-778, 843-845 (1908); vol. 30, pp. 11-14, 89-92, 117-120, 318- 320, 357-358, 428-430, 1909. Wiard, Edward S., Ore dressing in the Coeur d’Alene district, Idaho. Eng. Mining Journ., vol. 88, pp. 1055-1060, 1909. Allen, R. C., Equipment and methods at the Hecla mine. Eng. Mining Journ., vol. 89, pp. 311-3138, 1910. Hershey, Oscar H., Some Tertiary and Quaternary geology of western Montana, northern Idaho, and eastern Washington. Geol. Soc. Amer., Bull. 23, pp. 517— 536, 1912. Genesis of lead-silver ores in Wardner district, Idaho. Mining Sci. Press, vol. 104, pp. 750-743, 786-790, 825-827, 1912. Origin of lead, zine, and silver in the Coeur d’Alene. Mining Sci. Press, vol. 107, pp. 489-4938, 529-533, 1913. Origin and distribution of ore in the Coeur d’Alene, 32 pp. (Private publication, 1916, see Mining Sci. Press, vol. 112, p. 734, 1916.) Genesis of Success zinc-lead deposit (discussion). Econ. Geology, vol. 12, pp. 548-558, 1917. Geology of the Success mine. Mining Sci. Press, vol. 116, p. 470, 1918. Clayton, Joshua E., The Coeur d’Alene silver-lead mines. Eng. Mining Journ., vol. 45, pp. 108-109, 1888. Moore, 8. R., Geology of the Suecess mine. Mining Sci. Press, vol. 116, p. 8, 1918. Umpleby, J. B., Genesis of the Success zine-lead deposit, Coeur d’ Alene district, Idaho. Econ. Geology, vol. 12, pp. 138-153, 1917. Ray, James C., The copper beds of the Coeur d’Alene. Mining Sci. Press, vol. 110, pp. 299-301, 1915. Lammers, Theo. L., The Murray gold belt, Idaho. Mining Sci. Press, vol. 94, pp. 6386-637, 1907. Campbell, W., The microstructure of a complex ore from the Frisco mine, Gem, Idaho. Eng. Mining Journ., vol. 87, pp. 260-261, 1909. Calkins, F. C., and Jones, E. L., jr., Geology of the St. Joe-Clearwater region, Idaho. U.S. Geol. Survey Bull. 530, pp. 75-86, 1913. Economic geology of the region around Mullan, Idaho, and Saltese, Montana. U.S. Geol. Survey Bull. 540, pp. 167-211, 1914. THE MINERALS OF IDAHO ‘37 Shannon, Earl V., Secondary enrichment in the Caledonia mine, Coeur d’ Alene district, Idaho. Econ. Geology, vol. 8, pp. 565-570, 1913. On a supposed new occurrence of plattnerite in the Coeur d’Alene. Amer. Journ. Sci., vol. 36, pp. 427-428, 1913. Crystals of pyromorphite. Amer. Journ. Sci., vol. 43, pp. 325-327, 1917. Notes on unusual masses of plattnerite. Amer. Mineralogist, vol. 2, pp. 15-17, 1917. On mulianite, a new member of the jamesonite group from two localities. Amer. Journ. Sci., vol. 45, pp. 66-70, 1918. Some minerals from the Stanley antimony mine, Idaho. Amer. Mineralogist, vol. 3, pp. 23-27, 1918. Anglesite from the Coeur d’Alene district, Idaho. Amer. Journ. Sci., vol. 47, pp. 287-292, 1919. Linarite and leadhillite from Idaho. Amer. Mineralogist, vol. 4, pp. 93-94, 1919. - The occurrence of bindheimite as an ore mineral. Econ. Geology vol. 15, pp. 88-93, 1920. Petrography of some lamprophyrie dike rocks of the Coeur d’Alene district, Idaho. Proc. U. 8. Nat. Museum, vol. 57, pp. 475-495, 1920. Notes on anglesite, calcite, tetrahedrite, etc. Proc. U.S. Nat. Museum, vol. 58, pp. 487-453, 1920. Boulangerite, bismutoplagionite, naumannite, and a silver-bearing variety of jamesonite. Proc. U. 8. Nat. Museum, vol. 58, pp. 589-607, 1920. Ferroanthophyllite, an orthorhombic iron amphibole from Idaho. Proc. U. 8. Nat. Museum, vol. 59, pp. 397-401, 1921. An occurrence of iron-cobalt-bearing gersdorffite from Idaho. Wash. Acad. Sci. Journ., vol. 14, pp. 275-277, 1924. Hawkins, E. N., and Hawkins, J. D. Plattnerite from Idaho. Amer. Journ. Sci., vol. 38, pp. 165-166, 1889. Wheeler, H. A., Plattnerite from Idaho. Amer. Journ. Sci., vol. 38, pp. 79, 1889. Yeates, Wm. S., Plattnerite and its occurrence near Mullan, Idaho. Amer. Journ. Sci., vol. 43, pp. 407-412, 1892. Stewart, Chas. A., A comparison of the Coeur d’Alene monzonite with other plutonic rocks of Idaho. Journ. Geology, vol. 22, pp. 684-688, 1914. Jones, Edw. L., jr., A reconnaissance of the Pine Creek district, Idaho. U.S. Geol. Survey, Bull. 710A, pp. 1-36, 1919. Umpleby, J. B., and Jones, Edw. L., jr., Geology and ore deposits of Sho- shone County, Idaho. U.S. Geol. Survey Bull. 732, pp. 1-156, 1923. 113. Bald Mountain (Monitor). Cu, Au. 514 miles west of Saltese, Mont. N. P. R. R., C. M. & St. P. R. R. Pre-Cambrian sediments cut by diabase. Veins. Collier, A. J., Ore deposits in the St. Joe River Basin, Idaho. Bull. 285, 1906, pp. 135-136. Pardee, J. T., Geology and mineralization of the upper St. Joe River Basin, Idaho. Bull. 470, 1911, pp. 39-61. Top. sheet Avery. 114. Beaver (Coeur d’ Alene). Pb, Ag, Cu, Au, (D. Pl.). 4 miles northwest of Burke, N. P. R. R. Pre-Cambrian sediments. Veins. Ransome, F. L., Ore deposits of the Coeur d’Alene district, Idaho. Bull. 260, 1905, pp. 274-303. 38 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 114. Beaver—Continued. Ransome, F. L., and Calkins, F. C., The geology and ore deposits of the Coeur d’Alene district, Idaho. P. P. 62, 1908. Min. Res. 1905, p. 240. 1906, pp. 264, 445-446. 1907, pt. 1, p. 308. 1908, pt. 1, p. 481. 1909, pt. 1, pp. 353-354. Umpleby & Jones, Bull. 732, above. U.S. Bureau of Mines, Bull. 166, p. 19, 1919. Top sheet, Coeur d’Alene special. 115. Black Prince. Cu. St. Joe station, C. M. & St. P. R. R. Pre-Cambrian quartzite cut by granite. Veins. Collier, A. J., Bull. 285 (above), 1906, p. 136. Pardee, J. T., Bull. 470 (above), 1911, pp. 39-61. Top. sheet, Avery. 116. Eagle (Murray, Coeur d’Alene). Au, (Pb, Ag). Paragon station, I. N. R. R. Pre-Cambrian sediments cut by acidic intrusives. Veins. Lindgren, W., A geological reconnaissance across the Bitterroot Range and Clearwater Mountainsin Montanaand Idaho. P. P. 27, pp. 108-111, 1904. Ransome, F. L., Bull. 260 (above), pp. 274-303, 1905. Ransome and Calkins. P. P. 62 (above), 1908. Min. Res. 1905, p. 240. 1906, pp. 264, 445-446. 1907, pt. 1, p. 308. 1908, pt. 1, p. 481. 1909, pt. 1, pp. 354, 579. Top. sheet, Coeur d’Alene special. 117. Evolution (Coeur d’Alene). Pb, Ag, Cu, Au. Kellogg station, O. W. R. & N. R. R. Pre-Cambrian sediments. Veins. Ransome, F. L., Bull. 260, pp. 274-303 (above), 1905. Ransome and Calkins, P. P. 62 (above), 1908. Umpleby and Jones (above), Bull. 732, 1923. Min. Res. 1905, p. 240. 1906, pp. 264, 445, 446. 1908, pt. 1, p. 432. 1909, pt. 1, p. 354. U.S. Bureau of Mines, Bull. 166, p. 19, 1919. Top, sheet, Coeur d’Alene special. 118. Hunter (Mullan, Coeur d’Alene). Pb, Ag, Cu, Au. Mullan station, N. P. R. R. Pre-Cambrian sediments. Veins. Ransome (above), Bull. 260, pp. 274-303, 1905. Ransome and Calkins (above), P. P. 62, 1908. Calkins and Jones (above), Bull. 540. pp. 167-211, 1914. U.S. Bureau of Mines, Bull. 166, p. 20, 1919. THE MINERALS OF IDAHO 89 118. Hunter—Continued. Min. Res. 1905, p. 240. 1906, pp. 264, 445-446. 1907, pt. 1, pp. 308-309. 1908, pt. 1, pp. 207-208, 432-433. 1909, pt. 1, pp. 354-355. Top. sheet Coeur d’Alene special. 119. Leland (Burke, Coeur d’Alene). Pb, Ag, Au, Cu, Zn. Burke station, N. P. R. R. Pre-Cambrian sediments cut by monozonite. Veins. Ransome, F. L. (above), Bull. 260, 1905, pp. 274-303. Ransome and Calkins (above), P. P. 62, 1908. Umpleby and Jones (above), Bull. 732, 1923. U.S. Bureau of Mines Bull. 166, 1919. Min. Res. 1905, pp. 240-250. 1906, pp. 264-265, 445-446. 1907, pt. 1, pp. 309-310. 1908, pt. 1, p. 433. 1909, pt. 1, pp. 355-356. Top. sheet Coeur d’Alene special. 120. Pine Creek. Pb, Ag, Zn. 12 miles SSE. Kingston, O. W. R. & N. R. R. Pre-Cambrian sediments. Veins. Calkins, F. C., and MacDonald, D. F., A geological reconnaissance in northern Idaho and northwestern Montana. Bull. 384, 1909, pp. 94-95. Jones, E. L. jr., A reconnaissance of the Pine Creek district, Idaho. Bull. 7104, pp. 1-36, 1919. Brainard, Robt. I., Antimony mining in the Coeur d’ Alene district, Idaho. Mining World, vol. 44, pp. 351-353, 1916. U. 8. Bureau of Mines Bull. 166, p. 21, 1919. Top. sheet, Cataldo. 121. Placer Center (Wallace, Coeur d’Alene). Pb, Ag, Cu. Zn, W. Wallace station, N. P. R. R. Pre-Cambrian sediments cut by monzonite. Veins. Lindgren, W. (above), P. P. 27, pp. 108-111, 1904. Ransome, F. L. (above), Bull. 260, pp. 274-303, 1905. Ransome and Calkins (above), P. P. 62, 1908. Min. Res. 1905, p. 241. 1906, pp. 265, 445-446. 1907, pt. 1, p. 310. 1908, pt. 1, pp. 434, 723. 1909, pt. 1, p. 356. U.S. Bur. Mines, Bull. 166, p. 22, 1919. Top. sheet, Coeur d’ Alene special. 122. Slate Creek. Pb, Ag. 15 miles south of Wallace, N. P. R. R. Pre-Cambrian sediments cut by acidic intrusives. Replacements and veins. Collier, A. J., Ore deposits of the St. Joe River Basin, Idaho. Bull. 285, 1906, pp. 133-134. Calkins and Jones (above), Bull. 530, 1913. U.S. Bureau of mines, Bull. 166, p. 25, 1919. 40 BULLETIN 131, UNITED: STATES NATIONAL MUSEUM 124. St. Joe. Au (Pl). 25 miles west of Iron Mountain, Mont. N. P. R. R. Stream gravels. Calkins and Jones (above), Bull. 530, 1912. Collier (above), Bull. 285, 1906. Pardee (above), Bull. 470, 1911. Min. Res. 1909, pt. 1, p. 356. U. S. Bureau of Mines, Bull. 166 p. 24, 1919. 125. St. Regis (Coeur d’Alene). Au, Cu. Lookout Station, N. P. R. R. Pre-Cambrian sediments. Veins. Calkins, F. C., and Jones, E. L. jr., Economic geology of the region around Mullan, Idaho, and Saltese, Mont. Bull. 540, pp. 167-211, 1912. Ransome, F. L., Ore deposits of the Coeur d’Alene district, Idaho. Bull. 260, 1905, pp. 274-303. Ransome, F. L. and Calkins, F. C. (above), P. P. 62, 1908. Min. Res. 1905, p. 241. 1906, pp. 266, 445-446. 1907, pt. 1, p. 310. Top. sheet, Coeur d’ Alene special. 126. Summit (Coeur d’Alene). Au, Pb, Cu, Ag. 10 miles SE. of Paragon, I. N. R. R. Pre-Cambrian sediments. Veins. Ransome, F. L. (above), Bull. 260, 1905, pp. 274-303. Ransome, F. L., and Calkins, F. C. (above), P. P. 62, 1908. U.S. Bureau of Mines, Bull. 166, p. 22, 1919. Min. Res. 1905, p. 241. 1906, pp. 266, 445-446. 1907, -pt. 1, pp. 3f0—311, 712. 1908, pt. 1, p. 434. Top. sheet Coeur d’ Alene special. 127. Yreka (Wardner, Coeur d’Alene). Pb, Ag, Au, Cu. Kellogg station, O. W. R. & N. R. R. Pre-Cambrian sediments. Veins. Lindgren, W., P. P. 27, pp. 108-111 1904. Ransome, F. L., Bull. 260, 1905, pp. 274-803. Ransome, F. L. and Calkins F. C., P. P. 62, 1908. Umpleby, J. B., and Jones, E. L. Bull. 723, 1923. Min. Res. 1885, p. 387, 1886, p. 146. 1887, pp. 107-109. 1888, pp. 88-89. 1905, p. 241. 1906, pp. 266, 445-446. 1908, pt. 1, p. 434. 1909, pt. 1, p. 356-357. McCormick, E., The ore deposits of Yreka mining district, Idaho. Eng. Mining Journ., vol. 69, p. 404, 1900. THE MINERALS OF IDAHO 41 WASHINGTON AND ADAMS COUNTIES Reid, G. D., The Seven Devils and Snake River district. Eng. and Mining Journ., vol. 84, pp. 401-402, 1907. Packard, R. L., On an occurrence of copper in western Idaho. Amer. Journ. Sci., vol. 50, pp. 298-300, 1895. Bell, R. N., Sapphires in Idaho. Mining World, vol. 26, p. 449, 1907. 128. Black Lake. Au (D, PIl.). 40 miles NNW. Council, P. & I. N. R. R. Min. Res. 1905, p. 242. 1906, p. 267. 129. Heath. Cu, Ag, Au. 24 miles NW. Cambridge, P. & I. N. R. R. Triassic(?) sediments cut by diorite(?). Contact metamorphie(?). Lindgren, W., The gold and silver veins of De Lamar, Silver City, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, 1900, pp. 253-254. Idaho Bur. Mines & Geol., Bull. 1, pp. 83, ete. 1920. Min. Res. 1882, p. 229. 1906, p. 267. 130. Meadows. Au (PI.). 16 miles NE. Evergreen, P. & I. N. R. R. Min. Res. 1905, p. 242. 1906, p. 267. 131. Mineral. Pb, Ag, Cu, Au. 29 miles NNE. Huntington, Oreg., O. W. R. R. & N. Co. Greenstones, quartz diorite. Replacements, veins. Lindgren, W., The Gold belt of the Blue Mountains in Oregon. 22nd. Ann. Rept., pt. 2, 1901, pp. 754-756. Turner, H. W., The ore deposits at Mineral, Idaho. Econ. Geology, vol. 3, pp. 492-502, 1908. 132. Monroe Creek (Weiser). Au. (D. Pl.). 10 miles north of Weiser, O. S. L. R. R.; O. W. R. & N. R. R. Top. sheet Weiser. 133. Placer Basin. Au. 37 miles NNE. of Council, P. & I. N. R. R. Veins. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, p. 253, 1900. 134. Seven Devils. Cu, Au, Ag. 37 miles NW. of Council, P. & I. N. R. R. Triassic (?) sediments cut by diorite. Contact metamorphic. Lindgren, W., The gold and silver veins of Silver City, De Lamar, and other mining districts in Idaho. Twentieth Ann. Rept., pt. 3, p. 249, 1900. , Weed, W. H., The copper mines of the United States in 1905. Bull. 285, 1906, pp. 108-109. 42 BULLETIN 131, UNITED STATES NATIONAL MUSEUM 134. Seven Devils—Continued. Min. Res. 1898 (20th Ann. Rept., pt. 6), pp. 182-184. 1905, p. 242. 1906, p. 267. 1907, pt. 1, p. 312. 1908, pt. 1, p. 435. 1909, pt. 1, p. 357. Beals, Wm., jr., The Seven Devils Mining district, Idaho. Eng. Mining Journ., vol. 69, pp. 345-346, 1900. Palache, Chas., Note on epidote and garnet from Idaho. Amer. Journ. Sci., vol. 8, pp. 299-302, 1899. Melville, W. H., Powellite-calcium molybdate; a new mineral species. Amer. Journ. Sci., vol. 41, pp. 138-141, 1891. Livingston, D. C., and Laney, F. B., The copper deposits of the Seven Devils and adjacent districts. Idaho Bureau of Mines and Geology, Bull. 1, 1920. CLASSIFICATION OF THE VALUABLE MINERALS Inasmuch as the present volume is primarily a mineralogical compilation, no section is specifically dedicated to a discussion of the occurrence of the several valuable metals which are mined in the State. The available information regarding the distribution and occurrence of these metals is, however, pretty thoroughly presented in discussion of the occurrence of the minerals themselves. Thus the gold mines of the State are discussed under native gold, since this is practically the only important gold mineral. Similarly, the lead deposits of the area are described under galena and cerusite, the two most important minerals of the ores of that metal. As a guide to assist in finding information relative to the distribution of the metallic ores, the following classification of the minerals is presented, arranged according to their metallic constituents. ANTIMONY Stibnite, antimony sulphide. Kermesite, antimony oxysulphide. Jamesonite, lead-antimony sulphide. Miargyrite, silver-antimony sulphide. Pyrargyrite, silver-antimony sulphide. Stephanite, silver-antimony sulphide. Polybasite, silver-antimony sulphide. Owyheeite, lead-silver antimony sulphide. Boulangerite, lead-antimony sulphide. Tetrahedrite, copper-antimony sulphide. Cervantite, antimony oxide. ' Stibiconite, antimony oxide. Valentinite, antimony oxide. Bindheimite, lead antimony oxide. ARSENIC Realgar, arsenic sulphide. Cobaltite, cobalt-arsenic sulphide. Arsenopyrite, iron-arsenic sulphide. Niccolite, nickel arsenide. THE MINERALS OF IDAHO Smaltite, cobalt arsenide. Proustite, silver arsenic sulphide. Enargite, copper-arsenic sulphide. ‘Tennantite, copper-arsenic sulphide. Erythrite, cobalt-arsenic oxide. Scorodite, iron-arsenic oxide. Annabergite, nickel-arsenic oxide. Mimetite, lead-arsenic oxide. BARIUM Barite, barium sulphate. BERYLLIUM Beryl, beryllium-aluminium silicate. BISMUTH Bismuth. Bismuthinite, bismuth sulphide. ‘Galenobismutite, bismuth-lead sulphide. Aikinite, bismuth-lead-copper sulphide. ‘Tetradymite, bismuth telluride. ‘Guanajuatite, bismuth selenide. Bismutosphaerite, bismuth carbonate. Bismutite, bismuth carbonate. BORON Tourmaline, iron-aluminium-boron, etc., silicate. Ludwigite, magnesia-iron borate. CADMIUM ‘Greenockite, cadmium sulphide. CERIUM Monazite, cerium phosphate. Also samarskite, gadolinite, aeschynite, polycrase, etc. CHROMIUM Chromite, chromium-iron oxide. COBALT Cobaltite, cobalt-arsenic sulphide. Smaltite, cobalt arsenide. Danaite, iron cobalt-arsenic sulphide. Gersdorffite, iron-nickel-cobalt-arsenic sulphide. Erythrite, cobalt-arsenic-oxide. Asbolite, cobalt-manganese oxide. COPPER Native copper. Chalcocite, copper sulphide. Covellite, copper sulphide. Stromeyerite, copper-silver sulphide. Bornite, copper-iron sulphide. Chalecopyrite, copper-iron sulphide. Tetrahedrite, copper-antimony sulphide. Tennantite, copper-arsenic sulphide. Enargite, copper-arsenic sulphide. Cuprite, copper oxide. Melaconite, copper oxide. Malachite, copper carbonate. 43 44 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Azurite, copper carbonate. Aurichalcite, copper-zine carbonate. Chrysocolla, copper silicate. Copper pitch, copper silicate. Caledonite, copper-lead sulphate. Linarite, copper-lead sulphate. Chalcanthite, copper sulphate. Brochantite, copper sulphate. 2 COLUMBIUM Columbite, iron columbate. Samarskite, rare earth columbate. Polycrase, rare earth columbate. Euxenite, rare earth columbate. GOLD Native gold. Sylvanite, gold-silver telluride. Calaverite, gold telluride. IRON Metallic iron (meteorite). Pyrrhotite, iron sulphide. Bornite, copper-iron sulphide. Chaleopyrite, copper-iron sulphide. Marcasite, iron sulphide. Pyrite, iron sulphide. Arsenopyrite, arsenic-iron sulphide. Hematite, iron oxide. Ilmenite, iron-titanium oxide. Magnetite, iron oxide. Chromite, iron-chromium oxide. Turgite, hydrous iron oxide. Goethite, hydrous iron oxide. Limonite, hydrous iron oxide. Ankerite, magnesium-iron carbonate. Siderite, iron carbonate. LEAD Native lead. Galena, lead sulphide. Jamesonite. lead-antimony sulphide. Boulangerite, lead-antimony sulphide. Owyheeite, lead-silver-antimony sulphide. Massicot, lead oxide. Minium, lead oxide. Cerusite, lead carbonate. Plattnerite, lead dioxide. Pyromorphite, lead phosphate. Mimetite, lead arsenate. Vanadinite, lead vanadate. Bindheimite, lead antimonate. Wulfenite, lead molybdate. Anglesite, lead sulphate. Leadhillite, lead sulphate-carbonate. Caledonite, lead-copper sulphate. Linarite, lead-copper sulphate. THE MINERALS OF IDAHO MANGANESE Braunite, manganese oxide. Psilomelane, manganese oxide. Pyrolusite, manganese oxide. Rhodochrosite, manganese carbonate. MERCURY Cinnabar, mercury sulphide. MOLYBDENUM Molybdenite, molybdenum sulphide. Molybdite, iron molybdate. Wulfenite, lead molybdate. Powellite, calcium molybdate. NICKEL Gersdorffite, nickel-iron-cobalt-arsenic sulphide. . PHOSPHOROUS Apatite, calelum phosphate. Phosphorite, calcium phosphate. Collophane, calcium phosphate. Pyromorphite, lead phosphate. Vivianite, iron phosphate. Evansite, aluminium phosphate. PLATINUM Metallic platinum. SELENIUM Naumannite, silver selenide. Guanajuatite, bismuth selenide. SILVER Metailie silver. Argentite, silver sulphide. Naumannite, silver selenide. Stromeyerite, silver-copper sulphide. Miargyrite, silver-antimony sulphide. Pyrostilpnite, silver-antimony sulphide. Pyrargyrite, silver-antimony sulphide. Stephanite, silver-antimony sulphide. Polybasite, silver-antimony sulphide. Owheeite, silver-lead-antimony sulphide. Proustite, silver-arsenic sulphide. Xanthaconite, silver-arsenic sulphide. Cerargyrite, silver chloride. Embolite, silver bromide. TELLURIUM Sylvanite, gold-silver telluride. Calaverite, gold-silver telluride. Tetradymite, bismuth telluride. THORIUM Monazite, cerium phosphate containing thorium. Polycrase. Samarskite. Brannerite, etc. TIN Cassiterite, tin dioxide. 45 46 BULLETIN 131, UNITED STATES NATIONAL MUSEUM ; atae bee TITANIUM Rutile, titanium dioxide. Ilmenite, iron-titanium oxide. Titanite, calcium-titanium silicate. Brannerite, uranium titanate. Also the rare earth minerals, polycrase, euxenite, samarskite, etc. TUNGSTEN Wolframite, iron-manganese tungstate. Ferberite, iron tungstate. Hubnerite, manganese tungstate. Scheelite, calcium tungstate. Tungstite, tungsten oxide. i URANIUM Samarskite. Brannerite. Polycrase, etc. ZINC Sphalerite, zinc sulphide. Wurtzite, zine sulphide. Smithsonite, zinc carbonate. Aurichalcite, zinc-copper carbonate. Calamine, zinc silicate. 2 : k revi ZIRCONIUM Zircon, zirconium silicate. DESCRIPTIONS OF MINERALS DIAMOND (1) Carbon, C. Isometrie.. ADAMS COUNTY Diamonds have been authentically reported to occur in Idaho only in the Rock Flat gold mine in Adams County at the head of Little Goose Creek Canyon, 5 miles east of New Meadows. Here three small crystals were found in heavy concentrates from a testing opera- tion on several cubic meters of the gravel. The largest of the dia- monds was an almost perfect octahedron weighing one-third of a carat and having a grayish color and typically greasy luster. The angles were somewhat rounded with a fused appearance. The heavy residue of concentrate from each cubic yard of gravel weighed 90 pounds and, in addition of 15 cents worth of coarse gold, contained 3 per cent of ilmenite, magnetite, and a little chromite, and 20 per cent of zircon sand, and the balance being made up of corundum, garnet, and monazite. Variously colored corundum crystals are common here.* OWYHEE COUNTY A brief reference in an old Government publication states that diamonds have been reported to exist on Owyhee River **; a few small stones have been reported and probably some were found in the placer 3’ Robert N. Bell, 15th Ann. Rept. Idaho State Mine Inspector, pp. 218-219, 1913. 3a Wm. P. Blake, Annotated catalogue of the principal mineral species hitherto recognized in California and the adjoining States and Territories. Browne and Taylor, Min. Resources U. S., 1866, p. 201. THE MINERALS OF IDAHO 47 mines, under the same conditions and of about the same quality as those in California. Some excitement has occasionally arisen about these Idaho diamonds. In 1864 to 1866 local and mining papers made many references to reported or anticipated discoveries; but nothing of any importance was found. In the winter of 1892-93 the matter again attracted some attention. Only small quartz crys- tals and no diamonds were found, the name “Diamond Basin” having given colorto the reported findings. Diamond Basin lies on the Snake River in Owyhee County. The excitement, intense for a time, sub- sided before the winter was over.‘ It is possible that a few small diamonds may occur in placers in other portions of the State, but the possibility of deposits of stones of gem quality being found is very remote. The source of the Rock Flat crystals is not known, but the fact that chromite and a trace of platinum have been reported from the same claim may indicate their derivation from a small intrusive mass of peridotite. Scattered stones have been found from time to time in the gold placers of Cali- fornia, but no diamond deposits have been found in that State in which the geological environment is, on the whole, much more favorable for the occurrence of this mineral. GRAPHITE (2) PLUMBAGO, BLACK LEAD Carbon, C. Hexagonal. The black hexagonal form of carbon, graphite, is not abundant in Idaho and no deposits of commercial importance are known there. The most common occurrence of this mineral is as a very finely dis- seminated coloring matter in slaty rocks in various parts of the State as, for example, the Prichard formation in the Coeur d’Alene district and the ore-bearing Devonian slates of the Wood River district in Blaine County. ADAMS COUNTY Graphite has been mentioned as occurring in the Seven Devils district as a minor constituent of the ores in some of the contact- metamorphic copper deposits. BLAINE COUNTY Some attempt has been made at exploring certain graphite-rich streaks in the graphitic slates of the Devonian formation on Trail Creek at the town of Ketchum on upper Wood River. The claims opened by Messrs. Hampton and Griffith in 1908 and a small pro- duction of amorphous graphite was reported in 1909 but nothing since.° 4 George F. Kunz, Precious stones. U.S. Geol. Survey, Mineral Resources for 1892, p. 759. 5 U.S. Geol. Survey, Mineral Resources, 1913, pt. 2, p. 199. 48 BULLETIN 131, UNITED STATES NATIONAL MUSEUM BUTTE COUNTY B. F. Morrison of Martin, Butte County, has submitted a black highly polished sheared graphitic shale. CUSTER COUNTY A specimen of graphitic schist containing clean-cut crystalline flakes of graphite has been sent to the National Museum by a cor- respondent in Challis, Idaho. The material is similar to the rock mined for graphite in some localities in the Appalachian States. It is not definitely known that the rock is from Idaho and inquiries regarding it have not been answered. Other specimens sent in for examination by Guy E. Matthews, of Boise, and said to have come from a large ledge near the summit of the Sawtooth Mountains, consist of small hexagonal scales thickly disseminated in quartzite and of reddish black smears on sheared quartz schist. CAMAS COUNTY A sample of impure fine-grained graphite has been submitted to the Museum for identification by John F. Williams from Fairfield, Camas County. IDAHO COUNTY Graphitic schists are reported to occur on Salmon River near Grangeville. Analysis of a specimen of the material showed 7.6 per cent of fixed carbon.® SULPHUR (3) Sulphur, S. Orthorhombic. ADAMS COUNTY In the Red Ledge mine, in the Seven Devils district, sulphur occurs in crusts, often 2 centimeters or more thick, mixed with the sul- phates melanterite, pisanite, and chalcanthite. Steep, vertical cliffs of quartz monzonite are stained bright red by hematite and perhaps a little cuprite from the oxidation of pyrite and chalcopyrite dissemi- nated through the rock. Small caves at the base of the cliffs con- tain crusts of soluble sulphates and sulphur, often several centimeters thick, the sulphates having been carried downward by percolating waters from the sulphide-impregnated rock. The sulphur has doubt- less been produced by decomposition of the sulphates. BANNOCK COUNTY Sulphur in native form occurs abundantly 5 miles east of Soda Springs on the Oregon Short Line Railroad. An attempt was made to work these deposits in the late nineties, and a considerable amount of sulphur was produced in 1901 and 1902, but the plan was aban- doned and the plant was dismantled in 1910. Exploitation was again begun in 1918. The sulphur occurs in connection with a group 8 U.S. Geol. Survey, Mineral Resources for 1913, pt. 2, p. 199. THE MINERALS OF IDAHO 49 of sulphur springs, which range from the size of a washbasin to some which are large enough for a good-sized swimming pool. The water is milky from precipitated sulphur and is acid, much carbon dioxide and hydrogen sulphide being given off. The bulk of the sulphur, which is associated with small crystals of gypsum, forms the cement of a fault agglomerate or breccia composed of fragments of tuff, lime- stone, and quartzite. Small pyramidal crystals are found lining cavities of crystalline and amorphous masses in the interstices of the breccia. The crystallinity is shown by the spherical radiated figures formed upon some surfaces obtained by breaking, while the smooth or conchoidal fracture on other surfaces serves to indicate the amor- phous variety. A rather spectacular form, namely, stalactites in vertical crevices traversing the breccia, occurs in the south wall of the quarry on the Wood Canyon side of the divide. This variety has an almost canary-yellow color on fresh fracture, which changes rapidly on exposure to dull, submetallic gray. Much of the low- grade ore also has this gray color. Air bubbles in many of the sta- lactites may indicate that the sulphur was exuded in liquid form. Alum occurs rarely in the deposits.’ BLAINE COUNTY Powdery sulphur occurs, partly filling little cavities left by the removal of pyrite in quartz of the oxidized portions of the Clipper Bullion vein, Mineral Hill district. This mineral was found by Mr. D. F. Hewett in a prospect 1144 miles southeast of Bellevue associ- ated with anglesite and wulfenite. CUSTER COUNTY A specimen of cavernous earthy limonite from the oxidized ore about 30 feet below the surface in the Lost Packer mine contained residual friable masses of chalcopyrite and pale yellow druses of minute crystals of native sulphur. SHOSHONE COUNTY Sulphur has been noted in the Caledonia and Hypotheek mines as an alteration product of sulphides in the oxidized ores. In the upper workings of the Caledonia mine native sulphur was a constituent of a yellowish earthy material consisting largely of crushed quartz, with a little limonite and bindheimite. The presence of sulphur in this material was shown by its taking fire and burning with a blue flame when placed on a hot stove. In the Hypotheek mine near Kingston sulphur occurred as minute yellow globules inclosed in transparent anglesite crystals lining cavities in galena. 7R. W. Richards and J. H. Bridges. Sulphur deposits near Soda Springs, Idaho. U.S. Geol. Survey, Bull. 470, pp. 499-503. 1911. 50 BULLETIN 131, UNITED STATES NATIONAL MUSEUM ARSENIC (8) Arsenic, As. Rhombohedral. BONNER COUNTY Arsenic is known to occur only at one locality in a small prospect on Vulcan Hill overlooking North Gold Creek, 2 miles from the town of Lakeview, on Lake Pend d’Oreille. The mineral occurs as a narrow vein in granite near the contact with Cambrian rocks. The arsenic vein is parallel to the galena-bearing vein prospected by the tunnel, and it is reported that where one pinched the other swelled. A very little pyrite, calcite, and epidote are associated with the arsenic. Polished surfaces of the arsenic, when examined with the metallographic microscope, are found to be pure and homogeneous. The material was collected and identified by Edward Sampson, of the United States Geological Survey. BISMUTH (11) Bismuth, Bi. Rhombohedral. CUSTER COUNTY Bismuth in native form occurs in silver-white to reddish grains disseminated through quartz in the Empire group of claims of the Idaho-Montgomery Mining Co., in Washington Basin at the head of Salmon River. Bismuthinite, barite, pyrrhotite, and pyrite are associated with the bismuth, which is in part altered to bismuth carbonates. KOOTENAI COUNTY Bismuth occurs in narrow quartz veins at a contact between granite and slates on Beauty Bay Creek near Beauty Bay on Lake Coeur d’Alene. These veins, which are several in number, cut across the contact from the igneous rock into the sedimentary formation, but are said to contain bismuth only where inclosed in the latter. All of the quartz in the surface workings contains some bismuth in disseminated grains associated with pyrite and a little bismuthinite. Pannings are reported to contain also some gold, silver, and a little tin. One vein of the group contains considerable masses of arseno- pyrite and specular hematite. LEMHI COUNTY Fine specimens of native bismuth are reported * to have come from one of the cobalt mines of the Blackbird district. No infor- mation of the mode of occurrence of this material could be obtained. GOLD (13) Native Gold, Au. Isometric. The mining of gold has been in the past, and to a somewhat lesser extent now is, an important industry in the State. Esti- mates compiled by the United States Geological Survey give the 8 Robert N. Bell. Personal letter. 1917. THE MINERALS OF IDAHO 51 total production in Idaho from the earliest discoveries in 1861 to the end of 1917 as having a mint value of $130,910,969, which amounts to approximately half a million pounds of metallic gold. While many lode mines have been developed in the area and have made large production, the greatest bulk of the gold yield has come from placer mines. Auriferous veins are widespread in occurrence. The most im- portant mines, however, fall into several groups, the largest group being that in the west-central part of the State mainly in Boise County, but extending into Ada and Elmore counties and including, among others, the Black Hornet, McIntyre (Boise), Gambrinus, Deadwood, Quartzburg-Grimes Pass, Summit Flat (Pioneerville), Westview (Willow Creek or Pearl), Atlanta, Black Warrior, Neal, Pine Grove, and Rocky Bar districts. The country rock in all of these districts is the granite of the western part of the central Idaho batholith and near the veins this granite is usually very greatly altered by thermal solutions with abundant development of sericite. The lodes occur along well-defined fissures and vary from clean cut filled veins to mineralized shear zones containing seams and stringers of auriferous material. The gangue is, for the most part quartz which, where unaffected by oxidation, contains greater or less quantities of sulphides, while in certain mines the sulphides occur as solid masses practically without quartz. At and near the sur- face the sulphides are in most cases thoroughly oxidised, the ore then consisting of quartz containing much soft and limonitic material which incloses the abundant spongy gold in free milling and easily recoverable form. As greater depth is attained in mining, however, the unaltered primary ore is encountered, in which the gold is as- sociated with or contained in the prevalent sulphides, chief among which are pyrite, arsenopyrite, sphalerite, and galena. Bismuth sulphide or bismuth-lead sulphide (locally called antimonite) are locally characteristic of the richest ores. The primary sulphide (‘‘base” or ‘‘refractory”’) ores are not amenable to the simpler and less expensive methods of treatment and the encountering of such unoxidized ore has led to the temporary or permanent shutdown of a large number of mines in this area. The second major group of gold lodes is located in Idaho and Clearwater Counties and includes the Elk City, Dewey, Dixie, Florence, Newsome, Oro Grande, Buffalo Hump, Warren, and Pierce districts. These districts are occupied either by the northern continuation of the granitic batholith or by pre-Cambrian meta- morphic rocks cut by granitic dikes. In most of the districts of this group the lodes are clean-cut quartz veins without great quanti- ties of sulphides and the gold, even in the unoxidized primary ore, is for the most part free milling. 52 BULLETIN 131, UNITED STATES NATIONAL MUSEUM A third group of gold lodes of various types occurs in Lemhi County near the Montana line, while a fourth small but formerly productive area is in the Coeur d’ Alene district in Shoshone County, where the gold occurred in banded quartz veins cutting black Algonkian slates. The precious metal districts in Owyhee County contain both gold and silver in veins mainly contained in Tertiary voleanic rocks. Similar to these are the deposits of the Thunder Mountain district in Idaho County, the Forney (Gravel Range) and Parker Mountain dis- trictsin Lemhi County, andthe Yankee Fork districtin Custer County. Many of the veins of this group are characterized by crustified quartz, pseudomorphous quartz, or chalcedony, with or without adularia, as gangue. The ores of a number of the mines contain bands of finely divided silver sulphide carrying some selenium. The native gold of these later Tertiary deposits is mostly pale in color and high in silver content, much of it being classifiable as electrum. Tellurides of gold are of very limited occurrence in the State, practically all of the gold being in native form. Of the rarer minerals accompanying the gold, bismuth sulphide (bismuthinite) and lead- bismuth sulphide (galenobismutite) have been mentioned. Scheel- ite accompanies the gold in the Charity vein in the Warren district and in several mines in the Coeur d’ Alene district. While no district or mine has attained a reputation for furnishing remarkably showy, beautiful, or well-crystallized specimens of native gold, a majority of the auriferous mines of the State have, at some time during their history, produced ore of such a grade as to make excellent cabinet material. Very few such specimens have been preserved. Descriptions of those in the National Museum collections are given below. Placer gold was the first form to be mined in the State and the total production of it greatly overshadows that of gold derived from lode mining. Dana, writing in 1890, says of Idaho ‘‘ Every county in the State yields placer gold.” Roughly the great placer regions are the same as those which have been mentioned as the principal groups of lode mining districts, the greatest area being that known as the Boise Basin. Gold occurs in placers in almost every district where auriferous lodes are known, usually in amount out of proportion to the value of the developed veins. Moreover some placer districts of importance have been worked in areas where no productive lodes are known. Such observations as this have given rise, in Idaho as elsewhere, to the fable of the Mother Lode. A sufficient source may be found, however, in the concentration from the disintegration and erosion of quantities of rock measurable in cubic miles including great vertical sections of the known veins, of THE MINERALS OF IDAHO 53 veins of appreciable gold content yet too low grade to have been worked, and also of inconsequential lenses and stringers of auriferous material which may have added greatly to the total but would not have been of any commercial importance if discovered singly. While the lighter constituents of the rocks have been gradually disintegrated and reduced to fine particles and carried to great distances, the gold and other heavy materials have remained behind. The granite, especially where softened or sericitized by hydrothermal alteration, is prone to be more rapidly removed than the vein quartz which makes up a large proportion of the pebbles in the placer gravels. The more productive placers are, for the most part, along the beds of the present streams, although profitable mines have been worked in high terrace gravels and in fossil stream channels which date from some previous period in the drainage history of the region. The _placer gold is concentrated, usually, within a few centimeters or at most a meter of bedrock and is associated with a variety of other heavy minerals. The character of these heavy minerals varies from place to place? Magnetite, ilmenite, and garnet are widespread, while monazite occurs in most of the placer regions in the Central Idaho granitic area, especially in the Boise Basin. Colorless zircon is also abundant, particularly in the Florence and Warren districts. Corundum occurs in considerable quantity near Pierce and Resort in Clearwater County with tourmaline, rutile, and ilmenite, and also at the Rock Flat placer near Meadows in Washington County. The latter locality is that mentioned above as yielding diamonds. Rare earth minerals are known from many places. In addition to the monazite just noted above, brannerite occurs in Stanley Basin, Custer County, and polycrase, samarskite, columbite, etc., are known from several placers in Boise County. Native amalgam occurs in Stanley Basin, while cassiterite and cinnabar have been found here and in the Pierce district. A heavy bismuth carbonate occurs with gold in the Poncia placer, Centerville district, recalling the occurrence of bismuth-bearing sulphides in the Gold Hill, Bel- zazzar, and other mines. The richer placers along streams were naturally first discovered and were worked by the simpler hand methods—by panning or with arrastre, rocker, and sluice, and many of them yielded fabulous returns by such methods. The high grade ground suitable for such exploitation was limited, however, and it was necessary to construct larger projects requiring miles of ditches and extensive pipelines to work the higher gravels. Following the bonanza period many of the placer camps were practically abandoned by white men in their § Karl V. Shannon. Mineralogy of some black sands from Idaho. Proc. U. S. National Museum, vol. 60, art. 3, 1921. 54 BULLETIN 131, UNITED STATES NATIONAL MUSEUM rushes to new fields and the only mining for long intervals was that carried on by the patient Chinese. Many of the camps have since become the sites of extensive modern dredging enterprises. Some relatively rich deposits have remained unworked for a variety of reasons—scarcity of water, depth of bedrock, lack of drainage, large size of boulders, shortness of season, or inaccessibility. The available placers of sufficiently high grade to be worked by ordinary methods are, however, pretty well exhausted. The sands of Snake River contain very finely divided gold in wide distribution. This gold has been mined here and there from the Wyoming line to Oregon. While practically all of the gravels along the river are auriferous, most of the deposits contain so little gold that they can hardly be called placers. Some small deposits yield sufficient to pay for extraction if worked on a large scale and a very few may be worked by hand methods. The problem of saving this gold has been much studied without a practical method being found. The gold is exceedingly finely divided, it requiring fully 1,500 grains r “colors” to weigh 1 cent in value, or approximately 3,000,000 of the grains to weigh one ounce, yet, under the microscope, each grain may be seen to be an individual nugget showing rounding and abrasion marks. The particles are often coated or spotted with a crystalline film of silica, making it necessary to grind the gold in a pan before it will amalgamate freely. In size the particles range within relatively narrow limits and there is no gradual shading from the finer particles into impalpable dust,!° These Snake River bars have been mined in Ada, Blaine, Bingham, Cassia, and Owyhee Counties. In composition the gold of both the veins and placers is variable, the variation being in the amount of silver with the gold, there being a transition into electrum, an alloy containing equal molecular parts of gold and silver as discussed below. The lowest grade gold is that of veins in the Tertiary lavas, much of it reaching electrum proportions of silver. In general the gold in the auriferous quartz-sulphide veins in granite is of higher grade, but that in quartz veins free from large amounts of sulphides and inclosed in slates or other metamorphic rocks is of still better grade. Gold in oxidized ore is commonly purer than that in unaltered primary ore, especially if the latter be sulphidic. This is due to the tendency of the silver to be selectively extracted by percolating meteoric waters. As an instance of this may be men- tioned the observation of Umpleby " that whereas the gold of the primary ore of the Golden Sunbeam mine, Yankee Fork district, Custer County, 1 is electrum, in the oxidized zone native gold and native silver occur in relatively pure form, Ce side by side, the two metals 10 Robert N. Bell. Annual Report of State THepeetors of Mines on the Mining Thausten of Idaho for 1906 , p. 115. 11 Joseph B. Umpleby. U.S. Geol. Survey Bull. 539, p. 88, 1913. THE MINERALS OF IDAHO 55 evidently having separated during the oxidation. Placer gold is commonly purer than that in the veins of the same area. Further- more the gold of gravel deposits is usually higher in grade the greater the amount of wear and the further it has been transported from its source, which are indicative of the length of time the particles have been exposed to the purifying influences of the ground water. An example of this cited by Lindgren ” illustrates the progressive refining of the gold in the Warren district. Here vein bullion is 300 to 500 fine (30 to 50 per cent Au), the placer gold in small streams is 650 fine (65 per cent Au), that in the larger streams and main creeks is 725 fine (72.5 per cent Au), while the gold along Salmon River derived from this district is 800 to 825 fine (80 to 82.5 per cent Au). For obvious reasons fine particles of gold are more rapidly purified by this process than are larger nuggets. The purest gold known in the State is the very finely ded “flour” gold of Snake River, all of which is better than 900 fine (90 per cent Au). While the view that placer gold becomes purer by the chemical action of ground water in the gravels is well founded, there is no evidence in support of the common fallacy that nuggets of gold grow by accre- tion from solutions in the alluvial deposits. Th addition to the chemical purification by the above process, long wear by water tends to eliminate impurities mechanically, the pounding tending to crush and expel the brittle gangue minerals such as quartz. Idaho is not known to have produced any exceptionally large masses of placer gold, the maximum recorded weight being in we neighborhood of 40 ounces (Coeur d’Alenes and Idaho Basin), Few samples of placer or lode gold from the State have been available for examination, but such as are in the possession of the National Museum are described below. In the following outline the most noteworthy gold localities of the State are mentioned, although a detailed discussion of the occur- rences of this metal in the State would occupy too much space. The figures of production as given are not extremely modern, many of the records being as old as 1896, and do not take into consideration the production of recent years, which in some cases exceeds that of the earlier period. They serve, however, to indicate the relative commercial importance of the various mines or districts. The ar- rangement follows the outline given in the list of Idaho mining dis- tricts above." 12 avaliiiae inde 20th Ann. Rept. U.S. Geol. Survey, es 3, p. 242, 1900. 13 The data given in this outline are not in any sense original, but are compiled, without further specific acknowledgment, from the several works cited in the bibliographic references given, for each of the nu- merous mining districts, in the preceding pages. 56 BULLETIN 131, UNITED STATES NATIONAL MUSEUM ADA COUNTY Although the Black Hornet district contains no important placers, a number of veins of gold-bearing quartz occur. Chief among these is the Black Hornet or Ironsides mine which had made a gold produc- tion of about $30,000 previous to 1897. The ore consists of quartz containing about 8 per cent of sulphides, chiefly arsenopyrite with less pyrite and sphalerite. Arsenopyrite also occurs in disseminated form in the altered (sericitized) granite of the walls immediately adjacent to the vein. In the Boise (McIntyre) district a number of auriferous veins have been developed, although there has never been any very great pro- duction. Some of the lodes are quartz veins and others are merely altered streaks in the granite along a fault plane. In some cases the values are entirely in gold but some small deposits of rich silver ore have been mined. In the Snake River placers desultory operations have been carried on from year to year in this county. A dredge capable of handling 1,500 cubic yards of gravel daily was installed in 1907. BINGHAM AND BONNEVILLE COUNTIES In the Mount Pisgah district some hydraulic mining has been done at Gray. The gold is 960 fine (96 per cent Au) and is worth $19.84 an ounce. In the Snake River placers there are a considerable number of small mines. Six operators were working in 1905; a production of 185.22 ounces of gold was reported for 1907, while the output for 1908 and 1909 was worth $2,717 and $1,448, respectively. The gold is 951 fine (95.1 per cent Au) and is valued at $19.66 an ounce. A sample of heavy concentrate from a Snake River placer mine at Rosa, Bingham County (Cat. 53625 U.S.N.M.) has an average grain diameter of 0.1 mm. and contains a few minute rounded grains of gold associated with abundant ilmenite and augite, occasional almandite and quartz, and rare zircon and olivine. BLAINE COUNTY In the Camas district fissure veins in granite carry free native gold with pyrrhotite, pyrite, and chalcopyrite, and less galena, sphalerite and arsenopyrite in a gangue of quartz with some siderite. The principal mines are the Camas No. 2 and the Tip Top. The | Camas No. 2 vein produced gold to the value of $58,392. In the Mineral Hill (Hailey) district the Croesus, Hope, and neigh- boring veins of what is known as the Hailey gold belt contain their principal values as free gold which is associated with considerable quantities of sulphides, mainly pyrrhotite and chalcopyrite with less galena and sphalerite in a quartz and siderite gangue. These are THE MINERALS OF IDAHO 57 entirely similar to the deposits of the Camas district, which may be considered as the southwestern continuation of the same zone. They are quite distinct from the lead-silver deposits of the Hailey region. The Red Warrior district is represented by a number of specimens in the National Museum, as follows: From the Golden Eagle Mine (Cat. No. 65671, U.S.N.M.) coarse native gold in irregular flakes in rusty quartz; from the Wide West mine bluish unoxidised quartz (Cat. No. 65680, U.S.N.M.) containing flakes of pale gold in minute cavities, quartz, with sparsely disseminated pyrite and sphalerite (Cat. No. 14764, U.S.N.M.), and heavy masses of auriferous pyrite and spongy limonite (Cat. No. 14765, U.S.N.M.). Ore from the Victor mine (Cat. No. 14767, U.S.N.M.) consists of coarse comb quartz which is slightly iron stained and that from the Avalanche mine (Cat. No. 14766, U.S.N.M.) consists of bluish auriferous quartz. The Snake River placers have been mined in Blaine County at Neely resulting in a small production of fine gold. The output was 187 ounces in 1904 and 258 ounces in 1905. BOISE COUNTY The Centerville (Idaho Basin) district is one of the most important gold regions of the State. The production from the discovery of the district to 1898 has been estimated at $44,651,800 of which about $4,000,000 was from lode mines and the balance from placers. The gold occurs in recent stream gravels and in terrace or bench gravels at various levels along Grimes, Granite, Moore, and other creeks. Some old stream channels now covered by basalt flows have been mined but have not proven very rich. The highest terrace gravels often contain rounded cobbles of gold-bearing quartz up to 30 cm. in diameter. In a body of gravels immediately east of Idaho City the gold is fairly coarse with a value of $16.50 an ounce before melting. Much of it occurs on bedrock or “false bedrock,’”’ the latter being the Payette formation of Tertiary lake sediments which carry a little finely divided pale gold associated with monazite in some layers, The heavy residues associated with the placer gold contain abundant monazite in sharp crystals. Samples from several placers near Centerville and Idaho City, show, in addition to themonaziteand the usual garnet, magnetite, ilmenite, etc., larger crystals of poly- crase and samarskite, sharp crystals of columbite, and other minerals as described under the separate headings. A sample of pan con- centrate from the Leary and Brogan placer, Poncia tract, Centerville, contains all of the above minerals and also heavy pebbles of bismuth carbonate. A specimen of placer gold from near Centerville (Cat. No. 55776, U.S.N.M.) consists of well worn flat flakes of gold uniformly 1 mm. in diameter. Two nuggets from Bill Williams 54347—267 5 58 BULLETIN 131, UNITED STATES NATIONAL MUSEUM claim (Cat. No. 55464, U.S.N.M.) mined in 1865 are about 1 cm. in diameter and are well-rounded pebbles of dark yellow gold con- taining some quartz; nuggets of well rounded gold from Bowers Bar, Placerville (Cat. No. 55788, U.S.N.M.) also contain quartz. A specimen from the Green White claim on Moose Creek below Idaho City (Cat. No. 55470, U.S.N.M.) is a pebble about 5 cm. in diameter of equal parts of granular brownish quartz and gold. In the Deadwood district the Merry Blue and Union mines pro- duced some gold from ore worked in an arrastre in 1907 and 1909. In the Gold Fork (Roseberry) district placer gold occurs in gravels on McKinley Fork in Long Valley. The Evans and Paddy Valley are the principal gravel mines. The gold is in part well worn, in part rough and attached to quartz. Its source is problematic as no veins are known. The Quartzburg-Grimes Pass district contains numerous veins of auriferous ore. The Ebenezer claim contained rich surface oxidized ore, but the primary sulphide-bearing ore is very refractory. The Belzazzar mine has galenobismutite (q. v.) associated with the gold in the richest ore. The Gold Hill and Pioneer claims, worked together, form the most important lode mine in the region, having produced gold to the value of $2,225,000 previous to 1898. The ore contains narrow seams which are very rich in gold. The Home- ward Bound-Elizabeth-Mayflower vein averages 114 meters in width and its decomposed surface ores were worked in an arrastre but heavy masses of sulphides were encountered at depth. The Gold Hill is a well-defined quartz vein in granite varying from a few centimeters to 2 meters in width. Some sulphides, mainly pyrite, are associated with the gold. The Iowa vein, a short distance north of the Gold Hill, is a narrow seam with streaks extremely rich in gold. The Carroll-Driscoll group produced much gold by sluicing disintegrated veins on the Ivanhoe and Capital claims. The primary ore in the upper tunnel consists of veinlets of massive pyrite and a little quartz which carry free gold.. The lower tunnel shows several sulphide veins in a wide shear zone containing large quantities of sericitic gouge. The mineralization consisted of gold with tetrahedrite, pyrite, galena, pale-colored sphalerite, and a little barite in quartz. This has been largely shattered and incorporated in a later gouge of sericite containing masses of pyrite showing well-developed crystals. The Kennebec claim yielded rich sluice ground. Numer- ous veins containing free gold in oxidized limonitic material occur n and along the quartz porphyry dike east of Wolf Creek, including the Golden Chariot, Buena Vista, Big Six, Mineral Hill, and other claims. Near Grimes Pass the Morning Star, Mountain Queen, Pioneer, and other veins yielded oxidized ore consisting of limonite containing native gold with some cerusite, etc. The Barry, Peer- THE MINERALS OF IDAHO 59 less, and King veins at the headwaters of Klk Creek, the Wilson group a little farther north and other veins between Summit Flat and Kempner yield free gold with some sulphides in quartz veins. A specimen of oxidized ore from the Overlook mine contains spongy and mossy pale colored gold in cavities from the removal of sulphides in leached and rusty quartz. Placers occur along Lost River and Bear River near Kempner. In the Westview (Willow Creek, Pearl, Rock Creek) district placers were worked in the early days, and the Red Warrior mine was located in 1870. This district contains a great number of veins which are fault fissures in granite on either side of which the rock is altered by sericitization and impregnated with pyrite. Along the fissures occur narrow seams of auriferous sulphides—pyrite, black, or dark brown coarse grained sphalerite, arsenopyrite, and galena which are rich in gold. The sparse gangue consists of quartz and calcite. No visible gold can be seen even on panning the richest sulphides. The surface ore is soft and limonitic and contains free gold associated with some cerusite. BONNER COUNTY In the Mooyie Yaak district the Buckhorn mines east of Mooyie River and 10 miles north of Kootenai River have produced ore con- taining native gold associated with galena. CASSIA COUNTY The Snake River placers have made a small annual production of fine gold for many years. CLEARWATER COUNTY In the Burnt Creek district productive gold placers around Dent are worked by hydraulicking and sluicing. In the Musselshell Creek (Wieppe) district placer gold has for years been mined from gravels along Lolo Creek. The deposits are not of extraordinary richness. The gold is fine in size but is relatively low grade, being worth only $15 to $17 an ounce. The Pierce district was the first important placer district discovered in the State. The placers were never remarkably rich but produced well in 1861-62. The production in 1874 was $70,000. There has been desultory placer and quartz mining ever since. The placer production as given for 1908 was $41,255 and for 1909 with 11 mines operating $43,390. Much of the recent work has been done by dredges. The gold averages 0.820 fine (82 per cent.Au). CUSTER COUNTY In the Loon Creek district the gold ores consist of auriferous chal- copyrite in a quartz-siderite gangue, the principal deposit being the Lost Packer mine. Such ore contains 2 to 3 ounces of gold to the ton. 60 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Some placer deposits of phenomenal richness occurred. A strip of ground 75 feet wide and 1 mile long which was worked in the sixties produced $2,000,000, a single pan of gravel sometimes yielding as high as $300. The gold is coarse, 50 per cent of the product aver- aging 25 cents or sometimes more to the color while nuggets 25 grams in weight are not uncommon. The average value of the placer gold is $18 an ounce. A sample of placer gold from Hurd’s Claim, Loon Creek, mined in 1869, (Cat. No. 55763, U.S.N.M.), consists of small dark-yellow nuggets which are irregular and much flattened. In the Stanley Basin district some narrow quartz veins in granite carry gold. The chief production, however, is from the placers of Stanley Creek and Joes Gulch, which have yielded about $100,000, the average return for some years varying from $3,000 to $4,500 a year. The gold is coarse—flax to wheat size—and runs 0.717 fine (71.70 per cent Au) bringing $15 an ounce. At the Willis dredge property the gold, which is concentrated on the bedrock, is worth only $13 an ounce. The gold here is associated with native amalgam and cinnabar while elsewhere in the district the rare earth mineral brannerite has been found in the placers. Gold occurs in the Yankee Fork district with silver in veins of late Tertiary age in voleanic rocks, the gangue being fine-grained quartz and adularia with some opal and chalcedony. The gold is usually very finely divided and is concentrated in narrow dark streaks in the vein, which react for selenium. Some coarser gold is reported from the Morrison vein. The oxidized ore consists of firm quartz heavily stained with iron and manganese oxides. The principal vein mines are the General Custer, Lucky Boy, Charles Dickens, Momson, Golden Sunbeam, McFadden, etc. Placers which have produced gold to the value of $50,000 were discovered on Jordan Creek in the middle seventies. One nugget weighing nearly a kilogram was found near the outcrop of the Morrison vein, others weighed several hundred grams, and many exceeded 25 grams. A specimen lot of gold (Cat, No. 55,475, U.S.N.M.) mined from Bairs (or Blairs?) claim on Yankee Fork consists of fine flattened scales 2 mm. in maximum diameter. ELMORE COUNTY In the Atlanta district the gold production from the Atlanta lode has been considerable, some portions of the veins being predominantly gold-bearing, although the district is best known for its phenomenal silver ores. In the Black Warrior district a nominal production of gold has been obtained from lode mines, chiefly the Double Standard, White Ribbon, Fourth of July, and Magnolia. THE MINERALS OF IDAHO 61 In the Highland Valley district near Twin Springs bench gravel deposits are washed with the water from melting snows. The season is only 30 to 35 days annually. The gold is worth $16.02 an ounce. The Neal district produced gold to the value of $200,000 previous to 1898 from veins in fault fissures and along minor shearing planes in granite. The gangue is quartz and sulphides are common. Spongy skeletal gold is common in the oxidized ore. The gold is worth $15 an ounce. The Pine Grove district has produced some gold from quartz veins containing auriferous sulphides. The Rocky Bar district was originally an important placer camp, but in 1895 was reported to be worked only by Chinese. Lode deposits have been mined in the Old Alturas, Idaho, Vishnu, and other mines. The ores consist of quartz containing auriferous sul- phides in the primary ore and oxidation products with native gold above. The gold of the veins is worth $14 an ounce. Specimens of primary ore from the Vishnu mine (Cat. Nos. 14761-14762, U.S.N.M.) consist of auriferous sulphides in quartz and of the oxidized ore (Cat. No. 14763, U.S.N.M.) contain gold in rusty quartz. A sample of placer gold (Cat. No. 55469, U. S.N.M.) con- sisting of very pale colored unworn gold is labeled as from Dry Creek above Loom Creek, Elmore County. IDAHO COUNTY The Big Creek district contains large low grade gold deposits which, mineralogically, are very uninteresting. The Goldman and McRae and Moore are the principal mines. In the Crooks Corral district some placer gold is obtained by hydraulicking bench gravels of the Snake River side of the high divide between Snake and Salmon Rivers, which are here only 12 miles apart. The deposit has been found in places to be very rich, but the work is retarded by the high elevation and scarcity of water. The gold is 0.954 fine (95.40 per cent Au). In the Dewey (Harpster) district, gold is produced from ores consisting of auriferous chalcopyrite in silicified greenstone schist. Small lots of the ore are very rich. The Dewey is the principal mine. The Dixie district contains both placers and gold quartz veins. The placer gold is 0.820 fine (82 per cent), having a value of $16.95 an ounce. There is often more or less cinnabar associated in the sand with the placer gold. The Majestic, Dixie-Royal, Diamond Consolidated, and Monadnock are the principal mines. J. B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 86, 1917. THE MINERALS OF IDAHO 117 NICCOLITE (71) Nickel arsenide, NiAs. Hexagonal. LEMHI COUNTY Niccolite is reported to occur as small indistinct crystals of a pale copper-red color with dark tarnish in ores of the Togo claim in the Blackbird district, where it is associated with smaltite and other cobalt-nickel minerals. It is said to alter to annabergite. PYRRHOTITE (74) Iron sulphide, Fe7S, to FeS. Hexagonal The hexagonal form of iron sulphide commonly known as magnetic pyrite is a fairly common mineral, occurring usually in massive granular form. It may be distinguished from the more common pyrite by its faintly coppery color and the property of being attracted byamagnet. Localities which have been noted are mentioned below. BLAINE COUNTY Massive pyrrhotite forms a prominent constituent of the ores of the Croesus, Camas, and Tip Top veins. These are gold veins in granite and much of the ore consists of intergrown auriferous sul- hides, including galena, pyrite, pyrrhotite, chalcopyrite, and arseno- pyrite.’ Coarse granular pyrrhotite occurs also in the ore of the Golden Glow and other mines of the Rosetta district, with pyrite and sphalerite in quartz. CUSTER COUNTY Pyrrhotite may be extracted in small amount from crushed samples of most of the sulphide ore of the Alder Creek district. The individual grains are so minute that they can be detected only with the aid of a magnet. In the Lost Packer mine in the Loon Creek district pyrrhotite occurs sparingly as small crystals inclosed either in chal- copyrite or in quartz.” In the Seafoam district pyrrhotite occurs in a vein in limestone with galena sphalerite and pyrite. About 400 feet west of the Golconda discovery a vein of auriferous pyrrhotite 5 feet wide occurs in limestone. This pyrrhotite assays $14 a ton in gold. In Washington Basin pyrrhotite is the most abundant sul- phide of the great sulphidic masses of the Empire ledge. LATAH COUNTY In the Hoodoo district in the Mizpah and adjacent prospects pyrrhotite is common in the ores associated with chalcopyrite. It sometimes forms considerable masses, often containing coarse crystals of biotite.” %J.B.Umpleby. U.S. Geol. Survey, Bull. 528, p. 78, 1913. 89 Waldemar Lindgren. U.S. Geol. Survey, Ann. 20, pt. 3, pp. 207-208, 1900. J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 54, 1917. %J.B.Umpleby. U.S. Geol. Survey, Bull. 539, p. 53, 1913. J.B. Umpleby and D. C. Livingston. Idaho Bur. Geol. and Mines, Bull. 3, p. 18. % D.C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 95, 1920. 118 BULLETIN 131, UNITED STATES NATIONAL MUSEUM LEMHI COUNTY In Lemhi County pyrrhotite is a common mineral in the cobalt. ores of the Blackbird district intergrown with quartz and possibly also as a segregation in diabase. It is all slightly nickeliferous, one specimen from the Togo claim yielding upon analysis 0.8 per cent nickel.* A specimen from the Togo claim examined by the writer contained masses of clean glistening pyrrhotite up to 2 centimeters. in diameter in quartz. These gave a distinct reaction for nickel with dimethylglyoxime. In the Indian Creek district pyrrhotite occurs as a constituent of gold ores, especially in the Kittie Burton mine, where it is associated with pyrite and quartz. OWYHEE COUNTY Pyrrhotite occurs in the form of coarse bronzy grains intergrown with galena and sphalerite in heavy masses of auriferous sulphides from the gold vein of the Bergh mine 11 miles north of De Lamar. SHOSHONE COUNTY In the Coeur d’ Alene district massive pyrrhotite was abundantly present in the deep level ores of the Standard-Mammoth and Green- hill-Cleveland ore shoots, where it was intergrown with pyrite, siderite sphalerite, and magnetite and galena. It occurred similarly though less abundantly in the Tiger Poorman mine. Masses of granular pyrrhotite up to several inches in diameter occur in the rich galena ores of the Hercules mine and it is present in the Helena-Frisco and Morning mines. East of Kellogg pyrrhotite is very abundant in heavy masses with pyrite and chalcopyrite in a quartz ankerite gangue in many commercially valueless veins in the Prichard forma- tion as the Teddy, Lucky Boy, Wisconsin, Enterprise, Evolution, and other claims. It occurs abundantly in many of the mines on Pine Creek intergrown with other sulphiaes. In ore from the Inter- national mine it occurs in quartz intergrown with contemporaneous pyrite, galena, and sphalerite, all of eich replace the quartz along fractures: Specimens from the Nabob mine show large masses of pyrrhotite replacing quartz with a very little galena and Eheleopy rite. An interesting specimen from the Sherman mine contains large vitreous masses of pyrrhotite with conchoidal fracture in quartz with ankerite and prochlorite. The pyrrhotite forms films penetrating the coarse ankerite crystals along cleavage planes. Like pyrite pyrrhotite sometimes occurs disseminated in the Prichard formation remote from mineral veins. Pyrrhotite is also a constituent of copper ores in the Monitor, Black Prince, and other mines in the St. Joe Basin. %J.B.Umpleby. U.S. Geol. Survey Bull. 528, p. 163, 1913. THE MINERALS OF IDAHO 119 BORNITE (78) Copper iron sulphide, 2Cu,8. CuS. FeS. Isometric. Bornite is commonly known as peacock copper and is a relatively high grade copper ore. It is easily distinguished by its unusual colors. On fresh fracture the mineral is coppery or bronze red but it tarnishes quickly to blue or purple with occasionally shades of red and green. In Idaho chalcopyrite, which often is iridescent on fractures, is frequently erroneously called peacock ore. This is the principal ore mineral in the Seven Devils district and occurs in minor amount in a number of other districts. ADAMS COUNTY (Including Washington County in part) Bornite in massive form is the principal primary copper mineral in the Seven Devils copper district where it generally occurs in association with epidote and garnet in contact metamorphic deposits in limestone (Cat. Nos. 51871 and 67391, U.S.N.M.). Upon weather- ing it alters to chrysocolla and malachite or sometimes to brochan- tite.*° The bornite from the contact deposits is argentiferous, carrying 20 ounces of silver a ton.*® Bornite occurs also as brilliant masses in white quartz veins as in the Great Eastern vein and it forms the principal metallic mineral in a peculiar pegmatitic ortho- clase-quartz vein in the Panama Pacific prospect.” BANNOCK COUNTY Bornite occurs with chalcocite in quartz in fissures in conglomerate in ore of the Moonlight mine of the Pocatello Gold and Copper Mining Co. near Pocatello. In the specimens seen the bornite is in considerable part altered to dull purplish black ‘‘copper-pitch.”’ CUSTER COUNTY Bornite is rare in the contact metamorphic copper ores of the Mackay district (White Knob), the principal mineral of the un- oxidized copper ores here being chalcopyrite as contrasted with the Seven Devils district. Where it does occur bornite is apparently secondary and often forms narrow veinlets along joints and cracks in chalcopyrite.® In specimens from the second east drift, 300 level, Empire mine bornite occurs as disseminated grains with chalcopyrite in garnet rock. In another specimen from the ad- joining Tiger claim masses of bornite, now largely altered to chryso- colla and copper pitch and a turquoise blue clayey copper silicate, occur with fluorite in garnet rock. % Charles Palache. Amer. Jour. Sci., vol. 8, pp. 299-302, 1899. % W.H. Melville. U.S. Geol. Survey Bull. 90, p. 34, 1892. 7 D.C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 38, 1920. % F. B. Weeks and V. C. Heikes. U.S. Geol. Survey Bull. 340, p. 180, 1908. J. B. Umpleby. U.S. Geol. Survey Prof. Paper 97, p. 50, 1917. 120 BULLETIN 131, UNITED STATES NATIONAL MUSEUM KOOTENAI COUNTY Bornite is found in several prospects in the vicinity of Lake Pend d’Oreille, as, for example in the June Bug claim on the eastern shore where the bornite occurs in a quartz vein with chalcopyrite and specular hematite. LEMHI COUNTY Bornite is common in Lemhi County in the ore deposits along the Continental Divide where it comonly accompanies free gold! In the Copper Queen mine bornite constitutes an ore of copper and is the most abundant sulphide, clean masses of the mineral occurring in a quartz vein. A specimen of ore from the Halcomb property, Carmen Creek district, contains a peculiar bornite which on tarnished surfaces grows brown scales like those formed on mohawk- ite and some chalcocite. SHOSHONE COUNTY Bornite occurred in the ore formerly worked in the Snowstorm mine as minute grains disseminated in quartzite with chalcocite and chalcopyrite in amount sufficient to constitute a low-grade copper ore. In quartz veins which intersect this disseminated mineraliza- tion masses of nearly pure bornite up to 25 kilograms (50 pounds) in weight were ocasionally found. Bornite has also been reported from a number of copper prospects east of Mullan. WASHINGTON COUNTY Bornite is said to occur in a number of small vein deposits in the vicinity of Weiser. CHALCOPYRITE (83) Copper iron sulphide, CuS.FeS. Tetragonal, Sphenoidal. Chalcopyrite, commonly known as pyrites of copper, is, like bornite, a double sulphide of copper and iron. It contains relatively much less copper than bornite, however, the copper content of pure chalcopyrite being only 34.5 per cent while bornite, when pure, contains 55.5 per cent. It is consequently a lower grade ore. AlI- though crystals of chalcopyrite are known from a few localities, the common form of the mineral in Idaho is massive or granular or as disseminated grains, scattered through quartz or other gangue or mixed with other sulphides. In a few localities it is mined as a copper ore and it occurs commonly in many mines and prospects as an accessory sulphide of no commercial value. The color of the mineral on fresh fracture is golden yellow, much yellower than pyrite, which it otherwise resembles. Often this mineral assumes a brilliant iridescent tarnish on joints and fractures and for this reason it is often called peacock copper by Idaho miners, although this name belongs rightly to bornite. Like other common minerals 1J.B. Umpleby. U.S. Geol. Survey Bull. 528, p. 75, 1913. THE MINERALS OF IDAHO Loy this is so widespread in the State that only a part of the occurrences which have been specially noted can be mentioned. ADAMS COUNTY (Including Washington County in part) In the contact metamorphic copper deposits of the Seven Devils district chalcopyrite is abundant in the ore, although subordinate to bornite in all the deposits of this type except the Arkansaw mine in which bornite is but sparingly present and chalcopyrite is the only important ore mineral. Chalcopyrite is the principal primary mineral in peculiar pegmatitic quartz-orthoclase filled veins at the Lucky Strike prospect occasionally intergrown with bornite and partly enriched by replacement by chalcocite and covellite and it occurs similarly, though in small amount, intergrown with bornite in the Panama Pacific mine, where it has developed in hair lines and dots along cleavage lines in bornite. It is the principal ore mineral in the Gaarden mine and is abundant replacing andesite along a fracture zone up to 2 meters wide in the River Queen mine.” BANNOCK COUNTY In the Fort Hall mine, Fort Hall district, chalcopyrite constitutes an ore of copper. It occurs as granular masses with some pyrite and galena in a gangue of quartz and white calcite forming seams in folded shaly limestone.* BLAINE COUNTY In Blaine County chalcopyrite occurs in moderate amount in the Argent and Jay Gould and other lead-silver mines of the Hailey or Wood River district. In the gold veins it is a constituent of heavy masses of auriferous sulphides as in the Croesus, Camas, Tip Top, and other mines. BOISE COUNTY In Boise County chalcopyrite is a common constituent of the auriferous sulphide masses of the gold veins. Specimens from the Mountain Chief mine, Quartzburg district, contain chalcopyrite intergrown with sphalerite and as bronzy yellow masses in heavy aggregates of auriferous pyrite and arsenopyrite. In ore from the Carroll-Driscoll mine chalcopyrite is accompanied by pyrite, sphal- erite, and less tetrahedrite as masses of sulphides in quartz. The chalcopyrite is blue along joints and fractures from replacement by covellite. Small cavities in the ore contain minute blue sphenoidal crystals of chalcopyrite coated by covellite. Massive chalcopyrite is ~ 12D. C. Livingston and F. B. Laney. Idaho Bur. Geol. & Mines Bull. 1, pp. 37-66, 1920. 3 F. B. Weeks and V. C. Heikes. Notes on the Fort Hall Mining district, Idaho. U.S. Geol. Survey Bull. 340, pp. 175-183, 1908. . 54347—26}—_9 122 BULLETIN 131, UNITED STATES NATIONAL MUSEUM abundant in the Coon Dog No. 1 property in the Summit Flat dis- trict, some veins carrying enough of the mineral to form a low grade: copper ore. Much of the chalcopyrite here is also blue from incipient replacement by covellite. It is associated with pyrite and sphalerite in quartz. CUSTER COUNTY Chalcopyrite is an important mineral in the Loon Creek district. where the ores of the important mines consist of auriferous chalcopy- rite in a siderite-quartz gangue. The Lost Packer is the principal mine working this type of ore and has produced $500,000, The chalcopyrite, which is all massive or finely granular, occurs replacing quartz or siderite along seams. It contains from 214 to 3 ounces of gold a ton and from 6 to 9 ounces of silver. All of the goid is ap- parently contained in the chalcopyrite.‘ In the Bayhorse district chalcopyrite commonly accompanies the- tetrahedrite-siderite ores of the Ramshorn and other mines. Fine golden yellow bands of chalcopyrite border narrow veins of tetrahedrite from the Ramshorn mine (Cat. No. 56521, U.S.N.M.) and are mixed with tetrahedrite from the Bull of the Woods mine (Cat. No. 56618, U.S.N.M.). In a specimen from the Utah Boy No. 5 tunnel of the Ramshorn mine chalcopyrite occurs in drusy crusts of minute crystals with galena in cavities in siderite-tetra- hedrite ore. In the Alder Creek (White Knob, Mackay) district chalcopyrite is by far the most abundant primary copper mineral in the ores of the contact metamorphic deposits in limestone. It occurs as an interstitial filling in garnet rock and, in a few places, as grains con- centrically distributed in garnet crystals. Magnetite and chalcopy- rite seldom occur in the same hand specimen and even in an ore shoot where one is abundant the other is scarce. It is intimately associated with pyrite and in some cases completely surrounds garnet crystals.® FREMONT COUNTY Chalcopyrite occurs in barite with copper pitch and other altera- tion products in ore from The Weimer Copper mine 2 miles east of Kaufman in the Skull Canyon district. It is probably the principal primary copper mineral of this mine, the ore of which is very largely oxidized. IDAHO COUNTY Chalcopyrite is an accessory mineral in gold ores of a number of mining districts. In the Buffalo Hump district the ores of the 4J. B. Umpleby. U.S. Geol. Survey Bull. 539, p. 96, 1913. 5J. B. Umpleby. U.S. Geol. Survey Prof. Paper 97, 1913. THE MINERALS OF IDAHO 123 Jumbo mine contain it as the principal sulphide, with pyrite and galena scattered through quartz and ore from the Venture claim shows disseminated patches of chalcopyrite partly altered to copper pitch. Auriferous chalcopyrite distributed through white quartz forms the gold ore of the South Fork mine 7 miles southwest of Eik City and it occurs similarly in many of the mines of the area. LATAH COUNTY Chalcopyrite is common in the Hoodoo district as disseminated mineralization in a number of prospects and in considerable masses, sometimes 1 meter (3 or 4 feet) wide and 6 meters (20 feet) long, of nearly pure chalcopyrite in the Mizpah mine. It is associated with pyrrhotite and biotite.*¢ LEMHI COUNTY Chalcopyrite is a persistent accessory mineral in Lemhi County occurring in all of the mining districts and nearly all of the mines. In places it is associated with gold but usually it is an inconspicuous companion of pyrite. It occurs in very subordinate amounts in the lead silver deposits.® OWYHEE COUNTY In Owyhee County chalcopyrite is common in small grains sparsely disseminated in the ore of the Black Jack, Trade Dollar, Morning Star, Poorman, and other rich silver mines. In the Black Jack mine most of the gold is contained in chalcopyrite.’ A typical specimen of ore from a raise 1, 300 feet from the portal of the Blaine tunnel, Silver City district contains chalcopyrite with argentite finely disseminated in an aggregate of quartz and adularia. Chal- copyrite occurs also mixed with other sulphides in unoxidized ore of the South Mountain district as in the Bay State mine, where it is intergrown with arsenopyrite, sphalerite, and a little galena. SHOSHONE COUNTY In the Coeur d’Alene district chalcopyrite is widely distributed in the ores being found occasionally in most of the mines. It is the principal ore mineral in copper prospects east of Mullan, where it occurs pure in considerable masses. In the Snowstorm and National mines it forms fine disseminations with chalcocite, etc., in quartzite. Small amounts of the mineral commonly accompany the rich lead- silver ores. It occurrs especially in the Greenhill-Cleveland ore shoot at Mace in Burke Canyon in parallel bands with pyrrhotite constituting the first mineralization of the vein and in pure golden yellow masses with coarse grained galena in streaks which cut the se D. C. Livingston and F. B. Laney. Idaho Bur. Geol. & Mines, Bull., p. 95, 1920. 6J. B. Umpleby. U.S. Geol. Survey Bull. 528, p. 76, 1913. 7 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, 1900. 124 BULLETIN 131, UNITED STATES NATIONAL MUSEUM main mass of the vein filling. In the Caledonia it forms irregular grains and masses included in tetrahedrite or replacing siderite and also as larger masses of pure chalcopyrite, sometimes 250 kilograms (500 pounds) in weight. In certain veins rich in iron sulphides which occur in the Prichard slates near Kellogg chalcopyrite is common as in the Teddy, Lom- bardy, Wisconsin, Enterprise, and other claims. The gangue here is quartz and ankerite. Over 20 tons of chalcopyrite ore were shipped from the Wisconsin claim some years ago as copper ore. In the Pine Creek district chalcopyrite is a common constituent of the mixed sulphide lead-zine ores where it occurs in a quartz and sometimes ankerite gangue. Banded ore from the Highland-Sur- prise mine contains alternating streaks of chalcopyrite, galena, and sphalerite. In the Shetland claim it is abundant as grains and small masses in quartz with galena and sphalerite and the occurrence in numerous other mines is the same. In the Northern Light, Bobby Anderson, Carbonate, Lookout Mountain, and Hypotheek mines it occurs in isolated and pure masses of moderate size in white quartz. On the North Fork and Little North Fork of the Coeur d’ Alene River chalcopyrite occurs in numerous prospects as the Britt, Hand- spike, Shuck, Alva Brown, Riverside, Hamburgh-American, and Horst-Powell (Empire). At the latter property a considerable amount of chalcopyrite ore has been mined. In the St. Joe drainage area chalcopyrite is abundant in a consider- able number of prospects, some of which have made a small produc- tion of copper ore. It is the only important primary sulphide and occurs mixed with a little pyrite and pyrrhotite in a gangue of quartz and ankerite. The Monitor and Black Prince are the principal mines of this group. WASHINGTON COUNTY Chalcopyrite is a constituent of the silver ores mined in the Min- eral district around the town of Mineral, where it occurs in veins with tetrahedrite, pyrite, galena, and sphalerite.* SMALTITE (87) Cobalt diarsenide, CoAs, Isometric, pyritohedral. LEMHI COUNTY Umpleby ® states that a cobalt arsenide, possibly smaltite, occurs in the cobalt ores of the Blackbird district in grains of microscopic size as a replacement of quartzite and schist, and is perhaps the most abundant cobalt mineral of the district. All specimens of the ores which have been available to the writer for examination have proven to carry cobaltite rather than smaltite, although the latter probably is present. 8 Waldemar Lindgren. U.S. Geol. Survey, 22d Ann. Rept., pt. 2, p. 754, 1901. 9J,B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 77, 1913. THE MINERALS OF IDAHO £25 PYRITE (85) Tron disulphide, FeS, Isometric, pyritohedral Pyrite, commonly known to the miners as pyrites of iron, is the most common and widely distributed metallic sulphide in Idaho, as in most other areas, occurring in practically every ore deposit of whatever sort and also in many regions in disseminated form in the country rock. In ores it is usually a valueless and troublesome asso- ciate of valuable metallic minerals, although in gold veins the pyrite fl ALE et HY Wy My SAM SY! Wy Wey Whi] Nai a } Hh Wilf ih fi\\\ | | fi if yi | Wi)( 1 eral tH Mii ZL {hit \ Mil | a ‘Hl il Hebe al ps tl i WU it i } i hi i | | | Fics. 7-8.—7, SMALL PYRITE CRYSTALS EMBEDDED IN QUARTZ, CROESUS MINE, BLAINE COUNTY. 8, PYRITE, DOMINANTLY PYRITOHEDRAL CRYSTALS EMBEDDED IN CALCITE FROM THE PARKER MINE, WARM SPRINGS DISTRICT, BLAINE COUNTY is sometimes notably auriferous, and is concentrated and smelted for its gold content. When available in large bodies adjacent to markets, pyrite is burned for the production of sulphuric acid, but deposits of the mineral sufficiently large and pure for this purpose have not as yet been found in Idaho in situations favorable for economic exploitation. Only the more important of the known occurrences in the State are mentioned below. 126 BULLETIN 131, UNITED STATES NATIONAL MUSEUM BLAINE COUNTY Pyrite occurring in the gold veins of this county is auriferous, as in the Camas, Tip Top, Croesus, Wide West, and other mines. A specimen from the Croesus mine in the Hailey gold belt shows rather highly modified pyrite crystals in quartz. One crystal from this specimen was measured and had the forms and habit shown in Figure 7. The forms and angles measured are given in the following table: Measurements of pyrite from Croesus mine Form Symbol Measured Calculated | fa een Quality, description No. | Letter Miller | Gdt. ¢ p 9° p | | ° , ° , ° , °Q , 1 ie 001, 0 Excellent, striated =-- == 22 she. Seana Os 00;/22eeeese 0 00 Del ene eee O1Q) |= Oconto 222 1 SRS RT NS ee 0 00/90 00; 0 00; 90 00 3 ‘| 012 6a OO ee ee SSS Se 0 00} 26 35}; O 00} 26 34 AN ean sees OZ |e O2ee eee Oe ss re as ee omnes 0 00] 638 20; O 00} 63 26 5 {f 1204. 460. ¢.| Mxcellent.. 00.68" coo Cais 26 24 | 90 00 26 34| 90 00 Ghee ee 111 1 Verycood2h-2) sae eae eee 45 O01] 54 36) 45 00) 54 44 7 123 SF [oe see GO ies et SS eee ee 26 17 | 36 20) 26 34} 36 42 Bal pee 132 wa News GO Ee goes ao eae 18 16] 58 02) 18 26) 57 41 9 231 23 Excellent 222) 2 ae Ls Sees 33 31 | 74 31] 33 41 | 74 30 10 | ease 249 | BE ale VCRs O0Gssea a eee ee a ee eee 26 31) 26 36 | 26 34] 26 25 | The crystals, though small, rarely reaching 5 mm. in diameter, are lustrous and yield excellent reflections. They are easily sepa- rated from the inclosing quartz gangue. The specimen from which the measured crystal was taken is labeled as from the stope on the long 5 drift on the fourth level, Croesus mine. A specimen of ore from the Parker mine, Warm Springs district, shows brilliant and modified pyrite crystals in coarse white calcite associated with quartz containing sphalerite. One of these which was measured had the forms and habit shown in Figure 8 and gave the following measurements: Measurements of pyrite from Parker mine | Form Symbol Measured Calculated ——_———— | Quality, description No.| Letter Miller | QGdt. | ¢ p ¢ p | | ° , ° , ° ‘ ° ’ La: { OOO! Good.) ablative ca peal EE | ieee 05700 teen = 0 00 2 ba Chane 010 Ooo) | SWery, £000 Bene ena eee eee 0 00} 90 00| 0 00} 90 06 Delie. sss & ' 012 036 {);Poor,;doublessss2 6k eee eae 1 11] 26 20} O 00} 26 34 ae Ser asoul Se lll il | Hixcellente eee sake ee eee ia See 45 20] 55 00! 45 00 | 54 44 5 Geese e* 121 12 yWieryigood 2322 ao ie Sakae ee 26 54/66 02) 26 34/65 54 6 | One eee 252 Seg) Median: oes eee ee eee eon 21 17/70 09; 21 48] 69 37 inetd te 528 a 131 13 pei eto eee eee ose en eee 18 43 | 72 48|18 26) 72 27 Si yee eee 234 42.) Very poor, blurred? “22207 2222222 eae - 32 33 | 40 00| 33 41 | 42 02 | | | | Specimens from the fifth level of the Muldoon mine, Little Wood River (Muldoon) district, contain numerous well-formed pyrite crystals of pyritohedral habit embedded in sericite. Sood THE MINERALS OF IDAHO 123% BOISE COONTY In the various mining districts of Boise County pyrite is abundant, mot only in the gold-bearing veins but also in the altered wall rock adjacent to the veins where it accompanies sericite. In the Quartz- burg district, in the Mountain Chief mine, pyrite occurs in the richest ores as large pale masses consisting of imperfect cubic crystals up to 3 cm. in diameter with bismuthinite in quartz sometimes intergrown with sphalerite, arsenopyrite, and chalcopyrite in masses of auriferous sulphides, or as small brilliant cubic crystals disseminated in the -sericitized wall rock adjacent to the veins. In ore from the Native Missourian mine auriferous pyrite occurs with sphalerite as small disseminated grains in quartz. At the Carroll-Driscoll property pyrite is intergrown with other auriferous sulphides in quartz in the ore and also as large masses embedded in sericite gouge, the latter -often showing pyritohedral crystals up to 1.5 cm. in diameter. This is the best erystallized pyrite thus far examined from the State. Some of the crystals are rather highly modified. A portion of one of the more complex individuals was measured and is faithfully reproduced in the drawing (fig. 9). This gave the angles recorded in the table below. Several of the forms appear to be new but require substantiation, so that no letters have been assigned them, the faces in the drawing being merely numbered to agree with the table. The crystallized pyrite from this locality requires further crystallographic study. Measurements of pyrite from Carroll-Driscoll mine ; Form | Symbol Measured Calculated Bae aes ae oe Quality, description | ra aaa ay —— No.| Letter | Miller | Gat. ° p orl ieee — — | | | | | ° , ° , ° , ° ‘ 1 \e { 001; O Mery i good wstte = 348% Fe BU OA 01000 | 229 0 00 Deine are oa OLD Wa Ooo Ieee Oe ee ae eee | 0 00/90 00} O 00/90 00 3 Mf { O145 NE Olae hie lnxcellontaten2sete = ot ee ee 0 00/14 04] 0 00] 14 02 Bact arate | 041 | 04 Good Se ee eee ee eee ae | O 00 | 76 26 0 00 | 75 58 5 ite { 02745, ,0-—> | Roorjoscillated 2. _ 5222-244 ate | 0 00/15 24! 0 00/15 56 Oia 5 072): O—» | Poor, blirred=. 22-2255 --5 222228 | O 00} 73 40] O 00} 74 03 | O12 i eOVen eeexcellent 25 44: Penis elect oe a | 0 00; 26 39/ 0 00 | 26 34 Sil ress Seance 021, 02 BUTE eke cant cs ee ee en ee | O 00} 62 46 0 00 | 63 26 9 J ry, GAO y Pera y' sGood use oe ee Ft a 26 66 | 90 00| 26 34) 90 00 AOR ROP os < 2 | 032 | O- WMeditin's ese e ee nee ene yd ae | 0 00} 56 25| O 00} 56 18 11 |}. j 043 o— EI XCOllOTI US setae ae ee es 0 00 | 53 00] O 00! 53 08 LAN eee an 034 | 844+ |e = = GOR es aim ges 2 Sk Se 0 00 | 37 00; O 00} 36 52 13 340 ol WiOlY: 200dsaoe wa cce cee le seen ee cee 36 51 | 90 00} 36 52] 90 00 aS eee 0.11.9 0—- IEG CUI Se es oe he ee he ee ee! 0 00) 50 16 0 00 | 50 42 Louies 22 oe 670 | o— Mery poor, striated: i222. 2s 22-2: 40 13 | 90 00 | 40 36 | 90 00 1 CTY as | oll Ol (C (eoie ME ee ee ee eee 0 00! 44 55 0 00! 45 00 17 i { 112 iy xcellonts ee 3 Pe hel 2 es 44 43] 35 08 | 45 00] 35 16 Tb parsers 121 12 Medium striated $2 eee e -- 2 ee 26 06 | 65 51] 26 34] 65 54 DO a Ds 22 sao) 111 1 Ey xcellent-t2 i Ost ea he 44 40 | 54 37] 45 00 | 54 44 SUN) Wenee oa 122 | Wl re PEO Ons eee een es Fa ee 26. 06 | 48 04] 26 34) 48 11 ly tos rete 233 | —1 Mery poorsd ints sis tS i mes Sha 31 -31 |} 52 13] 33 41) 50 14 eC Ee ee 148 — Aol WW VOLY DOOL, NOSIPie-0 2. oe ene essa seks 165,50 27 10. | 1402-27 = 16 23h DE Les 2SbUIe — Werte || Mod iti - = eee sDeres ese dae ee cee 32 11] 30 45 | 33 41 | 31 00 DEI YEe een we | 234 at ROORS 2 eas eee a aetna aoe s Vile MLL 32 26} 42 41) 33 41/42 02 Di Dee ee es | DAS eee Poor striated eee ws VR ae 26 06) 58 58 | 26 34) 56 08 DB gt Oe sees 231 || 23 VEE Ya DO Oren een een erin lew RSE S Ete 31 56.|.71 33 | 33 41 | 74 30 27 () Cult bless. set Megan sees Ree at CAE A 32 07 | 37 26] 30 58] 37 52 28 (1) DN ON ea ete VERY DOOTES 228k Se Ey eke ew AT ety) 15: 5071°86) 30) 15: 67 1/36, 03 29 | () 128 =a, IE Ae LORE ees SBR rere s hie eae 5 27 37) 15 34) 26 34/15. 37 30 (4) 4. 5. 20 —-\ VEC Ton esate eee te eee ed 40 08/18 19 | 38 40! 17 45 | 1 Indicates probable but unsubstantiated new form. 128 BULLETIN 131, UNITED STATES NATIONAL MUSEUM A specimen from the dump of the Gold Hill mine consists of quartz porphyry containing abundantly disseminated pyritohedral crystals of pyrite. A large and completely sericitized phenocryst of feldspar in this rock carries groups of slightly larger pyrite crystals of dom- it i i | | i Hi | | 10 Fias. 9-10.—9, PYRITE. HIGHLY MODIFIED CRYSTAL FROM CARROLL-DRISCOLL MINE, BOISE COUNTY. 10, PYRITE. DOMINANTLY CUBIC CRYSTAL FROM SERICITIZED FELDSPAR. GOLD HILL MINE, BOISE COUNTY inantly cubic habit with the modifying faces shown in Figure 10. The forms and angles measured on one of these crystals are given in the following table: Measurements of pyrite from Gold Hill mine Form Symbol | Measured Calculated epee ee ee Quality, description No.| Letter Miller | Gdt. | @ p aaa hace ee ee ari | oe ae | ° t2 ° , ° , | Q , 1 001 0 Good) ’striated es 22 eos eres eed OOO See see 00 2 c 010 Gao |) 22 06 Ko ans as aera eae Tanitee ead ae AE Ee 0 00| 90 00; O 60/} 90 00 3 Pp 111 1 Very 12000 eee eee ea ee 45 02] 54 47/45 00) 54 44 4 wu 122 a4 PSin Snel see eee eee eee a 26 32) 48 10] 26 34) 48 11 5 123 Fe Sl Oe ae eee rs Ee ES fee ees 26 32 | 36 43] 26 34 | 36 42 6 ro 132 a om Nie ree me ec Se tae ee mT Ae 18 26| 57 44/18 26] 57 41 7 e 124 i} Bair smalls: Sac! Seo ee eS 26 32) 30 .00 | 26 34} 29 12 1 } | eee THE MINERALS OF IDAHO 129 Nodules of pyrite inclosed in clay of Neocene lake beds on Turners claim near Idaho City contain some gold and silver.’ In ore from the gold vein of the Golden Age mine, Pioneerville district, auriferous pyrite occurs in cubic crystals with sphalerite, and in a specimen of typical ore from a stope below the tunnel level of this mine it is abundant in grains and imperfect brignt crystals with galena sphaler- ite and tetrahedrite, disseminated through somewhat crushed quartz associated with sericitized granite. In a specimen from the Coon Dog No. 1 vein striated cubic crystals of pyrite up to 1 cm. on an edge are embedded in quartz with chalcopyrite and sphalerite, the latter being coated on fractures with covellite. In the Coon Dog No. 4 pyrite occurs in coarse cubic crystals thickly disseminated in quartz in a 65 cm. (26-inch) vein of sulphides in granite porphyry, where it is associated with abundant chalcopyrite and a little of a reddish gray antimonial mineral which may be tetrahedrite but which re- sembles famatinite. This ore contains good values in silver. Masses of coarse imperfect striated pyritohedral crystals occur in ore from the Gem of the Mountains mine, and in the Overlook mine coarse imperfect pyrite crystals are intergrown with galena, sphalerite, and tetrahedrite forming masses of sulphides in quartzose gold ore. In the Blackbird tunnel on the Enterprise vein small brilliant pyrite crystals occur disseminated through sericitized rock and inter- grown with sphalerite in the ore, and small brilliant pyritohedral crystals are present in granite on the Fairmont claim. In the Pear! district much of the gold ore occurs as narrow seams of sulphides in sericitized granite consisting principally of sphalerite and pyrite. Specimens from the Lincoln mine contain small pyrite crystals showing oscillatory combination of cube and pyritohedron in drusy cavities in dark brown sphalerite. Specimens from the Black Pearl dump consist of masses of pyrite with sphalerite and galena in sericitized granite. CLEARWATER COUNTY Pyrite is common in gold ores. Specimens from the Lolo M. & P. Co. property, Musselshell (Weippe) district contain pyrite cubes in quartz up to 2 cm. in diameter in part altered to pseudomorphs of limonite. CUSTER COUNTY Next to chalcopyrite, pyrite is the most abundant primary sul- phide in the lime-silicate contact deposits in limestone in the Alder Creek district. It occurs both as coherent grains and as intricately fractured grains with chalcopyrite along the fractures. The chalcopy- rite in many such specimens represents more than half the total area. In some places the pyrite is interstitial with respect to garnet cry- 10 Waldemar Lindgren. U.S. Geol. Survey, 18th Ann. Rept., pt. 3, p. 665, 1898. 54347—267——-10 130 BULLETIN 131, UNITED STATES NATIONAL MUSEUM stals.11_ Pyrite is a persistent mineral in all the deposits in the north- western part of the county. In the walls of the late Tertiary veins abundant cubes of it accompany the metasomatic alteration."* In a prospect at the head of Little Fall Creek near the head of Lost. River well-developed pyrite crystals are associated with galena. At the Red Bird mine in the Bay Horse district on the No. 8 level a mass of pyrite 17 meters (55 feet) wide has been opened. This pyrite: occurs as fine-grained masses and also as porous aggregates of plumose groups of crystals which resemble marcasite but are of pyritohedral form. ELMORE COUNTY Pyrite is common in all mines. Small pyritohedrons are dissemi- nated in silicified and mineralized granite from the Boise-Rochester mine, Atlanta district. IDAHO COUNTY Pyrite is a constituent of the gold ores of most Idaho County dis- tricts and is usually auriferous. It occurs scattered through the quartz of the ores in only moderate amount. Large imperfect crys- tals, grains, and masses accompany minute amounts of galena and chalcopyrite in ore from the Hercules and Blue Ribbon mines, Elk City district. Itis the principal sulphide in the Black Pine mine, also in this district, where it is disseminated in quartz with galena, tetrahedrite, sphalerite, and native gold. The ore of the Mineral Zone mine consists of granular auriferous pyrite in rusty quartz. In the Buffalo Hump district sparsely distributed auriferous pyrite in quartz forms the gold ore of the Concord (Mother Lede) and other mines. In the Penman and other mines of the Oro Grande district pyrite,. which is practically the only sulphide disseminated in quartz, is again the ore of gold. In the Thunder Mountain district in the Dewey mine pyrite: nodules occurring in volcanic tuff had coarse leaf gold at their center. LEMHI COUNTY In Lemhi County pyrite appears in all the deposits, and in the gold veins it is auriferous. In the Mackinaw district it is the most abundant mineral, occurring as coarse cubes included in the quartz, and makes up about one-third of the bulk of the gold ore. A typical specimen of ore from the A. D. & M. mine, Gibbonsville, containing $150 a ton in gold, shows pyrite as the only sulphide as small brilliant. cubes in a gangue of quartz and calcite. iJ. B.Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 54, 1917. iia J, B. Umpleby. U.S. Geol. Survey, Bull. 539, p. 53, 1913. 12 J, B. Umpleby and D. C. Livingston. Idaho State Bur. Mines and Geol., Bull. 3, p. 6, 1920. THE MINERALS OF IDAHO 131 In a specimen from the Rabbitfoot mine in the eastern part of the Gravel Range district pyrite appears in an unusual form. Litho- physae-like cavities in silicified rhyolite contain tabular hexagonal crystals up to 2 mm. in diameter, now composed of granular pyrite. These look very much like pseudomorphs after mica crystals, although it is possible that the original crystals were some other mineral, such as polybasite or pyrrhotite. OWYHEE COUNTY In the Silver City and other silver mining districts of Owyhee County pyrite is not common in the veins, but occurs abundantly in the altered lavas of the wall rocks. In the South Mountain district it is a constituent of heavy masses of intergrown sulphides and contact silicates. SHOSHONE COUNTY In Shoshone County pyrite is common in all veins and also over wide areas sparsely disseminated in the sedimentary rocks, especially those of the Prichard formation. In places the pyrite in the slates is in the form of isolated cubic crystals which may reach 5 cm. (2 inches) in diameter. Minute and deeply striated brilliantly lustrous cubic crystals occur with larger crystals of arsenopyrite replacing sericitic slates in the walls of the Stanley antimony vein at Burke. It is universally present in the lead-silver veins but seldom in large pure masses and not often in well-formed crystals. Certain beds of quartzite in the Wardner mines are largely replaced by pyrite so fine grained as to be difficult of recognition. This pyrite decomposes very readily and specimens, when placed in a dry place become coated with a hairlike growth of crystals of ferrous sulphate. The tem- perature of certain stopes in the Bunker Hill mine is greatly raised by the heat generated by the decomposing pyrite. Fine-grained pyrite occurs abundantly, intergrown with pyrrhotite and some chalcopyrite, in a quartz-ankerite gangue in nonproductive veins of the ‘‘ Wisconsin type” east of Kellogg. Beautifully iridescent druses of minute crystals appear in vuggy quartz in the Lombardy vein in Italian Gulch north of Kellogg and druses of brilliant crystals occur in a gouge in a small tunnel overlooking Elk Creek Slough above the mouth of Elk Creek. Pyritohedral crystals 2 em. (1 inch) or less in diameter have been found in sericitic shale in the Yankee Boy silver mine on Big Creek. Globular and sperical forms of pyrite with internally radiating structure have been obtained from the Greenhill-Cleveland mine at Mace and the Gold Hunter mine at Mullan. Pyrite occurs in intimate intergrowth with galena and sphalerite in many of the mines of the Pine Creek Basin. The pyrite in the Golden Chest and other gold mines of the Murray section is auriferous. 132 BULLETIN 131, UNITED STATES NATIONAL MUSEUM WASHINGTON COUNTY In Washington County many of the large hematite deposits in the vicinity of Iron Mountain have been found to pass at shallow depth into massive bodies of pyrite. On the Segwine claims a 5-meter (15- foot) lens of pyrite is exposed and in the Little Gem claim there is a vein of pyrite 2 meters (7 feet) wide and a zone of garnet rock thickly impregnated with pyrite for a width of 30 meters (90 feet). In the Mineral district pyrite occurs commonly in gold and silver ores associated with galena, sphalerite, tetrahedrite, etc. An unusual variety has been reported from this district containing 10.9 per cent of manganese ' and a little silver. COBALTITE (89) Cobalt sulpharsenide, CoS,.CoAsp. Isometric, pyritohedral. LEMHI COUNTY Cobaltite is abundant in many cobalt mines and prospects in the Blackbird district being, so far as the specimens at hand indicate, the only important cobalt ore mineral of this field. It occurs as reddish gray grains, crystals, and granular masses. Very fine-grained reddish patches in schist from the Gray Eagle property are unaltered in the closed tube over the Bunsen burner but at blast temperature give characteristic rings of arsenic sulphide and arsenic, and are thus cobaltite. Ore from the Tom Jefferson claim contains minute reddish-gray crystals of cobaltite with chalco- pyrite making up a sulphide band 1 cm. wide in schist. Crystals from this specimen were measured and found to be isometric pyritohedral in crystallization with faces of the cube, octahe- dron, and pyritohedron. Specimens from the Brooklyn claim also show crystals of cobaltite up to 2 mm. in diameter associated with chalcopyrite. These show rather perfect cubic cleavage. It dissolves with avidity in concentrated nitric acid with separation of sulphur and yields a pink solution which becomes green when a little hydrochloric acid is added. It is unaltered when heated in a closed tube over a Bunsen burner and gives arsenical fumes when heated before the blowpipe on charcoal. It contains no iron and gives no nickel reaction with dimethylglyoxime. The crystals have the forms shown in Figure 13, the cube modified by octahedron and pyritohe- dron. The measurements which establish their isometric form are given in the following table: 13 Robert N. Bell. 20th Ann. Rept. Mining Industry of Idaho, pp. 107-109, Boise, 1918. 4 Lang. Private communication in supplement sixth edition of Dana’s System of Mineralogy, p. 1045. THE MINERALS OF IDAHO 133 Measurements of cobaltiie from Brooklyn claim Form | Symbol | Measured Calculated l STAR Quality, description | = (real No.| Letter | Miller | Gat. | ¢ | p ¢ | p |- [ayy | | | ° / ° , ° vi ° , 1 \e | { 001 OnuiVeryagoods Jae Se ee A oe RA Ne es Op OOM fe ees 0 00 Baers e ssl 010 QoojiGrood tk ta Pet $a ee 2 Pe et Es Oe 0 02/90 00} O 00/90 00 3 | | 120 Cofv| segs tes ee eee 26 22/90 00} 26 34/90 00 4 pesssioe _ 012 O46)" Good SARE ReL EU oa ee 0 00} 26 07] O 00| 26 34 5 | | 021 O23. sic Miedinm 2 si 2s5- ons sas2ee se oe 0 00 | 64 20} 0 00/63 26 v Do. oo2e | 111 Di) Maire else ky oa ee caer eae | 44 56 | 54 51 | 45 00| 54 44 } } } | Bascom Latest Out claim on the west fork of Blackbird Creek has abundant small crystals of cobaltite, seldom reaching 1 mm. in diameter, disseminated in streaks in granular quartz containing some schist inclusions (pl. 2, upper). These crystals are easily isolated from the matrix and are found to be cuboctahedrons as shown in Figures 11 and 12. The measurements which identify the forms are, in detail, as follows: Measurements of cobaltite from Latest Out claim Form Symbol | Measured | Calculated Quality, description | - | | No.| Letter Miller QGdt. 9? p ? | p | ° wi ° 7, ° , | fo} , 1 \e { 001 OM Gitair se ale een Gate ey ae a eee 0.005 |or nt | 0 00 AN press ae eS 000 Oco|22—3- OE oe re ee ent, 90 00} 90 00) 90 00 90 00 SU EO aaa 111 1 IMeditim 2 22022 oe Eh eet eT) 45 00 | 54 55| 45 00 | 54 44 | | | | This mineral has well-defined cubic cleavage. It behaves like the preceding when heated in the closed tube or on charcoal. A sample separated by heavy solutions from this sample was partially ana- lyzed. It contains 20.08 per cent of sulphur and 2.18 per cent of iron. No trace of nickel could be detected. A specimen from the Wiley J. Rose property 1 mile north of the old camp of Blackbird contains a solid vein of granular cobaltite partly altered to erythrite in a quartzose schist and another specimen from the same vicinity has granular crystalline streaks of cobaltite in schistose quartz making up half the bulk of the specimen. This cobaltite was analyzed, yielding the following results: Analysis of cobaltite, Lemhi County Constituent Per cent. MAL ACC GY Pr ER ie tee SE Se aE 32. 38 ENETE GE YAU) See taee ta Meng nc ett cet MATE MN RN DRS pe ee cor ACa a ss sels 4.33 RUMP SURE Se ori et ca gel ot. CAPER ee ee ee None. PET SEIN CA CAS) eee ee Le ee oe, Sees Se LO EIO OS ER LF 44, 07 Bera IeS Er nn ye teee p P ae e Oh a an eclas Se 18. 10 134 BULLETIN 131, UNITED STATES NATIONAL MUSEUM In the Haynes Stellite Co.’s mine on Blackbird Creek, 4 miles below the old camp of Blackbird and 2 miles above the mouth of the creek, cobaltite occurs as extremely finely diffused microscopic grains of reddish-gray color in black tourmalized quartz associated with larger crystals of danaite. Such material, which makes up the ore, shows no cobaltite to the naked eye unless polished. Another specimen from this property contains crystals of reddish cobaltite up to 5 mm. in diameter disseminated in quartz with schistose biotite, chlorite, and long prisms of apatite (pl. 6, lower). These es ") 11 12 13 Figs. 11-13.—11, COBALTITE. LATEST OUT CLAIM, BLACKBIRD DISTRICT, LEMHI COUNTY. CUBE TRUNCATED BY OCTAHEDRON. 12, COBALTITE. SAME LOCALITY. 13, COBALTITE. CUBE TRUNCATED BY OCTAHEDRON AND PYRITOHEDRON. ‘TOM JEFFERSON CLAIM, BLACKBIRD DISTRICT crystals are, for the most part, simple cubes or octahedrons, and show well-defined cubic cleavage. A specimen of ore from the Nickel Plate mine shows granular residual patches of cobaltite in greenish masses of oxidation products consisting principally of olivenite and scorodite. GERSDORFFITE (90) Nickel-cobalt-iron sulpharsenide, (Ni, Fe, Co) AsS. Isometric. - An isometric sulpharsenide of nickel, iron, and cobalt recently received for examination and report at the National Museum may be classed as gersdorffite. Bis BULLETIN 131 U. S. NATIONAL MUSEUM COBALTITE FOR DESCRIPTION OF PLATE SEE PAGES 133 AND 134 THE MINERALS OF IDAHO 135 SHOSHONE COUNTY A lot of material received from Erwin Ploetzke contained a gray sulpharsenide of nickel, cobalt, and iron. The specimens were mailed from Burke and a letter accompanying them stated that they were from a prospect of Mr. Ploetzke in Idaho. Inquiries as to the exact locality met with no reply from Mr. Ploetzke. Recently an identical lot of material was received from A. Beals, of Avery, Idaho. An inquiry directed to Mr. Beals elicited the information that both lots were from the same prospect, in which Ploetzke is a partner, and which is located 7 miles from Avery on Slate Creek, 1 mile from the mouth of the creek. The specimens consist of greasy-appearing greenish sheared quartz containing the gersdorffite associated with pyrrhotite and chalcopy- rite. The gangue shows a small amount of a grayish carbonate, probably Bronte! The quartz contains small open spaces lined with imperfect quartz crystals on which rest occasional whitish crys- tals of barite and minute pale green globular or barrel-shaped aggre- gates of a scaly micaceous mineral. The latter is probably a chlorite. It is biaxial positive with 2V medium small, estimated at 30°, and refractive index about 1.62. As a later deposit in the cavities there occur rose-red crusts of minute crystals of erythrite (cobalt bloom) too small to be measured but identified by their characteristic optical properties, and some dead-black material which may be heterogenite. The gersdorffite occurs in masses up to several centimeters in dia- meter either alone or mixed with the other sulphides. The mineral is not massive but consists of closely spaced small individual crystals, less than a millimeter in diameter, separated by quartz. Portions may be selected with a large proportion of the mineral and practically free from the other sulphides. Such were crushed and sized by screening and the quartz separated with methylene iodide. A few grains of pyrrhotite were extracted with a hand magnet. Microscopic exami- nation showed this prepared sample to be free from other sulphides. It was analyzed, yielding the following results and ratios: Analysis and ratios of gersdorffite from Avery (E. V. Shannon, analyst) Calculations of ratios | Per cent | | CAN ase S ae cane ea ne nee eye knees LW pate ee nee ne SAS 3. 48 BigUSea eel Annee AS paelig ones nei peat iil. ocak eepos00l | OntEd Pico mttigers Petpet cn ifs ees ee TCD roe | 14.98| 24340586 1.021 Bate ele iacs naire n aie ecb Gryeres st gsm geet Lay oan fart ee | 10.57 | 189 MERE c NTRS ROR a irre OTN oO tes wee PeLIN tases ek 43,80 | .584 .584 1.02X1 Seiichi es ee byes heaps -y pesan leh, gees Aas atta cl, | 1770 | 1552 552 96x! fijtales Serre Alevenbs . rock from the Nickel Plate mine. Polished specimens of typical ore from the Haynes Stellite Co.’s mine on Blackbird Creek 2 miles above the NG mouth of the creek, collected by Frank L. Hess show silver-white fic. 22—Danaits. WuiTe crystars EM- crystals up to 5 mm, in diameter "#22 !8 Ot Navwessnnnine wv sparingly disseminated in a quartz tourmaline rock containing finely disseminated cobaltite. The large crystals are of the cobaltiferous variety of arsenopyrite which has been given the varietal name danaite. By carefully cracking away the surrounding gangue it was found possible to secure one of these crystals which was suitable for goniometric measurement. These crystals are stout prismatic by elongation of the a axis and have the habit shown in the drawing figure 22, the dominant forms 144 BULLETIN 131, UNITED STATES NATIONAL MUSEUM being the pinacoid a(100) and the dome (011) with smaller faces of m(110), g(111), and v(212). The measurements obtained are as follows: Forms and angles on danaiie from Lemhi County | | | Form Symbol | Measured | Calculated | Quality, description EA ee eee - No.| Letter | Gdt. | Miller | | ¢ | p | ¢ | p “ | a fe Rea jee xs} | Ko. yy ° ' | ofa zie ’ ry a W's) 10° | Mlodinn poor. eye ees 56 32/90 00| 55 46| 90 00 PAV eee 1 ito: LO ies | eee O22 eye eb Ee 56 30/90 00} 55 46} 90 00 Slabs aoe o1 O11 1 ek 0 0) Cea es ee ee 0 06! 49 22; O 00) 49 59 Aalbers le VOL Of Oe a eub ateta ies eye ow aN Eh 0 04| 49 22} 0 00} 49 59 eGo ones | 1 111 Goode ne ees see Pe ee eee | 56 23 | 65 26) 55 46) 64 44 Gal, paseo | 1% 212 Medivme =< ee ei ey ead | 70 55| 61 58| 71 13] 61 36 A crystal of the danaite which on polished surface appeared pure and homogeneous was analyzed, yielding good results although, after deducting adhering gangue, the sample weighed only 0.1482 gram. The results of this analysis are given in column 1 below while in columns 2 and 3 are given, for comparison, analyses of danaite from the original locality, Franconia, N. H., and from Skutterud, Norway.” Analyses of danaite 9g J a | (1) Idaho ae (3) Norway | LPS, irsenion le i. Pa TUN Ae NOS eR 46.93 41, 44 46. 76 STAT UE ee is ee IRA SPARS OE 2 trey nah Vn eR | 17. 10 17. 84 17. 34 pone. Fs J. de, LEMUR a | 27. 26 32. 94 26. 36 Gotan a De ace GE OY TT em ane ca 8.71 6.45 9. OL Motels. ee PRR ST NSE a orale ete ais | 100. 00 98. 67 99. 47 As shown by the analysis the Idaho material is even higher in cobalt than the original material to which the varietal name was given. The mineral contained no trace of nickel as tested with dimethylglyoxime. The blowpipe reactions are the usual ones for arsenopyrite. In the closed tube in the bunsen flame a broad reddish- black ring of arsenic sulphide above a brilliant metallic ring of me- tallic arsenic is obtained. This test serves to distinguish arsenopy- rite from the associated cobaltite, which requires heating over the blast flame to a much higher temperature before these characteristic closed tube rings are formed. In the open tube the danaite gives a copious sublimate of arsenic trioxide and fumes of sulphur dioxide, It is soluble in hot concentrated nitric acid with separation of some sulphur. The solution, after being diluted with water, is faintly pink. 16 Dana, System of mineralogy, sixth edition, p. 99. THE MINERALS OF IDAHO 145 MARCASITE (96) Tron disulphide, FeS, Orthorhombic Marcasite, commonly cailed white iron pyrite, is identical with pyrite in composition but differs in crystallization. When it is massive it is difficult to distinguish from pyrite, although it is usually paler in color and is more readily decomposed by weathering. It is much rarer than pyrite. BLAINE COUNTY Marcasite is reported to have been mined in the Wood River district as an ore of gold.” OWYHEE COUNTY Marcasite occurs in a number of silver mines in the Silver City district. In the Chautauqua tunnel and in the Trade Dollar and De Lamar mines it occurs in dendritic forms in quartz, and in speci- mens from the Garfield tunnel it is abundant in clay.'® LEMHI COUNTY Beautifully spherical nodules of marcasite up to 14% inches (4 cm.) in diameter occur in the Tertiary beds a mile south of Salmon These are usually dull on the outside and are aggregated into fan- tastic forms like those of ordinary concretions. When broken open they are found to consist of very pale greenish granular marcasite having an indistinctly radiated structure. The inclosing rock is loosely cemented clay sandstone.'® SHOSHONE COUNTY In the Gold Hunter mine at Mullan cavities in the ore sometimes contain bright spherical or botryoidal masses of iron sulphide, already mentioned under pyrite. These masses are bright and have a pale yellowish color and brassy luster. The exteriors are usually smooth and when broken open the masses are seen to be radiated columnar in structure. It is quite probable that some of these masses are marcasite. SYLVANITE (104) Gold silver telluride (Au, Ag) Te». Monoclinic. Despite the large number of gold veins in Idaho, tellurides have been met but rarely and in small amount. Sylvanite is the name most used by miners and prospectors for ores in which the gold is not visible to the naked eye and reports of the occurrence of sylvanite or of tellurides must be discounted for this reason. So far as known no accurate mineralogical identification of any gold telluride from 17U.S. Geol. Survey, Bull. 624, p. 119, 1917. 18 Waldemar Lindgren. U.S. Geol. Survey, 20th. Ann. Report, pt. 3, 1900. J. B.Umpleby. U.S. Geol. Survey, Bull. 528, p. 78, 1913. 146 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Idaho has ever been made and the only locality from which the writer has seen specimens is John Doctors Pilot mine in the Coeur d’ Alene district in Shoshone County. The most authentically reported occurrences are as follows: IDAHO COUNTY Tellurides of gold and silver occurred in the Little Giant vein in the Warren district associated with argentite and native silver. Lindgren *® mentions the report, but says that he was unable to find any tellurides when he visited the property. Tellurides are said to have occurred with galena, pyrite, chal- copyrite, and coarse wire gold in quartz veins on Bear Creek in the Marshall Lake district 40 miles southwest of Buffalo Hump.”! Tellurides of gold are reported to occur in the Black Pine mine in the Elk City district as very finely disseminated grains in dark stains in quartz ore containing galena and free gold. LEWIS COUNTY Tellurides are said to occur in the Deer Creek property on the southern slope of Craig Mountain on the drainage of Deer Creek, a tributary to Salmon River.” SHOSHONE COUNTY A gold telluride of silver-white color possessing well-defined cleav- age, which is probably sylvanite, was observed by the writer in specimens of tellurium-bearing ore in the possession of John Doctor from a pocket of very rich gold ore found in the Pilot claim at Murray in the Coeur d’Alene district. KERMESITE (107) Antimony oxysulphide, Sb2O8:. Monoclinic. Kermesite is a red mineral often found in small amounts in anti- monial ores where it has been formed by slight oxidation of stibnite. It is probably present in most of the antimony deposits of the State, but has not been carefully looked for. SHOSHONE COUNTY Thin coatings of deep red to brownish red powder on cracks in stibnite from the Stanley antimony mine at Burke are probably kermesite and similar material doubtless occurs in the other antimony mines of the district. 20 Waldemar Lindgren. U.S. Geological Survey, 20th Ann. Report, pt. 3, p. 245, 1900. 21 Robert N. Bell. Mining Industry of Idaho for 1913, p. 176. 2 D.C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 101. THE MINERALS OF IDAHO 14% CHALCOSTIBITE (117) Copper sulphantimonite, Cu28.Sb28;. Orthorhombic. Chalcostibite is a comparatively rare mineral which has been doubtfully identified from one mine in Idaho. It is possibly present elsewhere as a gray massive mineral lumped under the name “gray copper,” which rightly belongs to tetrahedrite, but which probably includes a number of other minerals containing copper, sulphur, and antimony, which can be identified only by a chemical analysis or by erystallographic study. SHOSHONE COUNTY A specimen of ‘‘gray copper” collected by F. L. Ransome in the Standard-Mammoth mine in the Coeur d’Alene district was tested qualitatively by Dr. Waldemar T. Schaller, who concluded from its closed tube reaction that it was probably chalcostibite rather than the more common tetrahedrite.* The mineral is in grains a few milli- meters in diameter intergrown with some chalcopyrite and sparsely disseminated through milky white quartz containing occasional patches of chloropal (?) and galena. Such material has been observed frequently by the writer in the lower leveis of both the Greenhill- Cleveland and Standard-Mammoth ore shoots in narrow quartz veins which are later than and cut the main mass of the ore. These sometimes contained vugs in which were developed crystals of this gray mineral up to 1 centimeter in diameter, of rhombic aspect, but so shattered that they fell to pieces almost immediately. Chalco- pyrite and chloropal (?) were usually associated with this mineral in the quartz. GALENOBISMUTITE (118) Lead sulphobismuthite, PbS. Bi.Ss. Orthorhombic. BOISE COUNTY The rare mineral galenobismutite, previously definitely known only from the original locality in Nordmark, Sweden, has been described from the Belzazzar mine in the Quartzburg district.” The specimen, which was selected as a typical specimen of the ore, came from the dump of the Belzazzar mine near the Jerusalem Valley road, a little west of Quartzburg. It consists in the main of trans- lucent to transparent crystalline white vein quartz. The sequence of deposition of the minerals is not entirely clear, but there is a band of more or less pure pyrite adjacent to the wall of the vein which appears to be the earliest mineral of the ore. The quartz is slightly sheeted parallel to the walls of the vein and small grains of pyrite are distributed along the partings. Pyrite occurs also in crystalline 22 F.L. Ransome. U.S. Geol. Survey, Prof. Paper 62, p. 93, 1908. 4 Earl V. Shannon. On galenobismutite from a gold quartz vein in Boise County, Idaho. Jour. Washington Academy of Science, vol. 11, pp. 298-300, 1921. 148 BULLETIN 131, UNITED STATES NATIONAL MUSEUM erains through the quartz and as sharply bounded cubic crystals in greatly sericitized fragments of wall rock which occur in the quartz. The quartz is loose textured and contains small angular cavities between the crystals. The galenobismutite occurs interstitially with relation to the quartz crystals and projects as fibrous bundles of prismatic needles into the cavities. It is clearly the youngest min- eral of the vein, which is the common paragenetic position of the majority of lead sulpho-salts. The galenobismutite is rather light gray in color and tarnishes to a yellowish color. Its luster is rather more brillant than that of the antimonial sulphosalts of lead and the mineral greatly resembles bismuthinite in general appearance. It forms elongated prisms im- bedded in quartz or minute deeply striated crystals in open cavities. The streak is black on porcelain or brownish black when rubbed. The hardness is about 2.5. Material for analysis was secured free from other impurities than quartz and pyrite as shown by microscopic study of polished surfaces. After deducting these impurities the analysis gave the following results: Analysis of galenobismutite from Belzazzar mine Constituent Per cent Calculation of ratios Mead GP I) ae So eae a ae Se AOR Er gon, ele a 23.93 | 0.116 Tron(Fe) oe PING IO Asotin) Te Io | 39 | .006 |$0.149 149X1 1.63X1 Copper 2 5 oaatat hanced teaches aia a 1.73 . 027 mtimony (Sb) > 2 Sts sb Pee RRA yd CINE Ss oes ae Ee 2. 56 . 021 eee ; Rise ce ot ea re eee REC 53.59] ,.258 |f 2/9 140x2 1.00x2 Sulphur*(8)' (Calej224 eo Oe Set eee 17. 80 .555 | .555 1394 1.00K4 | The ratios yield the usual formula, PbBi.S, or PbS.Bi.S;. Such material as the galenobismutite has long been recognized as a charac- teristic mineral of rich gold ores in this region and has passed under the name “antimony” in the supposition that it was stibnite. These occurrences were probably in part galenobismutite and in part bis- muthinite. A gray mineral resembling the galenobismutite was noted in small amount associated with pyrite and a little sphalerite in quartz in ore from the upper tunnel of the Granite State mine, Pearl district. This may be bismuthinite or galenobismutite. It was insufficient in amount for chemical examination. MIARGYRITE (121) Silver sulphantimonite, Ag.S.Sb2S83. Monoclinic. OWYHEE COUNTY Miargyrite is a comparatively rare silver mineral which had not been identified from any American locality until Penfield found it in specimens from the Silver City district collected by Lindgren. The following description of the crystals from this locality is taken from a_i THE MINERALS OF IDAHO 149 Penfield’s report.??> Apparently the mineral has been abundant in the ores of several of the mines, the ore of the Henrietta mine con- taining more miargyrite than pyrargyrite and proustite. In color the mineral is steel black with metallic luster and it gives a red streak. An analysis or a crystallographic examination is necessary to dis- tinguish it from pyrargyrite. In the Henrietta ores it occurred as crusts of crystals on quartz often coated by white clay. The crystals commonly average less than 3mm. in diameter and are usually not well adapted for crystallographic measurement, since the majority of them are either dull, appearing as though they had been slightly corroded, or are striated. The habits are as shown in Figures 23 and 24 and the forms observed, which are the common and characteristic ones for the species, are as follows: a(100) m(101) 6 bal 8) d(311) c(001) 0(101) s(211) k(124) The basal plane c is generally striated parallel with its intersection with the orthodome o. The pyramids d and s occur in oscillatory 23 Fics, 23-24.—MIARGYRITE. HENRIETTA MINE, OWYHEE COUNTY. AFTER PENFIELD combination, both with one another and with the orthopinacoid a and the pyramid ¢t, and consequently are striated to such an extent that they appear as a rounding of the edges between a and ¢ rather than as distinct faces. The faces lettered & are dull and give no dis- tinct reflections but from their position and the direction of their intersection with adjoining faces it is assumed that the form has been correctly identified as the pyramid (124) which is one of the com- mon forms of the species. * U.S. Geol. Survey, 20th Ann. Rept., pt. 3, pp. 168-916, 1900. 150 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Considering the character of the crystals the measurements recorded in the following table approximate as closely as can be expected to the values derived from the fundamental measurements of Lewis given in Dana’s mineralogy. Measurement of miargyrite from Henrietta mine : 3 - Measured | Calculated | Angle EN RS UME AGES FERRE SV SE SELL EEE 2 sat EET ° , ° , COOL) E/N (100) aes oe els Vala ec ae ee a's SiMe ae A pa Uline Sere UE | 98 00 | 98 37 98 09 | | 98 16 | COD Ava OL IE Ee Oe oie VE Ba Beers 2 RELI. 40 15 | 41 24 COOL) 3/\.0 COL) a as en i ING CT UN lg ST PE ER gee ee ORG | 48 07 | 48 2) LOO). NEL) TER EES EC GS Sis ER Ea a ge od Me eS: et 69 25 69 45. 69 24 FUN WII). NE ye Me A Sond! | Ree eee Pati ge 131. | 14 17 When roasted before the blowpipe on charcoal the mineral gives a coating of oxide of antimony and a globule of silver results from long continued heating. Several specimens of ore from the Henrietta mine, which are pre- served in the National Museum all show some crystals of miargytire. and a specimen of this mineral in the University of California mineral collection is labeled as from the Rising Star mine, which is in the Flint district. This last specimen was examined optically by Larsen®¢ who found it to be optically positive with 2V moderate; nearly opaque and with thelowest refractive index (a) greater than 2.72. DUFRENOYSITE (126) Lead sulpharsenite, 2PbS. As253. Orthorhombic. BLAINE COUNTY Dufrenoysite is reported to occur in the Wood River district in considerable quantity with ores of lead.2* No specimens have been seen by the writer. BOISE COUNTY This mineral is also reported to occur in the Crown Point vein in the Banner district.22. Very few specimens of the rich ores of this vein have been preserved and none showing dufrenoysite have been available for examination. 2a Esper S. Larsen. U.S. Geol. Survey, Bull. 679, p. 110, 1921. 2% Albert Williams, jr. Useful Minerals of the United States in U. S. Geol. Survey Mineral Resources: for United States., 1887, p. 723, copied in U. 8. Geol. Survey Bull. 624, p. 117, where the latter locality has apparently erroneously been changed to read Bonner County. THE MINERALS OF IDAHO Lot AIKINITE (138) Copper lead sulphobismuthite, CugS.2PbS. Bin8;. Orthorhombic. ADAMS COUNTY A specimen from the Seven Devils Mining district labeled ““SD 51, North Drift in R.R. tunnel, Seven Devils,” is a mere fragment consisting largely of a white or light gray metallic mineral resembling bismuthinite, intergrown with cubes of pyrite in a gangue of white calcite and quartz. When the calcite was in part dissolved away by acid the gray mineral was found to consist of very indistinct flattened striated plates. By crushing the entire small specimen, picking out the quartz and pyrite as far as possible and running the balance through methylene iodide heavy solution a sample of one-fourth gram was obtained for analysis. The mineral gave a strong bismuth reaction with potassium iodide-sulphur mixture before the blowpipe and also gave qualitative reactions for lead and copper. The analysis, recalculated to 100 per cent after deducting 7.72 per cent of quartz and 5.40 per cent of pyrite gives the following percentages and ratios: Analysis and ratios of bismuth mineral from the Seven Devils Constituent | Per cent Ratios Tead (Pb) oe iL it PRA SES ORAL WES, Sey Gest Serb os 39. 54| 0.1909 0.048X4 1.00 X 4 RSIS OtA CU) ee ee ee ee ee es er eS ee eee ode ae 20 | .0975 049 X 2 1.02 X 2 Bismuth (Bi)--___.________- ABS DOO: Ce Tae 36. 58 | .1759 .044K4 .92X%4 STipited (S)eeewenee suet ek ON eh ir Pe | (17.68)| 15513 1050 X11. (1.0411 BTR Goh aera Perks eee nc ered eee ee ns Mn eA! AS E | 100. 00 | These ratios give the formula Pb,Cu,Bi,S,, or 4PbS.Cu,S.2Bi,S;. Thus if the copper be considered cuprous it does not agree with the commonly given formula for aikinite. If the copper be assumed to be cupric the formula can be simplified to 3(Pb,Cu)S. Bi,S;. The material was too scanty to definitely settle the exact nature of this material, the single analysis made upon impure and _ insufficient material being not dependable enough to base a new species upon although it is possible that a new mineral is here represented. This deserves further study upon more material. Until its nature is definitely settled it may best be referred to aikinite. BOULANGERITE Lead sulphantimonite, 5PbS.2Sb283. Orthorhombic. Within recent years boulangerite has been found to be a rather abundant constituent of ores, both in Idaho and elsewhere. Much of the fibrous material which has heretofore been called jamesonite is in reality boulangerite. The mineral occurs in lead-silver ores as an accessory constituent, having been found abundantly both in the Wood River district in Blaine County and in the Coeur d’Alene 152 BULLETIN 131, UNITED STATES NATIONAL MUSEUM district in Shoshone County. No.®;| Letter Miller | Gdt. | © p | 9 | p - = Dela yee een ee | ° , ° , | ° / | ° , 12|a@..--.-.| 1010 | 000 | Very good._................---- -.--| 0 18| 90 00) 0 00} 90 00 G6) | faa 22-2 1122 +% | Excellent_-__......____.-____.-.__..- | 30 18 | 24 26] 30 00 | 24 28 aVOr: 4151 | +41 | Very good_............-----.------- 110 56| 67 22/10 53] 67 18 3 | ees | 4152 | +214 | Medium poor-..--.---.---.--------- | 11 06 | 50 26 | 10 53 | 50 17 a Number of faces measured. 3% J.B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 78, 1913. *6 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 128. 158 BULLETIN 131, UNITED STATES NATIONAL MUSEUM A specimen from the California or Marguerite shaft on War Eagle Mountain, Silver City district, contains finely disseminated argentite, chalcopyrite, etc., forming streaks in white fine granular or flinty quartz. This contains small drusy cavities lined with quartz crystals, with occasional well-developed pyrargyrite crystals, 2 millimeters or more in size. One of these which was measured is illustrated in the drawing, Figure 28. The measurements obtained upon it are as follows: Measurements of pyrargyrite, Marguerite mine Form Symbol | Observed Calculated = SSS Quality, description Sage aT a |g] a No.| Letter Miller QGdt. g p ° p ° , ° , ° , ° , 1 aGse ss. 1010 | 9 POORER Sea eee eee er 0 22; 90 00; O 00} 90 00 Qgbeseee TT ZOR oo ess jaa ree AG ees Se ei ee See decals 5 eee ee 30 20| 90 00]! 30 00! 90 00 3 1122 SEVER GOOG ae ates SNE a Rae Sa eee 30 10] 24 16] 30 00} 24 28 APN steesee 1121552 dA POOR a eee eae Ree ee eS 8 2472) 25) 8 Asal izest 5. A peta A eae GOW Rast ential eis rata 12° .03)°31 (05) 10 53))) 31 02 SHOSHONE COUNTY Ruby silver, which occurs sparingly in the ore of the Yankee Boy mine on Big Creek and is reported from the Polaris mine, is probably in part pyrargyrite, as it is rather dark in color. Specimens showing thin films of pyrargyrite coating joints in galena were collected by the writer from the stope above the 2,000-foot level of the Standard- Mammoth ore shoot at Mace. This occurrence is interesting, as the pyrargyrite apparently represented a very last stage of the vein- forming activity, the earlier mineralizations here being very base and low grade and containing large quantities of pyrite, arsenopyrite, pyrrhotite, etc., and relatively little silver. PROUSTITE (145) Silver sulpharsenite, 3Ag,S.As2S3. Hexagonal, rhombohedral. Proustite, commonly known as light ruby silver, is similar to pyrar- gyrite, differing in being lighter red in color and in having arsenic instead of antimony as an essential constituent. It is of rather fre- quent occurrence in silver ores in Idaho. BLAINE COUNTY In the Era district in the Ella mine at the head of Ella Canyon proustite occurs in small grains in the oxidized ores associated with argentite, cerargyrite, and tetrahedrite.*7. In the Hub mine, Lava Creek district, 2 miles southwest of Martin, proustite occurs with stephanite in a quartz-calcite gangue. The silver minerals occur as 37 J. B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 121, 1917. THE MINERALS OF IDAHO 159 minute crystals embedded in the gangue material and intergrown with the pyrite, and also as narrow veinlets cutting across the sul- phide ore.*8 BOISE COUNTY Ruby silver, probably proustite, has been reported as a rarity in ores of the Shamrock and Lincoln mines in the Pearl district.* LEMHI COUNTY Proustite occurs as small red crusts on ores from the Carmen Creek district, and is reported as occurring in ores of the Texas and Spring Mountain districts.* OWYHEE COUNTY In Owyhee County proustite has been found rather frequently in most mines. In the Henrietta mine it occurred but was not abundant, being replaced in the ores by miargyrite and pyrostilpnite. In the Poorman mine a remarkable occurrence of proustite is reported to have occurred about 100 feet below the surface. The mineral formed a solid mass weighing over 500 pounds, and it is stated that its surface showed roughly the planes and angles of a crystal. Upon being fractured it showed through the mass a uniform crystalline structure. A portion of this mass was sent to the Paris Exposition of 1867, where it was awarded a gold medal." Lindgren states that if this is correct, and the testimony appears to be reliable, this constitutes one of the most remarkable occurrences of this mineral known.” D’Aligny * describes the material exhibited by Wells D. Walbridge, of Ruby City, as silver ores from the Poorman lode (No. 306), con- sisting of four large specimens of native silver, ruby silver, chloride and sulphuret of silver, valued at $5,000. SHOSHONE COUNTY In the Coeur d’Alene district proustite occurs in the Yankee Boy mine, and is reported from fhe Polaris and Big Creek mines on Big Creek near Kellogg. The ores of these mines consist mainly of highly argentiferous tetrahedrite with less galena and pyrite in a gangue of quartz and siderite. The proustite is rare in the vein proper, but occurs in thin films and as flattened and distorted crystals in joints in the slaty wall rocks adjacent to the veins. 89 Waldemar Lindgren. U.S. Geol. Survey, 18th Ann. Rept., pt. 3, p. 713, 1897. J.B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 78, 1913. 41 J. Ross Browne. Mineral Resources of the United States for 1868, p. 523. #2 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 153, 1900. 48 Henry F. Q. D’Aligny. Catalogue of minerals of the United States of America exhibited at the Paris Exposition. Paris, 1867, p. 12. 160 BULLETIN 131, UNITED STATES NATIONAL MUSEUM PYROSTILPNITE (146) Silver sulphantimonite, 3Ag.8.Sb283. Monoclinic. OWYHEE COUNTY Pyrostilpnite, known also as fire blende, is identical with pyrar- gyrite in composition but differs in crystal form. It is an exceedingly rare mineral which has been identified by Penfield “4 as a single crystal associated with miargyrite from the Henrietta mine, SilveT City district. This was fiery red in color and yielded characteristic blowpipe reactions for silver, antimony, and sulphur. It was about 114 millimeters in greatest diameter and agreed exactly in habit with a specimen of the corresponding arsenic compound xanthoconite from Freiburg, Saxony, presented to the Brush collection by Prof. A. Weisbach and with the description and figure by Miers of xantho- conite from Markirch, Elsass. The faces were striated to such an extent that no reliable measurements could be obtained from them. While it was probably was not rare associated with the miargyrite of the Henrietta mine, almost no specimens from this mine have been preserved and no other specimen showing pyrostilpnite is known. XANTHOCONITE (146a) Silver sulpharsenite, 3Ag.S.As.83. Monoclinic. OWYHEE COUNTY The rare silver mineral xanthoconite is identical with proustite in composition but differs in crystallization and is usually yellow to orange-red or brown in color. It is reported to have occurred in the rich ores of the Flint district associated with polybasite and steph- anite.** None of the mineral was recognized in the few specimens of the rich ores from this district which have been available for examination. Browne was a Freiberg man, familiar with silver minerals, and his identification is probably to be relied upon. OWYHEEITE Lead silver sulphantimonite, 8PbS.2Ag2S8.5Sb283. Orthorhombic. OWYHEE COUNTY A mineral making up a considerable portion of a specimen of silver ore from the Poorman lode, Silver City district, was described as a silver bearing variety of jamesonite “¢ and later was given the name owyheeite, it being evident that it was a distinct species.** © The mineral occurs in rather large amount in a typical rather coarsely crystalline white vein quartz which is loose textured as from combs 44S. L. Penfield, quoted by Lindgren. U.S. Geol. Survey, 20th Ann. Rept. pt. 3, p. 169, 1909. 45 J. Ross Browne. Mineral Resources of United States, 1868, p. 528. sso Earl V. Shannon. Proc. U. S. Nat. Mus., vol. 58, pp. 601-604, 1920. 46 Earl V. Shannon. American Mineralogist, vol. 6, pp. 82-83, 1921. THE MINERALS OF IDAHO 161 grown together from opposite sides of a narrow vein. Where cavities occur in the specimen they are ,bounded by plane faces of quartz crystals. The deposition of the owyheeite began before the quartz crystals had ceased to grow, as the latter contain variously oriented needles of the metallic mineral in their tips. The deposition of the sulphosalt continued after the cessation of growth by the quartz crystals until nearly all of the intercrystal spaces were solidly filled with the owyheeite. When the quartz is broken up prismatic crystals are loosened leaving lustrous molds in the owyheeite. The only other minerals in the specimen are rare stains of pyrargyrite, resinous yellow grains of sphalerite and small nests of sericite. The owyheeite is very light gray to almost silver white on fresh fracture and the luster is metallic splendent. The masses are fine grained and show only a faint suggestion of fibrous structure to the eye. At the contact with the latest growth of quartz crystals the mineral is in distinct needles penetrating the quartz. Polished specimens, when examined microscopically with vertical illumination, show every gradation from wholly massive owyheeite to material made up of interlaced prismatic needles. Careful etching of the polished surfaces failed to indicate the presence of more than one mineral in the gray masses. In very rare and minute cavities in the quartz the owyheeite occurs in prismatic needles of microscopic size which are entirely too small for goniometric study. These needle-like crystals are very brittle, breaking across the elongation at the slightest touch in a manner indicating a well-defined cleavage in this direction. Upon exposure the mineral assumes a faintly yellow color. The hardness is about 2.5 and when rubbed upon paper the mark is gray like hard graphite but its streak upon unglazed porcelain is reddish brown. The blowpipe characteristics of the mineral are the usual ones for sulphantimonites of lead. In the open tube it yields sulphur dioxide and a copious sublimate of white antimony oxide. In the closed tube fragments melt and yield a faint band having an upper ring of antimony oxide succeeded downward by light rings of yellow sulphur, red antimony oxysulphide, and black antimony sulphide. The mineral is easily soluble in hot concentrated hydrochloric acid. Selected fragments of the owyheeite, separated from quartz, where analyzed with the results given below: Analysis of owyheeite from Poorman mine Constituent | Per cent | Ratios Bee) ere Ree eee EE rod 2 9.8 Lan th | 40.77 | 0.197 Tron (Pea eos cass ccc cco cocececceccececesceseeeseeeseeereeees | “16 | Oop} 205, 0. 0415 OPPO rae Ul) sateen one es eae ee nee eas ee cena aes woe nee ee =| 75 | .015 Biver(ie aerate ae cee Pe eae ee | 7.40 “goat <084 - 0422 PATIEIIMOM Va USD ie te town ced Sete eee eae ew ae ae Sees eae oe 30.61 | .255 .255 .042X6 BS ULLEILITITS (5) sees eer ee Ne ke See eee ee ene ee eae od aoe | 20. 81 |: 649.649 .042K15 54347—267—_12 162 BULLETIN 131, UNITED STATES NATIONAL MUSEUM The ratios indicate the formula Pb,Ag,Sb,S,, or 5PbS.Ag,S.3Sb,5,. A mineral described as an argentiferous jamesonite from Nevada by Burton is probably also owyheeite and Foshag has recently found the mineral in a specimen from a third locality in Nevada, so that its occurrence is not confined to Idaho. It may be found in other specimens of the rich silver ores from the Poorman mine. JAMESONITE (130) Lead iron sulphantimonite, 4PbS.FeS.3Sb,83. Orthorhombic For some years it has been the practice of many mineralogists to call all fibrous lead sulphantimonites not otherwise identified jame- sonite. Recent investigations by Spencer and Schaller have shown that jamesonite, which contains iron as an essential ingredient and possesses a cleavage across the needles rendering them brittle, is a comparatively uncommon mineral. As mentioned above, much of what has heretofore been called jamesonite is really boulangerite. Most of the occurrences of jamesonite mentioned in Idaho are not certainly correct, the identification of the mineral being only tentative. BLAINE COUNTY Jamesonite has been reported to occur in the Reliance mine, Era district, associated with pyrite, galena, sphalerite, and chalcopyrite in a fine-grained quartz-chalcedony gangue.“’ OWYHEE COUNTY Specimens of altered rhyolite from the dump of the 800 foot level of the De Lamar mine have open cavities which contain radiating prismatic fibers up to 1 cm. long of a steel gray sulphantimonite. The fact that the fibers are brittle and break sharply across the elongation indicates that the mineral is either jamesonite or owyhee- ite. Similar needles occur imbedded in quartz crystals or projecting into open cavities of quartz of ore from the Rising Star mine, Flint district. These are associated with argentiferous tetrahedrite. SHOSHONE COUNTY A specimen of a fibrous sulphantimonite from the stopes above the 2,000-foot level of the Standard-Mammoth mine contained a fibrous. sulphantimonite of lead which, upon partial analysis, yielded only 36.4 per cent of lead. This is probably jamesonite although boul- angerite was common in this ore body. 47J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 122, 1917. THE MINERALS OF IDAHO 1638 TETRAHEDRITE (148) Copper sulphantimonite, 5Cu,S8.2(Cu,Fe,Zn)8.2Sb.8;,. Isometric, tetrahedral. The mineral tetrahedrite, commonly known as “gray copper,” is of widespread occurrence in Idaho as an ore mineral, some mining districts having produced great quantities of ore in which it is the most prominent valuable constituent. It usually contains notable amounts of silver and its principal value is as a silver ore. ADAMS COUNTY Occasional bunches of tetrahedrite, locally called ‘copper glance,” occur with chalcopyrite and small amounts of covellite, replacing andesite tuffs along a shear zone in the River Queen mine in the Seven Devils district.** BLAINE COUNTY Tetrahedrite is common in the richer lead-silver ores of the Wood River district, having been reported especially from the Quaker City, Jay Gould, Bullion, Argent, and other mines. In the Bellevue King mine it is said that a 2-foot streak of tetrahedrite was encountered. The mineral usually occurs in banded veins with coarse-grained galena and the gray copper often occupies the center of the vein. In the Buckhorn mine on Elkhorn Hill near Ketchum, in the upper tunnel, 175 feet from the surface, there was found a 2-foot vein of solid tetrahedrite ore containing from 180 to 200 ounces of silver a ton. Tetrahedrite is reported to have been mined from the Columbia, Pilgrim, and other mines in the Sawtooth district and at Soldier Mountain 9 miles north of Corral. A specimen of ore from the Golden Glow mine, Rosetta district, contains massive dark gray tetrahedrite, partly altered to bindhiemite, in quartzite. BOISE COUNTY Tetrahedrite, or a mineral of similar appearance, occurs occasionally as a constituent of sulphide-bearing gold ores in the several mining districts in Boise County. It has been noted in small masses in specimens of ores from the Carroll-Driscoll mine associated with sphalerite, chalcopyrite, and a little barite. Specimens from the Overlook mine, Diana Mining Co., Pioneerviile district, contain masses of tetrahedrite up to 1 inch in diameter in quartz ore with galena, sphalerite, and pyrite. BONNER COUNTY Tetrahedrite is the principal ore mineral of the Little Joe or Keystone mine in the Blacktail district on the west shore of Lake Pend Oreille. The mineral occurs in a gangue of manganiferous 48D. C. Livingston and F. B. Laney . Idaho Bur. Mines and Geol. Bull, 1, p. 40, 1920. 164 BULLETIN 131, UNITED STATES NATIONAL MUSEUM siderite. Tetrahedrite is also the principal mineral in the silver ores of the Weber and other mines south of Lakeview on the south end of the lake. CUSTER COUNTY Tetrahedrite is exceedingly rare in the Alder Creek district, having been observed only in small particles in some of the partly oxidized ore from the Copper Bullion tunnel.® Tetrahedrite forms the prin- cipal valuable mineral in the ores of the Bayhorse district, which has perhaps produced more tetrahedrite ore than any area of similar size in the world. Ore, in which tetrahedrite is the only valuable metallic mineral, to the value of $6,250,000 has been mined from the four principal mines of the district.°° The tetrahedrite is practically always massive, dark gray, and with splendent luster on fresh fracture, which becomes metallic upon moderate exposure. The three prin- cipal mines producing tetrahedrite ore are the Ramshorn (product, $3,000,000), Sky Lark, and Silver Bell. The ore bodies are filled fissures in slates. The typical ore consists of about three-fourths siderite and tetrahedrite makes up about one-third of the remainder or about 8 per cent of the vein filling. A little arsenopyrite, galena, and chalcopyrite accompany the tetrahedrite. Sometimes a central vein an inch or two wide, of tetrahedrite, is bordered on either side by a layer of chalcopyrite a half inch or more in width; (Cat. No. 56521, U.S.N.M.). Other specimens show large masses of pure tetra- hedrite from the Ramshorn mine, in siderite. In small vugs in the ore crystals of tetrahedrite occur associated with crystals of arsenopy- rite and siderite. The crystals are usually coated with a mossy crust of minute crystals of chalcopyrite. A specimen from the Hoosier mine, Bay Horse, contains masses of this mineral, 1 to 2 inches in diameter, in granular pyrite. Specimens from the Skylark mine contain masses of tetrahedrite up to 4 inches through in oxidized gangue and smaller veins and masses partly altered to cuprite, malachite, azurite. A specimen from the No. 3 tunnel, Silver Bell mine, contains some residual masses in oxidized material. The tetrahedrite is sometimes altered to crusts of yellow-green or yellow waxy bindheimite, associated with azurite and velvety tufts of malachite (Cat. No. 51863, U.S.N.M.). Specimens from the Bull of The Woods, Bullion, and other mines are similarly largely massive tetrahedrite partly altered to malachite and azurite (Cat. No. 56518, U.S.N.M.). A specimen of very pure tetrahedrite from the Ramshorn mine was analyzed for Umpleby by R. C. Wells. The results of this analysis, together with the ratios, are given in the following table: 499J. B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 55, 1917. 50J. B. Umpleby. U.S. Geol. Survey, Bull. 539, pp. 34-35, 1913. THE MINERALS OF IDAHO 165 Analysis and ratios of tetrahedrite, Ramshorn mine | Constituent Per cent | Ratios ‘ | ——— CL STIS UG arene en een oe Bene ae ns ee 0. 08 | Cop Derr eee en i RS ee een 33. 39 | 0.525 BS ye eee eee eee ne eee 4. 86 045 vO ees eee Ar eae eke eee es: WR ees et ee 4.64 | .083 PZT) Cee ere ee ae Pe ae ee 3. 53 .054(0.707 .059X12 .98x12 IMiancaneGsets 22-28 Seo = oo Se Soe Sota teaeo cast eesasas L019 (z= LCG) ee rene ee Be ES RR ne Oe an et BES ace. |. -- PAW GJ11 QTV aeeee ee sens Corer en eee eee cee nee cee 25. 22 -210| SEUSS eS oR a 1.46 | ‘019 .231 .058x4 974 BS ISTU Lee s oeeen ho te See ae es oenscs . 34 | -002 SUL Ue eee cen ae a re ee re eee ee 25.74 | .803 .803 .062X13 1.0313 The ratios agree rather well with the formula proposed by Wherry and Foshag, namely RySbiSi3 or Ry’R’’2Sb.S13, which expanded is 5R’,S.2R’’S.2Sb,S;,. The iron and zinc are, however, present slightly in excess of the total bivalent bases required, so that it is not necessary to assume the presence of any bivalent copper, the formula consequently being written 5(Cu,Ag),9.2(Fe,Zn)8.28b,S,. The ratio of silver to copper is 1: 13.3 and that of zine to iron is 1: 1.54, or very nearly 2:3. The analytical ratios agree somewhat better with the more complex formula 10(Cu,Ag),8.5(Fe,Zn)S.48b,8,, which may be further expanded to show the relation between iron and zine to 10(Cu,Ag),S.3FeS.2ZnS.4Sb,S,. Such a compiex formula is not ordinarily justified by a single analysis and is here presented only because a tetrahedrite from Shoshone County gave identical results as discussed below. ELMORE COUNTY Tetrahedrite occurs in small quantity in the Monarch mine, Atlanta district. IDAHO COUNTY Tetrahedrite occurs as silver-rich grains and masses with free gold, ruby silver, and pyrite in the Little Giant, Rescue, Goodenough, and other veins of the Warren district, and also as a constituent of silver- gold ores of the Big Buffalo, Jumbo, and other mines of the Buffalo Hump district. It probably occurs in gold ores of other mining dis- tricts of the county. A specimen of ore from the Black Pine mine, Elk City district, contains grains of ‘gray copper” sparingly dis- seminated in quartz with galena, sphalerite, pyrite, and free gold. 166 BULLETIN 131, UNITED STATES NATIONAL MUSEUM LEMHI COUNTY Gray copper ore containing 1.9 per cent of silver occurs as irregular patches and grains in ores of the Blue Wing district. The minera] occurs in quartz with sphalerite, hiibnerite, and molybdenite.” OWYHEE COUNTY In Owyhee County tetrahedrite is common in ores of the Flint district, associated with other silver-bearing minerals, as masses and grains in white quartz. SHOSHONE COUNTY Tetrahedrite is common in Shoshone County, in the Coeur d’Alene district, being perhaps the only primary silver-bearing silver mineral of the silver-lead ores. Its best development is in the ores of the so-called “‘dry belt”? veins, which are narrow-filled fissures in shales 29 30 Figs. 29-30.—TETRAHEDRITE. HYPOTHEEK MINE, SHOSHONE COUNTY of the Wallace formation, the Yankee Boy mine on Big Creek, and the Polaris mine in Polaris Gulch being the most exploited deposits of this type. The tetrahedrite, which is the most prominent ore mineral, is usually massive, although small crystals have been noted in vugs in ore from the Yankee Boy mine. The gangue is either quartz or coarse buff manganiferous siderite and the veins also con- tain some pyrite, specular hematite, galena, and a little proustite or pyrargyrite. The mineral from these veins is usually highly argen- tiferous and is mined as a silver ore. There are a number of veins of the same general type between Kellogg and Wallace. The tetra- hedrite from the Polaris mine is said to be arsenic and mercury bearing. Closed tube tests did not indicate the presence of either of these elements in tetrahedrite from the Yankee Boy mine. Tetrahedrite occurs also in many of the lead-silver ores, having been especially noted in the Standard-Mammoth, Hercules, and Gold Hunter mines. There is reason to believe that the silver con- tent of the galena ores is more or less proportional to their tetrahe- drite content and the mineral probably occurs in microscopic grains in many ores in which it can not be recognized with the eye. Speci- 51 J.B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 111, 1913. THE MINERALS OF IDAHO 167 mens of argentiferous galena from the Bunker Hill mine showing 0.08 and 0.09 per cent of silver, upon assay, proved to contain microscopic grains of tetrahedrite when polished and examined under a metallo- graphic microscope as did a specimen from the Hercules mine con- taining 0.108 per cent of silver.*? The Caledonia mine at Wardner contained bodies, often of considerable size, consisting almost entirely” of massive tetrahedrite, in quartzite, sometimes with included irregular patches of chalcopyrite, although there was very little tetrahedrite in the galena ore from other parts of the mine. Ore mined from these silver-rich tetrahedrite bodies sometimes carried 3,000 ounces to the ton. Tetrahedrite has been noted in the Hypotheek mine at Kingston in a calcite gangue with pyrite and arsenopyrite and also as crystals along cracks in quartz. The crystals reach 5 mm. in diameter and show bright faces which yield excellent reflections of the signal. The development is such, however, that the tetrahedral symmetry is not apparent. A typically developed crystal is shown in Figure 29 and the most completely developed and symmetrical crystal measured is shown insomewhat idealized form in Figure 30. The formsrecognized are o (111), n (211), d (110), and r (332). This tetrahedrite was analyzed, the analysis giving the following results and ratios, after having been recalculated to 100 per cent after deducting quartz: Analysis and ratios of tetrahedrite from Hypotheek mine (E. V. Shannon, analyst) Constituent | Per cent Ratios gore ee ee Rl oye ee Ne, eee oe ee | ae 70 0.593 1h Ol ee sae ee ee ee ee ae ae | TACOs lae-e- = ic) DIED Mle tn te ec ee Ad | 5.13 .092 0.744 0.06312 1.0012 FETC ae Behe eee 2d eR ae 2 toe es | i 3.87 | .059. FAYSOT11G See eee eee ee ae as PE eee ot ce kee FACG. josaaes Wnitivitnges soe elders ese geen 26.81 | “sap 223° .057X 4. 92K 4 UMN ek SP ee oe ee ae acc eee | 26.49 .826 .826 .064X13 1.0313 PROGR ees ra sae ee een aoe es Loe eee a teesd | 100. 00 The ratios agree fairly well with Wherry and Foshag’s formula, but, like the preceding, this formula is satisfied without assuming the presence of any cupric copper and the analysis is best represented by the formula derived for the mineral from the Ramshorn mine, namely 10Cu,S.3FeS.2ZnS.4Sb.S;. The practical absence of silver is noteworthy, as is the absence of more than a trace of arsenic, since the mineral occurs in a vein containing abundant arsenopyrite. Tetrahedrite has been noted from other veins of the Pine Creek Basin, as the Big 8, Lookout-Mountain, Carbonate, Northern Light, 82 F.N. Quild. A microscopic study of the silver ores and their associated minerals. Economic Geology vol. 12, pp. 305-306, 1917. 168 BULLETIN 131, UNITED STATES NATIONAL MUSEUM and Bobbie Anderson, and in all of these veins it seems to be prac- tically nonargentiferous. Similar silver-free tetrahedrite has also been noted in small amount in the ore of the Wisconsin claim east of Kellogg, where it is later than the quartz-ankerite-pyrrhotite minerali- zation in which it fills seams. WASHINGTON COUNTY The silver-bearing ores of the Mineral district, chief among which are the Silver Bell, Maria, and Black Hawk, with numerous lesser prospects, all contain notable amounts of tetrahedrite associated with galena, sphalerite, pyrite, etc.*3 TENNANTITE (149) Copper sulpharsenite, 5Cu.S. Isometric, tetrahedral. 2 (Cu,Fe,Zn)S. 2As283. BEAR LAKE COUNTY Tennantite, like tetrahedrite, is commonly known as gray copper. The two minerals are very similar in all their properties, the principal difference being in the relative proportions of arsenic and antimony, those containing arsenic in excess of antimony being classified as tennantite. A ‘‘gray copper” from the Humming Bird mine, in Paris Canyon near Paris in the St. Charles district, contains more arsenic than antimony and hence is referable to tennantite.*? The mineral, which is massive, occurs in a breccia composed of quartz and jasper and is partly altered to azurite and malachite. It is quite possible that, were the gray copper ores from all localities in the State submitted to a careful chemical examination more of them would be found to be predominantly arsenical. STEPHANITE (153) Silver sulphantimonite, 5Ag2.8.Sb283. Orthorhombic, hemimorphic. The black silver mineral commonly known as antimonial silver or brittle silver has been a prominent ore mineral in much of the high- grade silver ore mined in the State. BLAINE COUNTY In the Lava Creek district stephanite occurs as small disseminated grains in quartz and intergrown with pyrite and also with proustite in veinlets cutting the sulphide ore.* 53 Waldemar Lindgren. U.S. Geol. Survey, 22d Ann. Rept., pt. 2, pp. 754-755, 1901. sso. R. W. Richards. U.S. Geol. Survey, Bull. 470, p. 179, 1911. “J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 123, 1917. THE MINERALS OF IDAHO 169 BOISE COUNTY Stephanite occurred abundantly in quartz with pyrargyrite and cerargyrite in a silver vein which was found 40 feet north of the gold vein on the Washington claim, Idaho City district.°° In a specimen of ore from this locality the mineral, which is brilliant gray with good cleavage, occurs plastered around quartz crystals in minute combs. In specimens from the tunnel level, Banner mine, Banner district, fine dark steel gray masses which are probably stephanite occur with pyrargyrite, coarse granular sphalerite, and some pyrite, between crystals of interlocking quartz combs in narrow veins in altered granite. ELMORE COUNTY In Elmore County stephanite has been the most abundant and important ore mineral in the rich silver ores of the Atlanta district. The mineral occurs as granular, imperfectly crystalline, and columnar black masses associated with a less amount of pyrargyrite in comb quartz. Often the pyrargyrite forms lines along the sides of narrow veins while the centers are filled with stephanite (Cat. No. 51864, U.S.N.M.). In some specimens the stephanite occurs as grains with pyrargyrite in coarse granular galena. (Cat. No. 30199, U.S.N.M.). In the Atlanta lode stephanite was the most abundant ore in the bonanza deposits; next in quantity came pyrargyrite, while argentite, stromeyerite, and native silver were present in relatively small quan- tities. ‘‘The rich streak of black stephanite and ruby silver varied in width from 1 foot to 6 or 7 feet, alongside which was a band of similar width of payable ore containing free gold with disseminated silver minerals, making the workable vein from 2 to 15 feet wide and extending in length underground in the Monarch and Buffalo claims nearly 2,000 feet on the course of the lode.’’ *8 OWYHEE COUNTY Stephanite is prominent in the ores of the Flint district, being reported by J. Ross Browne early in the history of the district. It is to be found in specimens collected from the Rising Star and other mines within recent years. POLYBASITE (156) Silver sulphantimonite, 8Ag28.Sb283. Monoclinic, perihexagonal. Polybasite is probably a common mineral in many of the silver ores of the State and has been reported from a number of districts. It is to be noted, however, that most of the identifications of the mineral are made upon visual characteristics only and are in need of con- 66 Waldemar Lindgren. 18th Ann. Rept. U. S. Geol. Survey, pt. 3, pp. 688-689, 1897. 86 Joshua E, Clayton. Trans. Amer. Inst. Min Eng., vol. 5, Feb. 1877, pp. 468-473. 170 BULLETIN 131, UNITED STATES NATIONAL MUSEUM firmation by exact methods. The mineral often has a red streak or powder and many occurrences might be identified as pyrargyrite on this property. BOISE COUNTY In Boise County polybasite is reported to occur commonly as a constituent of rich silver ores in the Banner district where it is asso- ciated with pyrargyrite, cerargyrite, and native silver. BONNER COUNTY Polybasite has been identified by Edward Sampson, of the United States Geological Survey, in a specimen of rich ore from the Blue Bird mine near Talache on the north side of Blacktail Moun- tain on the west shore of Lake Pend d’Oreille. The mineral occurs as a thin platy layer along joints in the ore, associated with native silver. The plates show no crystal outlines, but exhibit tabular faces of the basal pinacoid on which the triangular rul- ings characteristic of the min- eral are visible. The streak of the mineral is black but the powder under the miscroscope is very slightly translucent with a suggestion of red color. ELMORE COUNTY Polybasite occurred com- monly but in minor amount as a constituent of rich silver Fic. 31.—POLYBASITE. TABULAR CRYSTAL FROM RICH i 1 d QULCH MINE, SILVER City DISTRICY, OWYHEE County OF€S of the Atlanta lode, Atlanta district. OWYHEE COUNTY In Owyhee County polybasite is probably common in the silver ores of the Silver City, De Lamar, and Flint districts. In ore from the De Lamar mine it occurs as abundant dark gray, steel gray masses up to 1 cm. in diameter, showing distinct cleavage, in quartz (Cat. No. 74623, U.S.N.M.). In the Leviathan mine polybasite is associated with pyrargyrite and stephanite. In similar form the mineral has been abundant in many of the rich silver mines of the Silver City district, particularly the Poorman mine. It is reported that in 1864 a specimen of pure polybasite weighing 6 pounds and THE MINERALS OF IDAHO 17d containing 75 per cent of silver from the Morning Star discovery shaft was on exhibition in a Portland bank with a shipment of silver bullion.*’ This mineral is also common in the ores of the Flint district in massive form in quartz. Except for their cleavage these masses resemble tetrahedrite. This mineral has been noted in the ore from the the Rising Star mine, and is reported to have occurred with stephanite and xanthoconite in the rich ores first mined in the district.°8 A specimen from a vein in drift 500 feet north, 2,650 feet from the portal of the Rich Gulch mine, west slope of Florida Mountain, Silver City district, shows a narrow quartz vein averaging 1 cm. in width inclosed in greatly sericitized rock. The quartz is drusy along the center and the druses are lined with polybasite in minute but sharp and brilliant hexagonal thin tabular crystals. One of these was measured and found to have the forms and develop- ment shown in Figure 31, the forms being a(100), m(110), c(001), r(112), r6(112), n(101), nm, (101). These are iron-black in color and have hexagonal and triangular markings on the basal pinacoid. They have a distinctly red streak like that of pyrargyrite. SHOSHONE COUNTY A gray mineral resembling polybasite has been noted in quartz of ore from the Pilot mine, Murray, associated with gold and silver tellurides and native gold. PEARCEITE Basic silver sulpharsenite, 8Ag:S.As283. Monoclinic, perihexagonal. BONNER COUNTY Pearceite, the arsenic analogue of polybasite, has been recognized in ore from the Conjecture mine, Lakeview district, south of Lake Pend d’Oreille. Several stages of mineralization were recognized in this vein. The earlier mineralization consists of manganiferous ankerite and sphalerite which is replaced by galena and tetrahedrite. The galena is partly replaced by pearceite and both are later replaced by anglesite.*® ENARGITE (158) Copper sulpharsenite, Cuz8.4CuS. As2S3. Orthorhombic. CUSTER COUNTY Enargite occurs in massive form as a primary constituent of some of the ores on Dickens Hill, in the Yankee Fork district.” It has been noted only in small amount in a few specimens. 57 Portland Daily Oregonian, Dec. 13, 1864. Capt. John Mullan, Miners and Travelers Guide to Oregon- Washington, ete. New York, 1865, p. 106. 58 J. Ross Browne. Mineral Resources of United States, 1868, p. 528. 589 Edward Sampson. Oral communication, 1922. 60J,B. Umpleby. U.S. Geol. Survey, Bull. 539, p. 52, 1913. 172 BULLETIN 131, UNITED STATES NATIONAL MUSEUM HALITE (166) ROCK SALT Sodium chloride, NaCl. Isometric. BANNOCK COUNTY Salt has been obtained for many years from saturated salt brines which are obtained from brine springs which seep from barren patches of stony gravel in the valley bottoms on Rock Creek, Crow Creek, and Tygee Valley. White salt often forms a crust about these springs which are probably underlain by extensive deposits of rock salt. In deepening a spring in Crow Creek Valley, 38 miles northeast of Montpelier, rock salt was encountered 6 feet below the surface. This was penetrated to a depth of 20 feet without reaching the bottom of the deposit. This salt is exceptionally pure sodium chloride. OWYHEE COUNTY Sodium chloride occurs in small amount mixed with epsomite, gypsum, nitrates, etc., in nitrate prospects on Jump Creek, Sucker Creek, and in adjoining regions southeast of Homedale, Oreg.™ CERARGYRITE (169) HORN SILVER Silver chloride, AgCl. Isometric. Cerargyrite is, in Idaho as in most other silver producing States, the most important and in many mines the only important silver mineral in the oxidized ores. Unless present in considerable amount it is very inconspicuous and is hable to be unnoticed in rusty quart- zose ores in which it is present in some abundance. Ores which are leached and cellular from oxidation yet which contain high values in silver are commonly called chloride ores, even though the cer- argyrite may never be present in visible grains. There is a tendency which has been noted among Idaho miners to refer to as “‘chlorides’”’ any yellowish or greenish yellow coloration in the oxidized ores. This is incorrect as the silver chloride is rarely yellow. These so called ‘‘chlorides’’ are usually ocherous bindheimite, an antimonate of lead although pyromorphite is also called chloride ore. Where present cerargyrite is usually in grains, globules, or thin crusts on quartz mixed with limonite. It may be recognized by its softness and sectility and by its property of turning grayish lavender in color when exposed to sunlight. 610, L. Breger. U.S. Geol. Survey, Bull. 430, p. 555, 1910. ®@.R. Mansfield. U.S. Geol. Survey, Bull. 620, pp. 19-44, 1916. THE MINERALS OF IDAHO Lie BLAINE COUNTY Cerargyrite has been found in small grains and films with other silver minerals and cerusite in the ores of the Ella mine, in Ella Canyon in the Era district. In the Wood River districts it was common in the ores near the surface in many small veins and with native silver and sulphides of silver in the Silver Star mine. BOISE COUNTY In the Idaho City district a vein on the Washington claim parallel to the gold vein carried predominant silver as cerargyrite near the surface and as stephanite and ruby silver in depth. In the Banner district cerargyrite occurred abundantly in the oxidized portions of the rich silver veins. CUSTER COUNTY Cerargyrite occurs in the Whale mine with free gold, in the Mon- tana mine in films and grains in drusy iron-stained quartz (Cat. No. 56526, U.S.N.M.) and in the oxidized portions of the General Custer, Charles Dickens, and possibly other mines. In the Bay Horse dis- trict it occurs in the Beardsley, Pacific, and Silver Bell mines with argentite; in the Red Bird Mine in sand carbonate; and in the River View mine in cerusite and in cellular iron-stained quartz (Cat. No. 56522, U.S.N.M.). ELMORE COUNTY Cerargyrite 1s reported to have occurred in some abundance in surface ores of the Monarch and other mines of the Atlanta district. IDAHO COUNTY Small amounts of cerargyrite have been reported from veins in the Florence and Warren districts. LEMHI COUNTY Cerargyrite has been mined from the districts in the southeastern portion of the county, where small particles occur in ores formed by the oxidation of argentiferous galena. It occurs also as a secondary product in the Carmen Creek mine and in the Blue Wing district.” OWYHEE COUNTY Cerargyrite was probably present in the surface ores of all silver mines of this county. In the Silver City district it was especially abundant in heavily iron-stained quartz in the Hornsilver mine. In the St. Clair mine it occurred with moderately coarse galena in cel- lular iron-stained quartz (Cat. No. 5473, U.S.N.M.) and in the War Eagle it formed films in iron-stained cellular portions of quartz 68J.B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 76, 1913. 1A BULLETIN 131, UNITED STATES NATIONAL MUSEUM containing finely disseminated argentite. In the Poorman mine it is common as films in granular quartz and in spongy quartz con- taining steaks of disseminated argentite. In the bonanza surface ores of the Poorman lode remarkable amounts of cerargyrite were found. The mineral occurred in sheets along both walls of the vein and slabs a foot square and one-sixteenth of an inch thick could be peeled off. Masses weighing many pounds were frequently obtained.” It was often well crystallized and in some cases the crystals were half an inch across. These were mostly cubes and cuboctahedrons but occasionally with other planes and in twins consisting of inter- penetrating cubes, the angles of one projecting from the faces of the other.“ Exceptionally fine specimens from this remarkable occur- rence have fortunately found their way into the Yale University collection and thus have been preserved. Horn silver occurred in the De Lamar and adjacent mines and in ore from the Laxley mine, South Mountain district, the chloride occurs in altered spongy matrix with malachite and bindheimite stains. SHOSHONE COUNTY Cerargyrite has never been definitely identified from any locality in the Coeur d’Alene district, although it is quite probably present in the richer oxidized lead silver ores. Miners in this district often call any yellowish colored mineral “‘chlorides,”’ particularly ocherous bindheimite, pyromorphite, and in one case, greenish scorodite. EMBOLITE (170) BROMIDE OF SILVER Silver chloride-bromide, AgCl. AgBr. Isometric. The chlorobromide of silver which usually occurs in soft wax-like films, grains, or crusts resembling cerargyrite or horn silver, but having a yellow or yellow-green color, has not been certainly identified in Idaho. Bromide of silver has been reported from a number of localities, as, for example, the Little Giant vein in the Warren district in Idaho County,® but no specimens have been available for ex- amination and it is not known whether the mineral is embolite or bromyrite, both of which are commonly called bromide of silver. Bromides of silver are reported by miners and prospectors from many districts, but these reports are not reliable, as western miners use the term ‘bromides’? indiscriminately to indicate any greenish or bluish colored silver bearing material. Such ‘bromides’? are in most cases earthy cerargyrite-bearing oxidized ores stained by copper compounds. 64 J. Ross Browne. Mineral Resources of United States, 1867, p. 523. 65 E.S. Dana. System of Mineralogy, p. 158, 1895. 66 Waldemar Lindgren. U.S. Geol. Survey, 20th. Annual eport, pt. 3, p. 246, 1900. THE MINERALS OF IDAHO 175 BROMYRITE BROMIDE OF SILVER Silver bromide, AgBr. Isometric. The remarks given above under embolite apply equally well to the chlorine-free silver bromide, bromyrite, the two minerals being similar in all their properties. While bromyrite probably has been present in some of the rich oxidized silver ores of the State it has not been definitely identified and no specimens have been available for identi- fication. IODYRITE (173) IODIDE OF SILVER Silver Iodide, AgI. Hexagonal, hemimorphic. Like the bromides of silver, silver iodide has occasionally been reported to occur in oxidized silver ores from Idaho,” but no speci- mens have been available for examination. The mineral is similar to cerargyrite and bromyrite in general properties and, since it has been found abundantly in Nevada, it probably occurred also in cerargyrite ores in Idaho. FLUORITE (175) FLUORSPAR Calcium fluoride, CaF». Isometric. No noteworthy deposits of fluorspar are known in Idaho, the occurrence of this mineral being limited to the ores of a few districts where it forms an unimportant accessory gangue material. CUSTER COUNTY Fluorite occurs in wide distribution in the Alder Creek or Mackay (White Knob) district in the contact metamorphic copper deposits and in the lime silicate rock near them. Chunks weighing several pounds are present in the dumps from the big quarry of the Empire mine.@ This is in the form of broad crystalline masses with perfect octahedral cleavage and varying from colorless to faintly purple. It is mixed with some copper silicates. Other specimens are pale purple cleavable masses containing small yellow-green garnet crystals. Fluorite is also common as purple grains in garnet-magnetite rock from 500 feet down the east slope of White Knob and ore from the Tiger claim contains pale green fluorite cleavages associated with bornite and copper silicates in garnet rock. Near the head of the North Fork of Lost River fluorite occurs as pale green octahedral crystals up to 1 cm. in diameter in a narrow & J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 53, 1917. ‘72 Reported as identified by W. P. Blake in specimens of ore from the ‘‘ Boise Region.’’ Oregon Daily Times, Nov. 28, 1864. Capt. John Mullan, Miners and Travelers Guide, New York, 1865, p. 108. 176 BULLETIN 131, UNITED STATES NATIONAL MUSEUM vein of cellular quartz in andesite. On Summit Creek near where the Ketchum-Mackay road crosses the divide fluorite occurs as colorless to white octahedral crystals with platy pseudomorphous quartz in talus slopes composed of Ordovician slate. Specimens of oxidized ore from the Pacific mine, Bay Horse district, have small colorless to white cubic crystals resting upon crusts of calamine. These were examined optically and found to be isotropic with an index of refraction of 1.437+.002. These properties identify the mineral as fluorite. This occurrence is interesting as the fluorite is a very late deposit having formed sub- sequent to the crystallization of the calamine. In the Stanley Basin district on Little Casino Creek the bedrock contains a system of north-south fissures containing quartz and a considerable amount of fluorite along one of which is a gouge seam carrying gold.® IDAHO COUNTY Purple fluorite has been reported to occur in very fine intergrowth with quartz in a large low-grade pyritic gold lode at the Independ- ence prospect in the Big Creek district. The best description of the deposit available makes no mention of the mineral. OWYHEE COUNTY A specimen of ore from a stope in the east drift of the Silver City mine, Silver City district, consists of a comb of quartz crystals bearing loosely attached large grains of pyrargyrite and some small white grains, most of which are irregular, although some appear cubic. These seem later in age than the pyrargyrite. This white mineral was examined optically by A. Rodolfo Martinez, who found it to be isotropic with a refractive index of 1.434. It is thus shown to be fluorite. A specimen from a tunnel on the south side of Long Gulch below the Blaine tunnel, Silver City district, shows octahedral crystals of pale lavender fluorite up to 3 mm. in diameter resting upon adularia crystals. LAWRENCITE (178) Ferrous chloride, FeCl. Lawrencite or ferrous iron chloride is a soft green to brownish- green substance which is known to occur only in meteoric iron. It exudes from freshly cut or broken surfaces of meteorites and oxidizes almost immediately to brown rust. This compound was abundantly present in the meteoric iron which was found in a gold placer on Hayden Creek, Lemhi County.” 6 J. B. Umpleby and D. C. Livingston. Idaho Bur. Mines and Geol. Bull. 3, p. 15, 1920. 69 William Earl Hidden. Amer. Journ. Sci., vol. 9, p. 367, 1900. U. S. NATIONAL MUSEUM BULLETIN 13! PL. 3 PSEUDOMORPHOUS AND CRYSTALLIZED QUARTZ FOR DESCRIPTION OF PLATE SEE PAGE 179 ~I “I THE MINERALS OF IDAHO 1 QUARTZ (210) Silicon dioxide, SiO» Hexagonal Rhombohedral. The mineral quartz, under which are included many varieties, including chalcedony, is an exceedingly common mineral and occurs very widely distributed in Idaho as elsewhere. The several varieties are discussed separately below under the several varietal names, in accordance with the following outline: A. Phenocrystalline varieties. a. Common quartz, massive. b. Rock erystal. c. Amethyst. d. Pseudomorphous. B. Cryptocrystalline varieties. e. Chalcedony and agate. f. Jasper. Numerous other varieties of this mineral are recognized but they are not known to occur in good specimens in Idaho. A. PHENOCRYSTALLINE VARIETIES a. COMMON QUARTZ ~ MILKY QUARTZ, BULL QUARTZ, VEIN QUARTZ, GREASY QUARTZ. Common massive quartz occurs throughout the State in veins and masses in rocks of all kinds, both as a gangue in metal bearing veins and as large deposits which are not known to contain any valuable metal. It varies in color from clean milky white, as for example in the gold veins of many districts in Idaho County, to bluish, or gray varieties, which pass under the miners name of ‘‘bull quartz.”’ En- tirely similar massive quartz occurs in considerable masses in pegma- tites and in grains in granites and other igneous rocks. When these rocks disintegrate the quartz, being chemically the most stable con- stituent, remains behind in the form of waterworn grains and most sand is made up of such quartz grains. Consolidation of the sand gives rise to extensive formations of sandstone, also consisting essen- tially of more or less pure quartz, and by further metamorphism the sandstone is converted to quartzite, much of which is comparable in purity to the massive quartz of veins. b. ROCK CRYSTAL Under this head are included all the forms of colorless quartz which occur in distinct crystals. Small crystals of quartz occur in very wide distribution. The following occurrences have been noted. Boise County.—Small crystals occasionally occur in open spaces in the gangue of the gold veins. A specimen of sericitized and pyri- tized porphyry from the Gold Hill mine dump, Quartzburg district, 178 BULLETIN 131, UNITED STATES NATIONAL MUSEUM contains grayish phenocrysts of quartz which are rounded dihexagonal pyramids. Custer County.—Euhedral doubly terminated crystals of quartz up to an inch or more in length occur embedded in siderite of ores of the Bay Horse district. These are sometimes somewhat milky and show zonal growth lines.” Near Challis quartz occurs in small amount coating platy (argentine) calcite and as spherulitic and spindle- shaped microscopic grains associated with ptilolite.1 In the cirque at the head of Wildhorse Canyon at the eastern base of Hyndman Peak quartz occurs in crusts of clear transparent crystals lining many hollow veins in quartzite and gneiss. In basaltic lavas at many places in the upper valley of Lost River clear transparent quartz crystals line chalcedony geodes weathered out of the lava. These crystal-lined geodes are sometimes a foot in diameter. Elmore County.—Vuggy quartz in veins of the Vishnu mine, Rocky - Bar district, contains small crystals of quartz. Owyhee County.—The gangue of the silver veins of the Silver City and adjacent districts in Owyhee county contains large amounts of quartz which is in part crystalline, in part chalcedonic and, in the De Lamar district, pseudomorphous, as described below. Numerous cavities and vugs occur in the ores and these are frequently lined with druses or larger crystals of transparent quartz, frequently intimately associated with ore minerals (pl. 3, lower). Fine crystals forming a continuous crust are to be found on the Blaine tunnel dump, Silver City district, and the Banner vein on Long Gulch, 34 mile south of Silver City, contaims numerous vugs lined with beautiful quartz crystals. A specimen from the Silver City mine consisting of a quartz-adularia intergrowth contains cavities lined with transparent colorless quartz crystals 3 to 5 mm. long which are prisms terminated by only three faces of one rhombohedron. Crystals of this same habit occur also in ore from the Mahogany mine (Cat. No. 14776, U.S.N.M.). Much of the pseudomorphous quartz from the De Lamar mine contains drusy quartz in minute crystals. Lemhi County.—Fine druses of small quartz crystals have been seen coating galena in ore from the Pittsburg-Idaho mine, Gilmore district. Shoshone County.—Fine sparkling specimens of drusy quartz coating chalcopyrite occur in the ore of the Empire (Horst-Powell) mine on the Little North Fork of the Coeur d’Alene River. c. AMETHYST Amethyst is essentially the same as rock crystal except that the crystals are colored purple, probably by small amounts of manganese. Amethystine quartz crystals have been noted in Idaho lining chalce- 7 J.B. Umpleby. U.S. Geol. Survey, Bull. 539, pl. 7, 1913. 71 Clarence S. Ross and Earl V. Shannon. Proc. U.S. Nat. Museum, vol. 64, Art. 19, 1923. a THE MINERALS OF IDAHO 179 dony geodes weathered from Tertiary basalts in the area covered by the Hailey quadrangle in Blaine County, especially on Pole Creek, a tributary to Little Wood River and in Custer County in Low Hills, near the Junction of the North Fork of Lost River with the main stream. The amethysts are rare, most of the geodes containing colorless crystals, and no deeply colored stones have been seen. Occasionally clear quartz crystals have an interior phantom crystal outline in pale amethyst. d. PSEUDOMORPHOUS QUARTZ HACKLY QUARTZ Owyhee County.—The De Lamar, Webfoot, Chautauqua, and other veins in the same vicinity are all distinguished by the universal presence of a laminated quartz which is clearly of pseudomorphic origin. Occasionally thereis some of the more massive flinty variety, but the laminated variety prevails from the croppings of the Big Reef and Garfield to the lowest level of the De Lamar mine. This laminated quartz forms a cellular network of thin and straight intersecting laminae of quartz. These meshes generally consist of a narrow median line adjoined on both sides by quartz, projecting as minute crystals on the surface of the laminae. The angles of intersection of the latter do not appear to follow any certain law. In some cases the outside of the laminae may be smooth and the inside only covered by the projecting points of crystals (pl. 3, upper) ; moreover the inside of these pseudomorphs is usually chambered by thin laminae, coated by comb quartz on both sides. Under the micro- scope these ores show intermingled coarser and finer quartz. The coarser part shows grains from 0.1 to 0.2 mm. in diameter, which have a decided tendency to crystal form though the influence of other individuals has prevented its perfect development. With higher magnifying power the fine grained material also dissolves into similar quartz mosaic. Both are mixed, the finer aggregate forming lamellar or triangular areas separated by coarser masses. Valencia- nite in abundant and minute crystals of rhombic form was identified without doubt in the quartz from the Chautauqua tunnel. It has not yet been discovered in that from the De Lamar mine.” Such hackly pseudomorphs have been found in precious metal veins in other areas, particularly in the Jarbidge district, Nevada. The structure seems quite certainly pseudomorphous after calcite of the peculiar tabular habit, parallel to the basal pinacoid. A specimen consisting of thick tabular plates of calcite making up a cellular - aggregate was collected by Lindgren from the Owyhee shaft. The structure of this specimen is entirely analogous to that of some 72 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 170. 180 BULLETIN 131, UNITED STATES NATIONAL MUSEUM specimens of the pseudomorphous quartz. Typical argentine calcite having the platy structure and pearly luster is also present in a specimen from a tunnel dump on the south side of Long Gulch below the Blaine tunnel. B. CRYPTOCRYSTALLINE VARIETIES e. CHALCEDONY Chalcedony is essentially the same as agate, except in that agates usually are more or less highly colored by included impurities, most frequently iron oxide. The chalcedony occurs in Idaho occasionally in veins but more frequently in cavities in basic igneous rocks. Blaine County.—Translucent white or bluish chalcedony occurs in the Tertiary basalts in many places in the Hailey Quadrangle and adjacent regions and many of the lava hills are strewn with nodules and fragments of translucent chalcedony, usually white but some- times colored by the presence of included iron oxide. Many of the irregular or rounded lumps have originally filled amygdaloid cavities in lava. Usually the first lining of the cavity has been calcite followed by the chalcedonic silica and the nodules show on their outer surface the gash-like molds of the acute rhombohedral crystals of calcite. Sometimes the masses are solid chalcedony with a con- centrically banded structure, but more frequently they are hollow, sometimes with a botryoidal inner surface, but more frequently with a lining of quartz crystals, usually colorless but occasionally amethystine. Custer County.—Chalcedony occurs in the lava areas of Custer County in the same manner as in Blaine County, especially near the North Fork of Lost River. Specimens of the rare zeolite, mordenite, from near Challis have a crust of chalcedony between the mordenite and the inclosing rock and nodules of chalcedony occur in the area. Cherty silica referable to chalcedony occurs in some limestones in the vicinity of Mackay. Owyhee County.—Chalcedony occurs in lavas and a dense flinty chalcedonic silica occurs in some of the silver veins as a gangue mineral. A brownish radially fibrous variety occurs in ores of the Oro Fino mine. A specimen from the new ore shoot, De Lamar mine, consists of fine grained gray chalcedonic silica and a specimen from the Summercamp tunnel, De Lamar district, consists of dense very fine grained chalcedonic silica with lusterless fracture with pyrite replacing rhyolite. Lemhi County.—Chalcedonic silica forms a gangue material in veins of the Parker Mountain district. THE MINERALS OF IDAHO 181 Valtey County.—Chalcedonie silica replacing limestone forms the principal gangue of the cinnabar deposits of the Yellow Pine quick- silver district.” f. JASPER Fine grained siliceous material heavily impregnated and colored by iron oxides which may correctly be called jasper, occurs at a number of places in Idaho. Custer County.—Jasper commonly occurs in the lavas in the same areas Which contain abundant chalcedony nodules, usually as veinlets and stringers. In the Alder Creek (Mackay) district much of the ore contains red and yellow ferrugineous jasper which is associated with indefinite copper silicates allied to chrysocolla. Nodules of brown jasper surrounded by crusts of chloropal have been sent to the National Museum by D. C. L. Kirtley from Challis. Bear Lake County.—The possibility of a new copper ore-jasper gem or ornamental stone from the Humming Bird mine, in Paris Canyon, near Montpelier, has been considered. The constituent minerals are quartz with a very fine red dust pigment, and malachite. Under the microscope the quartz is seen to be granular, with close fitting grains, and is dusted full with minute red specks, probably hematite. The malachite is in bright green grains and masses with a radial fibrous and occasional spherulitic crystallization. The quartz incloses numerous small grains or buhrs of malachite bristling with needles. In the hand specimen the rock is bright jaspery red with dark green splotches throughout. The quartz is close grained and tough and takes a good polish. The malachite is softer though suffi- ciently hard to be polished along with the quartz. The contrast between the two colors is pleasing and for use in small ornaments, scarf pins, brooches, etc., the rock would serve well.” Blaine County.—Jasper of the usual red and brown colors is com- mon in Tertiary lavas, having been especially noted in the area east of Little Wood River near the southern boundary of the Hailey topographic sheet. Fremont County.—A jaspery material forms the principal gangue material in the ores of the Old Scott mine in the Skull Canyon district. Specimens which have been examined show galena crystals up to 1 cm. in diameter isolated in yellow to brownish-red jasper.” Washington County.—Jasper occurs as a gangue of manganese ores on Snake River 20 miles below Huntington.”. ma E.S. Larsen and D.C. Livingston. U.S. Geol. Survey, Bull. 715, pp. 73-83, 1920. 73 Douglas B. Sterrett. U.S. Geol. Survey, Mineral Resources 1909, pt. 2, p. 804. “4J.B.Umpleby. Prof. Paper, 97, U.S. Geol. Survey, p. 119, 1917. 73 D.C. Livingston. Univ. of Idaho, vol. 14, Bull. 2, pp. 32-33, 1919. 182 BULLETIN 131, UNITED STATES NATIONAL MUSEUM TRIDYMITE (211) Silicon dioxide, SiO: Hexagonal. CLARK COUNTY The hexagonal form of silica, tridymite, is probably a more com- mon mineral of lavas than is usually supposed, since it is usually recognizable only with the aid of a microscope. This mineral was found by Dr. E. S. Larsen to make up a considerable proportion of a number of specimens of rhyolitic lavas collected by H. T. Stearns in the vicinity of Libbys Hot Springs west of Dubois. OPAL (212) Silicon dioxide, usually with some water. Amorphous. Opal ranging from brown to white opaque common opal, through various kinds of semiopal to fine precious opal has been found at a number of localities in Idaho, the principal occurrences being those noted below. BOISE COUNTY Sandstone cemented by fire opal has been collected from Neocene lake beds on both sides of Moore Creek at Idaho City.” CUSTER COUNTY Silica in the form of opal is abundant in miscroscopic grains in the copper silicate ore of the Alder Creek (Mackay) district. It is easily recognized in index solutions by its isotropism and low index of refraction.” KOOTENAI COUNTY Specimens, some of large size, of common opal obtained from near Setters, in the Spokane Valley between Spokane and Coeur d’ Alene City, have been sent to the National Museum by Henry Fair, of Spokane. The material ranges from translucent to almost transparent and is yellow and greenish yellow to resinous brown in color. There is also some nearly opaque white opal in the lot. Nothing is known regarding the occurrence of this material. LATAH COUNTY In August, 1890, fine opal was found in digging a well near Whelan, 20 miles from Colfax, Wash., near Moscow, Idaho, and almost on the line between Idaho and Washington. It occurred more or less plentifully, and the last 4 feet of the rock contained cavities filled with precious opal. This opal occurs in a basalt in which most if not all of the feldspar and pyroxene as well as the groundmass seem to be altered. Buildings were erected and the locality named Gem City. The total yield of the mines during the 76 Waldemar Lindgren. U.S. Geol. Survey, 18th Annual Report, pt. 3, p. 665, 1897. 7J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 54, 1917. THE MINERALS OF IDAHO 183 summer and fall of 1891 amounted to over $5,000. The material is stated to have been fine, in many respects equal to the best material from the Hungarian or Australian mines. A gem, weighing 314 carats, from this district was held at the rather extravagant figure of $500, partly perhaps on account of its American origin, and a rough mass of 2 ounces for $1,200. The deposits apparently were worked mainly on the Washington side of the line, but it is reported that in that year two companies were working on the Idaho side in Latah County.” It is reported that, in 1893, the North America Gem and Opal Mining Co., which operated the mines at Moscow, did no work owing to litigation.” There is little further mention of any work done on these deposits until 1904 when the mines were reported reopened. No subsequent production has been reported, although it was later stated that in Latah and adjoining counties precious opal of the finest quality that has been found on this continent occurs near Salmon River as nodules in a very hard trachytic rock resembling the rock in which opal is found in Hungary. A single stone from this locality was worth $1,000. A report based on the Washington side of the area states that the country is rolling meadow land adapted to the growing of wheat and that relatively little attention was paid to the possibilities of gem mining. The dumps contain piles of vesicular basalt, which is evidently part of a flow covering large areas in this region. Some of the rock is partly weathered and of a gray color but the fresh rock is grayish black and hard. In places hyaline opal occurs, filling vesicles and seams in the rock; and in places patches of precious opal can be found by breaking considerable rock. In places precious opal was found thickly scattered through the rock and some very fine gem opal was obtained.” Some very good specimens of dark gray opalized wood have been seen from near Kendrick. LEMHI COUNTY Homogeneous masses of flinty common opal of various colors, including yellow, flesh pink, and black have been sent to the National Museum from May, a post office in Lemhi County, Idaho. Opals were discovered in Lemhi County in 1902 on Panther Creek on the west side of the valley about 6 miles below its head and at an altitude of 7,000 feet. Here a large dike of porphyry runs parallel to the creek for nearly a mile and a half, forming a ledge partly 78 George F. Kunz. U.S. Geol. Survey, Mineral Resources of United States, 1892, p. 776. 7? George F. Kunz. U.S. Geol. Survey, Mineral Resources of United States, 1893, p. 698. 80 George F. Kunz. U.S. Geol. Survey, Mineral Resources, 1904, p. 956. §1 George F. Kunz. Ann. N. Y. Acad. Sci., vol. 21, pp. 214-215, 1912. 82 Douglas B. Sterrett. U.S. Geol. Survey, Mineral Resources, 1910, pt. 2, p .874. 184 BULLETIN 131, UNITED STATES NATIONAL MUSEUM covered with overwash from the mountain slope, but in places outcropping several feet high. The width is approximately 150 feet and the rock is full of opals of all sorts—miulky, blue, green, brown, pink, etc., and among them some perfectly transparent fire or flame opal. Many of the masses are large, but to obtain good sized stones from them is difficult as the opals are very brittle and the rock is very hard. The locator obtained one stone of 60 carats which showed green reflections and a brown opal of 150 carats, but otherwise no good stones above 10 carats weight. The opal here is largely of the glassy variety with broad flames of color, but it is fragile and not well suited for jewelry. There is a large proportion of loss by breakage.** Umpleby mentions this locality as on Panther Creek in the eastern part of the Gravel Range district. He states that the opal occurs as linings in the vesicles of rhyolite flows but that precious opal does not appear to be present in commercial quantities.* LINCOLN COUNTY Very fine specimens of very well preserved opalized wood are widely distributed in collections labeled as from Clover Creek, Lincoln County. The material is buff to yellow and black in color and is remarkable for the perfect preservation of the grain and original structure. Specimens of polished cross sections preserved in the National Museum are shown in plate 4. No data are available as to the occurrence of this material, which was originally collected by Otto Uhrlaub, of Bliss. Dr. Frank H. Knowlton reports that the wood is all of a dicotyledonous tree, quite certainly oak, and is probably late Tertiary in age. It is quite possible that the material is from Miocene lake sediments. OWYHEE COUNTY Opal has long been known to occur in Owyhee County. In 1893 it was said that the Owyhee opal mines were situated on section 13, township 1 north, range 4 west, Boise meridian, about 3 miles from Snake River in Owyhee County. The work done on the mine amounted to about 8 months work for 2 men. The opal taken out amounted to about 7,000 carats in the rough, varying from transparent fire opal to the finest noble white opal; but nearly all of this was either given away or poorly marketed. The opals were said to occur in a nearly vertical dark andesite dike about 25 feet wide which outcropped for a distance of 750 feet. In the center this contained a layer of very hard jasper 4 to 5 feet wide on each side of which the opals occurred in seams and flat pockets. The 83 Geo. F. Kunz. Mineral Resources, United States Geol. Survey, 1902, p. 853. 84 Joseph B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 174, 1913. | U. S. NATIONAL MUSEUM BULLETIN I3! PL. 4 OPALIZED OAK Woop FOR DESCRIPTION OF PLATE SEE PAGE 184 THE MINERALS OF IDAHO 185 opals had been found for a distance of 250 feet on the surface and the greatest depth reached in the open cuts was 20 feet. North of and parallel with this ledge was another, 8 feet wide, traced for 50 feet, from which 1,000 carats of good opals were obtained. The deposits have been briefly mentioned by Lindgren, Drake, and Schrader.* They were visited by Sterrett in 1910, when no work Was in progress on any of them. He gives a very complete description of the deposits which is repeated below.™ Deposits have been opened on Squaw Creek and along the Cald- well-Rockville road about 2 miles east of south of Sommer camp. The deposit in the valley of Squaw Creek below the junction with Little Squaw Creek is situated in a small rounded hill about 1 mile above the ranch of Jim Keith. The elevation is about 3,500 feet above sea level and that of the mountains about 1,000 feet higher. The country is treeless, and low hills in the valley are covered only with sage brush and a small quantity of grass. A few small pits have been made on the summit of the hill and on the south side, cutting into the partially disintegrated basalt in which the opals occur. The basalt is highly vesicular, and under the microscope is found to be composed chiefly of lath-shaped crystals of labradorite, augite, and a brownish glass. The basalt is a portion of a flow which partly fills the canyon of Squaw Creek and rests on rhyolite and rhyolite tuff, the most important formation of the region. The partially disintegrated basalt breaks up fairly easy and is removed from the pits in large blocks. These blocks are broken up and the opal picked out. The opal occurs as amygdaloid in the steam holes and cavities in the basalt. The greater part of the cavities contain no opal, and only a part of the opal is of the precious variety, much of it being milky white or colorless. In some of the blocks of basalt broken into, the opal is plentiful and much of it has a fine play of colors. Most of the opal is in small pieces and large pieces of precious opal are rare. Some of the vesicles are filled with chal- cedony and opal. Fragments of chalcedony and chalcedony with white opal 2 inches across were observed loose in the soil of the hill. Some of this material is banded both with curved bands and straight onyx bands. Similar specimens of chalcedony and white opal were seen in other places in the valley. One of the larger mines, 3 miles west of Enterprise, contained two sets of workings on different sides of a draw or valley and from 35 to 65 feet above the bottom of the draw. The principal workings are on the west side and consist of several open cuts, the largest about 50 feet long and 25 feet deep and a tunnel 40 feet long. The %o Geo. F. Kunz. U.S. Geol. Survey, Mineral Resources United States, 1893, p. 698. 85 Silver City folio (No. 104), Geol. Atlas United States, U. S. Geol. Survey, 1904. 86 Douglas B. Sterrett. U.S. Geol. Survey, Mineral Resources of United States, 1910, p. 872-874. 54347—26}——138 186 BULLETIN 131, UNITED STATES NATIONAL MUSEUM other openings are about 150 yards to the northeast diagonally across. the draw and consist of open cuts. The opal deposits are in whitish chalklike decomposed rhyolite in which occur inclusions of blocks and rounded masses of gray to brown glassy perlitic ryholite. The perlitic rhyolite appears to be the same as the inclosing decomposed rhyolite but has not undergone alteration. A weathered yellowish fine porphyry bed occurs over the opal bearing rhyolite outcropping as a hard stratum. The for- mations have a gentle northerly dip and the rhyolite can be recog- nized at numerous places by its light-colored outcrop. The opal occurs in seams and veinlets, filling cracks and joints, as a filling in a brecciated fracture zone, and in nodular masses, both in the altered rhyolite and in the perlite. White and milky opal was plentiful around the dumps and a few small chips of precious opal were seen. Judging from the extent of the work done it is probable that valuable opal was found. At another opal deposit about 2 miles east of south of Sommer camp and 4 miles west of Enterprise, about half a dozen pits have been made within 200 vards of one another, which range in size from 4 to 20 feet in depth and about the same in width. They are in a bed of partly decomposed whitish rhyolite interbedded with brownish glassy rhyolite. The formations are gently folded and the rhyolite outcrops at several places to the south along the road on the hill above. The beds have an aggregate north dip. Other prospects were opened on some of the upper outcrops of the rhyolite. Con- siderable chalcedony and white, milky, and bluish opal were seen on the dumps around the pits. White opal and translucent gray chal- cedony are banded together in some specimens like onyx. Very little precious opal was seen around the old openings. A number of specimens of opal labeled as from 3 miles west of Enterprise are preserved in the National Museum. ‘The opal occurs in a black highly vesicular lava in which only a small proportion of the cavities are filled with opal. Apparently a soft ferric silicate, chloropal or a related mineral first lined or partly filled the cavities after which the opal was deposited. In some cases it appears as though a carbonate, since removed, preceded the opal. Fossil bones collected from sandstone near Opaline at an elevation of 2,400 feet were encrusted with opal and some of their cavities con- tained fire opal. The bones were identified by Prof. O. C. Marsh as Protohippus of Pliocene age.*’ 87 Waldemar Lindgren. U.S. Geol. Survey, 20th. Ann. Rept., pt. 3, p. 99, 1900. THE MINERALS OF IDAHO 187 VALENTINITE (216) Antimony trioxide, Sb20Q3. Orthorhom. SHOSHONE COUNTY The antimony oxide valentinite occurs sparingly in the ores of the Stanley antimony mine in Gorge Gulch above Burke in the Coeur d’Alene district in the form of drusy coatings and crusts on stibnite and quartz. Although these crusts are very thin they often cover several square inches of surface. Those which rest on quartz are pale brown in color while the ones on stibnite are usually olive green. The luster is waxy and the mineral looks like cerargyrite or embolite. Valentinite may also occur in the earthy oxidation products which are common near the outcrops of the Coeur d’Alene antimony and other antimony veins on Pine Creek. MOLYBDITE Hydrous ferric molybdate, Fe,03 .8MoO; .7144H20. Orthorhombie. ADAMS COUNTY Molybdite has been reported from the Peacock claim, Seven Devils district, where it occurred as an olive green earthy substance associated with powellite in a specimen consisting mainly of garnet and bornite.*8 Livingston and Laney * state that molybdite occurs sparingly in the contact metamorphic copper ores as an alteration product of molybdenite. Melville regarded the molybdite associated with the powellite as secondary after the calcium molybdate and derived from it by the action of carbonated waters. BOUNDARY COUNTY Molybdite is abundant in good specimens as thick silky pale yellow films and crusts coating quartz which contains molybdenite from veins in granite 21 miles by trail southwest of Porthill. Specimens of this material were shown the writer by Frank L. Hess, of the United States Geological Survey. CUSTER COUNTY A little molybdite has been noted as a yellow ocherous stain associated with molybdenite and powellite in quartz in specimens reported to be from the Bay Horse district. ELMORE COUNTY Bright yellow molybdite occurs as an alteration product of molyb- denite on granite in a specimen sent to the National Museum by William R. Decker from Pine, Elmore County. 88 W.H. Melville. Amer. Jour. Sci., vol. 41, p. 138, 1891. §§D. C. Livingston and F. B. Laney. Idaho Bur. Geology and Mines, Bull. 1, p. 67, 1920. 188 BULLETIN 131, UNITED STATES NATIONAL MUSEUM LEMHI COUNTY Molybdite occurs sparingly as an alteration product of molyb- denite near the surface in the hubnerite-bearing tungsten vein of the Ima Mine, Blue Wing district. TUNGSTITE (220) Tungsten trioxide, WO;.H,0. Orthorhombie. Tungstite is a mineral. commonly formed in small amounts in the oxidation of other tungsten minerals. It is commonly bright yellow in color and earthy in appearance and is known by the common name of tungstic ocher. LEMHi COUNTY Tungstite occurs in small amount in the tungsten ores of the Blue Wing district as waxy to ocherous fillings in small cavities in rusty quartz which contains hubnerite. This material is found, upon microscopic examination, to be very finely crystalline with an index of refraction much above 1.84, which proves that it is tungstite rather than ferritungstite, which, while similar in appearance has an index of refraction of 1.80 and below. CERVANTITE Antimony oxide, Sb203.Sb205. Orthorhombic. Cervantite or antimony ocher is the name usually applied to yellow pulverulent materials occurring as oxidation products of stibnite. Such bright yellow ocherous materials have been called cervantite, although no definite confirmation of the identification has been obtained. The status of cervantite as a species is somewhat in doubt. BLAINE COUNTY Cervantite is reported to have been mined on Wood River. SHOSHONE COUNTY Both at the Stanley mine in George Gulch above Burke and at the Coeur d’Alene antimony mine of Pine Creek and probably at other antimony mines in the county, the stibnite of the ore is often slightly altered with the formation of thin coatings of a bright yellow ocherous material which has been called antimony ocher or cervantite. This is always in very thin crusts, apparently passing over into the dirty whitish hydrated oxides mentioned under stibiconite.™ 90 E.S. Dana. System of Mineralogy, sixth edition, p. 1092, 1895. % Karl V. Shannon. Amer. Mineralogist, vol. 3, p. 24, 1918. THE MINERALS OF IDAHO 189 STIBICONITE (222) Hydrated antimony oxide, Sb20,.H,0. Amorphous. Stibiconite, like cervantite, is a species of poorly established com- position and is exceedingly variable, especially in water content. It probably includes several distinct minerals. All of the white to grayish and brown alteration products of stibnite are at present designated stibiconite, although no detailed work has been done on the Idaho materials. SHOSHONE COUNTY At the Stanley antimony mine above Burke lumps of stibnite are often coated with crusts from 1 to 5 em. thick, of dirty white altera- tion products. Nearest the stibnite these contain a layer, usually less than 1 cm. in thickness, of compact material of opaline appear- ance and pale brown color and waxy luster. This grades outward into chalky white material containing much more water than required for the stibiconite formula. In small cavities in quartz from the uppermost tunnel of the Stanley mine there occur thin coatings of a yellow, brownish yellow, or green material which is soluble in hydro- chloric acid. The solution reacts for antimony and iron. Specimens from the antimony mine near Glidden Pass are fibrous or bladed pseudomorphs of dirty white oxidation products after stibnite. Much of the vein material along the outcrop and in surface work- ings of the Coeur d’Alene antimony vein on Pine Creek consists of a breccia of bleached and altered slate fragments cemented by earthy or chalky white, grayish, or brown hydrated antimony oxides referable to stibiconite. CUPRITE (224) Cuprous oxide, Cu,0. Isometric. Cuprite, or red copper ore, is known from a number of copper- bearing veins in Idaho, where it has formed from the oxidation of primary copper-bearing sulphides. The following localities have been noted. CUSTER COUNTY In the Alder Creek (Mackay) district specimens of ore from the 300-foot level of the Alberta mine contain nodular bunches of cuprite embedded in chrysocolla. The nodules, which are an inch or less across, invariably are surrounded by a layer of tenorite about an eighth of an inch thick.” Specimens from the Mackay district contain some deep red crystals resting on limonite crusts on garnet rock containing disseminated chalcopyrite. These were suited for measurement on the goniometer J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 52, 1917. 190 BULLETIN 131, UNITED STATES NATIONAL MUSEUM and were combinations of the cube, c(010) predominating, with modi- fying faces of the octahedron p(111) and the rhombic dodecahedron d(110), as shown in Figure 32. The isometric symmetry is estab- lished by the following measurements: Angles of cuprite from Custer County Form | Symbol | | Measured Calculated | SS Quality, description | | a No.| Letter | Gat. | Miller | . | p | oe , = = == | | | | ° ‘ °o , ° , ° , Gh pa ae lee oa pea ae Me CV les ces 0 00 ae Pons OL | MOnY POE: 3 6 00/90 00} 0 00| 90 00 3 | 4 © {1 OP PMRSGiam Shee pe eee wae sg wT | 44 56/90 00] 45 00] 90 00 Mlgitcwa ce 1 Tita eee: dat note a teeeee rie LOU aeae | 45 09| 54 42/45 00] 54 44 p-------- - | In addition to the small symmetrical crystals there occur, on the same specimens, elongated crystals grading toward the capillary form of cuprite called chalcotrichite. These form reticulated meshes in which the angle of intersection is 90 degrees. Fics. 32-33.—32, CuPRITE. DOMINANTLY CUBIC CRYSTAL MODIFIED BY OCTAHEDRON AND DODECAHEDRON, MACKAY, CUSTER COUNTY. 33, CUPRITE. DOMINANTLY OCTAHEDRAL CRYSTAL MODIFIED BY DODECA- HEDRON AND CUBE. CALEDONIA MINE, SHOSHONE COUNTY Specimens from the Skylark mine, Bay Horse district, contain small deep red cuprite crystals coating cracks in rusty iron-stained rock. These are an oxidation product of tetrahedrite. The crystals THE MINERALS OF IDAHO 191 are octahedral in form but the larger exhibit small faces of the cube and rhombic dodecahedron. Some of them are moderately elongated. LATAH COUNTY Cuprite occurs in the shallow oxidized zone of the Mizpah deposit, Hoodoo district, associated with malachite, azurite, chrysocolla, etc.%4 LEMHI COUNTY Cuprite occurs in oxidized ore from the Indian Claim, Blackbird district, as grains in quartz. These show good cleavage and are surrounded by malachite and chrysocolla. Fine grained and massive forms are also found in a few parts of the Copper Queen and Copper King mines, and in the Patterson district. SHOSHONE COUNTY Much of the oxidized ore formerly mined in the Snowstorm mine near Larsen, above Mullan, Coeur d’Alene district, contained cuprite with malachite and iron oxides. Cuprite was common in the rich silver-copper ores of the upper levels of the Caledonia mine worked through the old shaft west of Wardner. The cuprite was the first product of the decomposition of tetrahedrite. Where tetrahedrite was oxidizing in a matrix of porous quartzite, beautiful specimens were commonly found showing residual cores of tetrahedrite surrounded by concentric rings of cuprite, azurite, malachite, and chrysocolla. Porous masses resem- bling coke were common in parts of the ore. These were brilliant gray with sparkling metallic luster, gave high returns in silver, and had a red streak. For these reasons they were commonly called ruby silver ore, but all of those examined were cellular tetrahedrite mixed with minute and brilliant crystals of cuprite. No reliable specimen of ruby silver has been seen from this mine. Massive granular and spongy cuprite also occurred in the ore, and cavities in the cuprite masses often contained minute grains and filiform wires of native copper. Distorted and much flattened crystals of cuprite were found in cracks. These are chiefly octahedral in form and Teach a maximum of about one-fourth of an inch in diameter. They are deep red and transparent with submetallic luster. Numerous specimens of rusty limonite-stained quartzite found on the 500-foot level about 1915 are spangled with minute transparent deep red cuprite crystals associated with cerusite crystals on a velvety layer of limonite. These are very perfect, the predominating form being the octahedron, with or without small modifying faces of the cube and dodecahedron, the form being as illustrated in Figure 33. The following measurements, which were made on a crystal taken from a #a TP. C. Livingston and F. B. Laney. Idaho Bur. Geol. and Mines, Bull. 1, p. 95, 1920. %J.B.Umpleby. U.S. Geol. Survey, Bull. 528, p. 76, 1913. 192 BULLETIN 131, UNITED STATES NATIONAL MUSEUM specimen in the collection of Col. W. A. Roebling, establish the identification and isometric symmetry of the mineral. Measurements on cuprite from Caledonia mine Form Symbol | Measured | Calculated ; = Quality, description ae No.| Letter Gat. | Miller | g p | ¢@ | p ° / ° , ° , | ° , 1 fe 0 OO G nGoOd eh a ee Le a ee On 00 fae aes |..0 00 Dal iDisemts sy ta Qco 010 | Medium____- the Sa Pa RE etn ete hae 0 00} 90 00 0 00/90 00 3 d OL Ol SP OOr: == 23a ee Se es Se 0 49) 44 56 0 00} 45 .00 | ete ano Sa co HON AE COLsNaTrO Wate ee ee eee 44 46 | 90 00) 45 00) 90 00 By Mes! eS. 1 1 | Excelent bs Se. su hae eee 44 59) 54 38 | 45 00| 54 44 Cuprite in earthy and massive form, has also been reported from the Monitor mine and probably occurs in other oxidized copper bearing ores in the copper belt east and south of Mullan. WASHINGTON AND ADAMS COUNTIES In the Seven Devils district cuprite is sparingly present in the oxidized copper ores of the contact metamorphic deposits. It is fairly abundant in the Blue Jacket mine, and while not abundant is not unusual in the Peacock mine.” Cuprite has been reported to occur in a silver-bearing ore at the River Queen deposit, one-half mile above Ballards. A specimen in the National Museum labeled as from Little Bar on Snake River contains masses of granular cuprite up to 5 cm. in diameter, con- taining cavities filled with capillary chalcotrichite. The associated minerals are chrysocolla and brown impure copper silicate. TENORITE (230) MELACONITE Cupric oxide, CuO. Amorphous-monoclinic (?) To what extent the black copper oxide occurs in Idaho is not known. The mineral has frequently been mentioned as occurring in oxidized copper ores of the State, but many of these may have been misidentified, the material, in some cases at least, being black copper silicate as further discussed under ‘‘melanochalcite.”’ The principal localities thus far reported are as follows: CUSTER COUNTY Bright black layers which envelop nodular masses of cuprite from the 300-foot level of the Empire mine in the Alder Creek district (Mackay) are probably tenorite. The material has malachite and *% D.C. Livingston and F. B. Laney. Bull. Idaho Bur. Mines and Geol., No. 1, p. 73, 1920. %§5 Idem, p. 82. THE MINERALS OF IDAHO 193 chrysocolla mixed with it and is in such small amounts that a careful chemical examination was not attempted. LEMHI COUNTY Some melaconite is reported to occur in the oxidized ore of the Copper King mine, Eureka district. SHOSHONE COUNTY Earthy to compact and waxy-lustered black material which was common in the oxidized ores of the upper levels of the Caledonia mine may have been all or in part melaconite. WASHINGTON AND ADAMS COUNTIES Melaconite has often been reported from the various copper mines of the Seven Devils district. Livingston and Laney” state that it is third in order of importance in the oxidized ores, although they place a question mark after the identification of the mineral. Numerous specimens from this district preserved in the National Museum labeled melaconite, contain a dense waxy black opaque material. A small sample of this material upon analysis proved to be an impure hydrated copper silicate. The analysis is given under “‘melanochalcite.”’ CORUNDUM (231) Aluminium oxide, Al.O3. Hexagonal, rhombohedral. Corundum has been reported from a number of localities in Idaho, always in loose gravel mined for gold. The mineral has in no instance been found in its original matrix. BOISE COUNTY Corundum has been reported to occur in heavy concentrates from gold placers on Gold Fork and other tributaries to Payette River. CLEARWATER COUNTY Various shades of blue and green sapphire have been reported to occur in gravel deposits near Pierce in Clearwater County, especially along Rhodes and Oro Fino Creeks. A large lot of the material picked from a placer concentrate from near Pierce (Cat. No. 87504 U.S.N.M.), consists of pebbles and rough worn crystals up to 2 cm. in greatest diameter. These vary greatly in color, ranging from deep blue through pale blue to greenish, chatoyant blue and opaque gray. Some have a sapphire blue core in a grayish to greenish shell. A few are pale grayish pink. Gray dull material greatly predomi- nates. None of the material approaches gem quality. The crystals %J.B.Umpleby. U.S. Geol. Surv., Prof. Paper, 97, pp. 54-55, 1917. 7D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 67, 1920. 54347—26t——_14 194 BULLETIN 131, UNITED STATES NATIONAL MUSEUM are rough, imperfect, and worn. Usually they are simple hexagonal prisms terminated by a basal pinacoid, but some are double hexag- onal pyramids. Some of them are coated with a white pearly mica which proved, upon microscopic examination, to be muscovite, and in the side of one corundum crystal a crystal of black tourmaline is embedded. CUSTER COUNTY Corundum is reported to occur in gold placers in Stanley Basin in Custer County. IDAHO COUNTY Corundum is found near Resort in Idaho County in gold placers. Three crystals from this locality have been examined. The first of these is a large opaque tapering hexagonal pyramid 2.5 cm. in diameter, the second a small hexagonal prism 1 cm. long by & mm. thick of pinkish gray color and the third a hexagonal table 1.5 cm. across having a fine bronze color and chatoyant luster. WASHINGTON COUNTY Corundum is found in concentrates from the Rock Flat gold placer near Meadows ‘The corundum is abundant associated with numerous garnets. In color the gray to amethyst shades _pre- dominate, although pink crystals yielding cut stones up to 1 carat occur and cornflower blue stones of from one-half to 1 carat could be cut from some. 2 >- 2. Calcium-magnesium carbonate- -_-_------- CaCO;.MgCO3 Amikenites sesso Calclum=ironcxcarbonates es. = 4) a sae CaCO 3.FeCO3 While the above formulas represent the end compounds, the natural minerals vary in composition by solid solution of the end members in each other. In the simple carbonates the miscibility seems limited. Siderite and rhodochrosite, of the simple carbonates, seem lable to variation in composition, but calcite is much less variable. There appears to be a complete gradation in the double carbonates between dolomite and ankerite. The minerals of this carbonate group do not occur in Idaho in good crystallizations nor as unusually fine specimens, but siderite and ankerite are widely distributed as gangue minerals in important ores and there seems to: be some definite relationship between the composition of the gangue carbonate and the nature of the valuable minerals of the ore. For this reason the data in regard to the members of this group at hand are presented in some detail. Enough time has not been available to permit the making of a sufficient number of analyses, in advance of the preparation of this section, to permit of very definite con- clusions, but it is hoped that the subject may be given more attention at a later date. CALCITE (270) Calcium carbonate, CaCO; Rhombohedral. No localities furnishing unusually large or fine erystallizations of calcite are known in Idaho, the mineral occurrmg most commonly as a gangue mineral in ore-bearing veins or as limestone and marble. The localities noted by the writer are in part as follows: 2 Clyde P. Ross. A new copper district near Salmon, Idaho. Eng. and Min. Jour., vol. 118, No. 6, Aug. 9, 1924, pp. 205-208, 1924. THE MINERALS OF IDAHO 215 ADAMS COUNTY In the Seven Devils district calcite in massive or granular form is common in the marble in which the ore deposits have been developed. A large specimen of vein material from the White Monument mine consists of large cleavage rhombohedrons of calcite, each of which serves as a core to a spherical layer of radial-fibrous calcite. The curved outer surface of these layers is drusy and formed by sharp calcite rhombohedrons which in turn are coated over with a thin layer of quartz crystals. The interspaces between the spheroidal] masses of calcite are filled with a mixture of dead-black melaconite and green chrysocolla with a small amount of malachite.” BANNOCK COUNTY Very coarsely crystalline snow-white calcite occurs as the gangue of chalcopyrite and galena in ore from the Fort Hall mine, Fort Hall district. Crystals of calcite occur with hematite in cavities in garnet-calcite rock from a locality on Lanes Creek, Bannock County, in NW. 14 sec. 9, T.68., R. 43 E. *These often show zoned layers of transparent material and buff calcite colored by included iron oxide. The habit of these crystals is shown in Figure 41 and the measurements made on them are given in the following table: Measurements on calcite from Bannock County, Figure 41 =: Form Symbol | | Measured | Calculated - - — | Quality, description ' ~~ No.| Letter Gat. | Miller | | ee e | p PEN ea Beet ae eee 2 | a | | | ° / | ° / | ° , ° , pe eee 41 MIDs A weln ce eT i eee a | 30 00 | 44 36/30 00| 44 36 2 | K-------- -1 1121 WOLY:DO0D!, oo. 22-28 52-228 eee 27 ..| 46 -. | 30 00 | 44 36 Silirces coe aya BIS STON OG 8) at dO eee eee see pis ee | 30 57| 58 16] 30 00/58 02 Ma conte Sy =—2 2241 PEG eninta ee Moan eee eae | 30 00 | 64 23 | 30 00] 63 07 Balgaeesen =—91 21gIy alee LOR ee es es ent 119 04] 58 23/19 06| 56 26 Gries fs 2°k —31 3141 | waren LOR eae ne cere = AN, 113 30] 65 30/13 54 | 64 02 The faces are dull with the characteristic appearance of calcite and do not yield very exact measurements. The associated garnet and hematite are described elsewhere. BLAINE COUNTY In Blaine County calcite is reported to occur in the ores of the Hailey (Mineral Hill) district as cleavable masses and as combs of scalenohedral crystals in the ores. 23 Charles Palache. Amer. Journ. Sci., vol. 8, p. 301, 1899. 216 BULLETIN 131, UNITED STATES NATIONAL MUSEUM hod BOISE COUNTY In Boise County calcite has been noted at a number of places. As a gangue mineral it has been noted in several mines of the Willow Creek district and it is abundant in the ore of the Friday mine.*4 The gangue in the Black Crook vein in the same district is quartz and pink calcite colored by manganese.” In the Overlook mine, Pioneerville district, calcite forms well- developed transparent colorless crystals up to 1 em. in length in a 41 43 Figs. 41-43.—41, CALCITE. CRYSTALS ASSOCIATED WITH HEMATITE AND GARNET, BANNOCK COUNTY. 42, CALCITE. OVERLOOK MINE, PIONEERVILLE DISTRICT, BOISE COUNTY. 43, CALCITE. ASSOCIATED WITH ZEOLITES IN BASALT. GLENNS FERRY, ELMORE COUNTY gold ore associated with quartz containing galena and pyrite. The forms present on the crystals, which are of the habit shown in Figure 42, are as follows (Dana notation): m(1010), a(1120), v(2131), r(1011), y(3251), and. 2(1341).78 CUSTER COUNTY In the Alder Creek district calcite occurs in both oxidized and primary ore of the contact-metamorphic copper deposits. In the primary ore it occurs both as veinlets and in vugs. It has not been 4 Waldemar Lindgren. U.S. Geol. Survey, 18th Ann. Rept., pt. 3, p. 716, 1898. 35 Tdem., p. 717. % Karl V.Shannon. Proc. U.S. Nat. Mus., vol. 53, pp. 442-443, 1920. THE MINERALS OF IDAHO Die observed in garnet rock that is clearly of porphyry derivation.” In the Bay Horse district calcite crystals have been noted lining cavities in the oxidized lead ore of the lead-silver deposits. In the Yankee Fork district calcite as a gangue mineral in the silver ores in asso- ciated with some quartz, chalcedony and opal, and is in the form of irregular areas and also as lamellar crystals of the variety described below as argentine. It is often largely replaced by quartz.’§ ELMORE COUNTY Specimens from 5 miles below Glenns Ferry in Elmore County collected by C. F. Bowen in 1911 consist of vesicular basalt, the cavities of which are lined with amber crystals of calcite up to 5 mm. in diameter overlain by two white zeolites, probably chabazite and thomsonite. The calcites are relatively simple in habit and develop- ment, as shown in the drawing, Figure 43, and the forms present are only the two rhombohedrons p(1121) and 9(2241). These gave the following angles: Measurement of calcite, Figure 43, Elmore County l Form | Symbol | Measured Calculated mers ra, | | Quality, description ear tes Pee SS No.| Letter | Gdt. | Miller ¢ | Pe ace. A, besa — | : ee | | ° / ° / ° , ° , Tadley eseess 22 +1 HOT: IP Oer-6 es ee Ter aes Pt 30 00| 44 38] 30 00 | 44 36 Dae es —2 Doat | Vieryi ZOO = n= oe eee ee | SOM OO 6739! 1630 00)) 67, 55 | | } | LEMHI COUNTY Calcite occurs at a number of places in Lemhi County. A speci- men from the Pittsburg-Idaho mine, Texas district, has been illus- trated by Umpleby.” 1 are era ae Ce Oe 58 08 | 35 46] 58 06 | 34 17 5 | new (?): REM e aog* ayes oH CO na Sie RR IAS rea Paso a7 19 26/61 31|17 49 | 62 09 Gils dos $3 | = 413 Lee ee oe Pane eae eer es 83 47] 61 31] 81 09 | 57 22 Fe}. ROL AS lt | 545 GOOGATESer Se EAL AE TA enh SALE OE Be: 63. 534/53 °37"| 63+ °32*|-62° "17 | Crystal 3, shown in figure 51 is similar to crystal 1, but without’ d(102) and with one face of B(332). This crystal gave the following measurements: Measurements of aragonite, Figure 51 Form Symbol | Measured Calculated —— | Quality, description No.| Letter Gdt. | Miller ¢g p ¢@ p ee | e: oot eee ° , ° , ° , ° , I) Gi zt 20 10 1051031 Poor; multiples: .-- 2:2) f°... stat 59 | 86 11) 58 06) 85 48 Mes Me oe 0, 24 OF Zea lui pIOXCOMONG.- setae ease ee ee 00 | 87 29 0 00} 86 41 auhtse cee bk 02 OZ Ti MeByZO0d 4 sek We aa ye 8 30} 538 38] O 00) 55 14 CN pad 210 aie es 3 Boz sa MVELVUPOORS oece sae eno eh ee 14|] 65 04] 58 06] 63 57 5 | new (?)- ah AI375| Meditim: 29: £4542 22 serene a2 36 | 61 37] 81 09} 57 22 Opec aose-.. a3 152% [sc 3 Os 5 Se ie cnn eas thee Be 4S 52 | 61 53}17 49} 62 09 In addition to the peculiarly unsymmetrical development there will be noted in the angle tables a marked and rather constant devia- tion of the measured from the theoretical angles. This may in part be due to the difficulty of orienting crystals of this habit for measure- ment on the goniometer and to the imperfect character of the crys- tals, but the consistent lack of agreement suggests rather a mineral 940 BULLETIN 131, UNITED STATES NATIONAL MUSEUM of slightly different axial ratios. That the present mineral is ara- gonite and not another carbonate of the same group was established by qualitative tests, which proved the absence of barium, strontium, and lead. The faces measured are above referred to the nearest established form where possible. The previously undescribed forms here given are of doubtful authenticity. More material from the locality would be necessary to completely elucidate the peculiarities of this aragonite. CUSTER COUNTY Aragonite is found in the oxidized ore from the Beardsley mine- Bayhorse district. It forms sheaves of acicular crystals and coarse fibers associated with calcite. Some of the aragonite is associated with psilomelane, which occasionally has replaced it, giving pseudo- morphous rosettes of psilomelane after aragonite. LEMHI COUNTY Aragonite occurs in the ore of the Pittsburg-Idaho mine, Texas district, as branching plant-like forms which show no measurable crystals. A specimen of this material is illustrated by Umpleby.™ CERUSITE (281) Lead carbonate, PbCQO3. Orthorhombic. Cerusite is second only to galena in importance as an ore mineral in the argentiferous lead ores of Idaho. It forms from the galena under the action of percolating ground waters and the amount of the ore which has been thus altered to cerusite varies greatly in different ‘districts. Vast quantities of carbonate ores were mined from the Coeur d’Alene district, but these ores are largely exhausted in this district, but in the mining districts of the central and southern parts of the State cerusite is still more important than galena. The oxidized ores are known to miners and operators of mines in the State as “carbonate ores.’’ They vary greatly in appearance. When pure the cerusite is white or gray with a greasy luster, but much of the ore mined is greatly contaminated with silica and oxides of iron and manganese and varies through various shades of gray and brown to yellow or black. The appearance is often earthy and the only index to the lead content is the high specific gravity. In addi- tion to the iron and manganese oxides, there often occur, with the cerusite, yellow ocherous lead antimonate, bindheimite, and blue and green carbonates of copper, azurite, and malachite. In cavities in the massive cerusite there very frequently occur crystals, often very brilliant in luster and colorless or white. The cerusite crystals present a great variety of form and most of them are twinned in groups. These are the “crystallized lead” of the miners $1J.B Umpleby. U.S. Geol. Survey, Bull. 528, pl. 10, 1913. THE MINERALS OF IDAHO 241 who never refer to the crystals as carbonate. Although it is mani- festly impossible to list all of the occurrences of so widely distributed a mineral, a number of those which have been brought to my attention are mentioned below. A number of crystals were measured and, although they present no especial peculiarities, the measurements are reproduced with figures of many of the crystals merely to record the habits and developments of cerusite from the several localities, since crystals from the State have never before been described. An exhaustive treatment of the crystallography of the cerusite, especially of the Coeur d’ Alene district, would doubtless de- velop many facts of interest and might profitably be undertaken were the material available. In the present work only poor material has been at hand, principally, the crystals being accidentally included in ran- dom ore samples. BEAR LAKE COUNTY In the St. Charles district in the Bear River Range cerusite of dark color surrounds crys- talline aggregates of galena in (> a gangue of iron-stained lime- e | stone with some siderite.” \ | ie \ y 4 BLAINE COUNTY \ | eee \ L. ae C it : e | p of eee erusite is common in the Yee eee surface ores of almost every pre district of this county. It was Fie. 52—Cerusire. SIMPLE PRISMATIC CRYSTAL ELON- formerly common in the Hailey ABDOSTHEe Atm, Gotnex Glow anv, Wan region as massive ore and occa- sionally in groups of reticulated crystals. In the Era district cerusite is associated in the oxidized ores with small amounts of smith- sonite, cerargyrite, and proustite.“¢ In the Birch Creek mine, Birch Creek district, the cerusite, which has a peculiar grayish-black color thought to be due to the manganese it contains, is associated with smithsonite, galena, anglesite, and a little wulfenite.” 62 R. W. Richards. U.S. Geol. Survey, Bull. 470, p. 182, 1911. 62a J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 121, 1917. 63 Idem, p. 119. 242 BULLETIN 131, UNITED STATES NATIONAL MUSEUM A specimen labeled as from the croppings of the Golden Glow mine, Warm Springs district, consists of minute simple colorless cerusite crystals having the habit shown in the drawing, Figure 52, on spongy limonite. The measurements obtained on crystals from this specimen are given in the following table: Measurements of cerusite (fig. 52) from Golden Glow mine Form | Symbol Measured Calculated | | Quality, description Se SSS No.| Letter | Gdt. | Miller | ¢ P e e eee | = | ° , ° , ° , o Liters Weston 10) lee xcellontses 2 20c. =. eateries eae 58 44|90 00| 58 37] 90 00 Quine eee ae / 03 130 Mery DOODminute 2. es 2 eee 28 16 | 90 00} 28 39 | 90 00 ih Gaetan | 0% 012 Very: good; small: = sabe eer |; 0 00; 19 52} 0 00} 19 52 ZN Uy fae ea } 02 021 Ee Xcollent ey ese ee ee see | 0 00} 55 22) O 00] 55 20 DuyiVosssees 03 031 Poor; Narr0wee22 = 22-5 See ee | 0 00} 66 13) O 00) 65 15 Cv ikpeoee | od lll ery poorpminutels2. eee | DS) 52) (NODLe ot) rose rodn| eoaignl a A second specimen labeled as from Blaine County, but without more detailed locality, was probably from the Independence mine. It contained small cerusite crystals in cavities in galena. These were prisms elongated in the vertical direction and all twinned on the unit prism m(110), some of them greatly resembling quartz crystals as shown in Figure 54. The twinning is clearly shown in the crystals of the type shown in Figure 53, one of which was measured. This measured crystal gave the angles of the following table, each of the three crystals making up the twin being considered separately, the orientations being as shown in the drawing, Figure 53. The angles are for the normal position used for cerusite. Measurements of twinned cerusite from Blaine County, Figure 53. Form Symbol Measured Calculated aaa a rel Quality, description SSS SSS ee No.| Letter QGdt. Miller e p g p ° / ° , ° , ° ’ eae Sse co0 100 ELV DOOR Sco ee ee ee 90 26] 90 00/90 00/90 00 Cl Rit eee oO LO ase es OE Pe aT ee 61 10{| 90 00); 58 37/90 00 Diy woseaee Sy Qco 010 Goodie’ -prvmerng hs Le er eee 0 18/90 00; O 00} 90 00 APN gyi ee 1 111 Very good). 22 ee hei eee 58 40 | 54 28] 58 37) 54 14 Bema co 110 edium 2. ees ae ee eee en 60 44| 90 00); 58 37/90 00 Be Onst. Oco 010 Wait = 363535 eee Ea ae 1 32/90 00; 0 00} 90 00 Ti Dips 1 lll MOLY? DOOR Sams aoe e ee ent ues Clee 60 12| 54 47] 58 37)| 54 14 Be Ae ieee seem | a rel ee O00 oe saat Be Tie UE ky 26) | 90) 00/) 54 ee bela eeesce al ige ono co ALOT ie | eee GO een eC ae ee ane 58 36 | 90 001 58 37 | 90 10 D939 = eee Qco 010 Pooriclt .so3s ub a a 0 11/90 00}; 0 00} 90 00 iB ES thy sy pen ies 1 lll IE XCOUente gee: 223 erent nt yee 58 30) 54 06) 58 37 | 54 14 The three individuals of the twin bear the following angular rela- tions to each other. ° / Vo (=Vo of erystal 1) A (v1)o(=Vo of erystal 2)=120 34 (v1) o (Vo of crystal 2) A (v2)o(=vo of crystal 3)=122 14 (V2)o(=vo of crystal 3) A (vo) (=Vvo of crystal 1)=117 12 THE MINERALS OF IDAHO 243 The interpretation of such a twin is difficult, for example the face indicated on the figure by the letter 6? may in fact be an extension of m! and similar alternatives exist for all of the prismatic faces. Time was not available for further study of the results on this crystal, but it is possible that a different interpretation might be found Fias. 53-54.—53, CERUSITE. INDEPENDENCE MINE, BLAINE COUNTY. VERTICALLY ELONGATED TWIN ON m(110). 54, CERUSITE. SAME. TWIN SIMULATING QUARTZ CRYSTAL preferable. The results as given, identify the forms and establish the twinning plane as m(110). They also serve to explain the hexagonal aspect of the examples like that illustrated in Figure 54, which is another case of the same twinning but without reentrant angles. 944 BULLETIN 131, UNITED STATES NATIONAL MUSEUM BOISE COUNTY Cerusite is not rare in the oxidized gold ores of the Boise County gold mining districts. Much of the primary ore of the gold-bearing veins contains galena along with other sulphides, and in some cases the galena is highly auriferous. Where these veins are weathered the galena has been converted to cerusite, which is more or less mixed with limonite, and is frequently rich in spongy gold. It has been especially mentioned from the Wolf Creek area and from the Morning Star vein at Grimes Pass. Specimens from Hall Bros. property, Deadwood district, contain small colorless twinned cerusite crystals on lmonite- stained rock and small gray to black crystals associated with pyromorphite on rusty quartz. CUSTER COUNTY The carbonate is the most important ore of lead in Custer County, where it is mostly in earthy masses stained by iron and manganese oxides or in Fig. 55.—CERUSITE. SIMPLE PRISMATIC CRYSTAL ELON- the granular form known as GATED ON THE @ AXIS. RED BIRD MINE, BAYHORSE ,, ” PR aiaeR aC caren iG Gon sand carbonate.” The latter forms friable coarse to fine sandy masses and results from the shrinkage due to decrease in volume of the ore during oxidation. The carbonate is especially prominent in the deposits of the Bayhorse district where it forms the ore of the Beardsley, Excelsior, Pacific, River View, Cave, and other mines.** This is mainly in the form of the friable incoherent material heavily impregnated with manganese and iron oxides, known as sand carbonate. Specimens which have been examined from the Red Bird mine consist of glassy masses of pure white cerusite embedded in limonite or surrounding residual cores of galena, forming high-grade ore. Some of the ore masses contain vugs which are lined with calcite and cerusite crystals. One simple prismatic crystal from this mine which was measured is shown in the drawing, Figure 55. This gave the following measurements. $i J. B. Umpleby. U.S. Geol. Survey, Bull. 539, pp. 66-76, 1913. THE MINERALS OF IDAHO 245 Measurements of cerusite, Figure 55, Red Bird inine, normal position Form | Symbol Measured | Calculated 1 Quality, description — - ee No. Letter | Gdt. | Miller rr) p ¢ p Al) Doses osash Oo | 010 Bxcellontiv-t=t ae No.| Letter Gdt. | Miller ° p g p ° , ° , ° , ° , Potente 0 010 00 | 90 00} O 00}; 90 00 Ba eGeen 32 0 | 100 ai oh 00 | 90 00} 90 00] 90 00 Sib ae ee oO 110 45 | 90 00/| 58 37 | 90 00 Behe kaee eS co3 130 se 45 | 90 00 | 28 39 | 90 00 Bo Besse bo 01g 012 DWiCLVAROOG ween ee geet tek TR Se 0 00/19 52);:0 00) 19 52 Gaintst = ete 05 O51 MGM ee are Ee | O 00}; 74 42) O 00| 74 32 Te ier Tite pot Weise elects tip eet tie. SE t 58 36 | 54 12| 58 37| 54 14 8 | ee es 12 121s (2ece G2 ea Se a 39 24/61 49] 39 20) 61 51 9 | Gostons = 13 | 131 COC ea Ee Se | 28 32 | 67 56 | 28 39 | 67 58 | A twinned crystal which was measured is shown in the drawing, Figure 57. The relation between the two individuals of the twin is shown by the following angular relations: V.. for crystal 1=368°38’ v, Vo for crystal 2=245°50’ (v1). petede= 207? 14’—90°=217° 14’=v angle for the twinning plane, yg for which is then 28° 36’ showing the twinning plane to be r (130) calculated g for which is 28°39’. Of all of the twinned cerusite crystals from Idaho examined during the present work, those of this specimen are the only ones in which the twinning plane is other than m(110). A specimen from the bottom of the stope between the 300 and 400 levels, east vein, Pittsburg-Idaho mine is unusual in that it consists of pure compact gray massive cerusite containing abundant disseminated crystals of pyrite. Cerusite containing some iron oxide and residual galena from the Latest Out mine is black in color. OWYHEE COUNTY The rich oxidized ores formerly mined in the South Mountain dis- trict owed their value largely to cerusite as shown by old specimens 7J.B. Umpleby. U.S. Geol. Survey, Bull. 528, pp. 99-1069, 1913. 248 BULLETIN 131, UNITED STATES NATIONAL MUSEUM preserved in the National Museum. Ore from the Golconda mine consists of greasy massive white cerusite containing some minute white crystals in cavities. This cerusite is associated with a little minium and bindheimite as an alteration product of coarse galena. Specimens from the Washington mine show massive cerusite associated with coarse galena in a limonite-stained rock and a specimen from the Rocksyfellow mine shows earthy cerusite with anglesite and bind- heimite coating coarse cleavable galena. (Cat. No. 14882, U.S.N.M.) Fias. 56-57.—56, PRISMATIC CRYSTAL. PiTTspuRG-IDAHO MINE, LEMHI COUNTY. 57, SIMILAR CRYSTALS TWINNED ON 7(130) SHOSHONE COUNTY In Shoshone County cerusite has been the most abundant and characteristic mineral of the oxidized ores, Great bodies of carbonate ore have been mined from the Morning, You Like, Mammoth, Stan- dard, Tiger, Poorman, Hercules, Bunker Mill, Last Chance, Sullivan, Stemwinder, Tyler, Caledonia, Sierra Nevada, and other mines. THE MINERALS OF IDAHO 249 The ore of the oxidized zone is normally a relatively soft aggregate of massive cerusite, fragments of quartzite, and ocherous to compact limonite, with or without manganese oxides. There is usually more or less bindheimite mixed with the cerusite and rarely some azurite, malachite, linarite, plattnerite, pyromorphite, or anglesite. Cavities in the massive ore are lined with crystals of cerusite often of great delicacy and beauty. The crystallized cerusite is exceedingly variable in form and appearance. Single simple isolated crystals are rare, the mineral tending to form complex twinned aggregates. The carbonate ores are now largely exhausted and fine specimens of crystal- lized cerusite are rare although they are occasionally found in some of the newer mines or prospects or in lease workings in the old stopes of the large mines. Certainly no other district in North America and probably none in the world has exceeded this region in the production of fine speci- mens of cerusite, both in quality and number, yet these are now practically unobtainable. They have all been lost or destroyed and practically none have found their way into the large collections or museums of the country and their existence has not, heretofore, been mentioned in the literature. In the days when carbonate ores were being mined almost every miner had a private cabinet filled with choice specimens in a corner of his home and many gorgeous crystalli- zations Were on view in cigar cases, in hotels, boarding houses, and barrooms; and these could, in most cases, be had for the asking. Of late years, however, they have largely been lost to sight. The first lead-silver ores mined were the ones which contained the greatest amount of carbonate and furnished the finest crystallized cerusite—in the years from 1882 to 1890. Such ores were still mined commonly up to 1900 and in 1901 the Hercules ore body began pro- ducing specimens of truly wonderful character. There was for sev- eral years, at the mouth of the No. 3 Hercules tunnel, a grotto walled up with logs and provided with shelves on all sides where specimens of crystallized cerusite, native silver, and pyromorphite weighing from 10 to 200 pounds each were placed and exhibited to visitors by candlelight. When this receptacle became crowded, and specimens were constantly being added, a quantity would be cleared out and thrown in powder boxes in the head house for anyone who wanted them to carry them away. The showier pieces, and the ones most esteemed locally, were the pure columnar masses or brilliant long-fibrous ageregates and the solid masses of reticulated plates. The latter are honeycomb-like masses of thin plates flattened parallel to 6(010) and twinned on m(110) giving triangular intersections. Specimens show- ing crusts of small articulate crystals on gangue which would be highly acceptable to a mineralogist were hot highly regarded by the miners. The Hercules mine continued to furnish good cerusites for 54347—26}—_17 250 BULLETIN 131, UNITED STATES NATIONAL MUSEUM ten years after the other big mines—the Standard-Mammoth, Morn- ing (including You Like), Last Chance, and the several mines of the Bunker Hill group—had begun deep workings in sulphide ores. Although the chief operations by the big mining companies were deep developments, leases granted in the old surface: tunnels and stopes continued to produce carbonate ore and to furnish some good ceru- site crystals intermittently down to the close of the war in 1918. Fine cerusite was produced by the McBride lease on the Tyler mine Fics. 58-59.—58, CERUSITE; BUTTERFLY TWIN. SIERRA NEVADA MINE, SHOSHONE COUNTY. 59, CERU= SITE. TWINNED ON m(110). CALEDONIA MINE, WARDNER, SHOSHONE COUNTY in 1912-1914 and during this period the Last Chance was mining above the No. 1 level and encountered some well crystallized mate- rial. The Sierra Nevada, on Deadwood Gulch, an old flat vein in which the ore, mined out in the early days of the district, was all oxidized, was reopened about this time by Drew Peeples, who re- worked some of the old rejected material in the stopes and mined out some pillars of rich ore. Some exceedingly fine crystallized cerusite was found during these operations. In what was called the ‘square THE MINERALS OF IDAHO 251 set stope” were found butterfly contact twins of colorless trans- parent cerusite up to 3 inches in greatest diameter. The illustration, Figure 58, is based on measurements made on one of the smaller crystals of this lot. Brillant crusts of small twinned crystals rang- ing from colorless to gray and black or amber were common. The Mammoth mine at Mace was reopened by a lease through the No. 2 Mammoth tunnel in 1913 and some cerusite ore obtained which contained some cerusite crystals as well as fine specimens of plattnerite and pyromorphite. These were aggregates of tabular crystals twinned on m(110). One such group, which is typical of much of the twinned cerusite of this and other mines, is shown in Figure 62. The main crystal of this group gave the following angles: Measurements of cerusite from Mammoth mine Form Symbol Measured Calculated mec Quality, description Simei Ae, Letter | Gdt. | Miller Y p © p | | ° , ° , ° / ° , ICs ee Oo | 001 WET Vs ROO coats = we A Ne eee O00) | Bares 0 00 Die ot Vee) OLDS ye eee Ten ee ee a A erie Seer) Q 00; 90 00 0 00} 90 00 ease 2k co0 100s eS Lp i ae as Se A Se $0 03] 90 00]; S60 00! 90 00 Ae \ aD eed oO 110 IROOLSHALTOW Be sae ee a eee eee 58 39 | 90 00] 58 3790 00 Oe Breet co3 130 NOEVAS O00 8 aie ee ee i nea 8 28 36 | 90 00] 28 39 90 00 Gales te eee 0% OL2 ihe e285 OSS A Ee ee bee 0 08,19 43 0 00; 19 62 diel eee oe eee O1 O11 NCC EN fa) 019 [0 etapa eat, ey eee ee ee 0 03) 85 55}. '0 00) 385 52 Sales ieee We 02 021 TET Try eee eae se 0 03 | 55 30 0 00; 55 20 Obie ees 1 111 Wierys 2000 ee an cee et Ue Bet to 58 37) 54 12] 58 37] 54 14 This group illustrates the twinning which produces the large masses of reticulated plates. Much of the galena ore at the base of the oxi- dized zone contains cavities, from the removal of masses of siderite gangue which have cerusite crystals, usually water clear and colorless, implanted upon the unaltered sulphide. Some of these are simple and are difficult to distinguish from anglesite crystals which occur in the same manner. A relatively simple and untwinned crystal from a specimen of galena from the Last Chance mine, which is illustrated in the drawing, Figure 60, gave the following measurements: Measurements of cerusite, Last Chance mine, Figure 60, normal position Form Symbol Measured Calculated Saal aa aaaaInT SE RRERaaSaa Quality, description = No.| Letter Gdt. Miller g p 9 p ° ‘ ° ‘ ° ‘ ° ‘ ieee ate | 0 001 Bex cellem tsi vs ite ne Mite © ee oe es ae ena ee 0-:00"|- 222-22 0 00 PA Oe ee ta Ooo 010 WiGrVi 200d essen sae ea 0 00/90 01} 0 00} 90 00 Se ras ee co0 100 Mixcelleni peers ee ie aa ger 90 00/90 00] 90 00} 90 00 MPa Steen = 003 130 Goode ee eh A OE ae ND 28 44/90 00} 28 39 | 90 00 Dp 0% Ol een es CO ee Beek Sard a Ai 0 00; 19 59; O 00]19 52 6 k pssst eaial 01 O11 CRIP a SA ARES RANE Aen ns) NST AES 0 00; 35 50] O 00} 35 52 dNete ts tok 02 021 Excellent = Lars oer seal ee 0.00°|55 22 0 00} 55 20 tape oe a 03 031 Wetiy ene ere ee ORR Ae aed MARINE SA 0 00; 65 28} O 00} 65 15 Casicek Le 04 O40 "|S 3 AG Sse ke es te ELE Eee 0 00} 71 Ol 0 00); 70 55 BOM iacne-o =. 05 OO azo Oe ee EE MEAT ANSS NEN BOERS Ex 0 00| 74 33} O 00} 74 32 BP bare 352 £2 06 061 ih (Gob ta er teen Ae On a Re es Se ea 0 00| 76 24 0 00/77 O1 Bor eidass ee 1440 102 FR OOU Seat VASES REV N BAR ETON AS. 90 00} 30 36) 90 00) 30 39 Satine = sas: 1 111 Wier DOO Ns teat Nek Ue eee gees 58 46 | 54 18] 58 37 | 54 14 952, BULLETIN 131, UNITED STATES NATIONAL MUSEUM A twinned group of crystals resting in a cavity in galena from the Last Chance mine is typical of many crystallized twinned groups from the district and is consequently illustrated as an example in Fics. 60-61.—60, CERUSITE. SQUARISH SIMPLE CRYSTAL FROM CAVITY IN GALENA. LAST CHANCE MINE, WARDNER, SHOSHONE COUNTY. 61, CERUSITE. CHARACTERISTIC GROUP TWINNED ON m(110). FROM CAVITY IN GALENA. LAST CHANCE MINE, SHOSHONE COUNTY the drawing, Figure 61. The averages of the angles measured on the several crystals of this group, are as given in the following table: Angles of crystal of cerusite, Figure 61, Last Chance mine, Normal position \ Form Symbol Measured Calculated Quality, description No.| Letter Gdt. Miller g Cache chee 0 OOM) s|Excellontre: ay. 4 <6. he yh el ed Dae 0c O10}. ee = 6 a A So i NO at ALP cob eas 0 00 eae co0 TOOr Gee OG ap er ee eee nee ere ere ee 90 07 : 00 | 90 00} 90 00 Tawa «03 130 ere | See Geen oedema ee 28 24/90 00! 28 39/90 00 1 2 3 40h biter ¥_ oO Ope pees = GOES SER Sees Ree Dee Ee 58 36 | 90 00] 58 37 | 90 00 5 Golito= cose 0% OLZP | peaee COL See Barat sents cre) eed 0 00/19 57} 0 00}; 19 52 fg\ ese ee 01 Quy Soe: Goeth ee See 0 00/35 44] 0 00} 35 52 Sas cee 02 215 yn) Sees Gout aha ee eR ee aes 0 00/55 15}] 0 00} 55 20 On aysee se 440 Ee eee COs Re eae ee oe 90 00] 30 37/90 00} 30 39 10 54 16] 58 37 | 54 14 Dass | 1 PLM eyes dota: eee Te ce ee ae 58 42 The McBride-Morrell lease on the Tyler upper workings in 1912 encountered a small body of rich carbonate ore in which much fine crystalline cerusite appeared in places, mainly in the usual forms. These included coarse heavy columnar masses of brilliantly lustrous white material embedded in an ocherous impure manganese oxide; reticulated masses of platy crystals; and fibrous forms, often irides- THE MINERALS OF IDAHO 253 cent and steel-gray in color with metallic luster from thin outer coatings of manganese oxide. Other pure white masses of crystals were crusted with dendritic wires and moss-like masses of native silver. Some specimens, yellow from a thin outer coating of limonite, were made up of small model per- fect six-rayed penetration twins. Workings of the Bunker Hill Co., penetrating the oxidized portion of the Tyler vein from below about this time disclosed fine cerusite, par- ticularly in the Barney stope. Two stalactitic masses having a large botryoidal form were taken from this stope in 1915. These weighed nearly 100 pounds, were coated out- side with limonite, but inside they consisted of pure white cerusite of fibrous structure. These were em- bedded in the concrete of the bridge crossing the flume on McKinley Ave- nue in the town of Kellogg. A large specimen of fibrous cerusite from this stope which laid for some years on the floor of a storeroom of the old Bunker Hill office at Kellogg con- tained included unoxidized masses of resinous brown sphalerite. The Caledonia mine, opened through a shaft to the 300 and 500 foot levels, west of Wardner and on the east of Deadwood Gulch, in 1910 developed a rich body of carbonate ore and produced much _ cerusite prior to 1915 and yielded many excellent specimens, but much of the cerusite was massive and the yield of fine specimens was much smaller, in proportion, than in some Fic. 62—Cerusite. CuARAcTERIstIC GROUP other mines of the district. Some Nike Mobic cage? att et small clear glassy crystals were al- ways to be obtained and a few large glassy twins in considerable aggregates were obtained embedded in clayey gouge. The usual columnar and “taffy-like” fibrous white specimens were obtained, sometimes colored green by an outer layer of malachite. Some small colorless to slightly smoky crystals obtained from cavities 254 BULLETIN 181, UNITED STATES NATIONAL MUSEUM in leached quartz were mainly penetration and contact twins. One of these furnished the measurements which are the basis for the drawing, Figure 59. Several of the various mines of the Bunker Hill group, other than the Tyler, namely the Stemwinder, Sullivan, and others, have produced large amounts of carbonate ore in former years in which were found cerusite crystals and crystalline masses of the types already described and lease workings in these mines have obtained good material in recent years. The Senator-Stewart mine had no very great quantities of oxidized ore and in such as they had pyromorphite was perhaps more prom- inent than cerusite, but some good specimens of crystallized cer- usite were at times found in the upper tunnels, above the ore rail- way on the high mountain west of Deadwood Gulch. A small mine, the Hypotheek, recently opened in French Gulch, 3 miles south of Kingston, has an unusually deeply oxidized ore body and has produced some very fine cerusite specimens, although the anglesite from this mine is still finer, as noted elsewhere. The usual forms of crystallized cerusite occurred in this mine, varying from colorless to pink and through various shades of gray to black. This black cerusite, which was noted at this and other mines of the district, was especially examined on a specimen from the Hypotheek mine to determine the cause of the black color, which has been vari- ously explained as due to included unoxidized galena, manganese oxide, etc. The material gives a gray powder when finely ground. It dissolves in hot dilute nitric acid completely and the solution does not react for manganese except very faintly by the most delicate permanganate test nor does it contain any sulphur. The solution of the mineral in hydrochloric acid does not yield any hydrogen sulphide nor does it contain any iron. The mineral is not decolorized on heating nor yield any sublimate in the closed tube. These negative results show that the black color is not due to manganese, iron, lead sulphide, or organic matter. It seems possible that the color may be due to a small amount of microscopic disseminated lead dioxide, plattnerite, included in the cerusite. The most abundant crystals of cerusite from the Hypotheek mine were globular masses resembling a flattened cluster of grapes, pearly white in color, with a silky luster. These specimens, which were found in considerable numbers, embedded in soft limonite, were characteristic of the mine and differed from any specimens from elsewhere in the district. The carbonate, in good specimens, has been reported from numer- ous mines on Pine Creek and specimens have been seen from the High- land Chief, Carbonate, Northern Light, and Lookout Mountain. The latter property, located on the high mountain west of the forks of Pine Creek, has been the most recent source for crystallized cerusite THE MINERALS OF IDAHO 255 specimens. The management has, within recent years, shown a very gratifying interest in having the specimens preserved and has sent a number of lots to the National Museum, so that more crystals have been available for study from this mine than from all the rest of the Coeur d’ Alene region during the preparation of this bulletin. As a consequence an unusual number of crystals from this mine have been measured and the various habits encountered are illustrated in the drawings, Figures 63 to 69, inclusive. The specimens have come from the oxidized portion of the vein which intersects the quartzite EQN | ie er | Hh WL Pe hs re 63 f 64 Fics. 63-64.—63, CERUSITE. SIMPLE PRISMATIC CRYSTAL. DRAWN WITH @ AXIS VERTICAL. LOOKOUT MOUNTAIN MINE, PINE CREEK, SHOSHONE COUNTY. 64, CERUSITE. SIMPLE DARK-COLORED CRYSTAL DRAWN WITH @ AXIS VERTICAL. LOOKOUT MOUNTAIN MINE of the middle member of the Prichard formation. The minerals as- sociated with the cerusite, including linarite, leadhillite, caledonite, bindheimite, and pyromorphite are described in their appropriate place in this report. The crystals vary from 1 mm. to 5 cm. in greatest diameter. They are for the most part colorless, but vary through amber and various tones of gray to the black material like that mentioned from the Hypotheek mine. The measured crystals may be described individually to show the range in crystal habit shown by the material which is more or less typical for the district. 256 BULLETIN 131, UNITED STATES NATIONAL MUSEUM The first type which is well shown in the illustration, figure 63, is prismatic by elongation on the a axis, the usual elongation for cerusite, and they are attached by one end of the elongation. The crystals are minute and line cavities in massive impure cerusite which contains some admixed iron oxides, and malachite. The crys- tals are not twinned and they do not look like cerusite. In order to give a clearer idea of the habit and appearance of the crystals they are shown in the drawing, as they were measured, with the elongation vertical. The angles measured are stated for this orientation in the following table. Measurements of cerusite, Lookout mine, Figure 68, a axis vertical Form Symbol Measured Calculated Quality, description Se No.| Letter Gat. | Miller e p e p 1 ° t ° , ° , ° Lbs eee 2 0 001 Goods. oes Se re a ooe eee 90 43} 90 00} 90 00} 90 00 Dilg@aecte 0) TOO Hes Gs. asi ihre ee ener La oe GOO a ects 0 00 arose 02 010 WSCA! AES aie ee Sea eee 0 00; 90 00; 0 00; 90 00 Ae 1a © 110 Hxcollente-s2. ates a ese 0 09} 31 26; O 00) 31 23 Oia seee eee 3 SO Yar | eee GO a eee CS eee 0 09] 61 23} O 00/61 21 Gate ae 02 021 Raine Se tel Sc ws ees eee ee aes | 34 41 | 90 00 | 34 40; 90 00 a0 ee 03 (15) el ae COC Ze ee Rs a ee | 24 47|90 00 | 24 45); 90 00 Snlkyeesseee= 140 102 Mxcellent=.-\—- 25. Sa ee eee | 90 01) 59 40; 90 0O| 59 21 OF iz) seers 1 111 ery 200022 sie Stile er eee ee | 54 47 | 46 22 | 54 08 | 46 09 The second type of cerusite, illustrated in Figure 64, is relatively simple in development and occurs as small smoky gray crystals resting on leached quartz. These are in part simple and in part rayed twins and attached to them in parallel position are later brilliant colorless and more highly modified crystals. The simple crystals all have the habit shown in Figure 64, this crystal, like the last, being measured and drawn with the a@ axis vertical in order to better show its development. The angles measured, stated in the abnormal position as drawn, are given in the next table. Measurements of cerusite, Lookout mine, Figure 64, a axis vertical | Form Symbol | Measured | Calculated an Quality, description | No.| Letter | Gat. | Miller — ° Pr |e @ p | | ° , ° , ° , ° 1 0 001 | Wery poormarrow=—- 24 51 | 90 00) 90 00/90 00 2 Oo 010 Maile. es Pes ea ep SEES 06 | 90 00, 0 00) 90 00 3 © 110 i xcellent avs. ane eee 10 | 31 53.) 0 00} 31 .23 4 0% 012 Ope ORE eh Se 03 | 90 00} 70 08} 90 00 5 1 lll Woery poor va@ull: 22 a2 ee aes ee 47 | 46 22 | 54 08) 46 09 The more highly modified colorless prismatic crystals which appear as a later growth attached in parallel position to the preceding are THE MINERALS OF IDAHO 257 illustrated in normal position in Figure 65. These are of small size and appear both as simple crystals and as contact and penetration 65 Fics. 65-66.—65, CERUSITE. STOUT, COLORLESS CRYSTAL. LOOKOUT MOUNTAIN MINE. 66, CERUSITE. CRYSTAL MODERATELY ELONGATED ON @ AXIS SHOWING ORDINARY FORMS. LOOKOUT MOUNTAIN MINE twins on m(110). The measurements obtained on the one illustrated in the drawing are given in the next table. Measurements of cerusite, Lookout mine, Figure 65, normal posiiton Form Symbol Measured Calculated Quality, description Sa ait i ay No.| Letter Gdt. Miller ¢ | 0 9 p | ° , | ° , ° , ° ‘ Bole ce eae [gt 001 Wery, poor, narrow 22 e. eee \eaeeeene 90s O0nleseres.- 90 00 i Dek. arse | 0a 010 Mervigoods | i231) ost a doses, 8 | 0 00 | 90 00 | 0 00} 90 00 REO eens | 00 Watfioy PE Kcallont es oes ounce ee eee 90 00) 90 00} 90 00/90 00 Anti 2s st © 110 d | 00 | 58 37 | 90 00 ON eieoce = aoe | o3 130 00 | 28 39/90 00 6st P=- -| 1 111 22 | 58 37] 54 14 7a oC peperiontarteas | % 112 48 | 58 37 | 34 46 Oy IB eesn bk I» 32 121 55 | 39 20] 61 51 DN heaaan a2 | 01 O11 56 | 0 00] 35 52 Ut) Se Se | 0% 012 51| 0 00/19 52 54347—267 258 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Other specimens show simple, and more frequently, twinned color- less cerusite crystals up to 1 cm. in length, forming crusts on bleached quartzite. These are moderately elongated on the a axis. The simple crystals have the same habits as those making up the pene- tration twins. One of the simplest of these is shown in the drawing, Figure 66, and the angles measured on it are given, for normal posi- tion, in the following table: Measurements of cerusite, Lookout mine, Figure 66, normal position Form Symbol Measured Calculated Quality, description =e No.| Letter Gdt. Miller ¢ p ¢e p ° , ° , ° , ° , 1 RC 2Oe es 0 001 Goode =2 2 ae. ik a ee ire ee en 90 00j_-. 00) 90 00 Dios se Oco 010 Mery Poodis22 52 See ee ee 0 00; 90 00} 0 00); 90 00 Si pakeaw aes co0 100 Mxcellentus 2. ws Se ee ee ees 90 14/90 00/90 00) $0 00 SG ntibes eee co 110 OO See PT RIE Ae 58 30] 90 00] 58 37 | 90 00 Oulyneeee ts co3 130 EX COMeN Gs ae eT See 28 40/90 00} 28 39] 90 00 GaipKes es 01 011 GOoogre sas eee ee ene ee 0 05 | 38 32 0 00} 35 52 1a eee 03/9 032 Very. poor, striated =2)3-2 022s ee 0 05| 49 49] O 00} 47 19 Selanne 140 102 Poorsifaint 2 ee See eS 90 23 | 30 47/90 00! 30 39 Niga)gae eee 1 lil IM xcellont:s:- 2 ele ae ae 58 52) 54 18] 58 37] 54 14 A erystal from this lot of specimens similar to the last, but some- what more modified, with the additional forms 0(112), x(012), 7(021), 2(041), and 7(130), is shown in the next drawing, Figure 67. The angles for this crystal are as given in the following table, the elonga- tion (a axis) again being made vertical: Measurements of cerusite, Lookout mine, Figure 67, a axis vertical a ae Form Symbol Measured Calculated 7 Quality, description No.| Letter Gdt. Miller ¢g p ¢ p | ° / ° f: ° , ° , 0 001 00 | 90 00 | 90 00 Qco 010 00} 0 00| 90 00 co0 100 O27 ere 0 00 co 110 24; 0 00| 31 23 003 130 24 0 00); 61 21 0% 012 00 | 70 08 | 90 00 ol O11 00 | 54 08 | 90 00 02 021 00 | 34 40) 90 00 04 041 00 | 19 05/90 00 06 061 00 | 12 59/90 00 140 102 15 | 90 00] 59 21 1 lll 06 | 54 08 | 46 09 % 112 52 | 70 08 | 60 52 A third crystal of this series similar in most respects to the last has the additional forms w(211) and s(121), as shown in the drawing, Figure 68. This crystal contains the largest number of forms found on any cerusite crystal measured. The habit of the crystals is thus not marked by any great complexity and no unusual forms are present. The agreement between the measured and calculated angles is so close that there can be no reasonable question as to the THE MINERALS OF IDAHO. 259 correctness of the orientation and the identification of the forms. Many of the crystals are not simple individuals, but are made up of a large number of units in parallel position, but these are so exactly Fics. 67-68.—CERUSITE. UNTWINNED COLORLESS CRYSTALS. LOOKOUT MOUNTAIN MIN parallel that all of the faces, reflecting simultaneously, give a single perfectly sharp signal, permitting very exact measurements. The angles of the crystal of Figure 68, in normal position, are as follows: Measurements of cerusite, Lookout mine, Figure 68, normal position Form Symbol Measured Calculated SP Quality, description a No.| Letter Gat. Miller g p yg p ° , ° , ° ie ° , Pewee 0 100 FE CBILON bse eee en rca ee 90 06; 90 00} 90 00; 80 00 Zt BE ae Qco 010 Ver c00ds! 3) pee ees beeus 0 00/90 00 0 00); 90 00 OHMS no oo HOF ses OE ae ee I RR a ela ae 58 36 | 90 00); 58 37] 90 00 ey ee 003 L3Oigs lessee AO x 73 ee yy fs bee ate 28 388 | S90 00} 28 39] 90 00 MA Cet hoe ot 0% 012 IWEGCIUMIE Str eaten. te sac eee 0 00; 19 38 0 00; 19 52 6h s-2.- 3 OL ORL a]. -6 Os dsersass 2h 3 ake e. gare ei u 0 00] 385 44 0 00 | 35 52 Nulei sot 02 O21 rata COB ee re ee Sk oe 0°00 |'55 15 0 CO | 55 20 Baze wae hae 04 G4 pA} 22 GOLt Een tA OAS a gee 0 00 | 70 04 0 00/70 55 Sale sets ol 140 102 Mery 200d: 25 oe en ee ss 89 40] 30 28}; 90 00} 30 39 OI es 1 lll WO xcellen toon cess eee eos) oer 64 1 158 3701054) 14 UNS (1 Se % ye oh GOSS Saws Sere Se el le 58 20] 34 27) 58 37 | 34 46 Hype. 2 12 121 COO CIR an tae eel eee eee 30 OFC Is 44) 58> 37 ba Sess LS) Ce eae 21 211 ESS On Ges eee ee ee ree 73 01 | 67 56 | [ike Str Y (2 ee Se 260 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Although even in the preceding crystals, which are shown in the drawings as simple crystals, twins are more abundant than single individuals, the solitary ones are drawn to lessen the labor of pre- paring the illustrations. The twins are penetration and contact twins and are thus similar to preceding illustrations of twinned groups, each individual of the group being like the one selected for illustration. Certain specimens from the Lookout mine show trans- parent contact twins of pale amber color up to 1 cm. in diameter, incrusting quartzite. These are of peculiar aspect and were inter- preted with some difficulty. The habit is well shown in Figure 69. One of these gave the following measurements: Measurements of cerusite, Lookout mine, Figure 69, normal position Form Symbol Measured Calculated = => pitch ore. ™ Nut LEMHI COUNTY In Lemhi County malachite is mentioned from a large number of mines,” although no striking speci- << | mens of the mineral have been seen from the county. In the Blue Wing district malachite occurs locally in the oxidized ores along with other oxida- tion products of chalcopyrite in the veins which produce hubnerite ores. In the McDevitt district lee much malachite occurs, with a little azurite as an ate i oxidation derivative of bornite near the surface in 3 Fig. 70.—MALA- the Copper Queen mine. In the Carmen Creek cmt. Crystar . fs ° 5 . . . : TWINNED ON @ district malachite occurs in similar association and (190), Wermer similarly in the Queen of the Hills, John Torney, ™!N#, Kavrmay ¥ DISTRICT, FRE- and other mines of the Eureka district and in the Blackbird district. LEWIS COUNTY MONT COUNTY. Malachite occurs in oxidized ore of the Horseman property in the Deer Creek district. 7 SHOSHONE COUNTY In Shoshone County malachite is found in numerous places in the Coeur d’Alene and tributary districts. In the southern copper area malachite occurs in limonite in the Monitor, Richmond, and other mines. In the Snowstorm mine malachite was found in much of the oxidized ore as an impregnation in quartzite, but was probably much less abundant than chrysocolla. Malachite occurs locally in ™ D. C. Livingston and F. B. Laney. Idaho Bur. Mines, and Geol. Bull. 1, pp. 95-96, 1920. *3J.B. Umpleby. U.S. Geol. Survey, Bull. 528, pp. 110, 121, 157, 158, 1913. 76D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol. Bull, 1, p. 100, 1920. 264 BULLETIN 131, UNITED STATES NATIONAL MUSEUM all of the oxidized lead-silver deposits associated with cerusite, having been noted in the upper levels of the Mammoth, Last-Chance, Hercules, and other lead mines. Radial bunches and small mam- millary masses occurred in oxidized lead ore in the Sierra Nevada mine in Deadwood Gulch and in the lead-copper ore of the Cale- donia mine. In the latter mine, which produced more malachite than any other lead mine in the district, much of the malachite formed a green impregnation in quartzite surrounding other copper minerals. Fibrous or mammillary green forms occurred with ceru- site and cuprite and delicate acicular crystals were found in spongy masses of limonite. Occasionally pearly crystals of cerusite were stained a delicate green by a thin outer layer of malachite. Some beautiful little specimens showing radiating acicular prisms of malachite embedded in soft limonite have been obtained from the Horst-Powell (Empire) and Handspike mines on the Little North Fork of Coeur d’Alene River. Specimens showing radial and small mammillary masses of malachite in limonite-silica skeletons and others having radiating green needles in cavities in quartz have been seen from the Hypotheek mine on French Gulch, 3 miles south of Kingston. AZURITE (289) Basic copper carbonate, 3CuO.2CO>.H20. Monoclinic. The fine blue copper carbonate, azurite, occurs commonly with the related green carbonate malachite as stains, incrustations, and deep blue crystals where primary copper sulphides have been subjected to oxidation. The mineral is almost coextensive in distribution with malachite as the two are almost invariably formed together. Azu- rite is a little less common or abundant than malachite, however, since malachite is the more stable compound and azurite tends to change to malachite. ADAMS COUNTY In Adams County azurite is common as blue stains and incrusta- tions in many of the copper mines of the Seven Devils district, but it is nowhere very abundant or in exceptionally fine specimens. As an ore mineral, it is fourth in importance in the oxidized ores.” BLAINE COUNTY Azurite has been found in small amounts in the Wood River region, where it forms from the oxidation of tetrahedrite and other copper- bearing primary minerals. In the Hamilton (Clyde) district azurite has been found in the Copper Bluff mine 114 miles from the mouth of Basinger Canyon northeast of Clyde as thin blue crusts and stains with malachite along bedding planes in massive blue dolo- mite.” 77—D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol. Bull. 1, p. 67, 1920. 78 J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 113, 1917. THE MINERALS OF IDAHO 265 CUSTER COUNTY Azurite accompanies malachite in the oxidized ores of the Alder Creek district. It is not an abundant mineral in the deposits, but is very generally present in the different stopes. Locally it is well crystallized in tabular crystals.” Else- where in the county this mineral appears in the oxidized portions of the veins, but is nowhere abundant enough to constitute an ore. In the Bayhorse district it occurs generally in small cavities in partly oxidized tetrahedrite ore. Minute crystals incrust tetrahedrite and chalcopyrite in specimens from the Bull of the Woods mine (Cat. No. 56518, U.S.N.M.) and thin coatings occur with malachite and bindheimite in partly oxidized galena-tetrahedrite ore from the Ramshorn mine (Cat. No. 51863, U.S.N.M.). A specimen from the No. 3 pf" °¢ ae tunnel, Silver Bell mine, Bayhorse district, A shows thin botryoidal coatings and drusy Le crusts and seams of azurite with oxidizing : \ Ye ey tetrahedrite. Small crystals in spongy lim- \ ,, | | ie 5 ; e ; Nes a " onite surrounding tetrahedrite in ore from eee ee the Skylark mine were measured and are ; 2 eines : a FiG.71.—AZURITE, SKYLARK MINE, illustrated in the Oriwane Bicure.7 se NES. ic con ax miemicn 5. = ae Ce Te ere ori ® FABLE RTE LARLY NN Aa 17. 93 18.4 OLAS Tas (Kg @) ee Serene creeped ea ey ine einai = ene a ne eee eee een a | 15. 12 16.9 Soda (Na20) THE MINERALS OF IDAHO 273 The specific gravity of the analyzed sample was found to be 2.54 (orthoclase = 2.57, Dana). A determination of alkalies in a specimen from the Trade Dollar vein gave George Steiger: Potash K,0 14.95 per cent, Soda (Na,O) 0.20 per cent. Another specimen from the same vein in basalt gave K,O, 13.56 per cent. In thin section the valencianite has the characteristics of orthoclase the index of refraction, a little lower than that of quartz, helping to distinguish it from that mineral. The crystals and grains are single individuals and many of the larger ones show optical anomalies probably due to pressure. In addition to Lindgren’s specimens, several collected more recently by KE. L. Jones, jr., of the United States Geological Survey, have been examined. A specimen from the Blaine tunnel dump consists of a fine flat siliaearttaini Ny crust of white to colorless crystals of rhombic a ot aspect reaching 7 mm. maximum diame- ne is x ter, coating a fissure in altered igneous 3 os rock. A specimen from a raise 1,300 feet Nee from the portal of the Blaine tunnel con- sists of altered rock fragments cemented by a granular quartz-adularia aggregate con- taining finely disseminated silver sulphides ae and chalcopyrite. Drusy cavities in this i Dena specimen are lined with well-formed crys- ze tals of colorless adularia up to 5 mm. in | oy diamater associated with small slender ae ee quartz crystals. A specimen from the? ore: oo, coe and van eee bin of the Silver City mine consists largely — gra) snowina Face or P(001). of coarse granular white valencianite in- © S™V#? CY pistaicr tergrown with quartz with small valencianite crystals of the usual habit in cavities. Another specimen from a tunnel dump on the south side of Long Gulch below the Blaine tunnel consists of frag- ments of altered and epidotized igneous rock cemented by quartz combs bearing curved and striated valencianite crystals up to 2 cm. in diameter. Some fluorite rests upon the valencianite. The simple habit which characterizes the cystals from most of the specimens which show only the prism (110) and the negative dome (101) is illustrated in Figure 72, which brings out the strikingly rhombohedral aspect of the crystals. In Figure 73 is shown a twin on (100), the Carlsbad law. The crystal illustrated in Figure 74 shows also the base (001). The prism faces are greatly striated vertically and are always curved yielding poor measurements and (101) and (001) are striated horizontally by oscillation. A crystal of the habit | _ 274 BULLETIN 131, UNITED STATES NATIONAL MUSEUM shown in Figure 74, which showed also narrow line faces of (010) from the Blaine tunnel gave the following measurements: Measurements of valencianite Form | Symbol | Measured Calculated Quality, description No.| Letter Gdt. | Miller g p 9 p pp ds eee) ae ————_|—_——_. | ° , ° , ° , ° , Meee | Oro 100! MIxCallenites 22s eto mee eee 90 00 | 26 29] 90 00/| 26 03 il) Xa eel 2 ee Oe 10i IW AVS oye ee Ee eh 90 41 | 24 12/90 00} 24 13 yl ee Ss Ooo | 010 Very POOre ooo 30 sek ee ee eee 0 55|90 00} 0 00} 90 00 Ae TE si og | co | 110 Very: poor, rounded=== +25. 2 59 32/90 00] 59 23) 90 00 | MICROCLINE (315) Potassium aluminium silicate, Triclinic. K,0.A1,03.6Si0,. The triclinic potash feldspar, microcline, is probably of frequent occurrence as a constituent of granitic igneous rocks in Idaho. Only the following occurrence has been especially mentioned. SHOSHONE COUNTY On Ninemile Creek, above the forks, where the railroad to the Success mine swings around the point of the hill and numerous cut- tings are made in the southern syenite border of the Coeur d’Alene batholith, a part of the rock is strikingly porphyritic with numerous phenocrysts of feldspar in a matrix apparently consisting in the main of parallel needles of hornblende. The feldspar crystals are uni- formly about an inch in length, are cream white to pinkish in color and many of them show carlsbad twinning. This feldspar has been found by F. C. Calkins to be microcline.* ALBITE (316) SODA FELDSPAR Aluminium-sodium silicate, Triclinic. 2) a20.Al,03.68i0,. like the other feldspars albite is probably much more widespread in cccurrence in the state than existing records might seem to indicate. Oniy a single specific occurrence of mineralogic interest has been reported. ADAMS COUNTY At the Helena claim in the Seven Devils district intrusive granodio- rite near its contact with limestone is rather intensely altered with the development of much zoisite. It has also suffered considerable sericitization and in many places contains open vugs or spaces lined with drusy well terminated colorless albite crystals.27 It has not 8 ¥. L. Ransome and F. C. Calkins. U.S. Geol. Survey, Prof. Paper 62, p. 49, 1908. 87 D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, pp. 64, 75-76, 1920. THE MINERALS OF IDAHO 215 been possible to secure any specimens of this material for crystallo- graphic study. ANDESINE (318) SODA-LIME FELDSPAR Sodium calcium aluminium silicate. Variable solid solution of albite (NaAISi,Os) and Triclinic. anorthite (CaAl,Siz0s) in proportions from Ab3An,; to Ab; An. Although andesine is of frequent occurrence as a rock making min- eral, especially in the lavas of intermediate composition which are common in Idaho, the occurrences thus far described are of petro- graphic rather than mineralogic interest. The single occurrence de- scribed below is of this character, but furnishes material suitable for mineral specimens. FREMONT COUNTY The writer is indebted to H. T. Stearns, of the United States Geological Survey, for information on the interesting occurrence of andesine here described, as well as the occurrence of labradorite de- scribed below. The area is covered by a report in preparation by Mr. Stearns on the geology and water resources of the Mud Lake drainage basin, [daho, to be published as a Water Supply Paper by the United States Geological Survey. The locality is Crystal Butte, about 18 miles north of St. Anthony and 8 miles southeast of Ivan, The rock is a lava, probably an andesite or basalt, which constitutes a fissure eruption with several cones, which Mr. Stearns regards as belonging to a period of igneous activity intermediate between the Tertiary andesites and the Snake River basalts. The rocks are made up of a dense black groundmass containing scattered large and well- formed phenocrysts of transparent plagioclase. These phenocrysts, weathered free from their matrix and strewing the surface of the cone, have given it the name Crystal Butte. Most of the specimens examined are loose crystals. These reach a maximum diameter of about 7 cm. They are all tabular to (010), and some of them are twinned on the albite law. They are well bounded by crystal faces and are transparent, except where stained by infiltrated iron oxide or filled with fractures. In color they vary from colorless to pale yellow, and some small pieces are of gem quality. A fragment from a typical crystal of this lot when examined optically proved to consist of calcic andesine. In powder under the microscope it is transparent and colorless; biaxial positive with 21 large, dispersion r>v pronounced. No twinning lamellae were seen. The indices of refraction are a=1.551, B=1.555, y=1.558. These indices identify the mineral as andesine of the composition Ab,;;An4;. 276 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Cleavage plates lying on 010 show the acute bisectrix, and yield an extinction angle of Z’ Ac=15° +. LABRADORITE LIME-SODA FELDSPAR Sodium-calcium aluminium silicate, inter- mediate between albite (NaAISi303) and anorthite (CaAlSi,Os), ranging in pro- Triclinic. portions from Ab;An,; to Ab; Ans. Labradorite is a common feldspar in intermediate igneous rocks as diabases, basalts, and gabbros, and as a constituent of such rocks it is known from many localities in Idaho. The only occurrence noted which is of interest to the mineralogist is the following: FREMONT COUNTY The occurrence of andesine in the lava of Crystal Butte has been described above. v. The indices of refraction measured are a=1.560, B=1.562, y=1.565. These indices indicate the feldspar to be a sodic labradorite of about the composition Ab,Ang or Ab:An=2:3. This feldspar is entirely similar nm appearance to the andesine last described, and it is probable that study of a number of specimens from the same series of lavas would show a gradation of the plagioclases between these two examples. THE PYROXENE GROUP Of the relatively large number of minerals included in the pyroxene group only diopside, hedenbergite, and augite will be mentioned as occurring in Idaho. Probably others occur, but they have not as yet been given detailed mention in the literature nor have specimens showing features of interest been available for description. The most common pyroxenes in the State are those of the diopside-hedenbergite series. The end members of this series are: Diopside Calcium-magnesium pyroxene CaO.Mg0O.2Si02 Hedenbergite Calcium-iron pyroxene CaO.FeO.2S8i02 THE MINERALS OF IDAHO yt Every gradation between these two end members is possible, and isomorphous mixtures intermediate and near the 1:1 ratio are some- times designated by the varietal name sahlite. Augite is similar to the diopside series, but differs in containing a notable amount of alumina. Members of the diopside-hedenbergite series commonly occur as metamorphic minerals, especially in limestone, while augite characteristically occurs as a rock making mineral on basic igneous rocks. The approximate composition of a pyroxene of the diopside-heden- bergite series may be determined from its refractive index. The optical properties of the end members of the series are: Diopside 2V=59° Z/Ac=38'%° 8=1.671 Biref.=0.030 Hedenbergite 2V=60° ZiI\C=48° B=1.737 Biref.= .019 In the absence of chemical data the minerals of the series may be allocated by the following approximate classification: Diopside 6 refractive index from 1.671 to 1.693. Sahlite B refractive index from 1.693 to 1.715. Hedenbergite 8 refractive index from 1.715 to 1.737. Other less common members of the pyroxene group probably occur in Idaho, but in general little attention has heretofore been paid to the silicate minerals and few specimens have been collected for study. DIOPSIDE Calcium-magnesium silicate, Monoclinic. CaO.Mg0.28i0p. The calcium-magnesium pyroxene, diopside, including members of the diopside-hedenbergite series in which magnesia is notably preponderant over iron, is by far the most common pyroxene in Idaho. ADAMS COUNTY Diopside is listed by Livingston and Laney * as a mineral common in the contact-metamorphic copper deposits of the Seven Devils district, and it has been noted in many specimens from this district by the writer. A specimen from the roadside near the lower tunnel of the Queen mine consists principally of granular green diopside, of the variety known as coccolite, with calcite, brown garnet, and disseminated grains of chalcopyrite. BLAINE COUNTY In the Hailey quadrangle diopside forms large rock masses. prob- ably derived from dolomitic marbles, in the crystalline rocks form- ing the crest of the range. Such diopside rocks are well exposed in the cirques of the west side of Mount Hyndman at the head of 8D C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 62, 1920 278 BULLETIN 131, UNITED STATES NATIONAL MUSEUM East Fork of Wood River. The diopside is coarse granular and varies from white to blue-gray in color. Near the large granitic instrusion west of Hailey the limestones contain abundant white pyroxene, probably malacolite, with fibrous wollastonite.® CUSTER COUNTY In the Alder Creek district pyroxene, next after garnet, is the most. abundant product of the metamorphism in the vicinity of the copper deposits. Diopside is the predominant constituent of the pyroxene rock formed from the limestone by metamorphism. During the earliest stages of the endomorphic alteration of the granite-porphyry the primary hornblende and biotite were altered to diopside. Finely disseminated diopside is scattered through much of the garnet rock and diopside, together with augite and hedenbergite, comprises bunches of pyroxene rock free from garnet. Such rock is dense, greenish, of aphanitic texture and has resinous to vitreous luster. In some thin sections of the massive pyroxene there occur a little plagioclase feldspar (Ab,;An,;) and chance grains of titanite, apatite, and fluorite. A specimen of typical diopside rock from near the second lateral, No. 3 crosscut, Alberta tunnel, analyzed by Chase Palmer, of the United States Geological Survey, gave the following results: °° Analysis of diopside rock from Mackay (Chase Palmer, analyst) Per cent. SLT as SO ye 2 a Ne NN SE i ee CC ig NR UE 51.755 Aura rt ea CAM Oye se se Ss Spy Se sg sy eS nN 4. 00 Merrie irom. CHS Oye eee Seg Ue IRN SAT ae err nce oe Oa 1. 02: Herrousirom(CHEO) hegre: et ANA REAL Sk ered ee a VE Te ee ves 6. 65 Magnesia (MeO) 2ete1d.. TeO HU ER ee Oe. EON SO ea 11. 38 MPN © Cea) hae aT ig SSD ae 24. 23 Sodas (Nisa) cs seo ee La NTIS es es ens ae Oe RO GAS I CRO) aie er ae Le MUN a Sp NRC ya ee . 18 Waters (Hs @): below pve. © ae ar ah ae es ean REA RN ce a .14 Water (HO) abovenl102s © ce ey ae ag Say a ER al ree 20 "BitantumMn Oxides CLIO pee Ns Lo ae RA A AMA Ao bene Nona ee ee . 32 Carbon: dioxide (CO) 81k O22 RGOd 220) GAOT Stange Sar eee . 00 Phosphoric acid: (PsO;) 22244 Ys 5 see ee a ea alos | epee renee . 24 Manganous oxide, (vir @)) 2st pes pi ree Aa 2 Sa a eae . 30 Total. sss Se 2 BSS EE ETE “Fi aT Pa ape a 100. 64 The specific gravity of the analyzed material was 3.304. Assuming that the analysis represents essentially a single mineral, the first six constituents may be given, as the essential oxides, together with their ratios, as follows: 89 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 195, 1900. J, B. Umpleby. U.S. Geol. Survey, Prof Paper 97, pp. 52, 58, etc., 1917. THE MINERALS OF IDAHO 279 | | Per cent | Ratios | ' | SLO 7 OLLIE gtk SAT ie Che ee ATO ETT roy. | 51.55 | 0.860 0.860 0.860 Cg ree ee 2 es a ce cea | 400} .038) gas TR se) pene cre penn ike 2 eda he ee a ee eee eee 1.02 | .006f ° FGG Oi ee ee Ne Ln pepe ep eewer resem fw 6.65 | .093 - 855 Vie () Mae Ra ree Tite eer ey eer enter ee. | 11,38] .285$ .810 So riemene eer ee erty ewe aie ae eee eee et | 24,23 | . 432 SEistal ese ete ag CoE ORG cg Ueno ee a 98. 83 | The ratio of ferrous iron to magnesia determines the position of the pyroxene in the diopside-hedenbergite series. The metasilicates of iron and magnesia are present in the above analysis in the molec- ular proportion of Fe:Mg=93:285 or 1:3.06, so that the material may be designated diopside. A specimen of low-grade molybdenum ore sent to the National Museum from Challis consists almost entirely of granular green diopside containing flakes of molybdenite. Another specimen sent in by J. W. Copper from Hill City, Custer County, consists in the main of green diopsidic pyroxene. In the Copper Basin district at the head of East Fork of Big Lost River diopside occurs abundantly in garnet-diopside zones in lime- stone, which are mined for copper.“ A specimen from the Parallel tunnel of the Reed and Davidson mine in this district consists of granular diopside, containing magnetite and copper silicates, in con- siderable part altered to nontronite (chloropal). In the Washington Basin district diopside occurs with the ore of the Empire ledge. In altered monzonite, in and adjacent to the vein, feldspar and biotite crystals are completely transformed to pyrrhotite and diopside. In the southern part of the vein pyrrhotite with about an equal amount or intermixed quartz and diopside forms a band 15 to 20 feet wide next to the hanging wall of the vein.” LEMHI COUNTY Diopside has been noted as colorless granular material associated with ludwigite in specimens from the Bruce Estate in the Texas district. It is probably common in this property, which is a low- grade contact-metamorphic copper deposit in limestone. OWYHEE COUNTY Diopside occurs to some extent with other metamorphic minerals in lime-silicate zones in limestone mined in the Golconda and other mines in the South Mountain district. Specimens of lime-silicate rock from the road on Williams Creek 2 miles below the mines, South Mountain district, consist very largely of pale gray-green diopside in “J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, pp. 104-105, 1917. 92 J.B. Umpleby. U.S. Geol. Survey, Bull. 580, pp. 245-246, 1915. % Earl V. Shannon. Proc. U.S. Nat. Museum, vol. 59, p. 667, 1921. 280 BULLETIN 131, UNITED STATES NATIONAL MUSEUM rough crystals up to 3 by 1 cm. in size. In powder under the micro- scope this pyroxene is transparent and colorless, is biaxial positive with 2V medium large; mean index, 8=1.680 and extinction ZAc= B6o-39°. SHOSHONE COUNTY No pyroxene has been noted in the ores of the Coeur d’Alene district, but a pale green to colorless species, probably diopside, is abundant in some of the contact metamorphosed sediments near the monzonite intrusions. It has been noted particularly ; vet in the Alameda tunnel near the Granite (Success) } i ee / mine, where some originally calcareous bands in the peony / sediments have been changed to aggregates of diop- aes a ey side, quartz, and green hornblende.” SAHLITE LIME-MAGNESTA-IRON PYROXENE i cs a \ Calcium-iron-magnesium silicate inter- Monoclinic. / / mediate between diopside and heden- im / AL . pe Te / bergite pyeite & In the absence of definite chemical or optical data it is not possible to definitely place the position of a pyroxene of this series and it is probable that some of those described above as diopside are in reality high enough in iron content to be designated by the varietal name sahlite. o A specimen from the Starlight mine in Elkhorn Gulch near Ketchum in the Warm Springs district '/ consists of a green mineral in prisms up to 5 mm. ( |) in length with interstitial calcite and considerable a coarse granular brilliant black sphalerite intergrown . with some pyrite. When the calcite is removed by te es solution in dilute acid the green mineral remains Warm Sprincs behind as lustrous prisms surrounded by spongy Cech BIAISE masses of minute crystals of lighter green color. The minute crystals are biaxial positive with 2V medium, extinction 46°, refractive index 6=1.705+0.003. The larger prisms are practically identical in optical properties with 6=1.708, so that the large and small crystals are both referable to sahlite. One of the larger crystals was measured and found to be pyroxene of normal habit. This crystal, which is illustrated in Figure 75, gave the following measurements: | | a | BLAINE COUNTY { | | | % F. L. Ransome and F. C. Calkins. U.S. Geol. Survey, Prof. Paper 62, p. 99, 1908 THE MINERALS OF IDAHO 981 Measurments of sahlite, Figure 75 Form Symbol | Measured Calculated Quality, description } — No.| Letter Gdt. Miller | @ p g | p ees |. 7 = | | 1 aan | eels | nr ee | ° ’ ° , ° , ° , Aiea. a 2% 0 001” |) Very poor, dimas=- 22.2.2 22-58. 2) 190 00] 16 12] 90 00 | 15 51 A (a: See ora | 000 1007 SViery 2O0dE S222 ~ eee ee eee 90 00| 90 00; 90 00, 90 00 yl bes eee | 000 O10 | Goodses age eee Fete toe | 0 00/90 00! 0 00 | 90 00 4) m...-.-- oO 110 ery, DOOl MALL OW serena eee a 43 21/90 00} 43 33} 90 00 Bln Des2s- 258 —10 101 Very poor, Gim-—- 22% 272 -- 82s 90 00| 13 47/90 00| 15 27 Ogee +12 21 ey ele ine ee ee | 35 43 | 54 40 | 35 36 | 55 24 | A second specimen of similar material probably from the same or an adjoining locality is also made up largely of pyroxene with calcite, but contains more of the black granular sphalerite and a few brown dodecahedral garnets. HEDENBERGITE LIME-IRON PYROXENE Calcium iron silicate, CaO. FeO.2Si0». Monoclinic. Only a few localities are known in the State for the iron end member of the diopside series which seems to be decidedly rarer than the magnesian diopside. ADAMS COUNTY Hedenbergite is listed by Livingston and Laney” with a question (?%) as occurring as a contact metamorphic mineral in the Seven Devils district. CUSTER COUNTY Hedenbergite has been noted in the Alder Creek district as a distinct mineral only in a few thin sections. Computation of analyses of the pyroxene shows that it enters into the diopside in solid solu- tion in amounts ranging from 9 to 23 per cent.” A specimen from the Basin prospect shows abundant hedenbergite as dull greenish to brown bladed fibrous masses mixed with galena. This prospect is located on the mountain north of Park Creek, which is the small stream occupying the low valley which connects the upper valley of Trail Creek with the headwaters of Lost River near where the Ketchum-Mackay road crosses the divide. Other specimens from the same tunnel contain epidote, garnet, prehnite, etc., in metamorphosed calcareous shale. Under the microscope the hedenbergite is opaque except in thin splinters, from the presence of an opaque brown pigment, probably limonite, due to its easy oxidation. Thin transparent splinters of the mineral appear color- less with no pleochroism. It is biaxial positive with a mean re- 9 ED. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 62, 1920. % J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 53, 64, 1917. 54347—267——_19 989 BULLETIN 131, UNITED STATES NATIONAL MUSEUM fractive index, 6 of 1.737. Sections of maximum extinction measure ZAc=48°. These properties indicate an iron pyroxene near the hedenbergite end of the series. OWYHEE COUNTY Hedenbergite occurs in contact-metamorphic deposits in limestone in the South Mountain district. It is the most abundant lime- silicate mineral in the Golconda mine where it is associated with ilvaite, calcite, sphalerite, chalcopyrite, etc. It ranges from a fine- grained massive rock to coarse masses of fibrous blades as much as 3 em. long by 1 em. thick. Some specimens from the Golconda dump are composed of finely fibrous silky-lustered rock of pale-green to brown color containing coarse calcite patches in which are em- bedded large crystals of ilvaite. The fine fibers tend to turn brown and oxidize rapidly with the formation of limonite, upon weathering. Examined under the microscope, this fine material is found to consist wholly of pyroxene dusted and stained with limonite. When the powdered mineral is treated with warm 1:1 hydrochloric acid the limonite is dissolved leaving the pyroxene better suited for optical examination. It is then pale-green, faintly colored, and nonpleo- chroic. Optically it is biaxial positive with 2V medium large, r>v perceptible. The maximum extinction is approximately ZAc=42°. The refractive indices are, roughly, a=1.715, B=1.722, y=1.738. The coarser varieties are optically identical. A medium coarse specimen of olive-green hedenbergite contains abundant chalcopyrite and one of the coarsest seen includes some coarse granular dark- colored sphalerite. The brownish olive-green color, fibrous ap- pearance on cleavage surfaces, and especially the tendency to quickly weather brown upon exposure, readily identify this pyroxene. AUGITE ALUMINOUS PYROXENE Variable silicate of lime, magnesia, fer- Monoclinic. rous and ferric iron and alumina. CaO.Mg0O.2SiO, with some CaO.FeO. 2S8i0, and (Mg.Fe)O.(Al, Fe)203.SiOs. Although augite is widespread in occurrence in Idaho as a pyroxe- nic constituent of igneous rocks, especially basalts, diabases, and andesites, no locality furnishing specimens of interest to the collector or mineralogist has yet been described in the State. In an area containing such quantities of eruptive rocks some localities will, in all probability, be discovered in which augite occurs in a basic igneous rock in phenocrysts of such size and quality as to make interesting mineralogical specimens. THE MINERALS OF IDAHO 2983 WOLLASTONITE (320) Calcium metasilicate, CaO.SiOo. Monoclinic. Wollastonite is a mineral which frequently develops in limestone by contact metamorphism adjacent to intrusive igneous masses. It is usually white in color with a more or less pearly luster and granular to fibrous structure. The granular varieties often resemble white marble and fibrous forms frequently simulate tremolite in appearance. The following localities have been noted in Idaho. ADAMS COUNTY Wollastonite has been listed with a question (?) by Livingston and Laney *? as occurring in limestone with other metamorphic silicates in the contact copper deposits of the Seven Devils district. BLAINE COUNTY Specimens from the Starlight mine in Elkhorn Gulch near Ketchum, in the Warm Springs district, contain white fibrous wollastonite making up a lime-silicate rock with garnet and sahlite. Under the microscope the wollastonite is fibrous with prismatic cleavage parallel to the length, parallel extinction and rather high birefringence. It is biaxial negative with 2V medium, 6 about 1.628. The axial plane is across the fibers, so that the elongation is Y. Brilliant black sphalerite is intimately intergrown with the wollastonite, some of the prismatic grains of wollastonite being completely isolated in the sphalerite. West of Hailey wollastonite occurs with diopside in metamorphosed limestone near the large granite instrusion.® In the Drummond claim, on Little Wood River, Muldoon dis- trict, the ore occurs in a zone of contavt metamorphism in which wollastonite and less garnet, diopside, and epidote have been de- veloped in a calcareous rock.* A specimen from this mine consists of about equal parts of pale brown garnet and dense fibrous silky- lustered white wollastonite, which is fibrous, biaxial negative opti- cally with 2V large and £ refractive index 1.620+ .002. CUSTER COUNTY A specimen from the Basin prospect north of the Trail Creek- Lost River Pass consists of pinkish fibrous sheets of wollastonite up to 4 mm. thick, in garnet-epidote rock. Under the microscope the wollastonite is biaxial and negative with 2V small. The fibers give parallel extinction with the optic axial plane across the length. The refractive index, 6 is 1.62. It is decomposed at boiling by 1:1 hydrochloric acid. 97D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 62, 1920. 98 Waldemar Lindgren. U.S. Geol. Survey, 20th. Ann. Rept., pt. 3, p. 195, 1900. 9% J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 109, 1917. 984 BULLETIN 131, UNITED STATES NATIONAL MUSEUM In the contact-metamorphic copper deposits of the Alder Creek district wollastonite occurs as scattered small grains in much of the marble and garnet rock. Locally it forms a layer a foot or less in width between granite porphyry and limestone. On the side of the wollastonite away from the igneous rock is a persistent narrow layer of pale blue marble bordered by a silicified zone of blue lime- stone which grades outward through a foot or 18 inches into the unaltered rock. The wollastonite rock is white, granular, and mas- sive, and resembles the marble.1 A specimen of such wollastonite rock from the Case tunnel, Champion group, analyzed by W. C. Wheeler gave the following results. Analysis of wollastonite rock, Mackay (W. C. Wheeler, analyst) Constituent Per cent STC SIO 3) ee NT Sea Ae 1g RT yt CO a Sea ee 50. 47 PAM rnb ra aig CAT Os) cere No el One eM Ap Cr ey a ee ee . 45 HerricsOxIGex(HesOg) ease = ore Se fay leg ee Lala ag keen Cpe OER Op ee en a . 16 Ferrous oxide (FeO)_____ cP Ris gat OUI OU AAR GA RL eRe mI, pele RHE (OO DO ra Mr AP eke Oe Palo Mia gmesia; GMEo@) elects See = BLNe eRe Se Use eae Eh eFC ap eer ON lege Et Le pee Ley, ime: (CaO) iii wissen ge Ae fou LS ee A hE eo eee tg 45. 99 Carbon. dioxiden(G Os)io 5 Boia eS ks 5 BO aap ke aa oie a ep . 69 MO Gall oS. fee OER SSR 9 pS ID ARAL AG ERB ho ae eee ee 2 eee 99. 03 This analysis, computed in terms of mineral molecules gives the following: Molecule Per cent Wrollastomite 32th) Ce Ne UE EER alle RE aie A ce Sy eee 91. 24 Diopsidews 2) oF ea EST era ae ye aes Soe ve eee ah eee ee 5. 61 Hledenpergiteng Se 215i Si Mar YUAN Ape ip il EU 2 2 lela eee a . 23 GAUL sites aE Soe inp a ee hd a 89 GCaleitecse ea ee ar See A gt ee on eae feel ed ony SOL ee 175 Quantze we ee ee ee eee SESS HE BIN aI geal a art ah enn 28 TG teal SSeS Ste IS RR yA aa Se 100. 00 ANTHOPHYLLITE (337) ASBESTUS Magnesium silicate, MgO.SiOz. Orthorhombic. Anthophyllite occurs in one locality in Idaho in very large masses which constitute bodies of low grade “mass-fiber”’ asbestus similar to that which is mined at Sall Mountain, Ga. Several attempts have been made to mine this material. The mineral probably oc- curs in lesser amounts elsewhere in the State. Anthophyllite often contains more or less ferrous iron and thus graduates toward the similar orthorhombic iron amphibole described below under the name ferroanthophyllite. 1J. B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, pp. 55, 65, pl. 13, 1917. THE MINERALS OF IDAHO IRS ADAMS COUNTY Anthophyllite is listed by Livingston and Laney?’ without further description, as a mineral of the contact metamorphis copper deposits in limestone in the Seven Devils district. IDAHO COUNTY Anthophyllite occurs in Idaho County 14 miles southeast of Kamiah in large masses similar to those of the asbestus mines of Salk Mountain, Ga. The mineral forms about half a dozen ledges within a few square miles. The largest of these ledges is lenticular in form and is 200 feet long, 40 feet wide and stands 30 feet above the ground. The lenses of anthophyllite apparently represent altered basic intru- sions into the surrounding mica schist. Prospecting has revealed the bottom of some of them so they do not continue to great depth. Several of the masses are known and there are probably others as yet undiscovered, so that a great quantity of the material is avail- able. The anthophyllite forms a mass-fiber asbestus, the fibers of which are arranged in small bundles 5 to 20 mm. in length and generally lying in all directions. Locally the fibers are arranged in radial groups which on cross-fractures yield rosettes sometimes 12 em. in diameter. The fibers are brittle and as asbestus the material is poorer than the poorest chrysotile. The deposits were formerly worked by the Spokane Asbestus Fire Brick Co., who shipped the material to Spokane, where it was sawed into bricks or ground for various purposes.?¢ A large specimen of the Kamiah asbestus was submitted for examination by Edward Sampson, of the United States Geological Survey. This consists of a group of rude prismoidal masses which resemble altered prismatic crystals of some mineral and are in- dividually composed of parallel fibers of anthophyllite. These in- dividual groups of fibers reach an extreme size of 10 by 10 cm. with an average of about 10 cm. in length by 3 cm. in thickness. The specimen is dirty white and somewhat iron-stained but, when fiberized, the fibers are fine, fairly flexible, and white. Selected and pure fibrous material from this specimen was analyzed with the following results: 7D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 62, 1920. 20 J. S, Diller. U.S. Geol. Survey ,Mineral Resources of United States, 1909, pt. 2, p. 729. 286 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Analysis of anthophyllite asbestus, Kamtah ; (E. V. Shannon, analyst) Constituent Per cent SH eS Oi ee kee er pt ect ete eae ge ere 57. 60 Alumina, (GA's Op) es a re ae ene Soe eC Ee en Ran SRE Lh Re ee 1. 94 Kerric’oxiden(Rei:@s) = 2. = Se cel Ie ere eee 8 ta) eee eo nee 1.58 Herrousvoxider(he@) ese = ae oe eee Po Si Ue aCe RN peck er ih MPL, 6. 62 Tear 6 (Ca ©) ee RR aR AN SN 2 Coe Trace DMiie ort easing ©) nse 8 ae ae oe ane ty op 30. 32 Water (HoO)pediovesl Ol: Cac se nile sclera ty) ee Se a I sh 2. 66 Wis teraGels @) ebelo wall Oc iG oe oes St ae ae eye dene ge eae ene . 20 SAN Ota Ay soe pepe kT NN as 20 al a aetna ea RNG = cae pee ae ODS 100. 92 This composition is essentially that of anthophyllite. Under the microscope the analyzed sample is in aggregates of exceedingly fine fibers which, in the aggregates, are apparently in parallel position and give a faint biaxial figure indicating the obtuse bisectrix perpendi- cular to the fibrous aggregate with the optic plane parallel to the length. These observations together with the fact that all of the fibers show parallel extinction with positive elongation indicate that the mineral is biaxial, positive with 2V large, orientation Z=c. The fibers are transparent and faintly brown. The refractive indices measured in the analyzed material are a=1.605, y=1.625, Bire- fringence=0.020. The optical properties of anthophyllite have been discussed by Bowen® who gives a diagram showing the increase in refractive indices with the increase of iron, stated as FeSiQ3. The total of both ferrous and ferric iron shown in the above analysis, calculated as FeSiO; gives approximately 15 per cent. The indices from Bowen’s curves, for an anthophyllite of this composition, are a=1.613, y=1.632, appreciably higher than those found. If, how- ever, only the ferrous iron be considered the indices derived from the curves are a=1.606, y=1.624, almost exactly those measured. This indicates that the ferric iron shown by the analysis is not es- sential, especially since it would be more influential than ferrous iron in increasing the indices. This supports the conclusion strongly suggested by the appearance of the specimen before grinding, that the ferric iron is extraneous and present as an infiltrated stain. A number of specimens labeled Orofino, which were sent to the United States Geological Survey for examination by Dean Francis A. Thompson, of the Idaho School of Mines, are probably from the same area. The first of these consists of a mass of slightly curved splintery brittle fibers with silky luster, abutting against a mass of granular crushed white and green material. The silky fibrous material, under the microscope, contains two slightly different materials which are probably both anthophyllite. The first of these is coarse prismatic under the microscope and is transparent and colorless with good N. L. Bowen. Jour. Wash. Acad. Sci., vol. 10, p. 413, 1920. THE MINERALS OF IDAHO Dot prismatic cleavages. The extinction is parallel, the elongation positive, and the crystals tend to lie on a face giving medium low birefringence and showing the emergence of a negative bisectrix, probably obtuse but looking like an acute bisectrix with 2V large. The refractive indices are a=1.612, 8 =1.621, y = 1.635, birefringence = 07.023. The second material associated with the preceding and apparently derived from it by alteration or shearing is made up of very fine fibers in matted aggregates having, in a section, a variable and non- pleochroic pale greenish-brown color and about the same birefringence as the other. The extinction is parallel and the elongation positive. The refractive indices are variable with a=about 1.595. The granular material of this specimen consists of glassy white to pinkish grains of the first mineral described above having scattered grains of actinolite which is identified by its green pleochroic color, negative optical character and extinction inclined about 17°. The second specimen from the lot labeled as from Orofino con- sists of a large splintery fibrous mass 40 cm. in length and having a dirty white color. Under the microscope this is made up of coarse blades tending to split into minute fibers of positive elongation and parallel extinction. The indices of refraction are approximately a=1.608, y=1.630, birefringence 0.022. Apparently all of the preceding are anthophylltes, varying in refractive indices probably with variation in iron and possibly water content. The finely fibrous forms are apparently secondary and derived by some mechanical process of weathering or shearing from a much coarser form of the same mineral. No indication of the source or origin of the anthophyllite is furnished by the specimens examined. SHOSHONE COUNTY The anthophyllite found by Ransome * in the Hercules mine is the high iron variety described below under the name ferroan- thophyllte. FERROANTHOPHYLLITE Tron silicate, FeO.SiO». Orthorhombie. The name ferroanthophyllite has been suggested for a member of the anthophyllite group in which the essential magnesia is wholly or largely replaced by ferrous iron.’ Specimens from Idaho have been described in detail. Similar iron anthophyllite had previously been described from Massachusetts and several Scandinavian localities. 4F.L. Ransome. U.S. Geol. Survey, Prof. Paper 62, p. 99, 1908. 5 Earl V. Shannon. Description of ferroanthophyllite, an orthorhombic iron amphibole from Idaho with a note on the nomenclature of the anthophyllite group. Proc. U. S. Nat. Museum, vol. 59, pp. 397-401, 1921. 288 BULLETIN 131, UNITED STATES NATIONAL MUSEUM SHOSHONE COUNTY The material described as ferroanthophyllite was collected in the Tamarack and Custer mine on Ninemile in the Coeur d’Alene district by Frank Barker who sent it to the United States National Museum for identification. The mineral contains galena and is stated to have occurred in the ore. While this mine is located no very great distance from the contact of an instrusive mass of quartz monzonite and several dikes of quartz-monzonite porphyry are reported to have been encountered in the mine workings, the inclos- ing rocks are unaltered quartzites in which metamorphic silicates in megascopically visible aggregates have not heretofore been re- ported. The occurrence of considerable amounts of this amphibole in the vein is therefore decidedly unusual. Inquiries and requests for additional specimens have been directed to both Mr. Barker and to the mining company but have not been answered. The material as received consists of splintery-flbrous masses of a pale grayish-green color when dry and olive-green when moist. In all about 250 grams of the material were received in broken pieces. The individual fibrous masses reach a maximum length of 6 cm. The material separates easily into fine silky fibers which are mod- erately strong and flexible, being comparable to a poor quality of chrysotile, which the mineral resembles. The only associated mineral is a little fine granular galena which occurs interstitially between the fibers, as small nodules around which the fibers are curved or as fillings of small fractures in the mineral. Under the microscope the mineral is in the form of very thin fibers which show positive elongation and parallel extinction. The indices of refraction determined are a=1.668, y=1.685, birefringence 0.017. Singly the fibers are colorless but thick aggregates of fibers are colored and pleochroic, X = pale brownish green, Z=deep brown- ish green. An analysis made upon selected fibrous material gave the following results: Analysis of ferroanthophyllite (E. V. Shannon, analyst) Per cent. Silt@as (Si Oise 8 ee ey ey ie ee i eg ee 49. 30 gANTirreyait Tact; « CAMS Og ic ewe ea oar eS ae ait area Ca sage ey 1. 30: HEEriGvOX1d eG CH Gs Oa) ee ere ee erate tt re CS ee re ne 2.15 HErrOUSsOX1GE {CMe yay eee er es IOLA A SNE gaan) ee ep Oe OL, OER SU TERT BYE 30. 50 Miangan Ousioxides (Nn @)) sets: ape en a eet rT Se i ok eee ere 3. 48. Maur e:3((C a ©) eases kee ee eae Ln ala tc a Nh it wean a eR 10. 73 AN ezaigor Sie «IV GO) a aa IR a . 66 Waters (HO): above: 11Q8 (Chis ee ee ee et er anne aol Dees Wiatern(ils@) tela. 22 OSGeo aia ear Di er ance a Ret eels Een re eli: THE MINERALS OF IDAHO 289 A single small specimen collected by Ransome ® in the Hercules mine was described as containing a light gray silky asbestiform silicate crystallized with galena. Under the microscope the exceed- ingly fine fibers showed rather low double refraction and parallel extinction. The mineral, as tested by Dr. W. T. Schaller, was not attacked by acids and fused with difficulty. The original specimen collected by Ransome was examined by the writer. It consists of parallel aggregates of pale gray fibers up to 2 cm. long, intergrown with granular galena. It is colorless in thin section with positive elongation. The indices of refraction, which are a=1.678, y=1.702, birefringence 0.024, indicate this to be ferroanthophyllite, probably purer than that from the Tamarack mine. TREMOLITE Lime-magnesia silicate, CaO.38 MgO.SiO». Monoclinic. Tremolite is a comparatively iron-free amphibole occurring usually as white to grayish fibrous masses. It is often difficultly distinguishable from anthophyllite without an optical examination or an analysis. It is probably of common occurrence in metamor- phosed limestone in Idaho but few specimens have been collected for study. BLAINE COUNTY A specimen labeled as from the face of the tunnel of the Red Elephant mine, Wood River region, consists of gray finely fibrous masses of tremolite containing small cubes of pyrite. Under the microscope the material is fibrous with prismatic cleavage and ex- tinction slightly inclined to the elongation. It is biaxial, negative, with 2V medium large, refractive index 8=1.623+0.003. The country rock here is calcareous shale in which the tremolite is doubt- less a mineral developed during metamorphism.’ CASSIA COUNTY A specimen labeled ‘“‘marble from marble quarry, Basin Idaho, T. 14S., R. 22 E.” consists of medium granular gray marble con- taining abundant gray blades and sheaves of tremolite up to 3 mm. thick by 15 mm. long. This mineral is colorless under the micro- scope and is biaxial negative with 2V large. The extinction is about 12°. CUSTER COUNTY Tremolite is comparatively rare in the contact-metamorphic copper deposits of the Alder Creek (Mackay) district, no good specimens having been reported. It occurs sparingly in the marble but is rare in the diopside rock.* 6 F.L. Ransome. U.S. Geol. Survey, Prof. Paper 62, p. 99, 1908. 7 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, pp. 202-203, 1900. 8 J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 55, 1917. 34347—267 20 990 BULLETIN 131, UNITED STATES NATIONAL MUSEUM SHOSHONE COUNTY A single peculiar occurrence of tremolite which has been deter- mined in Shoshone County deserves record, although the material is not of specimen value. The specimens are labeled as from the dump of a shaft near the head of Big Creek and Silver Creek. They consist of quartz containing large rhombic molds from the removal of some rhombohedral carbonate, probably ankerite. These cavi- ties are lined with a layer up to 3 mm. thick, of ocher-brown material with a faintly fibrous structure and silky luster. Under the micro- scope this is found to be a mixture of a bladed colorless mineral with fine limonite. In hot 1:1 hydrochloric acid the limonite is dissolved while the bladed mineral is undissolved. The optical properties of the blades are: Biaxial, negative, 2V medium large, extinction 15°-17°, B=1.623. These optical properties identify the mineral as tremolite. This amphibole was probably included in the original carbonate which has been removed by weathering. ACTINOLITE Lime-magnesia-iron silicate, Monoclinic. CaO.3(Mg, Fe) 0.4810». Actinolite differs from tremolite principally in containing more iron. It is usually in fibrous or acicular aggregates and is commonly deep green in color. The following occurrences have been noted in Idaho. ADAMS COUNTY Actinolite is listed by Livingston and Laney ® as an abundant and widespread contact-metamorphic mineral in the Seven Devils region. CUSTER COUNTY Acicular actinolite occurs sparingly in the contact silicate rocks of the Alder Creek district. Its most common occurrence is as finely divided crystals in the white marble.” The mineral occurs also in veins up to 2 inches wide consisting of fibrous or acicular crystals in apparently unchanged blue limestone." IDAHO COUNTY A small amount of green actinolite was noted in association with abundant anthophyllite in a specimen described above which was labeled as from Orofino, but which probably came from one of the Kamiah asbestus prospects. *D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 62, 1920. 10J. B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 49, 1917. J. F. Kemp and G. C. Gunther. Trans. Amer. Inst. Mining Eng., vol. 38, p. 269, 1908. THE MINERALS OF IDAHO 991 LEMHI COUNTY Actinolite occurs in the Carmen Creek mine, Carmen Creek dis- trict. The ore occurs as lenses of quartz distributed through a band of schist. Much of the schist is mineralized with the development of pyrite, chalcopyrite, actinolite, and epidote. Much of the quartz contains magnetite, but the actinolite and epidote are confined to the inclusions of schist. The material is largely oxidized. The actinolite has the usual green color and radiate-fibrous structure,” SHOSHONE COUNTY Some very fine specimens of actinolite have been seen from the southern part of Shoshone County. The material came from some copper prospect, the location of which was vaguely described as in the St. Joe country. They consist of radiating olive green fibers up to 25 cm. long in pure masses up to 12 kilograms (25 pounds) in weight. Other specimens in the same lot consist of scaly masses of black biotite, large cubes of pyrite, and a very coarse rhombohedral carbonate, probably ankerite. The actinolite fibers inclose the pyrite crystals. The specimens were obtained by Harvey Ross, of Kellogg and Spokane. HORNBLENDE (338) VARIETY OF AMPHIBOLE Variable silicate of lime, magnesia, and ferrous iron represented by the formula CaO.3(Mg,Fe)O.48i0, with variable Monoclinic. amounts of alumina and ferric iron probably entering as the compound (Mg, Fe)0O. (Al, Fe)203.SiOz. While hornblende is of relatively common occurrence in Idaho as a rock constituent, only a few of the occurrences have received any special attention. SHOSHONE COUNTY In the southern part of Shoshone County, especially along the St. Joe-Clearwater divide, the rocks of the sedimentary Belt series of Algonkian age have been intensely metamorphosed, due in part to the nearness of the great Idaho batholith and in part to dynamic stresses acting under a heavy load of sediments." Dikes and sills inclosed in the sedimentary rocks have in places suffered in the general metamorphism and have become schistose amphibolites in which the original pyroxene has changed to amphibole accompanied by the development of numerous garnets. Numerous metamorphic- 122J.B.Umpleby. U.S. Geol. Survey, Bull. 528, p. 127, 1913. 13 F.C. Calkins and E. L. Jones, jr. Geology of the St. Joe-Clearwater Region, Idaho, U8. Geol. Survey, Bull. 530, pp. 75-86, 1913. 992, BULLETIN 131, UNITED STATES NATIONAL MUSEUM minerals have developed in the sedimentary rocks, the most con- spicuous being garnet, staurolite, cyanite, and hornblende. The hornblende is a common product of this metamorphism, especially in the calcareous rocks of the Wallace (Newland) formation. Y>X. A selected sample, purified by the use of heavy solutions and an electromagnet, was used for analysis. Microscopic study indicated the presence of 4 per cent of diopside in the analyzed sample. The results of the analysis are below compared with analyses of hudsonite and hastingsite. Analyses of hudsonite and related low-magnesia amphiboles Gonstitaant A! radeon: (Eat ‘onstituen udson- | Hastings- | Idaho ite | ite SUNCHECS Ls) eee eee eee Sema ee Rene Ae oe ode we ase eueeeee 38. 50 36. 86 | 34. 18 MiitaniumioxideCMiOs) on aa eee ee sen os Bees ee net eee ne Trace. 1. 04 1553 PAULIITERUTI Anata) 3) ae ee an ee Ne ate oe 10. 88 12. 10 11, 52 ernichron Uh e6)O3) es 205 ses ee ose s een sees eos essen enescee 6. 70 7.41 12. 62 HOLTOLISHIrOM CHC) Messe con ee. ee ee {Ae 8 Bere oe essa 27. 28 23.35 21. 98 Wan ganoussOxiGeuWin@) 2222-25. 2 5 Soa es eee ee Trace. di . 63 INbaner TON CO 2a) ee eo a ee ec dobenceasesSeee eee 11.30 10. 59 9. 87 Weagmesiay (Mi O)is222 62 222 S22 een oe ee Sodee se LoS: ese ane 1. 40 1.90 1.35 BOG a nGNidi O) es soe oe ee se a See Paso ee scot ane neetee noses do5ce 1. 22 3. 20 3. 29 Otss ONC ©) mane ea ee ee oe ene ta sees SpE Ne Aa a ee eae 1. 66 1. 20 2. 29 Water (raO)abovewl0C'@ --25 2520 265 ele ens cons uecdissecesoeescse 127 . 60 oD Wiser (sO) i helowsl lOw Gs cece hc te Se ecco ee ett sce None. 20; | Seen aoe STO eens eae eee eee ee MEE Te 2s chee ie SS 100. 21 99. 72 99. 61 (1) Amphibole from Custer County, Idaho. E.V. Shannon, analyst. Manganese and titanium were not estimated but were colorimetrically shown to be unimportant. ; . (2) Hudsonite, Cornwall, Orange County, N. Y. J. L. Nelson, analyst. S. Weidman, Am. Jour. Sci., vol. 15, p. 231, 1903. - (3) Hastingsite, Dugannon, Ontario. Adams and Harrington, Amer. Jour. Sci., vol. 1, p. 213, 1896. The Idaho material is nearer hudsonite in composition and hence may be designated by this varietal name until the character and relationships of these minerals are satisfactorily interpreted. BERYL (344) Beryllium-aluminium silicate, 3BeO.- Hexagonal. Al,03.6SiO». Only two occurrences of beryl have thus far been reported from Idaho. 294 BULLETIN 131, UNITED STATES NATIONAL MUSEUM LATAH COUNTY Beryl is found in the pegmatites of the mica mines near Avon associated with feldspar, quartz, mica, etc. The mineral has been especially mentioned from the Levi Anderson and Muscovite mines, and probably occurs in others. Specimens from this locality show prismatic crystals up to 5 cm. in diameter and 15 cm. long. These have fairly smooth prismatic planes but the terminations are in- complete. In color they are all pale yellow-green and they vary from translucent to transparent. Some small fragments might be cut into pale colored gems. Often the crystals are greatly fractured and many of them are iron stained. NEZ PERCE COUNTY Ernest Schernikow of New York has reported the finding of two good blue beryl crystals near Lewiston. These were obtained from an Indian squaw who would not reveal their source.” THE GARNET GROUP The garnet includes a number of well-defined minerals crystalliz- ing in the isometric system and having the general formula: 3R/’0.R//"203.38i02 These vary by replacement of both the bivalent and trivalent oxides, thus R’’O may be FeO, CaO, MgO, or MnO and R’’’,0, may be AlLO,, Fe,O,, or Cr,O;. The end members of the group which are important in Idaho occurrences are: AT RT CGE ace Aen Se be See ed Sed aL ee Nal ee 3FeO. Al,03.3Si02 SPESsar Gite see. Sie a NU See a eg 3Mn0.Al1,03.3Si02 Grossullarites. 22-00 See Sana a anne 3CaO.Al,03.38Si02 Andracitesssssa: se sesame Riba ge, tne tay Lap aie 3CaO. Fe,03.38i02 The magnesium garnet, which has not thus far been demonstrated to be the major constituent of any Idaho garnet, has the formula: Pyrope MS PS eh iy a, ey Me SE YS eS eee ee 3Mg0O. Al,O3.38i02 Members of the group containing titanium, chromium, etc., are known but have not been reported from this State. While the ulti- mate classification of any garnet demands an analysis, it is possible, granting certain assumptions, to classify garnets for the purpose of description here by their general properties and mode of occur- rence. There seem to be limits to the miscibility of the several members. From available data it seems that, so far as [daho garnets are concerned (1) to pink to red or purplish garnets in pegmatite are variable isomorphous mixtures of almandite and spessartite; (2) red 14 Douglas B. Sterrett. Mica deposits of the United States, U.S. Geol. Survey Bull. 740, pp. 89-93, 1923. 15 U.S. Geol. Survey. Mineral Resources of United States for 1907, p. 799. THE MINERALS OF IDAHO 295 to brownish red garnets in schists and slates are principally alman- dite. While these are usually very largely almandite it is rare that one of them approaches the maximum refractive index of pure almandite, 1.830, since they usually contain small amounts of pyrope and spessartite which lower the index to below 1.820. The brown- red garnets grade into the last group by increase in manganese and they can not be separated from them either on the basis of color or refractive index. Some distinctly brown-red examples react strongly for manganese; (3) the brown to greenish or sometimes nearly color- less garnets occurring as the products of contact metamorphism at the contacts of limestone with granitic intrusives are variable mix- tures of grossularite and andradite. In this group the composition may be judged with some certainty by the refractive index. ALMANDITE-SPESSARITE SERIES All of the distinctly red garnets of the slaty and schistose rocks and the purplish to rose-red garnets from the pegmatites may be classified as almandite, since they doubtless contain a preponderance of the almandite molecule. The pegmatite garnets having the rose- red color are probably largely free from pyrope and consist of more or less pure isomorphous mixtures of the almandite and _ spessartite molecules. Thus their composition can be estimated from their refractive index as follows: Almandite..._.....-__- Rrefractive index between 1.820 and 1.830 Almandite-spessartite___ Refractive index between 1.810 and 1.820 Spessartite______________Rrefractive index between 1.800 and 1.810 This relationship may be completely confused by the entry of a little of the low index pyrope molecule into the mineral. The classi fication by color is fairly reliable, most but not all of the notably manganiferous garnets having the rose tint. The color is, however, the only basis for classification of the loose grains and pebbles found in placers, in the absence of a chemical analysis. It has, of course, been impossible to note all of the occurrences of red garnet known in the State, especially in the heavy residues from placer sands, and only a few of the more important can be mentioned here. ADAMS COUNTY Almandite is mentioned from the Peacock claim by Palache,'® but it is believed that the mineral was identified by color and specimens conforming to the description given, although red brown in color and superficially resembling almandite were found to be almost free from ferrous iron and to be andradite. Palache’s description is accord- ingly given under andradite. 16C, Palache. Amer. Journ. Sci., vol. 8, p. 300, 1899. 296 BULLETIN 131, UNITED STATES NATIONAL MUSEUM BOISE COUNTY In Boise County and many of the adjacent counties the heavy residues from placer gold washing operations contain abundant gar- net ranging from fine sand to rounded pebbles the size of a walnut. These are deep red in color and many of them are of gem quality. All of these are brownish-red in color, no distinctly rose red ones hay- ing been seen. A specimen of coarse concentrate from Centerville contains numerous such garnets. One bright red trapezohedral crystal 4 mm. in diameter has an index of refraction between 1.80 and 1.82 as has a brownish red irregular fragment from the same lot. A bright brownish-red trapezohedral crystal had an index very close to 1.815. v. In addition to embay- ments filled with the groundmass the forsterite carries a few inclusions of iron ore and chains of gas or liquid inclusions. The mineral shows no signs of alteration except for a narrow reddish |») border which probably represents incipient alteration /»/ to iddingsite. A Rosiwal determination on two thin sections showed 24.9 per cent by volume or 26.4 per cent by weight of olivine. The nepheline basalt carrying the forsterite is a rare rock. The rock forms a little knoll on a ridge that descends north- east along the north side of Wood Creek in the SW. ly of the SE. i sec. 18, T. 38., R. 38 E. Boise meri- dian. LEMHI COUNTY & 4 Forsterite occurs as a contact-metamorphic min- eral in two places in the Spring Mountain district in Lemhi County. In Dry Gulch on the Colorado group of claims where a quartz diorite dike invades the limestone the contact is cut by a tunnel which shows the metamorphic effect of the diorite intrusion. / The metamorphically developed minerals include cal- y cite, coarse flecks of muscovite and some biotite, CP all readily recognized megascopically. In addition Fic. 77—Forster- Pepperlike specks are scattered through much of ie. Bruce Es- the rock which, when examined microscopically, TATE, LEMHI ; 3 Obnc Gack prove to be forsterite, the iron-free olivine, and a little garnet. Ore minerals do not occur associated with these contact minerals, but a vein a short distance up the hill contains argentiferous galena, manganese oxide, pyrite, and chal- copyrite in a siliceous gangue.*! The third locality for forsterite, and, to judge from the single specimen available, the most important mineralogically, is the Bruce Estate, which, according to Umpleby,® is a large low-grade 30 George R. Mansfield and E. S. Larsen, jr. Journ. Wash. Acad. Sci., vol. 5, pp. 463-468, 1915. 31J. B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 88, 1913. %2J. B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 89, 1913. THE MINERALS OF IDAHO 309 contact-metamorphic copper deposit extending south from Dry Gulch in the Spring Mountain district. Ludwigite from this property is also described elsewhere in this volume. The specimen in question is a banded granular mass made up of about equal parts of granular magnetite and pale brown forsterite. There are small cavities in the forsterite lined with minute tabular forsterite crystals and later filled with calcite. These minute tabular crystals, when lying on the 010 face, give an optical interference figure indicating the obtuse bisectrix perpendicular to this plane Qa) mt NG 78 (Ay) FiGs. 78-79.—78, OLIVINE. VERTICALLY ELONGATED CRYSTAL FROM BLACK SAND FROM MINIDOKA. 79, OLIVINE. CRYSTAL ELONGATED ON THE @ AXIS with the axial plane across the vertical elongation. The mineral is therefore optically biaxial and positive with X=6, Y=c, Z=a; 2V very large. The refractive indices are: a=1.640, B=1.653, y =1.675. Several trials were made with various dilute acids with a view to dissolving out the calcite filling of the cavities in order to secure crys- tals for measurement. Practically all acids which dissolve the cal- cite attack the forsterite sufficiently to destroy the luster, but with acetic acid some measurable crystals were obtained, although they were so dulled as to give very poor measurements. The habit of these is shown in Figure 77 and they give the following forms and angles: 310 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Measurements of forsterite, Figure 77 Form Symbol Measured Calculated Quality, description tee ES No.| Letter Gdt. Miller 9 p g p ° , ° , ° / ° , Te eeone een Oco 010 90 00! 0 00); 90 00 PAE eae se Se ke oO 110 90 00 | 65 O01) 90 00 iA See co2 120 90 00 | 47 01! 90 00 yO bt / peek ee 005 150 90 23 14] 90 00 ol ape sete | 03 03 39 05| 0 00} 41 20 Ghee ose ce = | 1 lll 54 06 65 O1)} 54 15 CHRYSOLITE (376) OLIVINE, PERIDOT Magnesia-iron silicate, (2Mg,Fe)O.SiOz. Orthorhombie. Chrysolite or olivine has been reported from several localities as a constituent of basaltic igneous rocks in which it occurs as micro- scopic grains. It has also been described as a constituent of heavy concentrates from sands worked for placer gold from several localities along Snake River of which the following description is typical.* MINIDOKA COUNTY While olivine occurs sparingly in all of the sands from Snake River localities as clear pale-yellow angular grains, in several samples from Minidoka it is present as clear pale lemon-yellow crystals with highly lustrous faces. These resemble small topazes or crystals of chrysoberyl and their identity was not suspected until they were measured and found to have the angles of olivine. The dominant forms present are the prism m(110) and the dome A(021) with the prism s(120) and the brachypinacoid 6(010) less prominent. The macrodome d(101) and the pyramid f(121) occur rarely as very small faces as shown in Figure 78. The combinationof forms is the same on all of the crystals measured, but they vary in development, ranging from short prismatic parallel to the vertical axis (fig. 78) to moderately long prismatic by elongation on the @ axis (fig. 79). Similar clear yellow olivine grains from other Snake River localities do not show measurable faces. Occasionally the brilliant yellow crystals of olivine have an outer coating of pale brown clay, and many of them contain included grains of magnetite. The forms present were identified by the following measurements: 8 Earl V. Shannon. Mineralogy of some black sands from Idaho, etc., Proc. U. S. Nat. Museum, vol. 60, art. 3, p. 27, 1921. THE MINERALS OF IDAHO oe Measurements of olivine from Minidoka | Form Symbol | Measured Calculated s | Quality, description =: No.| Letter | Gdt Miller | ¢ | p ¢ | p | ° , | ° / | ° / | ° , Ae W0ern oes Oco 010 Good 00 | 90 00! 0 00} 90 00 2, co 110 Very good. 90 00 | 65 01) 90 00 3 co2 120 Good 19 | 90 00 | 47 01) 90 00 4 02 028 |e do - 00 | 49 16 0 00 | 49 33 5 10 101 Very poor 00 50 48 | 90 00/| 51 32 SCAPOLITE GROUP (386) Calcium-aluminium silicates, ete., variable. Tetragonal. The scapolite group includes a number of silicates of varying com- position. These are commonly regarded as consisting of isomorphous end members, marialite and meionite, having the following com- positions: VICIOIIUL Gas er we SNe Sh oF dn 4Ca0.3Al:03.6Si0O2.(CO2,803). WaT TG Goe en Le ose el 3Na20.3Al.03.18Si02.2 NaCl. Several intermediate members of the series have received names as listed below. While the optical properties naturally vary some- what, with the variation in proportions between the CO, and SO, in the meionite molecule, the various intermediate isomorphous mixtures of the two end members may be identified by the optical properties which are as follows: Si Birefrin- Name Composition | € w gence Marialito: 22222 s2. 2 leks tek Majoo Meo-_------- | Uniaxial (—)______ 15537 1. 5389 0. 002 Mizzonite..22..:55-22--..5).2_- Mazs Megs.....---|----- Ong --ce0 so 1. 588 1,551 013 Wrermerites = 2222 2 Maso Meso_-.-----|_---- O0e sae 1. 545 1. 567 022 ae5 Mezs.._.__-_|----- doe [sp Cece = Bos |e Metonite:. <= 22-222 22s. ss. Mao Meto-------|----- dO as es | 1.560 1. 597 037 The composition of scapolites from Idaho has not been determined by actual analysis and the classifications given below are based upon optical determinations. ADAMS. COUNTY Scapolite, probably mizzonite (dipyre), occurs in the metamorphic deposits adjacent to granodiorite contacts in the Seven Devils district, and has been especially noted at the Helena mine. It appears to be for the most part confined to the impure shaly portions of the limestone.*4 34D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 63, 1920. 312 BULLETIN 131, UNITED STATES NATIONAL MUSEUM CUSTER COUNTY The complex sodium-calcium silicates of the scapolite group occur rarely in the contact-metamorphic silicate rocks of the Alder Creek (Mackay) district.® LEMHI COUNTY A specimen of altered calcareous schist from the northeast corner of the Columbia mill, in the Yellow Jacket district, Lemhi County, _ contains many little veinlets of calcite, scattered quartz grains, pale green hornblende, poikilitic mizzonite, and a few flakes of biotite, each intergrown with or included in the other.** SHOSHONE COUNTY In the St. Joe-Clearwater region in the southern portion of Shoshone County, and mainly inciuded in the area of the Avery quadrangle, scapolite is abundantly developed by metamorphism in the Newland member of the Belt sedimentary series. The effect of metamorphism is clearly manifested in nearly the whole of the area by the argillaceous layers of this formation, which become altered, for the most part, to chocolate-colored biotitic hornstones of fine texture in which roundish grains of scapolite whose average diameter is about that of buckshot are abundant. On weathered surfaces the scapolite grains are white, in strong contrast with their dark matrix, from which they project in relief.*7 Through the courtesy of F. C. Calkins a large number of specimens of these scapolite-bearing rocks have been available for examination. The specimens containing rounded or nearly spherical bodies are most abundant. Typical ones of these are shown in Plate 7. The masses of scapolite vary in size and become larger and very poikilitic until they coalesce and form masses which on weathered surface have an organic aspect and resemble fossil algae. One specimen examined from the St. Joe River, about 1 mile above Siwash Creek, contains nearly spherical and shot-like masses of scapolite which make up over half of the rock. These average 2 mm. in diameter and are prominent on weathered surfaces. They break free from their matrix, which is fine scaly sparkling dark brown material. The scapolite bodies are whitish and opaque on their surface, but where broken they appear translucent with rather resinous luster. Under the microscope the material of the scapolite masses is extremely poikilitic, inclosing so many grains of other minerals as to make its optical properties difficult of determination. 35 James F. Kemp and C. G@. Gunther. Trans. Amer. Inst. Min. Eng., vol. 38, p. 321, 1908. 3% J.B. Umpleby. U.S. Geol. Surv., Bull. 528, p. 167, 1913. 37 F. C, Calkins and E. L. Jones, jr., U. S. Geol. Surv., Bull. 530, p. 79, 1913. PL. 7 BULLETIN 131 U. S. NATIONAL MUSEUM SCAPOLITE IN METAMORPHOSED ROCKS FOR DESCRIPTION OF PLATE SEE PAGE 313 THE MINERALS OF IDAHO 13 It is uniaxial, negative, and the refractive indices are approximately €= 1.545, w=1.562, birefringence 0.017. These identify the material as probably wernerite. The scapolites often show more or less imperfect crystal form, especially where developed along joints and seams, but the character- istic forms are the rounded shot-like masses (pl. 7, upper). One rock from between Moline and Eagle Creeks contains a large pro- portion of white fine granular patches associated with scattered spheroids of scapolite 2 mm. in average diameter. The scapolite of this specimen, likewise extremely poikilitic, has = 1.550, w= 1.570, birefringence 0.020 and is likewise wernerite. Typical crystals of the mineral, developed along a joint, are shown in the specimen illustrated in Plate 7, lower. These are not terminated, although some of them show prismatic faces. These have the indices €=1.562, w=1.547, birefringence 0.015. . Orthorhombic. AlSiO,. The few occurrences of topaz, well known as a gem stone, which have thus far been reported in Idaho are as follows: CASSIA COUNTY White topaz was reported to have been found at City of Rocks, 5 miles north of Moulton, Cassia County, in 1919.2 This material was not topaz, as shown later, but colorless quartz crystals.* 41 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 234, 1900. 42U.S. Geol. Survey, Mineral Resources of United States for 1919, pt. 2, p. 179. 43 Miles E. North, Reno, Nev. Personal letter, 1920. 320 BULLETIN 131, UNITED STATES NATIONAL MUSEUM CLARKE COUNTY Several good topaz crystals, colorless, and pale yellow prisms up to 7 mm. in diameter are reported to have been found by Mr. C. A. McCafferty, of Ideman, on Camas Creek.‘ IDAHO COUNTY A clear bluish topaz of great size was found in gold-bearing gravel on a tributary to Paddy Creek in the Warren district. ANDALUSITE (398) Aluminium silicate, Al,03.SiO». Orthorhombic. The following localities for andalusite in Idaho have been reported: BLAINE COUNTY Andalusite occurs as small grains and crystals as a contact mineral in metamorphosed shales at the contact of the large granitic mass west of Hailey in the Wood River district. LEMHI COUNTY Andalusite (chiastolite) is reported to occur with garnet and am- phibole in metamorphosed Algonkian sedimentary rocks in Lemhi County.” SHOSHONE COUNTY In the metaporphosed rocks surrounding the quartz-monzonite batholith of the Coeur d’Alene mining district andalusite is developed in some of the more aluminous beds of the Prichard formation in close proximity to the contact. This mineral forms prismatic knots a few millimeters long in a black metamorphosed slate, derived from the Prichard, near the monzonite contact on the Dobson Pass road, but although present in many other localities this mineral is not elsewhere conspicuous megascopically because of its occurrence in small irregular individuals without crystal form. Where it is abundant, however, it. gives the rock a pinkish tinge.* VALLEY COUNTY Andalusite occurs in the Yellow Pine quicksilver mining district in Valley County. The original sandstones and quartzose conglom- erates have been altered to hard quartzites and the less pure sand- stones to quartz schists. A specimen of the schist collected as typical ot the thick layer on the ridge southwest of the Smith camp proved 44H. T. Stearns. U.S. Geol. Survey. Oral communication. 45 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 243, 1900. 46 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 195, 1900. 47J.B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 31, 1913. 48 F, L. Ransome and F. L. Calkins. U.S. Geol. Survey, Prof. Paper 62, p. 50, 1908. THE MINERALS OF IDAHO 321 to be made up mostly of andalusite with some quartz, phlogopite, sericite, magnetite, and rutile. CYANITE (400) Aluminium silicate, Al,O3.8iOz. Triclinic The only important locality for cyanite thus far known in Idaho is in Shoshone County. SHOSHONE COUNTY Cyanite is frequently developed in metamorphosed sedimentary rocks of the Belt series in the southern portion of Shoshone County, especially in the southern half of the area of the Avery topographic sheet. The mineral occurs in micaceous schists as prismatic rude crystals, some of which reach a length of 30 cm. Many of these are coated on the outside with mica and a considerable proportion of them are completely altered to pseudomorphs of mica. Fine speci- mens may be obtained in places. Some specimens, the exact locality for which was not learned, contain abundant fine blue blades in small segregated quartz veins and green blades in micaceous schist adjacent to such veins. A specimen from 2% miles south of Trimmed Tree Mountain contains pale blue blades of cyanite up to 5 mm. in width by 3 cm. in length in a coarse matrix of chlorite, biotite, feld- spar, and black tourmaline. GADOLINITE (404) Basic silicate of beryllium, iron, and yttrium, approximating the formula Monoclinic. The only reference to the occurrence of the rare earth mineral gadolinite in Idaho is found in an analysis published in a Russian journal. The locality of the mineral is not given more definitely than simply Idaho in North America. The gadolinite analyzed had a specific gravity of 4.382. The analysis gave the following results: Analysis of gadolinite from Idaho (GQ. Chernik (Tschernick), analyst) Per cent Ree eri ACG ECO) sen teh CN eta ye ee eas 9. 98 PerrOus irom, (HeO) se ses anews E Pn e e e e e 12. 74 PUCCIO) eng tk ae ee ie ee Be Seo eee mL Maines (CA) = een ee cee ee ee Se. eee ae . 60 Se eea li) eck eer ee Le eee ee 24, 41 UME YG) Tet Um (Mu CO) 3)) Peteceond tem ae etc cn ee, ial 2. ey, . 30 SiaererenaVa, Oo ae ee ae, Se ee eee ae eee 42. 94 1. 94 Ceria (Ce203) BEES ots TY BE EAS BE cet eee) are ee eR gee eS eee ee =f 49 ©. S. Larsen and D. C. Livingston. Geology of the Yellow Pine mining district, Idaho. U.S. Geol. Survey, Bull. 715, p. 78, 1920. 80 Chernik. Journ. Soc. Phys. Chim. Russe., vol. 36, pp. 25-27 and 287-301, 1904; abstract Zeitschr Kryst. vol. 48, p 78, 1907. 543847—261 22 322 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Per cent Lanthana (La,O3), Praesia (Pr203), Neodymia (Nd2O3)_-_-------------- Syio2 Alumina (A],03), soda (Na,O) and potash (K,O)_------.--------------- Trace. Water: (HsQ) 2/05 eee po 2 aes 2 Sateen ak ieee Tae 2 eee ee a ee . 48 FS Gea ie he a Ra pl ae sk 8 le ORE Aan eR cn pe ae ee 99. 12 A second mineral occurring as dark bottle green inclusions in the gadolinite was also analyzed with the following results: Analysis of mineral included in gadolinite (G. Chernik (Tschernick), analyst) Per cent ViGurIa ONG O pee tee Ne oh Me Sys GE EME 2 aes oo a 51.-94 Gera (Cer Os) ers ae see a a eee ee eae HM SARS Ne, ant EE ae 14. 49 SSERTE ASE eee ee res She RN BS a ae rahe ae a pe 26. 08 Beryilia (BeO) See. As) ee ee ee ee eee . 54 TESOTLEVE (Dela Og) ho eee es Meee ah ah AC se EES yd EES eS eee PHU Rerroussirons (bP e@) 2s WN be oe Pec te ek eh eee ae 1. 58 Time;(CaQ@) iso 2 Soe kk ee ee ee eee . 62 Magnesia (MgO), Manganese (MnO), potash (KO), soda (Na2O)-_-_---- Trace. Water (ETS O)) ate Fee erate Oe re ca ene A a see ener a rer 97: PRO tallies sn is oe a hw eee al aA Sh Ea SN er as ee 98. 99 The specific gravity of the latter mineral is 4.536. Chernik states that it is a variety of gadolinite with the formula 16(Y203.2Si0,). 2(2Ce,03.3Si02). ThSiO,..Be.SiO,.2FeO.Ca0.5H.0. Doelter * gives as the formula for the gadolinite of the first analysis: 3(Be.Fe)O. Y203.28i02= Be2Fe Y 2Si2010 and for the mineral of the second analysis: It -TET iV Rs Rao RSigoO147-5H20 with RO:R.,O, :SiO, as 0.8:1:2. Doelter states that this can not be gadolinite and is either a mixture or a new mineral. ZOISITE (406) Calcium-aluminium silicate, Orthorhombic. 4Ca0.3A1,03.6S8i02.H20. Zoisite, both the ordinary whitish-colored material and the pink variety which is called thulite, have been identified microscopically in the Seven Devils district in Adams County and a single lot of specimens of zoisite from the Avery quadrangle in Shoshone County has been examined. ADAMS COUNTY Zoisite occurs in the Seven Devils district as a contact mineral as described by Livingston and Laney. At some places, notably the 51 ©. Doelter. Handbuch der Mineralchem., vol. 2, p. 179, 1915. 82D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, pp. 48, 62, etc., 1920. THE MINERALS OF IDAHO 323 Arkansaw and Helena mines, the feldspars of the altered granite have a decidedly pinkish tinge due to the alteration and develop- ment in them of a pink mineral, probably the pink variety of zoisite, thulite. In some specimens the pink mineral is abundant, especially so in veinlets which seem to have developed along fractures in the granite. While no chemical work has been done on this mineral its optical properties indicate that it is thulite. All of the feldspars, whether pink or not, contain much zoisite. In the Red Ledge mine—a low-grade disseminated deposit in por- phyritic and fragmental andesite—zoisite is rather widely distributed throughout the rock, and in some places, notably in the highly miner- alized rock forming the ore shoot in the main tunnel, it is abundant. It is usually formed as irregular masses of interlocking crystals or blades, and was apparently developed from both the feldspathic material in the groundmass and the feldspar phenocrysts. Much of it occurs in the vicinity of more or less completely altered pheno- cysts. SHOSHONE COUNTY Several specimens from a locality southeast of and across a branch of the Clearwater River from Goat Peak near the southeast corner of the Avery quadrangle contain zoisite in prismatic crystals in a quartz gangue. The specimens, which are from a surface out- crop, are somewhat iron stained. The zoisite is abundant as rude prisms up to 1 em. thick by 2 cm. long. Adjacent to the walls of the veins the quartz contains some biotite and garnet. Where un- stained by limonite the zoisite crystals are dirty white in color. They possess the usual cleavage parallel to b(010), are untermi- nated, and are bounded simply by the unit prism m(110) which is somewhat rounded and striated. Under the microscope the mineral is filled with small inclusions, aligned in a vertical direction, but is otherwise transparent and colorless. It is biaxial positive with 2V medium small, dispersion strong, r (|e2e COP Ree ee ee eee 29 43 | 48 17) 29 54/48 O1 —1 Il CGO Eee eee ee eee eS 51 30 | 34 54] 51 42] 35 13 — | DAZ pele Nery DO0re= sho ee Se ee 83 57 48 21] 81 03 | 48 16 —21 | 211 Ve G11 nn ee eee ee eee eee 25 55/51 38] 25 58/51 41 -14 ZIP GOOG Meee See ee 51 30 | 54 23] 51 42) 54 41 | No. WIMP wrwe rather short prismatic in habit. The same crystal, partly remeasured in normal position gave the following angles: Form Letter Measurements of epidote, Figure 94, normal position Symbol QGdt. Miller — o0 100 © 110 01 O11 0% 012 —1 lil —4| 112 —21 211 —-1% 212 Calculated Measured Quality, description = = ¢ | p e p pauses ° , | ° , ° ’ ° , Mery, 200d ss 22 222 22 ---| 9 00} 90 00] 90 00 90 00 Excellent: :- = 22-22-64 .22-25 2 35 14 | 90 00] 35 00} 90 00 (GOOG Se eo ee ee 15 10 | 62 00 | 14 44) 61 49 We dics oe eee ede s 28 37] 46 00| 27 44 | 45 34 (Coo anos es ae a eae 23 33/62 51 | 23 37/ 63 06 WOLysDOOr2 2 32 55= ) e e 8 56|42 48] 9 53] 42 30 ROOT Stee ts a a ee 48 48| 69 52]48 41 | 69 55 (LOOM ee 8 oe eet eee 41 05] 49 55/41 10/ 50 11 The crystal illustratd in Figure 95 is doubly terminated and_is This is likewise drawn with the elongation vertical although it was measured in normal position and gave the following angles: Measurements of epidote, Figure 95, normal position No. CWNMAaPwONH Symbol Gdt. Miller Quality, description (GO0d ree een eee eae Very poor.._...-- Wei 200d Sot ne eee ano NGLY? DOOME ens aee ee ee ease we enaeen Measured Calculated Y p " p ° , ° , ° , ° , 90 00 | 26 27] 90 00] 25 24 90 00 | 90 00] 90 00] 90 00 35 37190 00} 35 00] 90 00 14 42] 62 02|14 44] 61 49 28 10] 45 51 | 27 44/45 34 90 00] 60 41 | 90 00] 60 06 90 00] 70 10} 90 00] 71 35 90 00 | 48 41] 90 00] 47 54 90 00] 38 19| 90 00] 38 18 90 00] 8 24} 90 00] 8 57 33 43 | 63 08 | 23 37] 63 06 9 50] 42 37] 9 53] 42 30 41 57] 50 36/41 10] 50 11 328 BULLETIN 131, UNITED STATES NATIONAL MUSEUM The crystal illustrated in Figure 96, also measured with the elon- gation vertical, gave the angles recorded in the following table: Measurements of epidote crystal, Figure 96, elongation () vertical Form Symbol Measured Calculated aa eae Quality, description a No.| Letter Gdt. Miller ¢” Die gy” pe = ia | | ° , ° , ° / ° ¢ doce xt a8 Oy 001 G00 oe es a a 63 38] 90 00] 64 36/ 90 006 Dees see Sali OOO 100 Wery: 200d 2232. 3S Sea. ee 0 04/90 00; 0 00} 90 00 Sn leet wee me oO 110 x cellent 222222 a neoee a eee ew ee eae 0 00/35 09} O 00} 35 00 Bee e035 Es +10 101 90 00} 29 54/90 00 Di Nee 40 102 90 00) 42 06} 90 00: Galena ee —10 101 90 00 | 51 42/90 00 Diteseee a) 20 102 90 00] 81 03 | 90 00: Saree se ae —40 103 90 00/86 57] 90 00 Oh vai ete ae —20 90 00} 25 58} 90 00 10 | new?___-| —70 705(?) 90 00 | 40 18} $0 00 TRON 01 O11 31 22] 64 36/31 31 LOWS oka —l iil 35 05] 51 42 | 35 13 tShlgpae eee —% 112 48 00 | 81 03 | 48 16 Var genes = —2 221 32 28] 25 58] 32 19 15 eee -14% 212 54 35/51 42 | 54 41 160) eee es —21 | 211 Godda eee Ree ne ee eee een $5. 33.| 51) 467] 25) 158" | ol 48 | BLAINE COUNTY A specimen of massive dark green epidote from Blaine County has been sent to the National Museum for adeeaoe by B. Z. Smith, of Mountainhome, Idaho. CLEARWATER COUNTY Portions of deep green well-formed crystals of epidote up to 3 cm. in diameter are present in considerable number in a coarse concen- trate from placer gravels in Clearwater County associated with rutile, corundum, tourmaline, garnet, etc. CUSTER COUNTY Epidote is very rare in the contact-metamorphic copper deposits of the Alder Creek (Mackay) district as contrasted with its abundant occurrence in the deposits of similar genesis in the Seven Devils district. Specimens from the Basin prospect ou the mountain across Park Creek from the point where the Ketchum-Mackay road crosses the Trail Creek divide, contain epidote associated with garnet, heden- bergite, vesuvianite, wollastonite, prehnite, galena, etc. The epidote occurs especially as the lining of small open spaces which were later filled with prehnite. The epidote seems to be the latest of the sili- cate minerals except the prehnite, but some perfect doubly termin- ated crystals of epidote are completely surrounded by prehnite. The crystals are all of simple lath shape elongated on the b axis and flattened parallel to (101). The orthodome zone contains broad faces of (101) with narrower faces of (105), (103), (101), (301) and, THE MINERALS OF IDAHO 329 in one case, a face giving the indices (10.0.1). The epidotes are minute, rarely over 2 mm. long and are limpid transparent yellow- green in color. LEMHI COUNTY In Lemhi County epidote is often strikingly developed in the re- crystallized sedimentary rocks and also occurs as a contact mineral in the Mayflower group of claims in the Mackinaw district. The deposits here consist of quartz replacements along a brecciated zone in siliceous schist. The brecciated material is locally almost en- tirely made up of garnet with associated epidote and magnetite.*4 At the Carmen Creek mine in the Carmen Creek district the ore occurs as lenses of quartz distributed through a band of schist 8 to 15 feet wide, the quartz totaling about one-third of the width. Much of the schist itself is mineralized. In addition to the metallic minerals actinolite and magnetite are widely developed; green epidote is less common. Magnetite occurs in the vein quartz but the actino- lite and epidote are confined to the adjacent schist.® OWYHEE COUNTY Epidote is of common occurrence in places in the Silver City dis- trict where it replaces basalt or some other igneous rock adjacent to the silver veins. It is for the most part massive with aphanitic appearance and the usual yellow green or pistachio green color. A specimen from a raise 1,300 feet from the portal of the Blaine tunnel shows this fine grained epidote replacing basalt adjacent to the silver vein. A number of specimens from the dump of a tunnel on the south side of Long Gulch below the Blaine tunnel contain epidote. In the first of these small yellow-green epidote crystals replace frag- ments of altered rock inclosed in the quartz-adularia vein. In another, massive epidote haloes surround fragments of the igneous rock included in the vein and, in the third, a breccia of basalt frag- ments is cemented by quartz and massive yellow-green epidote, the latter in masses up to 2 by 6 cm. in size. No epidote has been seen from the contact-metamorphic ore- bodies of the South Mountain district. SHOSHONE COUNTY Epidote occurs as dull-green aphanitic veins and surfaces of im- perfect curved opaque greenish-yellow crystals lining fractures in an altered basic dike on the Corby claim on Pine Creek. PREHNITE (411) ; Calcium aluminium silicate, Orthorhombiec. H,0.2Ca0.Al,03.38i0>. Prehnite has been found in Idaho in two contact metamorphic deposits in Custer County, associated with garnet and epidote, etc. u J. B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 155, 1913. 55J.B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 127, 1913. 330 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Its occurrence in this association is of interest as it forms a link connecting such lime-silicate contact phenomena with the formation of zeolite-bearing veins in which prehnite is commonly found else- where. A single specimen from Kootenai County contains prehnite associated with zeolites. CUSTER COUNTY J. B. Umpleby reports prehnite as occurring in the ore of the Phi Kappa mine in Phi Kappa Canyon, tributary to upper Lost River in the Hailey quadrangle.** He also found it in specimens from the Basin group on the mountain nearly due north of and across Park Creek from the point where the Ketchum-Mackay road crosses the Trail Creek divide. Specimens from the latter locality have been examined in detail. The prehnite occurs in a rock largely composed of brown garnet as the filling of small cavities up to 3 cm. in diameter, which are lined with transparent green prismatic epidote crystals up to 5 mm. long, the prehnite evidently being the youngest mineral of the aggregate. Occasional isolated grains of sphalerite and galena occur in the prehnite. The prehnite is colorless to white and transparent to translucent in the hand specimen. It does not form free crystals but is in bladed cleavable masses. Close inspection is necessary to detect the mineral as the cleavage is not conspicuous and the prehnite closely resembles quartz to the naked eye. Under the microscope in powder the mineral is colorless and transparent and is biaxial positive with 2V medium and moderate dispersion, r>v. It exhibits the confused twinned structure and anomalous optical behaviour characteristic for the species. Sections perpendicular to an optic axis show no extinction but abnormal interference colors. The refractive indices, though somewhat variable, average a=1.626, B=1.629, y=1.652, all + .003; Birefringence, y—a=0.026. A sample, purified by means of heavy solutions, was analyzed with the following results: Analysis of prehnite, Basin prospect (E. V. Shannon, analyst) Per cent Silicag(SiOs) a = as ee a as DP ae 42, 26 PAU nama prin 7 CANS Og) aes cae ase eee Oe ee 24. 65 Herric-oxide! Ci'es@3) sk 2 oe EIS SER AE CTE SR ERE AIS oe ee 2. 10 inte (CaO). 2422 S22 a ee eee Te AI coe VT erie See kak ee ee eee 26. 86 Marnesiar( MgO) s.e4 sc be ae I oh oe ee ee oe eee ee . 04 Bariumsoxiden(BaO) soa eee he oa ee a a pe None. Water CHce@)itabove: Td Oo nC x0 cee ipsa as A ae ee 4,72 Wiater: Cs ©) below ill OSk a ae re eee ee ie ae eee ee None. TCO Gea ce cate hs SMR Le as eI gE Apc esa 100. 63 The composition shown by the analysis is that of normal prehnite. 5 J.B. Umpleby. Personal letter 1923, to be published in report by the U. S. Geological Survey on the Hailey quadrangle. THE MINERALS OF IDAHO go KOOTENAI COUNTY A specimen from Post Falls contains prehnite associated with stilbite, laumontite, etc., in a seam in a diabasic rock. The prehnite forms minute tabular crystals lining cavities as well as white to greenish granular masses. Optically the mineral of this occurrence is biaxial positive with 2V approximately 60°. The acute bisectrix is perpendicular to the tabular face of the crystals. The dispersion rv and three cleavages which intersect at high angles. 37 J, B. Umpleby, W. T. Schaller, and E. S. Larsen. Amer. Journ. Sci., vol. 36, p. 385, 1913. 8 J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 52, 1917. 39 Waldemar T. Schaller. U.S. Geol. Survey, Bull. 610, p. 152, 1916. 332 BULLETIN 131, UNITED STATES NATIONAL MUSEUM There is no known mineral species from which it may not readily be distinguished optically. Its birefringence and twinning suggest albite, but its refractive indices are much higher. Its relief, lack of color, and cleavage in thin section might at first glance lead to its being mistaken for a colorless pyroxene, but its refringence and birefringence are lower and its extinction angle is less than in all pyroxenes except aegirite. It is believed that custerite is a mineral of rare occurrence, for its optical properties are so distinctive that it would scarcely have been overlooked. In the hand specimen, however, it is so unpromising in appearance that thin sections of it. may never have been cut. The mineral should be looked for in fluorine-bearing contact zones, apparently in the border phases of metamorphism. When heated gently in the closed tube custerite turns a transitory yellow and phosphoresces with a golden yellow light. As seen in a darkened room the color of the glow is like that of a deep colored golden beryl. On increasing the heat the phosphorescence is de- stroyed and water is given off. The mineral does not decrepitate. A white ring due to fluorine is obtained by heating the mineral at a temperature sufficient to melt the glass tube. In the blowpipe flame custerite fuses with difficulty to an opaque white enamel. The mineral is very readily decomposed by acids, gelatinous silica separating so quickly when the powdered mineral is treated with hydrochloric acid (HCl) as to form a stiff coherent mass. The separated gelatinous silica floats around in an excess of acid the solu- tion itself not gelatinizing on further boiling. Custerite therefore does not ‘‘gelatinize’’ like natrolite. The chemical analyses showed that water, fluorine, silica, and lime were the essential constituents, the small amounts of iron and magnesium present being probably due to magnetite and diopside, respectively. Fairly fresh material suitable for analysis was avail- able in portions only of 0.25 to 0.75 gram. The analytical results are shown in the following table: Analysis and Ratios of Custerite (W. T. Schaller, analyst) (1) (2) | Average | Ratios Sade RR a Pa os NL Sa ri saa SE poem hl 2 al seas ie Silicay(Si@3) sat tn as i ae ee ee 32. 13 32. 20 32. 17 0. 536 Mime (CaO) See e ee a See so eR ee Fe) ES PORN Spsplis| es wee hee 65! 1 . 984 AWiatera (Els ©) ee lene See ee a en See Re eT ee 5. 53 5. 06 5. 30 . 294 Bluorine: (his pte gL ea eS Oe a See SRL Qh ses e ee 8.12 . 427 Miasnesia (Mig) tenses so 2 es ia eee 1.19 1.19 1.19 . 030 WisenGtitess:2 2222). Tete is PR ee ee ee eee . 85 1.14 1.00 | mbtal tabi i Qrhweartits. ate sheh peer Sol ai eel Ae aR. 102. 89 | Mess oxy gentiequivalenteotitorines ss.) a5 a oe ee eee ee eee een 3. 42 | Net totalcie 23 ao OT Sa Ie a eI oe 99. 47 | THE MINERALS OF IDAHO oe These results were verified by a partial analysis (water not being determined) of a different somewhat less pure portion of the same specimen of custerite. The results obtained are: SiO , 33.46, CaO 53.93, F 7.29, MgO 1.41, magnetite 2.13. Alkalies were not deter- mined on any of the samples because of paucity of material. Some of the whiter chalky-looking material gave less water than the fresh material, several different samples yielding 2 to 3 per cent H,O instead of the 5 or 6 per cent given in the above analyses. Whether this represents an alteration of the custerite or merely a much impurer sample could not be determined on the scanty material available. The formula derived for custerite is Ca,SiHFO, with some of the fluorine replaced by water (hydroxyl). The composition may be also expressed as a mixture of two compounds, 2Si0,. 4CaO. 2H,O and 2S5i0,.4Ca0.4F, with the first one slightly in excess. The relation of fluorine to water (hydroxyl) can be much better shown in the empirical formula according to which the ratios reduce to Ca,- $i,0,(OH, F), with the ratio of hydroxyl (OH) to fluorine (F) as 2.48 : 1.79 or nearly 4 : 3. No water was given off when custerite was heated to 110°, indi- cating that the water is an inherent part of the mineral. The temperature at which the water does go off was not determined, but the observation was repeatedly made that the phosphorescence phenomenon displayed itself and was destroyed by heat before the water was given off. Some powdered custerite, placed in a watch glass with several cubic centimeters of water, immediately gives a deep red color with a few drops of phenolpthalein. This reaction was described by Clarke, who has suggested that it is indicative of the presence of the univalent group CaOH. Custerite is related most nearly to the minerals cuspidine, hillebrandite, and zeophyllite. CHONDRODITE (415) Magnesium fluosilicate, 4MgO.2SiO)..Mg(F, OH)». Monoclinic. Chondrodite is a mineral usually occurring in metamorphosed limestone but is characteristic of limestones which have suffered regional metomorphism rather than of thelime-silicate zones of igneous contacts. The only occurrence of this mineral that has thus far been recorded in Idaho is in Custer County, where a lens of chon- droditic limestone was found by Prof. L. G. Westgate in mapping the geology of the Hailey Quadrangle in 1914. CUSTER COUNTY Chondrodite occurs in abundance in crystalline limestone from a locality near a small lake in a cirque at the head of Wildhorse Canyon at the east side of Mount Hyndman. The mineral forms rounded 334 BULLETIN 131, UNITED STATES NATIONAL MUSEUM irregular grains from 1 to 2 mm. in diameter which make up approxi- mately half of the rock, the other major constituent being crystalline calcite. The chondrodite shows no definite crystal faces when the calcite is removed by solution in acid. In the hand specimen it appears as grains of the usual resin-brown color. Under the microscope in powder the chondrodite is clear, transparent, and devoid of cleavage; is yellow-brown in color and distinctly pleochroic X=rich golden brown, Y=pale brownish yellow, Z=very pale brownish yellow; absorption, X>Y>Z. It is biaxial positive (+) with 2V medium large, dispersion, r>v, distinct. Refractive indices a=1.631, B=1.640, y=1.657, all +0.005, birefringence, y—a=.026. Asso- ciated with the chondrodite are a deep bottle green isotropic spinel with a refractive index of 1.735 + .002, and less of a colorless micaceous mineral which is nearly or quite uniaxial and positive with a refractive index of approximately 8=1.598. This is doubtless clinochlore. ILVAITE (417) LIEVRITE, YENITE Hydrous lime-iron silicate, H:0.Ca0O. Orthorhombie- 4FeO.Fe.03.48i02. The rare calcium-iron silicate, ilvaite, has been found in the South Mountain mining district in Owyhee County in crystals which, in size and perfection, are equal to the best known from any locality in the world.” OWYHEE COUNTY The ilvaite occurs in the ores of the Goleonda and perhaps other mines in typical contact-metamorphic deposits. A large area of fine grained granite or granodiorite here adjoins an area of highly metamorphosed sedimentary rocks, largely schists, quartzites, and marble. In a broad band of marble near the granite there is a series of masses of contact-metamorphic minerals including hedenbergite, garnet, and ilvaite, carrying in some places pyrrhotite, chalcopyrite, sphalerite, and galena. The minerals are aggregated in the irregular manner of contact-metamorphic deposits, the ilvaite being in bunches scattered through the masses. The specimens of ilvaite consist of im- perfectly crystallized black masses associated with granular reddish- brown garnet; of unterminated crystals having good prismatic planes, embedded in quartz; of large crystals embedded in calcite patches in a fine-grained hedenbergite rock; and of large and fine terminated prismatic crystals embedded in soft limonitie gossan (pl. 8, upper). The unterminated crystals embedded in quartz are commonly prismatic and are deformed by mutual interference but some of 6 Earl V. Shannon. Amer. Journ. Sci., vol. 45, p. 118, 1918. Pers 131 BULLETIN U. S. NATIONAL MUSEUM ILVAITE AND CUSTERITE FOR DESCRIPTION OF PLATE SEE PAGES 331 AND 334 THE MINERALS OF IDAHO ooo them, when removed from the inclosing quartz, are suitable for measurement on the reflecting goniometer. Only the prismatic zone is represented, these embedded crystals, so far as observed, being unterminated by crystal faces. The most common habits of the embedded crystals are like the prism zones of Figures 97 to 100, although all the forms observed in this zone on the terminated crystals were also found on the embedded crystals. The crystals are often ee We Pr s mais |b 100 FiGs. 97-102.—ILVAITE CRYSTALS FROM GOLCONDA MINE, SOUTH MOUNTAIN MINE, OWYHEE COUNTY deeply striated and rounded, apparently by oscillation between the prisms m(110) and s(120). They greatly resemble black tourmaline and upon casual examination might be mistaken for that mineral. The forms present on one of the best of these crystals were identi- fied as: a(100), (010), m(110), A(210), s(120), and d(140). The measurements obtained on one of the crystals occurring em- bedded in quartz are compared with the angles given by Dana for the species as follows: Observed Calcu- -| Average lated, (1) (2) Dana ° / ° /, ° / ° , TTT eve rs a hos ee ee ee eae B 66 38 67 46) 67 12 67 22 FT pear ake ne ea ee 37 28 38 00| 37 44 36 52 ene ee Ban itn 2 eS ea ee concen ne Seeenas 72 42 73 10; 72 56 73 45 336 BULLETIN 131, UNITED STATES NATIONAL MUSEUM This agreement with the calculated angles is as close as was ob- tained on any of the crystals measured. That there should be a discrepancy is not at all surprising in view of the character of the faces which are rounded and do not give sharp signals. Usually the faces give a band of signals a degree or more wide with a central more distinct cross which was measured. Where no central more dis- tinct cross was present it was necessary to take the mean between the two ends of the band. Vicinal faces seem common on ilvaite from other localities and this occurrence is no exception. In measur- ing the prism zone of any of the crystals distinct signals are often noted from narrow planes which give complex indices and differ from crystal to crystal. The best specimens of the Idaho ilvaite are the well terminated prisms like those illustrated in Plate 8. The smallest of these is the single large prismatic crystal about 6 cm. long and averaging perhaps 1.5 cm. in diameter with some smaller attached crystals. The second and larger specimen consists of an aggregate of such crystals in roughly parallel position. Attached to or projecting from these larger crystals were a number of small terminated prisms and it was upon these that most of the measurements were made. When received the specimens were covered with a thin film of brownish limonite of the ocherous gossan in which they were embedded. Scrubbing with a stiff brush removed all of the limonite and left the crystals clean and lustrous. Some drusy coatings of calcite were also easily removed leaving no scar upon the ilvaite. The ilvaite crystals are fragile and liable to crumble if roughly handled owing to the presence in them of minute irregular cracks which thoroughly traverse the mineral somewhat after the fashion of glass which has been heated and plunged into water. This fracturing of the crystals is probably traceable to strains incident upon volume changes in the associated and inclosing minerals during oxidation and hydration. Frequently a crystal seems to have been split longitudinally and the two halves slightly displaced this discrepancy, in one case, reach- ing five degrees. The fracture is parallel to 5(010), the most promi- nent cleavage, and is not visible on the crystal, being located on a deeply striated face. Its location is clearly shown on the projection made from the measurements. The terminated crystals show the same forms in the prism zone as do the crystals embedded in quartz, and the faces are not so good. The crystals are frequently distorted or unsymmetrical, as shown in Figure 101, where a form may be present as a broad face on one side of the crystal and absent or represented only as a narrow line on the opposite side. The results obtained in measuring the ter- minal faces were unsatisfactory. The only measurement of the angle r :r’ over c, which was obtained, gave the value 67° 02’ which THE MINERALS OF IDAHO 837 is 09’ short of the value given by Dana. For the interfacial angle 0 :0''’ the value given by Dana is 40° 29’ and the angles obtained on the Idaho crystals vary from 36° 34’ to 42° 45’. The variation is in part probably due to splitting of the crystals parallel to (010) and in part due to vicinal forms in the same zone. The Idaho Ilvaite has been analyzed by Hillebrand with the fol- lowing results." Analysis of Ilvaite, Golconda mine (W. F. Hillebrand, analyst) Per cent INCa. (SiO) oo 2222.6.0224..25 ee ee ee: 2S 29. 16 Perrin ea (GAN 5 @)s) ema, ook ee eee fe ee a a 22 Ferric iron (Fe,03)_..______-_-__-_---_-- enn EOS © 4 eee 22 20. 40 HETERO USeOmy (He ©) sree eet Pa. ee eee ee 29. 14 Man tanesc.omae. (NMnO) 2... a eee eee ch ane kone eee Sse 5. 51 eT rye) t s F ee cal S a B oe eee 13. 02 INI ONGSIA, CVIBO) 22.2 Oe 5 eee le ae A x cee ea .15 SOG te ONice@)) eee wets. ee SE eo ee en eee SS . 08 Water (H>O)) below. I10° C= 2 22 eo 8 8 A ne ee kee 15 Water (H2@) above 110° C.._... ee ee ee ay le 2. 64 LEG) (nam ee ee ee, oa 100. 77 In the Idaho ilvaite cleavage is present but not conspicuous parallel to 6(010). The fracture is uneven, hardness 5.75; specific gravity 4.059 (Hillebrand). The luster is vitreous and not sub- metallic as described from other localities; color, black; streak black with faint brownish tinge. The mineral is rather difficultly fusible before the blowpipe and upon fusion it intumesces slightly and yields a black magnetic bead. It is readily soluble in hot hydrochloric acid, yielding an amber solution which gelatinizes. Several unsuccessful attempts were made to cut oriented sections of the crystals for optical examination, but the mineral is too opaque to transmit sufficient light in the thinnest sections which could be ground. CALAMINE (423) Basic zine silicate, H,0.2ZnO.Si0O, Orthorhombic, hemimorphice. Calamine is a secondary zinc mineral always occurring as an altera- tion product of sphalerite in the oxidized portions of zinc-bearing ore deposits, where it is commonly associated with smithsonite and usually also with limonite and cerusite. The several Idaho occur- rences are not important as zine ores although fair mineral speci- mens have been obtained from each. CASSIA COUNTY Bluish-white to white radiating sheaves and druses of minute thin tabular calamine crystals occur in cavities in a chalky cellular white rock from the Black Pine mining district in Cassia County (Cat. No. 89,130, U.S.N.M.). 61 W. F. Hillebrand. U.S. Geol. Survey Bull. 591, p. 318. 338 BULLETIN 131, UNITED STATES NATIONAL MUSEUM CUSTER COUNTY In the Alder Creek district a little calamine occurs as acicular crystals set on a base of smithsonite in the Champion group prospect south-southeast of the Empire mine and at an elevation of 8,000 feet, south of Cliff Creek.” It is very rare here. A very few minute bladelike crystals of colorless calamine occur with the aurichalcite described elsewhere in this bulletin, in a specimen from three sets above the No. 4 level of the Empire mine at Mackay. 105 106 107 Figs. 103-107—CALAMINE CRYSTALS. 103, 104, PiIrtsBURG-IDAHO MINE, LEMHI County. 105, PACIFIC MINE, CUSTER COUNTY. 106, RED BIRD MINE, CUSTER COUNTY. 107, BEARDSLEY MINE, CUSTER COUNTY In Northwestern Custer County calamine occurs as bundles of clear white columnar crystals protruding from the walls of small cavities in the oxidized lead-silver ores of the Bay Horse district, particularly the Red Bird, Beardsley, River View, and Pacific mines.** A specimen from the River View mine consists of radiated-compact white calamine making up a cellular mass. Specimens from the Red Bird mine consist of botryoidal masses having a limonite-stained drusy surface made up of minute calamine crystals on which rest a few tiny white cubes of fluorite. The cala- mine crystals are vertically elongated and flattened parallel to the 6&J.B.Umpleby U.S. Geol. Survey, Prof. Paper 97, p. 50, 1917. 63 J.B. Umpleby. U.S. Geol. Survey, Bull. 539, p. 52, 1913. THE MINERALS OF IDAHO 339 &(010) face. The habit is illustrated in Figure 106. One which was measured gave the following angles: Calamine crystal, Red Bird mine, Figure 106 { Form | Symbol | | Measured | Calculated | Quality, description ——— No.| Letter | Gdt. | Miller | | 9 p 9 p ae eee | ese as — | | | ° , o / ° , ° , 1 : eS oe 0 pe vee MIM be neers eee | oe no OO; .. .. | 0 00 beet a nce 0c | 1 odie Ae ea eterna eee 22/90 00! 0 00/90 00 an 22 co TOMY eases Oe ee nas ee ees 51 34/90 00| 51 55/90 00 Bee 2c one POM jean t0le J Meryepods 12.26 oe sel 89 47 | 30 59| 90 00) 31 22 bit ae. _ 40 102 WeryDOOl!- -.-255 62 co eee cose 90 00/16 384/90 00} 16 57 Gute 8: 22 Peter eel. “GOOG. 2203 conc ede eeu eens 90 03 | 61 26 90 00} 61 20 lmipen eco | O1 | | O1L a CG Bene ee ne eee ene fae 25 oe 25 32 Specimens from the Pacific mine contain sheaves of white calamine crystals in cavities of galena-quartzite ore and also colorless crystals of calamine on drusy quartz associated with cerusite in oxidized ore. The crystals are similar to those last described from the Red Bird mine, except that the clinodome e(011) isnot so prominent. The habit of crystals from this mine is shown in Figure 105. These gave the following measurments: Measurements of calamine crystals, Pacific mine, Figure 105 | Form | Symbol | Measured Calculated 7 eth | Quality, description | aa No. Letter | Gdt. | Miller L @ : cae | | | | | ° , ° / | ° , ° / Si acta | 0 OOL... | Poor, dull. .-2 82 cotect shen hace eee O.00 ee / 0 00 2) Oe oo | Qoo 010 Poor, rounded 2 = 22225 2222225 22 2c Se 0 31/90 00) 0 00) 90 00 leit | 10; his Setar ee EOE oa Nance (50 05/90 00) 51 55 90 00 Be so | 008 pee Oe Me ee ee re | 22 12/90 00| 23 03 | 90 00 Be suo -2| O8 Olen Gogg hates cokes 28 ee eee eee | 0 30] 25 37| 0 00/25 32 Giga oa | 10 FOO ip Mire eet fos ne ccs eeeconaet | 90 20| 31 28/90 00) 31 22 Mitta oes\' ha) 301 | Very good..........------------------ /90 19] 61 35 | 90 00 | 61 20 } | | Specimens from the Beardsley mine show similar minute crystals forming druses with malachite and calcite on a siliceous matrix, and on chrysocolla. The latter crystals have the very simple habit shown in Figure 107, the only forms present being 6(010), m(110), and e(011). LEMHI COUNTY Calamine occurs in Lemhi County, particularly in the Pittsburg- Idaho and other mines of the Texas district in oxidized lead-silver ores in the usual beautiful needle crystals, usually set on a drusy base of smithsonite, as in the specimen illustrated by Umpleby.** A speci- men labeled as from the 400 foot level, Flat vein, Pittsburg-Idaho mine consists of manganese-stained clayey material containing cavities lined with long slender deeply striated calamine crystals 66 J.B. Umpleby. U.S. Geol. Survey, Bull. 528, pp. 75, 103, pl. 10, 1913. 340 BULLETIN 131, UNITED STATES NATIONAL MUSEUM of the habit illustrated in Figure 103. Upon measurement these gave the following angles: Measurements of calamine crystal, Pittsburg-Idaho mine, Figure 103 Quality, description ae Form Symbol | Measured | Calculated | | | | No.| Letter Gat. Miller ¢ | p | ° , ° , ° , | ° , tel PD oso toaes Qco 010 Poorsstriateds 2222-260 jase eee 0 00/90 00! 0 00/90 00 On eee uae co LTO Me, So ow. nee sees Dama ee 49 59/90 00] 51 55 | 90 00 Bure seat eae 01 O11 Mery DOOM =t 22 see sate aaa scee 0 00) 25 05| 0 00) 25 32 An fgrsctee SAD 10 101 Raine) SoS a ie ee ae 89 54/31 55|90 00| 31 22 5 tes ee 30 BORE Meese Oss osse- Sse a2 os eee ete le | 89 54/61 18/90 00) 61 20 The prism zone is deeply striated and rounded by oscillation between b(010) and m(110). The specimen illustrated by Umpleby from this mine contains numerous sheaves of the white bladed crystals resting upon smith- sonite. These are flattened parallel to (010). Some of them are unsymmetrically developed and then have a peculiarly monoclinic aspect. On such is illustrated in the drawing, Figure 104. This gave the following measurements: Measurements of calamine crystal, Pittsburg-Idaho mine, Figure 104 Form Symbol Measured Calculated cae Quality, description | No.| Letter | Gdt. | Miller ? p | ef) Xp a a = |-- = | ° , ° ‘ ° , ° , Pilbara ees COON Pr .O10r st Rairs blurred 22 testes oie Aenea 0 00/90 00] 0 00] 90 00 2s \ameee ee onli e110 dO SRL Aas ROT LE 51 08 | 90 00] 51 551/90 00 Ziqgauise ae COD eh TBO? Th Poor Se eee LUN Tue a ea A ene 15 03/90 00] 14 19] 90 00 Ae ic tens Hoe 0 001 Rairiminutescotieetiekel ales be eee O00) Zan eee 0 00 Bi See eae. 10 101 Goode neck Sen RE LL ai eee 89 50| 31 42] 90 00] 31 22 Giee yey 30 301 Poors dtl: ee TMs ES Fe 90 38] 60 57|90 00] 61 20 Fee LEE 20 201 Dull; n./syes iets EIU i ye 90 00| (n.s.) | 90 00] 50 39 Selves a & 21 211 Goo dea ee se Noein 68 35 | 52 49/68 36] 52 38 ! 1 In these crystals again the prismatic zone is strongly striated vertically and the interfacial angles are rounded by oscillation. OWYHEE COUNTY A single specimen in the Museum collections (Cat. No. 65653, U.S.N.M.) from the Laxley mine, South Mountain district, contains. calamine as drusy crusts of minute crystals and drusy surfaced globular masses lining cavities in compact limonite. The calamine crystals are normal in habit and tend to be aggregated into cockscomb like forms or groups. THE MINERALS OF IDAHO 841 TOURMALINE (426) Complex borosilicate, with the general Rhombohedral, formula: 12Si0O,.8B.03.9(Al,03.3RO) Hemimorphice. .3H20. Tourmaline is in reality a group of minerals represented by the above generalized formula and varying greatly in composition by variation between alumina and the bases represented by RO in the above formula and also in the character of the latter which may be ferrous iron, manganese, lime, magnesia, potash, soda, lithia, ete., giving rise to several varieties which have received separate names. With the single exception of the Boise County occurrence, the tourmaline thus far found in Idaho localities is all of the black iron- bearing variety which passes under the varietal name schorl or schorlite. This variety has no commercial use or value. The occur- rences are described in detail as far as known in the following: BLAINE COUNTY Ordinary iron tourmaline in coarse imperfect black crystals was found in the pegmatitic rock occurring in blocks in the talus at the head of the cirque on the south flank of Mount Hyndman, by the writer while assisting Prof. L. G. Westgate in the mapping of the areal geology of the Hailey quadrangle for the United States Geological Survey. This tourmaline presented no unusual features. A specimen sent to the National Museum for identification by B. A. Smith, of Martin, Idaho, consists almost entirely of tourmaline. The specimen is from a claim belonging to Mr. Smith in the Lava Creek district 20 miles west of Arco. The tourmaline forms radial fibers aggregated into spherulitic masses up to 5 mm. across and is greenish to brownish-black in the hand specimen with a silky luster. A little quartz is associated with the tourmaline in making up the rock. Under the microscope the mineral appears as slender prisms of negative elongation and parallel extinction which are intensely pleochroic in colorless to pale violet-brown parallel to the elongation and deep blue-gray to brownish-blue across the elongation. The refractive indices are €= 1.647, w= 1.671. BOISE COUNTY A specimen of a bluish gray mineral sent to the United States Geological Survey for identification from the Boise Basin has been identified as tourmaline by Dr. Waldemar T. Schaller. The mineral is in flat blades, which have the optical properties of the elbaite variety of tourmaline. It is easily fusible before the blowpipe and gives the characteristic boron flame. The tourmaline blades are associated with and contained in a rusty limonite stained sericite such as is common accompanying veins in the Boise Basin region. 342 BULLETIN 131, UNITED STATES NATIONAL MUSEUM CLEARWATER COUNTY Black and quite well formed, though broken, crystals of tourmaline up to 2 cm. in diameter occur in placer concentrates from Pierce, Clearwater County (Cat. No. 87504, U.S.N.M.). The concen- trates contain also corundum, epidote, garnet, etc. The tourmaline is probably associated with the corundum in its original source as one small crystal of tourmaline was seen embedded in a corundum crystal. LATAH COUNTY In Latah County ordinary black tourmaline occurs in rough crystals in the pegmatites which are mined for mica in the vicinity of Avon. This mineral is also frequently abundant in bands of the inclosing schist adjacent to the pegmatite masses.® LEMHI COUNTY Tourmaline occurs abundantly in some of the ores of the Black- bird district associated with cobaltite as a microscopic mineral, with quartz, making up quartz-tourmaline rocks, as first determined by Fran L. Hess of the United States Geological Survey. Specimens collected by Mr. Hess from the Haynes Stellite Co. mine on Black- bird Creek, 2 miles from its mouth, in the hand specimen appear as very fine grained gray masses showing no minerals distinguish- able to the unaided eye except sparsely scattered large steel-gray grains which have been shown by analysis to be danaite, the cobaltif- erous variety of arsenopyrite. When this ore is polished, however, the surface appears as a black gangue containing very abundant and extremely minute reddish gray metallic particles of cobaltite. The black gangue is quartz-tourmaline rock. When this ore is powdered to pass a 200 mesh sieve the constituent grains of the fine aggregate are separated and under high magnification appear as sharply octahedral or cuboctahedral crystals of the opaque metallic mineral and grains of quartz and tourmaline. The tourmaline forms either equidimensional irregular grains or very stout prisms, the elongation twice the diameter or less. It is strongly pleochroic, e=very pale violet brown to brownish gray, w=deep gray-blue. The refractive indices measured are = 1.635, w =1.658. A second specimen from this district, exact locality unknown, possibly from the same mine, is black in the specimen and is visibly coarser grained and sparkling. This is coated along cracks with beautiful rose-red erythrite. Under the microscope it consists of quartz and tourmaline like the last. While coarser grained the tourmaline is identical in color pleochroism and refractive indices. A specimen labeled gabbro-porphyry from the west end of the Beliel group is medium fine granular and micaceous in appearance 65 Douglas B. Sterrett. U.S. Geol. Survey, Bull. 740, pp. 86-93, 1923. THE MINERALS OF IDAHO 348 and structure and greenish-black in color. Under the microscope the most abundant mineral is mica, apparently high-iron biotite which is practically uniaxial and negative with «=1.603, w=1.655, both +.003. It is pleochroic in plates on edge with w=deep brown- ish olive-green, e=pale brown, Absorption w>>e. Next in abun- dance is tourmaline, which is unevenly distributed in the mass of the specimen. The tourmaline is uniaxial and negative with the indices ¢=1.627, w=1.650. It is very pleochroic with e=very pale lilac brown, w=deep indigo to blackish-blue. Absorption w>>e. The third mineral of the aggregate is colorless and breaks into flat plates like a mica and these, when on edge, show a high birefringence. This mineral is biaxial with 2V small to medium, and a mean index of refraction, 8=1.598. It may be muscovite. Na SHOSHONE COUNTY In Shoshone County in the Coeur d’Alene district tourmaline is a microscopic constituent 9 of the sedimentary rocks where it occurs in grains and imperfectly terminated prisms. Mr. Calkins, who has studied the occurrence of tourmaline in the area at large, regards it as a secondary constituent and not, like zircon, a mechanical inclusion in the sediments. It is never found in waterworn grains and, like siderite, it is most abundant where the rocks have been most disturbed. It does not, how- ever, exhibit any such close relation to the monzonite intrusion as to lead to its classifi- cation as an ordinary contact-metamorphic mineral. As a rule tourmaline crystals are most numerous and best developed in the F'6. 108.—TouRmatine. - : : AVERY QUADRANGLE, finer-grained sediments, particularly those hav- — gnostone County ing an abundant sericitic matrix. The coarse highly siliceous quartzites and the calcareous rocks of the Wallace formation are apparently the least favorable to the development of the mineral. Ordinary black tourmaline occurs in a number of places in the Avery quadrangle in southern Shoshone County. Specimens of white anorthosite from the southeastern part of the quadrangle have crystals and rosettes of brownish black tourmaline up to 2 cm. in diameter on joints. A specimen of fine-grained quartz from a pros- pect at the mouth of the creek east of Bluff Creek contains scattered grains and masses of black tourmaline. A specimen labeled pegmatite from a locality 2% miles south of Trimmed Tree consists mainly of 6 F. L. Ransome and F. C. Calkins. U.S. Geol. Survey., Prof. Paper 62, p. 101, 1908. 344 BULLETIN 131, UNITED STATES NATIONAL MUSEUM green chlorite and feldspar with long blades of cyanite and some biotite. Embedded in the feldspar are black needles of tourmaline up to 1 em. in length. One of these which was measured was ter- minated and of the habit shown in Figure 108. This gave the fol- lowing angles: Measurements of tourmaline, Avery Quadrangle Form Symbol | Measured Calculated Quality, description | No.| Letter Gdt Miller | g p 9° p | | ° , ° , ° , ° , Va|Kabesece = — No.| Letter Gdt. Miller | | y p 9 p oe = es ae jE |e es | ° , ° ‘ ° , ° , Hi etsce se 0 001 Surah poor = 8 satan eon ea an [ines 20M an aaa 20 00 Pi Paes 1 lil Wiariable, poor: ss. s2=22c=-2-222252 | 44 __| 48 51] 42 52] 48 O1 DaNOeee reese Qco 010 Bair pearly-- 2252 25.--2.222---422--- 0 36) 90 00; 0 00; 90 00 Asiiges sooo. co0 100 ere ne Ca ae 89 19} 90 00) 90 00) 90 00 | a = In Figure 116 one of the crystals is drawn, as measured, in the position adopted for stilbite by Dana. This habit Dana considers as pseudo-orthorhombic by twinning as shown by the optical struc- ture. The measured angles on one crystal are compared with the angles of Dana as follows: Measured Dana m(110) Am!’ ’ (UG eee ee SS 63° 19’ 61°10! COOL NGE CLO) S252 225s e eee eae 51S 10! 502 50 This agreement, the quality of the compound faces considered, is as close as can be expected. 3856 BULLETIN 131, UNITED STATES NATIONAL MUSEUM When the crystals are examined in polarized light lying on tne 6(010) face most of them show faint lines dividing the crystal into four quarters, by lines of apparent twinning, and the extinction of adjacent sectors is inclined 11-12° to each other and 6° to the dividing line which is parallel to the long edges of the crystals. Such crystals show the optic normal in convergent light. When the crystals are crushed they yield elongate fragments of ragged termination, showing that there is no cleavage parallel to the end face of the crystals oriented upright. Most of the fragments le on the 6(010) cleavage and give high birefringence colors and show the emergence of the optic normal. These are ragged in outline showing that the a(100) cleavage is very imperfect. Other elongate fragments which rest upon a(100) show the obtuse bisectrix normal to the gram. All fragments show negative elongation, so that the mineral is optically negative, 2V small. The optical orientation is X=c, Y=), Z=a. The refractive indices, which seem to be variable, average about: a=1.490, B=1.503, y=1.507. Many of the fragments, especially those lying on (100) show a lamellar structure and rather uneven extinction, suggesting albite twinning but very irregular and confused. Mr. Hewett regards the stilbite in this mine as having been intro- duced later than the ores. CUSTER COUNTY D. F. Hewett, of the United States Geological Survey, reports finding stilbite at Galena Summit on the north (Salmon River) side within 1,000 feet of the summit, in slabs up to 2 inches thick, in Tertiary andesite. KOOTENAI COUNTY Stilbite occurs with prehnite and other zeolites coating a fracture in a diabasic rock on a specimen from Post Falls, Idaho, submitted for examination by Henry Fair, of Spokane. The stilbite forms small colorless to slightly yellowish crystals lming cavities. These are rectangular and entirely like those described above from Adams County. They have the habit of typical epidesmine. When lying on the }(010) cleavage they show another prominent cleavage parallel to a(100). The mineral is optically negative, with X=c, Y=b, and Z=a. The bd pinacoidal sections show the emergence of the optic normal and extinction variably inclined from 0° to 11°. The refractive indices measured are a=1.500, B=1.505, y=1.507, all + 0.008. The exact locality for the specimen is not stated, but it is said to be from a claim belonging to a man who recently caused some local interest by pretending to find rubies and diamonds at the prospect from which the zeolites came. THE MINERALS OF IDAHO 357 LAUMONTITE (445) Hydrous lime-alumina silicate, Monoclinic. CaO. Al,03.4Si02.4H.O. Laumontite is a member of the zeolite group, which is peculiar in that it looses a part of its water of crystallization upon exposure to air and usually turns white and disintegrates. Small amounts of this mineral have been found in Idaho in Blaine and Kootenai Counties. BLAINE COUNTY Specimens of laumonite were collected by D. F. Hewett of the United States Geological Survey in the Wood River district, especially at the Bellevue King prospect near Bellevue. The laumontite, Ss which is typical in appearance, lines seams in a chloritized rock, and also occurs as veinlets up to 2 em. thick, which are filled in the center with calcite. The crystals, which are rarely over 2 mm. in length, are prismatic with the common habit illus- trated in Figure 118. KOOTENAI COUNTY A few prismatic imperfect crystals of laumontite e occur with stilbite, prehnite, etc., coating a fracture in diabasic rock in a specimen from Post Falls in Kootenai County. CHABAZITE (447) Variable hydrous silicate of lime, alkalies Rhombohedral. and alumina approximating the formu- la (Ca, Naz, K2)O.A1,03.48i102.6H20. Three occurrences of zeolites which have been aaien ae referred to chabazite have beenexamined. One of = mre. Common these is in a contact-metamorphic deposit in lime- ae pees stone and two are in cavities in lavas. The two pscrnear Betis. latter have only been included under this species Ml ae after much consideration and may, upon more de- tailed investigation than was permitted by the scanty material avail- able, be found to be in reality some other member of the zeolite group. ADAMS COUNTY A specimen from the Blue Jacket claim in the Seven Devils district contains chabazite, with less stilbite and heulandite, deposited on crack and joint surfaces in massive brown garnet rock. The chaba- zite is the most abundant of the three zeolites of the specimen, and forms simple rhombohedral crystals, illustrated in Figure 119, of an 8358 BULLETIN 131, UNITED STATES NATIONAL MUSEUM amber-brown color averaging 2 mm. on an edge. Under the micro- scope the powdered chabazite shows very low birefringence. Differ- ent grains from the same crystal give both positive and negative biaxial interference figures, with 2V medium large to small. The mean refractive index varies from 1.488 to 1.490. BOISE COUNTY Specimens labeled as from Warm Springs Creek east of Boise, con- sist of very vesicular basaltic rock, containing abundant cavities up to 2 cm. in diameter largely filled with a white zeolite which is referred to chabazite. The rock is a basalt, and contains conspicuous grains of iddingsite, the properties of which are given under that heading. The locality is given as on Warm Springs Creek, which is a tributary to Payette River from the north near the center of the Bear Valley topo- graphic map area. The zeolite forms crusts of intergrown color- less to whitish transparent to translucent crys- tals nearly filling many of the cavities. The crystals are not well developed and are grouped Meer Guerre in complex twinned aggregates. When the UN EHOMBOHEDEON, JOrms are at all welldéfined they haveds ae eee istrict, rhombohedral appearance, but no good meas- urements could be obtained. Some white radi- ated thomsonite is associated with the chabazite, and in many of the cavities there is a clayey greenish material between the chabazite and the wall of the vesicule. Optical determinations gave varied results on material which, under a binocular microscope, appeared to all be the same. Accord- ingly a quantity of the material was crushed and screened and treated with heavy liquids by which process a light, an intermediate, and a heavy product were obtained. The light product appeared homogeneous under the microscope and was transparent and colorless with uniformly low birefringence. Dim and rather unsatisfactory figures seem to show a relatively large axial angle with positive optical character, although about one grain out of each six or seven shows an apparently optically negative character. The refractive indices measured were somewhat variable but the maximum value for y was 1.494 and the minimum for a was 1.483. Perhaps the average is a=1.485, y=1.492. Much of the material shows a lamellar structure resembling the twinning of some feldspars, but very confused and irregular. Many of the grains show rectangular or rhombic boundaries as though determined by cleavages and the persistent difficulty experienced in obtaining THE MINERALS OF IDAHO 359 centered optical figures suggests cleavages inclined to the principal optical directions. This light product upon careful analysis, gave the following results: Analysis of chabazite from Warm Springs Creek (E. V. Shannon, analyst) Per cent SMe ee ae he ay oe A oe en okt 45. 32 AA WUTEEES OVE G.I 0) A ice en ee 18. 84 ene Ae Nice ee eet i Sh he Se bein aes ee A 9. 48 Buc og) eae oe Eh ee ee Sek ee 1. 40 aOR ROY oe cae Eh a te ee a mete a he Nap iecins VIGO) is ae cot nee as Be Seek ceed eh eewe a . 44 Water (H,0) above 110° C.22 eee 8 en see eee, 17. 80 Wveter eO) sbelow LN0? ens a St So eee acest Sa Stasdeeon 5228 EQUA ete ethene 2 te ie eet Boe ae Se ee oe 99, 28 The intermediate separation product has about the same optical properties as the above except that the y index of some grains is as high as 1.498 and there are numerous mixed grains of the zeolite and the clayey material. The heavy separation product consists of the clayey mineral, needles of thomsonite and a mineral which is clear and colorless under the microscope and seems to be in rhombic grains bounded by cleavages. Lying on edge these show rectangular form, parallel extinction, high birefringence, and the emergence of the optic normal. Lying on the broadest face they are rhombic in outline, show highly inclined sweeping extinction and very low birefringence, with some blue and chocolate brown low order interference colors. On this face there is a rude division into sectors between crossed nicols. These grains in the position to show low birefringence all show a very clean cut interference figure which is biaxial positive with 2V small to medium, dispersion r .199X1 .98X1 SodaiGNazO). So 2 eee ae es ee Sc eee ora Se a eae 10. 94 | eel Water’ (HsO)iabovell0° | ©-2eao ss ee ee ee ee 8.43 | .468) .234X2 1.17X2 ‘Water: (H20)-below-L10° C212. 2= Ss 2 See sa ee None. | Totals 2 a Oe es ee Sa SS ee es Ee 99. 06 | | The above ratios are not satisfactorily close to whole numbers to conform to the analcite formula given by Dana, both water and silica being high. Such variations have been noted in analyses of analcite from other localities and have been variously interpreted. The mineral is somewhat variable in composition. The paragenetic position of the analcite is late, as it grew between the laminae of calcite or occupied cavities left by removal of calcite and the analcite crystals inclosed mordemte and quartz. No other mineral is deposited on the analcite and it is probably the youngest mineral represented in the specimens from the Challis locality. THOMSONITE (456) Hydrous sodium-calcium aluminium sili- Orthorhombic. cate, Na,0.4Ca0.5A1,03. 10 SiO,.12H,0. Several occurrences of fibrous zeolites have been examined from Idaho localities; there has not been enough of the materials for chemical analysis and the optical determinations have not, in all cases, been satisfactory. Four occurrences are mentioned below but in two of these the mineral may not be thomsonite. THE MINERALS OF IDAHO 863 BLAINE COUNTY A fibrous zeolite occurs in specimens from Blaine County labeled Snake River lava from Little Smoky Creek northwest of Hailey. Little Smoky Creek is shown on the Sawtooth topographic sheet. The zeolite is fine fibrous and white, radiating from the walls toward the centers of irregular filled cavities up to 8 mm. in diameter, in a dense basaltic rock. Under the microscope this material is very finely fibrous and, so far as could be determined, has parallel extinction. Its birefringence is low and it has an opaque appearance due to air inclusions. Aggre- gates of fibers not quite in parallel position give an indistinct inter- ference figure which looks biaxial and positive with 2V large. The fibers all have negative elongation which is X and not Y as they remain negative in various positions. The material is not satis- factory for measurement of the indices of refraction. The mean index is approximately 1.51. This material does not agree in optical orientation with thomsonite but it is nearer thomsonite than to other fibrous zeolites in general properties and, like the similar material from Kootenai County described below, is kept under the thomsonite heading until more is known regarding the optical properties of these minerals. BOISE COUNTY Associated with the chabazite from Warm Spring Creek in the Bear Valley quadrangle, is a small amount of thomsonite which occurs as round solid amygdules which are radiate fine-fibrous in structure and are white in color with a silky luster. These are much less abundant than the chabazite and usually are only about 3 mm. in diameter. A partial analysis made upon a small sample of this material gave the following results: Partial analysis of thomsonite from Boise County (E. V. Shannon, analyst) Constituent Per cent SULCUS) Seen rn Se SPE 2 a ee ee 42, 43 Alumina (A1,03)____ — ae ee = PO es = ee 2 ee 27. 31 Mimen (On ©) aan Sere = SE 8 SS ge oe ee SL eee ee Lost. ECAR VERO) ina 2. eee. 3.. a Ne aL st Oe eee ee LOM Puieilies (Netw te Ol 8 ae an oo etn wee Hdodoe beets pee eee n. d. WeitenabovestlO: Cae ns. te in et See ete eee ee 12. 85 RV iea GESTED CL Gh Var De CO cee meee ne i, SP ng i ffl Sep ee 1. 28 T0559 | eee aeoeteme mre NE ope A Ge oe cn ne 2 84. 94 Under the microscope this material is fibrous with the elongation Y as shown when the fragments are rolled between crossed nicols under the gypsum plate. The refractive indices are about a=1.504, B=1.509, y=1.512. 364 BULLETIN 131, UNITED STATES NATIONAL MUSEUM ELMORE COUNTY Associated with the chabazite described above from 5 miles below Glenns Ferry are scattered small spherulites of a colorless mineral in: radiated blades. These are only a millimeter or two in diameter and are inconspicuous. Under the microscope the mineral is in coarse flat fibers, the elongation of which is Y. The axial plane is. thus across the length and the mineral is biaxial positive with 2V medium, dispersion r .480 1.05x3 OMe ds ©) een es ee ae ahs eS ees. Ses -18 | .003 Witter (HaO) rabovedl0S Ge. 222s 5. ooo eee seco oon ca ccceeee cakes 7.00 | .389 Water (H>s®) below 110% © 2 -- 22222222 oi ces ese ae 2. 70 -150 .150 1.00X1 SN REN Bo Ss a ge ee ee ee I a 98. 76 | The formula derived from this analysis is— 3(H,K),0.2A1,0,.5Si0,.H,O which is indeed like the composition which might be obtained from a mixture of muscovite and kaolinite. It is also similar to the composition obtained for the sericite from Boise County except in that the alumina is low and there is one molecule of water which is lost at 110° C. Optically the material is nearer leverrierite with the indices of refraction approximately a=1.547, y=1.556, bire- fringence 0.009. It is so exceedingly fine grained that it is not possible to say definitely that there is no amorphous material mixed with the minute crystalline flakes but the material all appears of the same refractive index and birefringence which is lower than for either muscovite or kaolinite. The evidence seems to be in favor of the conclusion that these clays are not so simple as just mixtures of kaolinite and sericite. Many of them may be pure sericite, even when low in potash, while others may be more properly classifiable as leverrierite, a mineral of similar properties whose exact relation to the muscovite and kaolinite groups is not yet known. These clays are further discussed under the headings leverrierite and kaolinite below. SHOSHONE COUNTY In Shoshone County extensive formations of quartzitic or slaty rocks are characterized by the more or less abundant occurrence of sericite throughout. The Burke formation is characteristically a slaty sericitic quartzite and the Wallace formation is, in places, practically a sericite slate or schist. The occurrence of this sericite is regional and its formation long antedates the deposition of the ores, and is in no way connected with them. A small amount of sericitization occurred during the period of vein-forming activity, but this consisted mainly of the conversion to sericite of crushed 376 BULLETIN 131, UNITED STATES NATIONAL MUSEUM material along fissures. The so-called tale of the gouges of fissures in the vicinity of the orebodies consists for the most part of sericite.* BIOTITE (462) BLACK MICA, IRON MICA Variable hydrous silicate of magnesia, Monoclinic. iron, alumina, etc., usually approxi- mating the formula (H,K),0. 2 (Mg, Fe) O.A1,03.3Si02. Biotite is similar in distribution and occurrence to the correspond- ing white mica or muscovite. It occurs similarly in schists and gneisses and is much more frequent as an original constituent of igneous rocks, both acidic and basic. Like muscovite, biotite is frequently found in larger plates and crystals in pegmatites, although no such occurrence in Idaho pegmatites has yet been brought to notice. A number of occurrences are noted below, most of them rather because they have been examined in the course of studying associated minerals than because they possess unusual features. CUSTER COUNTY Biotite occurs as an original constituent of the granite-porphyry of the Alder Creek district. During endomorphism it has changed to diopside.* LATAH COUNTY In the Mizpah mine, Hoodoo district, biotite occurs abundantly as isolated coarse crystals distributed through the solid chalcopyrite and pyrrhotite of the ore.% LEMHI COUNTY Biotite is developed in beautiful rosettes in some of the cobalt ores of the Blackbird district, notably those of the Togo claim.* A specimen from this district collected by Frank L. Hess of the United States Geological Survey, the exact locality for which is not known, consists of large blades of biotite in an indeterminate ser- pentinous matrix. The biotite blades reach a size of 6 by 2 cm. They are dark-greenish brown in color and each blade is divided, centrally, by a vertical line on each side of which are inclined striations giving a feathery appearance. A specimen of medium fine granular biotite.from the west end of the Beliel group has been mentioned above as containing tour- maline. Under the microscope this is practically uniaxial and 83 F. L. Ransome and F. C. Calkins. U.S. Geol. Survey, Prof. Paper 62, 1908. 8 J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 50, 1917. 85 D. C. Livingston and F. B. Laney. Idaho Bur. Geol. and Mines, Bull. 1, pp. 95-96, 1920. 88 J.B. Umpleby. U.S. Geol. Survey, Bull. 528, p. 75, 1913. THE MINERALS OF IDAHO SG negative with e=1.603, and #=1.655, both +0.003. Plates on edge show pleochroism with w=deep brownish olive-green, ¢=pale brown. Absorption w>>e«. Associated with the biotite of this specimen is some muscovite as well as a considerable amount. of tourmaline in microscopic crystals. SHOSHONE COUNTY A peculiar green biotite occurs in microscopic grains in the ores of the Success and other mines surroundine the monzonite area of Ninemile Creek.*’ Biotite occurs in gok 1 brown to black scales up to 1 cm. in diameter and often with sharp hexagonal outlines. in lamprophyric rocks at several places in the district.*® In the metamorphic rocks in the southern part of the county, particularly in the area included in the southern part of the Avery quadrangle, biotite is a common product of the metamorphism of the Belt sedi- mentary rocks, both in the form of schists containing coarse flakes of biotite and as fine purplish hornfels which consist largely of micro- scopic biotite. Such rocks, derived by the metamorphism of the Wallace formation, have been described as containing hornblende and scapolite. Bordering many small pegmatitic intrusions and larger granitic dikes in the biotitic metamorphic rocks there appear considerable layers of biotite in schistose aggregates of coarse brown to black plates. CHLORITOID (466) BRITTLE MICA, MASONITE Hydrous silicate of magnesia, lime, Monoclinic. iron, alumina, etc., approximating the formula: (Mg,Ca)0O.Al1,03. SiO,..H,0. Chloritoid is a relatively uncommon mineral, like the other mem- bers of its group. It is the only one of the so-called brittle-mica minerals thus far found in Idaho. LEMHI COUNTY Chloritoid occurs as the principal constituent of a lot of material which, according to the label, is typical of a contact-metamorphic mass occurring on the hanging wall side of a dike about 10 feet wide on the Nickel Plate and the adjoining property in the Blackbird district. In the hand specimen this material is coarse granular and dark grayish-green in color and is made up of interlocking crystals of the chloritoid averaging a little less than 1 cm. in diamteer. Associated 97 F.L. Ransome. U.S. Geol. Survey, Prof. Paper 62, p. 101, 1908. we, 88 Karl V. Shannon. Petrography of some lamprophyric dike rocks of the Coeur d’ Alene mining district, Idaho. Proc. U.S. National Museum, vol. 57, pp.475-495, 1920. 54347—-267 25 878 BULLETIN 131, UNITED STATES NATIONAL MUSEUM with the chloritoid are variable amounts of a green chlorite and colorless muscovite. The chlorite is described below. In thin section under the microscope the chloritoid appears to be the earliest mineral of the aggregate and this has been shattered and the chlorite and muscovite have filled the fractures. Optically the chloritoid is well characterized by its intense pleo- chroism. It is biaxial positive with 2V small to medium dispersion r > v very strong, crossed dispersion strong. The refractive indices are approximately a = 1.720, 8=1.722, y=1.731, birefringence =0.011. The optical orientation is X = b, ZAc=18° to 21°. Pleochroism: X=colorless to pale greenish-brown, Y=indigo blue, Z=pale brownish-green. Absorption Y >Z>X. The material was separated from the associated chlorite and mus- covite for analysis by means of heavy solutions and the electro- magnet. This was analyzed but the analysis was not extremely accurate since it was found that the sample contained about 3 per cent of cobaltiferous arsenopyrite present as the very finely dis- seminated dust-like grains and not discovered until the analysis was well advanced. After correcting as well as possible for this arseno- pyrite, the analysis, recalculated to 100 per cent, gave the following results and ratios: Analysis (corrected) and ratios of chloritoid (E. V. Shannon, analyst) Per cent | Ratios Silica (S109) oon oaeaeoaeeeoeeeeec estes ccccescoceeccceeteeeneeets 22. 07 | 0.376 0.376X1 0.95X1 lamina CANO) = Pose een ao St oo tee ee ee ee eee eee 38. . 880 Mario iron (kes Os\c2 <2 26.2 ane a ial a 2.98\| Lo1gf. 309X211. 001 INGrrOUSULON UN GO) cece sew aw ewe we ea ere ae eta Boge ater meena 202463 hen. 354) ENG) (CAO) ie 2 ee as ES I I a re Ss Ue een ae -93 | .017; .420XK1° 1.05X1 Magnesia (Mig@) ose ote ce eas See eee eae 1.96 .049 Water ((is@) etek oer ey ko EE eR Ee Ee eer ee eo Te Ree 7.14; .896 .396X1 1.00X1 The analysis approximates rather closely to the simple formula FeO. Al,03.Si02.H20. It is evident that the chloritoid must be present in large amount at the Idaho locality and, in view of the rarity of the mineral, speci- mens should be of considerable interest to collectors. THE CHLORITE GROUP The chlorites include a large number of named species whose exact relations to one another are not well understood. It is one of the least known of the natural mineral groups and it is often very diffi- cult to decide where, among the several species, to classify a given specimen, even when a complete analysis and optical measurements have been obtained. The minerals of the group are hydrous silicates THE MINERALS OF IDAHO 379 of ferrous and ferric iron, alumina, and magnesia. In composition and structure they are related to the micas and they almost invariably possess a coarse or fine micaceous structure. A majority of the members of the group are characterized by a green color. The following chlorites from Idaho localities have been classified as accurately as possible from the data available, but many of the identifications are but tentative. Few of the examinations could be completed on account of scarcity of material. ADAMS COUNTY Chlorite is listed, without further description, by Livingston and Laney, as occurring in the contact-metamorphic copper deposits in limestone in the Seven Devils district.®® CUSTER COUNTY A few small specimens from the Basin group, a prospect on the Custer County side of the divide at the head of Trail Creek in the Hailey quadrangle, mentioned under garnet, prehnite, etc., contain scaly aggregates of minute greenish-brown folia associated with garnet and epidote. Under the microscope this material appears as brown fibrous shreds which are nonpleochroic and have a mean refractive index of about 1.65. This mineral has the appearance of chalcodite which is an altered variety of the chlorite stilpnomelane. In specimens of mordenite and other zeolites from near Challis, in Custer County, which have been described in a previous paper °° and which have been mentioned above under mordenite and heulan- dite, about one-fourth of the total number of pebble-like fillings in an amygdaloid rock consist of a soft brownish-green chlorite. The other amygdules are filled with mordenite and heulandite. This chlorite does not occur in the same vesicles with any of the zeolitic minerals, but it is sparingly distributed in the silicified portions of the inclosing rock adjacent to some of the large zeolite-filled cavities. The small chlorite fillings which reach an extreme diameter of about 7 mm. are easily freed from the surrounding matrix and, when crushed, yield a homogeneous sample for analysis. Under the microscope the chlorite is seen to consist of yellow-green irregular folia. These are biaxial and optically negative (—) with 2V around 15°. The indices of refraction, which are high for a chlorite, are a=1.615, B=1.637, y=1.638, birefringence y—a=0.023. The min- eral is strongly pleochroic with X and Y olive-green and Z brownish yellow. This material was analyzed, yielding the following results and ratios: 8 D. C. Livingston and F, B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 62, 1920. 90 See under mordenite. 880 BULLETIN 131, UNITED STATES NATIONAL MUSEUM Analysis and ratios of chlorite from near Challis (E. V. Shannon, analyst) i | Per cent Ratios. Silica (SiO2) ss cg ha aA VER ye eg i cl a 4 As ab iy eS ee ee ES 30. 7 F i Alumina-(AlLOs 4. $214. Allah ae es nia Att Geers 12. HS y 19 Nee Mernicunons(ResOs) = sme ee a a A a ae gy taed Sr ty aera ip OZ al ie srt -176X1_ 1.03X1 Ferroustiron: (He) 1a rere ee a ee a Eee 22276" |) S317 Manganousioxide (Vin O)g=—- 25 en ee ee eee 1.24| .018 Tu ini) (CaO) Bese ae on an Ree See ees eee | Trace} }|2-65.2 -160X4 . 94X4 Magnesia (MgQ)-_____-_--- pre Fr ee Ae A eee ee | 12.36 | .307 Wistar (GETS OAD O Vie flO SRC ee ee ea ae ee eee | 9.76 | .542 Water (HO) below 110° C_2.c02:.0..... RAO OR Ge 1.80] :100f -160X4_ .9#X4 | Total | 99.92 | This analysis yields the formula 4(FKe,Mg)O.(Al,Fe),0,.3Si0,. 4H,0. With FeO:Mg=1:1 and FeO, : AlO,=1:2. This can not be definitely assigned to any member of the chlorite group, but is most closely related to diabantite and delessite, chlorites occurring characteristically as amygdule fillings in basic igneous rocks. The high content of ferric iron may in part be secondary and due to oxi- dation of a part of the iron originally present as ferrous oxide. Heated in the forceps before the blowpipe this chlorite exfoliates somewhat, becomes magnetic, and finally fuses with some difficulty to a black magnetic slag. In the closed tube it yields abundant water having an acid reaction, indicating a small fluorine content. It is quickly and completely soluble in hot 1:1 hydrochloric acid. In the same specimens there occurs a second chlorite which never completely fills the cavities but merely forms a thin lining 0.5 mm. or less in thickness in cavities containing fillings of mordenite and serves as a coloring matter in the surrounding andesite. It is impos- sible to obtain enough of this material in pure form for analysis. It is deep blue-green in the specimen and under the microscope is seen to consist of finely felted shreds and scales of a deep blue-green color which, in the aggregate, do not show any noticeable pleochroism. The indices of refraction are a=1.606, y=1.608, birefringence y—a=0.002. ‘This chlorite differs from the preceding both in color and birefringence. LEMHI COUNTY Green micaceous rosettes associated with apatite in porous schist in the cobalt ores of the Togo property, in the Blackbird district, consist of a chlorite which is biaxial and positive with 2V nearly 0°. The acute bisectrix is normal to the basal plates and the refractive index, B is is about 1.620. The mineral is pleochroic with X and Y blue-green and Z greenish brown. This chlorite is not appreciably decomposed by boiling with 1:1 hydrochloric acid. The specimens consisting largely of chloritoid from the Nickel Plate property, in the Blackbird district, which have been described above under chloritoid, contain a considerable amount of a green THE MINERALS OF IDAHO 381 chlorite. This chlorite is biaxial and negative with 2V nearly 0°. The refractive indices are a=1.650, 6 and y=1.660. The pleo- chroism is X=pale brown, Y and Z=green. The chlorite was sep- arated for analysis from the chloritoid and the associated muscovite by means of an electromagnet and heavy solutions. This was ana- lyzed but the presence of several per cent of cobaltiferous arseno- pyrite in dusted very minute grains in the sample was not suspected and the analysis was somewhat upset by its presence, as in the case of the chloritoid. After being corrected as well as possible for the several errors arising from this cause, it was recalculated to 100 per cent, yielding the following results and ratios: Analysis (recalculated) and ratios of chlorite [E. V. Shannon, analyst] Per cent | Ratios | a ee BibcaesiOs)o case ed 21.93 | 0.364 0.121X3 1.03X3 lamina (A103) 5-1-2 2-7-2} ) BOS! | -5..280)--». LI5K2) © * O8K2 Ferric iron (Fe203) Ferrous iron (FeO) = q . 520 MmpreCIUNE SO) ohn vs et ce 5. TA -118X6—. 97X6 RVR CeRMEtO ome Gyreus itt Fin isle. TS” ee Fae ric | 604 121X5 1.03X5 These ratios yield the formula 6(Fe,Mg)0.2A1,0,.3Si0,.5H,O. This chemically is very similar to some prochlorites. The formula is identical with that obtained for an analysis of corundophilite from Chester, Mass. The optical properties, both the optical character and the high refractive indices, are different from most of the minerals of the group. SHOSHONE COUNTY A specimen labeled pegmatite from 214 miles south of Trimmed Tree Mill in the Avery quadrangle consists mainly of feldspar and chlorite with less cyanite, tourmaline, and biotite. The chlorite is dull green and coarsely foliated in the hand specimen. Under the microscope it is biaxial positive with 2V approaching zero, acute bisectrix per- pendicular to the plates. The color is so pale that the pleochroism in tones of brownish green and brownish blue-green is not marked. The refractive indices, a and 6 are 1.595+0.003. This chlorite is probably intermediate between clinochlore and amesite, approaching the latter. A specimen from the Sherman mine on Pine Creek contains a very fine scaly deep green chlorite surrounding ankerite rhombohedra up to 2 cm. on an edge or replacing fragments of gray quartzite included in the quartz of the vein. Other minerals associated with the chlorite are pyrite and pyrrhotite which apparently are later. Under the microscope the chlorite is very fine granular with very low birefring- ence. It is apparently biaxial negative with 2V nearly 0°. The 382 BULLETIN 131, UNITED STATES NATIONAL MUSEUM pleochroism is not marked, X pale brownish green, Y and Z bluish green. Thea, @, and ¥ indices are about 1.640 to 1.645. Only asmall amount of the chlorite could be separated for analysis and there was not enough of the material to permit determination of the state of oxidation of the iron. Assuming it to all be ferrous, the analysis gave and following results and ratios: Analysis and ratios of chlorite from Sherman mine {E. V. Shannon, analyst] Per cent Ratios Silican(SiOs) caro: eens oe ay neler ee ae cees | 21.56 | 0.360 0.360 0.120X3 1.023 aoe RIES SZ ieee le ag ce Sis Cats Ae Uae emo | aoe ee .200 .100X%2 .85X2 OLLOUSI TOMI CWE O)) ees a ee ee Ey ee Eee eereee 2 etal un eee y . 54 NC ea Se ie er emmy ee yom nanan rel earn | Trace, ca .763 .127X6 1.09X6 gonesia (Vie @) 22 oes 2k eee a oe oe Se en eee ae 62] . 215 SW Gr (lg) ares ee eer nah we aN a ea | 9.88 | .549 .549 .110X5 .94X5 Cro) (bl he AN i ne La RAM meteors CNM nest | 99.90 This analysis leads to the formula 6(Fe,Mg)0.2A1,0,.3S10,.5H,0, or precisely that derived for the chlorite associated with the chloritoid from Lemhi County, described above, and the correspondence in optical properties is close enough to establish the practical identity of the chlorites from these two localities. A similar chlorite occurs as fine granular streaks associated with ferriferous calcite, quartz, and chalcopyrite in a specimen of ore from the Blackbear prospect in the Avery quadrangle. The chlorite has been mentioned in connection with the calcite, an analysis of which is given above under that heading. Under the microscope this chlorite is pleochroic in X and Y deep green, Z=greenish brown. It has low birefringence and gives no very definite interference figures but is apparently biaxial and positive with 2V very small. The refractive indices are approximately a=8=1.630, y=1.635. A very small sample was analyzed giving a very inferior analysis in which the magnesia was lost through accident and had to be taken by difference. The ferrous iron reported was actually determined to be present as such, but total iron was not esti- mated and the alumina may include a little ferric iron. The analysis gave the following results and ratios: Analysis and ratios of chlorite, Black Bear claim (E. V. Shannon, analyst) | Per cent | | Ratios slid. it aw | cae Silica (SiOs) oes eee a a ee eg | 24.80 | 0.413 0.413 0.0835 1.035 Alumina SLO SOA SES AMS BETSY AR ATS SS BASE SDE S 2 B64 225% 2259 LOPS >KS) 42 BOSS Herrous iron Che) =. 2. . = sae: = a ee ee 72 Magnesia (MgO). 10. oc tlise - Cid He | (1348) | “337 - 737 .082X9 1. 01X0 Waters @) soo og) ee De Us eee | 10. 14 | .563 .563 .080X7 .99X7 THE MINERALS OF IDAHO 883 This analysis may be compared with many analyses of prochlorite given by Dana. The formula yielded by the ratios is 9 (Mg,Fe) 0.3A1,03.5Si0,.7H,0. Other similar occurrences of fine-grained chlorites have been noted in other veins in the Coeur d’Alene region. They are nowhere con- spicuous. SERPENTINE (669) Hydrous magnesium silicate, Monoclinic. Although a common mineral elsewhere, serpentine has seldom been reported from Idaho, possibly having been overlooked because of its inconspicuous appearance and lack of commercial value. The follow- ing localities are known: ADAMS COUNTY Antigorite, the lamellar or platy variety of serpentine has been listed from the Seven Devils district by Livingston and Laney." BLAINE COUNTY Specimens from the Queen of the Hills Mine 114 miles west of Bellevue (Cat. No. 78,524 U.S.N.M.) consist of a fibrous mineral labeled asbestos, associated with calcite and fragments of sheared black slate. The asbestiform mineral is apparently fibrous serpentine. The calcite is in part in white cleavable granules embedded in the serpentine and is in part fibrous. The serpentine is pale buff in color and forms parallel-fibrous masses the fibers of which bulge around included calcite and are crumpled somewhat at the ends. The fibers reach a length of 11 cm. and individual masses are 5 cm. in breadth. The material has a harsh dry feel and little luster. The fibers are not easily separable and are more or less brittle. No analysis of the mineral has been made, but it is identified as chrysotile by its optical properties. In thin section under the microscope it is pale greenish brown to brown and is pleochroic, the color being more pronounced parallel to the fibers. The extinction is parallel, the elongation positive. The refractive indices vary somewhat but average a=1.50, y=1.52. CUSTER COUNTY Serpentine is a meager constituent of the copper-bearing deposits of the Alder Creek district, where it occurs as an alteration product after hornblende and diopside. In a raise from the north Alberta stope to the 300 foot level a band of serpentine with intermixed quartz and malachite follows the fault plane. This layer is about 2 inches wide and shows evidence of much shearing. The serpentine 91D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 62, 1920. 92 J, B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 54, 1917. 384 BULLETIN 131, UNITED STATES NATIONAL MUSEUM is slickensided and is leek-green in color with a splintery-fibrous structure. It may be classified as the variety known as picrolite. FREMONT COUNTY Asbestiform serpentine has been reported to occur north of Ashton.** GARNIERITE (483a) Variable hydrous silicate of magnesium and nickel approximating the formula Amorphous. (Ni,Mg)O.SiO2.H,0.nH20. Garnierite is an indefinite mineral, usually earthy to waxy in appear- ance with a green color. Where abundant it is mined as a source of nickel as in New Caledonia. Only one report of its occurrence in Idaho has been received. CUSTER COUNTY A vein of garnierite of considerable size has been reported to have been found near Clayton in Custer County.“ Nothing further has been learned about this report. No specimens have been examined. TALC (484) Hydrous magnesium silicate, 3Mg0O. Monoelinic. 4Si02.H,0. Tale occurs as a micaceous foliated and very soft mineral with smooth feel and also in less pure form making up beds or masses of rock known as steatite or soapstone. No attention has been paid to its occurrences in Idaho and practically none of importance are known. The clayey materials occurring as gouges along faults and fissures in metal mines in Idaho which the miners call “talc” are not talc but are usually sericite, leverrierite, kaolin or some other clayey mineral. ADAMS COUNTY Talc is listed by Livingston and Laney as a mineral of the contact- metamorphic deposits of the Seven Devils. SHOSHONE COUNTY A few specimens of talc have been seen in a lot of metamorphic minerals from somewhere in the St. Joe region. CELADONITE (489) Silicate of iron, magnesium and potas- Earthy, soft, minute-scealy. sium, Formula doubtful. OWYHEE COUNTY The rhyolite adjacent to the silver-gold veins of the De Lamar and other mines of the De Lamar district, which has been profoundly 93 Robert N. Bell. 19th Ann. Rept. on Mining Industry of Idaho for 1917, p. 99, 1918. 5! Robert N. Bell. Personal letter, 1919. THE MINERALS OF IDAHO 885 altered, contains streaks and veinlets of a greenish-brown fibrous mineral with high double refraction. It is believed to be a magnesian silicate carried up from the underlying basalt. It is, however, neither chlorite nor serpentine for the powder of two rocks in which it was abundantly present yielded no magnesia when treated with sulphuric acid. It is probably a mineral related to celadonite or ‘‘green earth.” KAOLINITE (492) Hydrous aluminium silicate, Monoclinic. 2H20.A1203.2Si0>. Ordinary high grade clays such as are used for porcelain, etc., are usually called kaolin, which name includes kaolinite and the corre- sponding amorphous mineral of the same composition, halloysite. Considering their widespread occurrence and commercial import- ance, surprisingly little is known regarding the mineralogy of the clays utilized in the ceramics industries. In addition to kaolinite and halloysite these may include minerals of the sericite-muscovite series and, very recently, it has become increasingly evident that the mineral leverrierite is a clay mineral of widespread occurrence. Kaolinite proper is a completely crystalline micaceous mineral and the best and coarsest examples thus far known are not plastic. The mineralogical nature of clays, if they are homogeneous, may be established by optical examination coupled with determinations of the amount of water contained and the temperatures at which it is released. Like other similar clayey minerals, kaolinite has its origin in the alteration of feldspars. Formerly it was considered principally a weathering product from the feldspars but a more recent tendency is to attribute a large amount of the kaolinization to hydrothermal processes. The following references to kaolin from Idaho may be quoted from existing literature but no critical discussion of the clays of the State can be offered. CUSTER COUNTY Kaolinite occurs in the Alder Creek district along fractures and in cavities in the oxidized ores. It seems to here be a normal product of the weathering of the aluminous garnet and of the igneous rocks." KOOTENAI COUNTY Deposits of fine white clay occur near Hutter Station in the Spokane Valley. These clays are very pure but they have not been submitted to a mineralogical examination. 95 Waldemar Lindgren. U.S. Geol. Survey, 20th. Ann. Rept., pt. 3, p. 179, 1900. % J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 53, 1917. 54357—26t——_26 386 BULLETIN 1381, UNITED STATES NATIONAL MUSEUM LATAH COUNTY Certain deposits of fire clays resulting from the decomposition of granite and pegmatite which are worked at Moscow and Troy have been described by Soper. These are for the most part residual kaolin containing quartz. OWYHEE COUNTY Clayey materials are of very frequent occurrence in the Silver City district. Chemical investigation has shown that these vary some- what in composition, some having the composition of pure kaolin, some of pure sericite, and many corresponding to a mixture of the two minerals. These have already been mentioned under sericite. In addition to kolinite and sericite, leverrierite, discussed below, is present in some mines. A white clay gouge from the Tip Top vein has a composition inter- mediate between kaolinite and sericite. A ‘“‘talc’’ forming the fillmg of fissures in the Henrietta mine, which was rich in miargyrite con- tained: Per cent Waters Ges ©) bo elo worl! OU © mia se ak ea le pe teZ0 Waters CEs Oirs wove OO a 56 ie ete ee cate ge ee 9. 40 PotashoGhjO) Lo. SUS Reid & 0a) oe As STAR AEE 3 Aa Rd 1. 86 Soda @Nap@) wars tei 2a Sale bara Vener ares NER Trace. This may be a mixture of kaolinite and sericite. In the De Lamar mine kaolinite occurs as white chalky or talcose material forming parts of the vein. Sometimes it is a metasomatic replacement of rhyolite. The white “talc” which underlies the “‘iron dike” in this mine and contains shot and larger masses of argentite (or naumannite q. v.) is apparently pure kaolinite. A specimen from the second level contained: Water 14.12 per cent, potash trace, gold 13.7 ounces per ton, silver 2.30 ounces per ton. Similar material from a veinlet of comb quartz is also probably kaolinite, as it contains no potash.® MONTMORILLONITE AND LEVERRIERITE (492) %¢ Hydrous aluminium silicate, compo- Monoclinic, clayey.. sition varying from approximately Al,O .38i02.4H.,O0 to about AlQOs;. 5Si02.7H20. There are certain clayey materials which have peculiar properties which distinguish them from the ordinary clay minerals kaolinite, sericite, and halloysite. Such a clay was described by Wherry and Larsen from a mine in Colorado and for it the name leverrierite was used while the authors consider rectorite, delanouite, kryptotile, and batchelorite as all being the same material. Since then it has become 97 J]. K. Soper. Journ. Amer. Ceram. Soc., vol. 1, pp. 94-98, 1918. 98 Waldemar Lindgren. U.S. Geol. Survey, 20th Ann. Rept., pt. 3, p. 171, 1900. %¢ It has not been possible to revise the text of this bulletin in accord with recent work on the mineralogy of the clay minerals by Ross and Shannon. THE MINERALS OF IDAHO 387 obvious that this mineral is of very common occurrence and Dr. E. S. Larsen has found, by optical examination, that the clays which have been called bentonite, ardmorite, etc., and which are commonly con- sidered to be altered volcanic dust, are related in their properties but differ somewhat chemically, agreeing with montmorillonite. The leverrierite and montmorillonite are completely crystalline, under the microscope, and are biaxial and negative. They have the micaceous platy structure also possessed by kaolinite and sericite. Their optical properties are sufficiently distinctive to permit them to be determined microscopically. Chemically these minerals are char- acterized by a large water content, a very considerable proportion of which is released below 110° C., as contrasted with sericite and kaolinite, the water of which is not given off much below a red heat. When the mineral powders are dehydrated at 110° C. and allowed to stand in damp air they regain the water which has been lost. When moist the leverrieritic clays are very plastic. Many of them, especially the varieties of montmorillonite called bentonite, absorb great quantities of water and expand remarkably into a jellylike mass. One occurrence of leverrierite and one of montmorillonite have been noted in Idaho, the latter a bentonite and the other a gouge clay. MONTMORILLONITE (bentonite) BOISE COUNTY A lot of clay having the appearance and general properties of ben- tonite was sent to the National Museum for identification by Edward Schwerd, of Boise. A letter directed to Mr. Schwerd asking for details as to the source and occurrence of this material failed to elicit a reply, but it is presumed that the locality is somewhere in the vicinity of Boise. In the hand specimen this material, dried in the air, appears as a fine-grained compact and homogenous clay of a yellowish to grayish- white color. -It is traversed by numerous contraction cracks and has a tendency to conchoidal fracture. It is lusterless until rubbed with a hard object, when it assumes a soap-like polish. The hardness is less than that of gypsum. Fracture surfaces bear small manganese oxide dendrites. When placed in water the material swells very strikingly to a sticky glutinous mass. When stirred with water it settles with moderate rapidity, leaving the water clear. It is almost free from grit. When examined optically the leverrierite of this sample is found to be very fine-grained and micaceous, with moder- ately high birefringence. It is found to contain a considerable amount of very fine-grained calcite as impurity. The apparent index of re- fraction is about 1.580, and the material is brown and filled with air inclusions. A sample treated with hydrochloric acid to remove cal- 888 BULLETIN 131, UNITED STATES NATIONAL MUSEUM cite and washed free from acid was analyzed, yielding the following results and ratios. In view of the fact that, owing to its fineness of grain, the material is unsatisfactory for optical study, its homogenous character is not entirely established. Analysis of bentonite (montmorillonite) from Boise County (E. V. Shannon, analyst) Per cent Ratios Silica l(Si@s) 22. sees 2ST s Siee ee AO acon se lo ee 57. 28 | 0.950 Titanium dioxide (CBIORe ee. Rika Tete ae eee we 000) 956 0.191X5 0.97X5 umina Og) sarees Ieee TLE be SEES Be ok Te ; ‘ Merric iron=(e3O3) 2 eee sece oe oe eee ee ee ee eee ee 4.02] . test -182 .182X1_. 93X11 Time (GhO) Has a eT SE ee A 12: | 12030 Mapnesian( MeO) cites ssa tes Sie Sen oe eae eee 3.28 | .O081} .112 ‘Baritina oxide: (a @) Geecetes SPORE Ue Sass Seon ee eee Trace. }--2--2 .204X%5 1.04%5 Water (Hs0)aboveill0?: Ce ee 6. 60 \ 907 Water (HO). below 110° © i765 _sihs 20D u tee pe eee 10. 50 |f * Motali2. LL IGes eels Paes h hee RO ery ER dae Bt rs | 99. 94 If the bivalent bases be assumed to replace water these ratios give the formula Al,O,.5SiO,.5H,O. In consideration of the fine grain of the clay and the fact that it was not suitable for careful optical work, too much discussion of the analysis is to be avoided. LEVERRIERITE (gouge clay) %% OWYHEE COUNTY A clay mineral, which resembles leverrierite, from the Silver City district has been described under sericite. Another and much better characterized leverrierite has been described from the Black Jack mine in the Carson district.°* This is a specimen (Cat. No. 24, 679, U.S.N.M.) labeled ‘“tallow-clay, Black Jack vein, Carson (Silver City) district.”” The specimen, which has been cut into a rectangular block, is smooth and resembles a hard soap. Its exterior is pale pink where it has darkened on exposure, but the interior is snowy white. The structure is laminated and platy, and when placed in water the material softens slowly and cracks up gradually. At the end of sev- eral hours immersion it had not disintegrated or swelled up in the manner of bentonite. Its hardness in the specimen is about 1, and when it is crushed between the teeth there is an absence of any grit. Under the microscope the material is transparent, colorless, and entirely crystalline, with a finely foliated or felted-fibrous structure. The elongation of traces of the plates is positive, so that, assuming the acute bisectrix perpendicular to the plates, the mineral is optically negative. The indices of refraction are a=1.488, y=1.513. These indices separate this mineral sharply from sericite and kaolinite, which 985 In a forthcoming paper by Edgar T. Wherry this mineral is renamed beidellite. % Earl V. Shannon. Notes on the mineralogy of three gouge clays from precious metal veins. Proc. U.S. Nat. Mus., vol. 62, art. 15, pp. 1-4, 1922. THE MINERALS OF IDAHO 389 have higher indices. The material compares, in refractive indices, with the lowest set of values given by Larsen for leverrierite. Heated in the closed tube the clay yields abundant neutral water at a very moderate temperature. In the forceps it decrepitates mildly and fuses with moderate ease on thin edges to a white blebby enamel, the fused portion becoming markedly incandescent. Mate- rial which had been proven free from contamination by optical study was available in quantity for analysis, and the analysis was carefully made on ample material. The loss of water at 110° C. was found to be 14.48 per cent, the mineral reaching constant weight at this temperature with 2 hours heating. The first hour the loss was 14.28 per cent. During the second hour additional loss of 0.20 per cent was sustained, while several hours additional heating occasioned no further loss. When exposed again to the air of the room, however, the material proved to be very hygroscopic, and a sample which had been dried to constant weight at 110° C. regained all of its original water content upon standing overnight in the air of the room. A similarly dehydrated sample regained 2.18 per cent of its original weight upon standing overnight in a desiccator over calcium chloride. Samples dehydrated at 110° C. and allowed to stand overnight over sulphuric acid show a gain of several per cent, following which they can not again be brought back to the original dry weight at this temperature. The analysis gave the following results and ratios: Analysis and ratios of leverrierite, Black Jack vein | Per cent | Ratios ¥ PEA QTC ae —— Bilican(Si@s)=-s! tee 2 eae Seia lees Save ep el sess seers te | 45.32 | 0. iA 0.7524 0:.251<87 . 1.003 J AVCrt a au a OES OF) a a ee D7Bal) waele\s lane ae Merricdront (MeiOs)ssst Petes a eee. saver A ede el he 20, 0045: -* 276. 276X111. 10X1 Se eee a “ee ee BONIGSIAN INGO) 2 sot Pome wisi espe tee Joi fas j é onsel 1 Potash URGO)ol. sec ee nies "12! “ooir -056 -280xX5 1. 12x5 Wate (HAG) above 110° G22” a wip | ten ater (H20) above a | .16 | . 453) 25 IMS , Water (H20) below 110° C 14. 48 | “gos 2-257. 251X5 1.00X5 These ratios yield the formula. -RO.R,0,.38i0,.5H,0, which may be expanded to RO.5Al1,0,.15Si0,.25H,O. Assuming the miscella- neous bases to replace water, the formula obtained is simply Al,O,. 3910,.5H,0. Other similar clays occurring in these silver veins as gouges may likewise be leverrierites, but Lindgren’s published determinations on many of them made by Hillebrand, as mentioned above under sericite and kaolinite, show too little low temperature water to be leverrierite. 890 BULLETIN 131, UNITED STATES NATIONAL MUSEUM HALLOYSITE (493) Hydrous aluminium silicate, Amorphous Al,03.28i02.2H,0+nH20. Halloysite is a clay mineral, corresponding to the crystalline kaolinite in composition, which is amorphous and isotropic under the microscope. It is probably a fairly common mineral in Idaho, but few specimens of the clays have been examined microscopically and it has been identified only from one locality, as follows: BANNOCK COUNTY A specimen of a clayey mineral sent to the National Museum for identification from Pocatello, Bannock County, is largely com- posed of an isotropic clay mineral which is doubtless halloysite. The material is stated to occur in large amount near Pocatello. The sample, dry, as received, is slightly creamy white in color and is very light and rather tough. When cut or rubbed it assumes the usual soapy luster. Upon being thrown into water or moistened it very energetically disintegrates into a sandy material which is not plastic. The clay adheres to the tongue and has a strong clayey odor. Upon being heated for 1 hour at 110° C. the material reached a constant weight with a loss of 12.86 per cent of water. Ignition to a full red heat resulted in the loss of an additional 9.62 per cent. A sample which had been dried at 110° C. gained 3.14 per cent of the original weight in 20 minutes in air and upon standing over- night in air regained all of the water lost at 110°. The mineral, dried at 110° C., and examined microscopically is very cloudy until it soaks up the oil. It is isotropic with and index of 1.550 to 1.552. It contains about 6 per cent of birefracting material, having the ap- pearance of feldspar which shows albite twinning and has a maximum index of refraction of 1.54. This is doubtless albite. URANOPHANE (503) Hydrous uranium-calcium silicate, Orthorhombic. Ca0.2U03.2S8i02.6H20. BOISE COUNTY The yellow uranium mineral, uranophane, is reported to occur in Boise County at Centerville in the Idaho Basin.t The source of this report has not been ascertained and no further confirmation has been received. Inasmuch as monazite, columbite, samarskite, polycrase, and other minerals characteristic of rare earth bearing pegmatites occur in this vicinity, the occurrence of uranophane is to be expected. 1U. 8S. Geological Survey, Bull. 624, p. 121, 1917. THE MINERALS OF IDAHO 391 CHRYSOCOLLA (504) Hydrous copper silicate, Cryptocrystalline. CuO.Si02.2H20. Chrysocolla, a mineral requiring further study to determine its exact chemical and mineralogical nature, is an abundant and important copper ore mineral in Idaho. The mineral varies from blue, through various shades of blue-green and green and then to browns, shading into what is described below as copper-pitch ore. It is usually waxy-in luster and appearance and massive or botryoidal on free surfaces. Upon microscopic examination the mineral is ordina- rily found to be crystalline and birefracting with definite optical properties, but the optical properties vary widely in specimens from different localities. An amorphous and isotropic copper silicate corresponding to chrysocolla has been called cornuite. Chrysocolla frequently resembles malachite, especially when present only as a stain and, of the two green copper minerals chrysocolla is the more abundant in Idaho. The principal occurrences of the silicate in this state are as follows: ADAMS COUNTY Chrysocolla is first in order of importance among the oxidized copper ore minerals in the contact-metamorphic copper deposits of the Seven Devils district, and is very abundant in many places, especially in the Arkansas mine. In fact the mineral is forming to-day from drippings in many places in the abandoned workings. It is intimately associated in places with copper pitch ore? The chrysocolla appears in masses of opaline texture associated with malachite and in small veinlets cutting the other vein minerals and penetrating all the interstices. Thin waxy green crusts of chrysocolla result from the alteration of bornite and often encrust masses of bornite (Cat. Nos. 51871, and 67391 U.S.N.M.). Speci- mens from the Arkansas mine are pure and green of various shades, the structure being massive or small botryoidal. Chrysocolla appears abundantly in ore from Peacock dump and is waxy, translucent, and various shades of pale blue-green, sea-green, sky-blue, ete. CUSTER COUNTY Although copper silicates are the most important constituents of the oxidized ores of the mines about Mackay in the Alder Creek district, the silicate ore is characteristically brown in color with vitreous to dull luster and is further discussed under copper-pitch below. Locally the silicate is chrysocolla which is bluish green with a vitreous luster. Specimens from the Tiger claim contain translucent emerald-green to blue-green or blue chrysocolla with fluorite. Other specimens 2D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, p. 67, 1029. 892 BULLETIN 131, UNITED STATES NATIONAL MUSEUM from this mine consist of garnet rock containing chrysocolla, fluorite, and copper pitch ore. The green chrysocolla grades into a pale bluish-green soft material of faint silky luster. Under the microscope this shows a finely foliated crystalline structure with moderate bi- refringence. The fibers have parallel extinction with positive elongation. The color in transmitted light is brownish-green in the ageregated fibers with no noticeable pleochroism. The mean refractive index is about 1.615. Specimens from the Peterson lease contain masses of sky-blue chrysocolla up to 2 cm. in diameter embedded in ferruginous clayey material. The chrysocolla has a radiated structure as though pseudomorphous after malachite. Specimens from the Copper Bullion tunnel consist of large masses of fairly pure corneous to vitreous blue-green chrysocolla. The chrys- ocolla has a botryoidal surface where lining small cavities which contain a little copper pitch and malachite. A bluish-green mass occurring in fluorite from the Empire mine is soft and waxy in appearance and resembles some serpentines. Under the microscope this is finely scaly in structure and entirely crystalline with medium low birefringence. It is biaxial positive with 2V near 0°. The refractive index averages about 1.583 but varies to 1.595. The mineral is easily soluble in cold 1:1 hydrochloric acid and the solution contains much copper with no iron, lime, nickel or magnesia. Associated with this is a yellow-green mineral which, under the microscope, appears as radial fibrous spherulites of greenish-yellow color and no notable pleochroism. The extinction is parallel, elongation positive, refractive index above 1.59. Umpleby noted the crystalline character of the green chrysocolla from the Mackay mines and described it. Under the microscope the material appears as acicular crystals with both parallel and radial disposition and as irregular grains and mammillary crusts. The mineral is uniaxial and optically positive with positive elongation and high birefringence. The indices of refraction, which are slightly variable, are w= 1.46, e=1.54. The material is distinctly pleochroic with w=colorless and e=pale bluish-green. It is hexagonal or tetragonal in crystallization with hardness about 3 and density 2.4. The luster is vitreous, color pale bluish-green, streak white; brittle. An analysis of the purest sample of this chrysocolla which could be selected yielded the following results: 8J. B. Umpleby. Crystallized chrysocolla from Mackay, Idaho. Journ. Wash. Acad. Sci., vol. 4, pp. 181-183, 1914. THE MINERALS OF IDAHO 393 Analysis of chrysocolla from Mackay (R. C. Wells, analyst) Per cent VRUIATSUM SHO) rape a eae be Bee ee Oe ee a 5 ee oe 39. 3 cero RICOn (CLG) 2a ewe geet yw Nee ee ee a en ee ee 32.0 Sy ube tm eign eam areas nnn eee ee ome. Noo ee hee eee ee 18.7 Aluminad(Ale@s) SevGRiE JAIL ANS rere See Ey toe ER a 2.4 mMme Oa) yee il creas fo be es ae epee Gai ee hy el gles id ZC LOSI AO (2:11) peers eer sak Pe eee eT eh ee ek ot 3. 6 RPM a CNA) a a os Ce ae eee Trace. WO hea acy ease ti eas oe ah ee ely a hy ee ork 2 teat OTe The analyzed material of the sample was estimated by microscopic examination, to have the following mineral composition: Per cent Chrysocolla.CaQsiOs2HsOWle ls - 28 elo jae eee be eteedadlitee be Sho OlMIpeeAsL Ost AlaOs eo O= one Se tees 2 ee ee Ae Opals... (5.60 per cent H.O)... 2. 2 2s epee nee 8. 2 RG Pale AeA eet 304 ek ey says Ne ee yl Pe the eters ele ie fo 1600. 0 The kaolinite occurs as films along microscopic cracks. The associated opal is bluish and contains some copper. The water content of the chrysocolla was found to vary widely. The chrysocolla is often in large masses and grains of the green silicate are often intimately associated with copper pitch ore. LATAH COUNTY Some chrysocolla occurs associated with copper pitch and other secondary copper minerals in oxidized copper ores from the Mizpah and other claims of the Hoodoo district. LEMHI COUNTY Chrysocolla has been noted as an oxidation product of chalcopyrite in the ores of the Copper King mine on Copper King Mountain in the Eureka district.* ONEIDA COUNTY Old specimens in the National Museum (Cat. No. 51870, U.S.N.M.) labeled Cariboo mine, Cariboo district, Oneida County, contain waxy blue-green to olive-green masses of chrysocolla up to 5 cm. in diameter. These include grains of chalcopyrite. SHOSHONE COUNTY Chrysocolla occurs occasionally in many places in the Coeur d’Alene district in small amounts as a secondary copper mineral. It is less common than malachite in the oxidized lead-silver ores. 4J.B.Umpleby. U.S. Geol. Survey, Bull. 528, p. 76, 1913. 394 BULLETIN 131, UNITED STATES NATIONAL MUSEUM The green silicate is most abundant in the copper area east and south of Mullan. It was the most important mineral of the oxidized ores of the Snowstorm mine, now largely exhausted, where it formed an impregnation in quartzite and coated cracks and open spaces with a translucent greenish blue botryoidal layer. In some cases thicker crusts are made up of concentric and alternating layers of various shades of green or blue-green and greenish-white chalky material or vitreous black copper pitch. A specimen from the third floor above the 800 level, east, consists in the main of green chrysocolla. This is very fine grained, waxy textured and with waxy to dull luster. It varies in color from green, or blue-green to robins egg blue and brown-olive. The green material is overlain by com- pact white material having the same texture as the chrysocolla and like it, filled with contraction cracks. Under the microscope this white material is nearly transparent and brownish olive-green in color. The smaller pieces are isotropic while some of the larger show pronounced double refraction with sweeping extinction. The latter give a distinct interference figure out of the field indicating them to be biaxial negative with 2V small. The average mean index is 1.612 to 1.618. No pleochroism was noted. In dilute acid this material is not dissolved but copper is extracted. It is probably one of the ciay minerals or possibly a serpentine-like substance containing some copper. ‘The chrysocolla of the specimen is like that described below from the Big Elk claim. A specimen from 10 feet beyond the fault on the 800 foot level is rusty quartzite incrusted by a pale-blue transparent minutely botryoidal crust with iridescent luster. Under the microscope this is isotropic with index of refraction ranging from 1.485 to 1.492. It is doubtless copper- colored opal. A specimen from the Big Elk prospect consists largely of fine waxy blue-green chrysocolla shading through olive-green into greenish- brown and brown limonitic materials. Botryoidal linings of the chrysocolla in cavities have a very thin outer glassy layer. Under the microscope the green chrysocolla is seen mainly as a very fine flaky aggregate, serpentine-like in structure, having appreciable birefringence and a dirty brownish-green color in transmitted light. Its mean refractive index is variable with a mean of about 1.575. The outer layer is made up of transparent aggregates of exceedingly fine fibers in nearly parallel position. It has a high birefringence, parallel extinction and positive elongation. The indices are some- what variable but a is considerably below 1.50, the exact value not having been measured, while y is 1.570. Specimens from the Richmond shaft contain a little green chryso- colla along with much greater amounts of copper pitch. THE MINERALS OF IDAHO 395 COPPER PITCH ORE (504a) MELANOCHALCITE Impure hydrated copper silicate, vari- Amorphous. able amounts of iron, manganese, zine, ete. A dark-brown to light-brown or black impure copper silicate containing variable amounts of iron and other substances has long been known by the old German name kupferpecherz or copper pitch ore. This is commonly regarded as an impure variety of chryso- colla, although specimens of doubtful nature and homogeneity have been described from different localities and have been given specific names, such as melanochalcite. The material appears very unlike the fine green opal-like chrysocolla with which it is often associated and, since it is a common ore mineral in Idaho it is here considered separately as a subheading under chrysocolla. The principal Idaho occurrences of this material are as follows. ADAMS COUNTY Copper pitch is a common ore mineral in the copper deposits of the Seven Devils district where it occurs intimately associated with chrysocolla, rarely in alternating concentric layers with the green chrysocolla, which it resembles in all respects except color.» Much of the copper pitch from this district is dead black in color, opaque and almost lusterless. Much of what has been described from here as melaconite is probably impure silicate. A specimen of the sup- posed melaconite from the Peacock claim is hard and compact. A small portion, subjected to a very crude analysis gave the following results: Analysis of ‘‘melaconite” from Seven Devils (E. V. Shannon, analyst) Per cent UICHs CSI Oa arr og ree ES ST 3224 IH ErricHrons (He; Og) ae re re ee ee ree AIO 12. 8 Copper oxide (CuO) ne 38. 6 Dio neRerOxicenGMnOyen a lee oe Oe Se Eo So oe 2.9 PRC TOMIG ENOL IC) eres Ailes oun re eee ee et Les ee 3. 4 Water 'CH;0) by difference [2 2) 200 Foye SvOon At WO deieiein 9. 9 HQ Geary ern ene eM a NNO creriee eR COT ek Ms ik Gd 3 100. 0 This material is doubtless copper-pitch rather than melaconite, A specimen from the Peacock dump shows abundant pitchlike dark brown material forming broad layers surrounding masses of bornite and grading outward into broad bands of green chrysocolla. Speci- mens from the quartz vein on the Queen claim show considerable masses of similar material in quartz containing residual masses and 5D. C. Livingston and F. B. Laney. Idaho Bur. Mines and Geol., Bull. 1, pp. 37, 67, etc., 1920. 396 BULLETIN 131, UNITED STATES NATIONAL MUSEUM grains of chalcopyrite. Such copper pitch is also abundant in the Lucky Strike prospect. BANNOCK COUNTY Dead black lusterless copper pitch inclosing much residual bornite in small grains occurs in ore of the Moonlight mine of the Pocatello Gold and Copper Mining Co., in the Fort Hall district. CUSTER COUNTY In the Alder Creek district in Custer County copper pitch is abund- ant in the oxidized ores. Its most common occurrence is in irregular cores which on their borders blend into chrysocolla. The substance seems to grade into chrysocolla in many specimens, but its contact with other minerals is sharp.® Specimens of typical ore from the Tiger claim contain masses of vitreous black copper pitch inclosing residual bornite and surrounded by chrysocolla. Specimens from the north tunnel of the Empire mine contain pitch hke brown mas- sive material inclosing chalcopyrite. Much of the oxidized ore of the Mackay copper deposits is an impure copper silicate which is characteristically brown in color with vitreous to dull luster and con- choidal fracture. It does not look cupriferous. It is in large part amorphous under the microscope and concentric structures commonly show alternating layers of different shades of red and yellow. An analysis of such brown isotropic ferruginous silicate yielded the results given below: Analysis of brown silicate ore, Mackay (R. C. Wells, analyst) Per cent Silica (SiO, ) et 288 Re Gi To Pa oe Se i ee 29. 6 Copper*oxide? (Ca @)2 Fors De eee ear ae EIN Se a ery ee es ee 19. 4 Water (Es @)) 2 22 Ste Ce ak et eh UN a ono ie lp en iS? Avumina((Al;O3) ete Ca hate BE saison pate Bi: ah lag eB apes us Tere eg na 5. 6 Bierrigainom: GHGs Os) Sth cae Se Ne art Ney re ps ae Ene cg ce ge ae pa 24. 0 Rerrous iron (Ee O)) 3: fe le a eae a cae ee ere 2 Wamrer (CaO) a oe ae RS Ee ee ee 1.9 Miagtesia (MgO) 25 St 2c S See ee Sa rae ee 5 Detar ee ea a ae a 99. 1 The material of the above analysis contained about 4 per cent of the green crystalline chrysocolla, described above, in isolated crys- tals, small aggregates, and narrow layers of closely packed fibers.? FREMONT COUNTY Dark brown copper pitch ore varying from dull through waxy to brilliant vitreous luster, inclosing ragged remnants of chalcopyrite occurs in specimens of ore from the Weimer copper mine, Skull Canyon district. 6J.B.Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 51, 1917. 7J. B. Umplegy. Idem. THE MINERALS OF IDAHO 397 IDAHO COUNTY Brown pitchlike masses of copper pitch occur surrounding chalco- pyrite in quartz from the Tom Thumb claim, Lolo Creek mining dis- trict. Similar black pitchlike material forms pseudomorphs after masses of chalcopyrite in quartz from the Venture claim, Buffalo Hump district. LATAH COUNTY Copper pitch occurs commonly with malachite, azurite, etc., in oxidized copper ore of the Mizpah mine, Hoodoo district, in Latah County.’ LEWIS COUNTY A little copper pitch occurs in copper stained quartz from the pp PI Horseman mine, Deer Creek district.® SHOSHONE COUNTY Copper pitch is one of the commonest secondary copper minerals in the copper prospects of outlying sections of the Coeur d’ Alene district. It has been noted from many of the copper mines and prospects in the vicinity of Mullan. It is usually the first product from the breaking down, through oxidation, of chalcopyrite or bornite and the chalcopyrite ores from shallow workings of the prospects is almost invariably invested with an outer halo of pitch- like brown material which penetrates it along cracks. Specimens from the Snowstorm mine show brown to black material intimately associated with green chrysocolla, sometimes alternating with the green material in concentric layers making up botryoidal crusts. Fine large masses of dark brown material containing scat- tered remnants of chalcopyrite have been obtained from the Rich- mond shaft and similar specimens have been seen from almost all of the copper prospects of the Mullan area. Copper pitch is almost invariably present also in association with chalcopyrite, from which it has been derived, in ores from the numer- ous copper prospects on the North Fork and Little North Fork of the Coeur d’ Alene River. CHLOROPAL (505) Hydrous ferric iron silicate, composition Earthy, amorphous to eryptocrystal- approximating Fe,03.3Si0,.5H,0. line or fine micaceous. The name chloropal probably covers a number of related silicates differing in composition, optical properties, etc. The most common and best characterized of these is probably the one known as non- tronite. The several Idaho occurrences mentioned below have not 8 D. C. Livingston and F. B. Laney. Idaho Bur. Geol. and Mines, Bull. 1, p. 95. ® Livingston and Laney. Idem, p. 100. 898 BULLETIN 1381, UNITED STATES NATIONAL MUSEUM been studied in detail because of lack of material and the identifi- cations are tentative. CUSTER COUNTY A specimen sent to the National Museum for identification from Challis, by Dr. C. L. Kirtley, consists of a rounded nodule of brown jasper invested in a friable granular green layer which appears to be impure chloropal of the variety known as nontronite. A specimen from the Reed and Davidson mine, Copper Basin district, is a soft and greenish rock to some extent resembling epidote. This is found, upon microscopic examination, to consist of granular diopside altering to what is probably the nontronite variety of chloropal. The rock contains much magnetite and a little chryso- colla and copper pitch. The chloropal appears under the microscope as confused and felted aggregates of very fine scales of moderately high birefringence which in transmitted light are moderately deep greenish brown in color and show no notable pleochroism. The index of refraction is somewhat variable with a mean of about 1.615 + 0.005. SHOSHONE COUNTY Greenish-brown grains and masses in quartz which contains grains of chalcostibite(?) from the Standard Mammoth mine at Mace are transparent, greenish brown and isotropic to metacolloidal with very fine microcrystalline structure under the microscope. The refractive index is about 1.625 to 1.627. Only a very small amount of the material was available for examination. It was not rare in the mine, however, where it occurred in quartz seams cutting the vein, and plenty of it can probably be found on the waste dump of the Mammoth lower tunnel. It is probably chloropal, but requires more detailed examination on more material. HISINGERITE (506) Hydrated ferric iron silicate, approximately Amorphous. Fe,03.2Si02.4H20. Hisingerite is a hydrated iron silicate which closely resembles some forms of limonite, on the one hand, or brown opal and much copper pitch ore. It is probably of rather common occurrence, but has been largely overlooked or mistaken for one of the minerals mentioned. The only place where the mineral has been definitely identified is in the Minnie Moore mine in Blaine County. BLAINE COUNTY Hisingerite is common in the Minnie Moore mine near Bellevue in the Wood River region, where it was first identified by D. F. Hewett. The material has been subjected to a detailed investiga- tion by Messrs. Hewett and Schaller, whose results will be published. THE MINERALS OF IDAHO 399 According to Mr. Hewett’s interpretation of the occurrence of the mineral, it has formed by replacement of siderite along cracks by heated solutions which elsewhere deposited zeolites. When first ex- posed the mineral is blood red in color, but upon drying it assumes the usual pitchy appearance and brown color and becomes filled with contraction cracks. IDDINGSITE (506a) Hydrous silicate of ferric iron, etc. (Mg, Ca)O. Orthorhombic Fe,03.38i02.4H20. The mineral iddingsite, long recognized microscopically as an alter- ation product of olivine in igneous rocks, has recently been found to be a well-defined hydrous ferric silicate with definite optical proper- ties. The mineral has been found in the several Idaho localities listed below and probably occurs elsewhere in basaltic or other ex- trusive rocks. BOISE COUNTY Lindgren states that !° brown-red products from the decomposition of olivine occur in basalt interbedded with the Payette lake beds on the north side of Moore Creek 1 mile above Idaho City. Iddingsite also occurs in specimens of basalt from Warm Springs Creek in the Bear Valley quadrangle, which contain the zeolites, chabazite, and thomsonite, already described. OWYHEE COUNTY Iddingsite occurs in very typical red-brown grains and patches up to 3 mm. in diameter in specimens of basalt from Bernard’s Ferry. It is clearly derived by the alteration of olivine. A sample of pure crystalline iddingsite separated from this rock by the use of heavy solutions and an electromagnet was analyzed with the following results: Analysis of iddingsite from Bernard’s Ferry (E. V. Shannon, analyst) Per cent SHCA PG OLO NATE MEL OUR AT) eee hs POLL SLICE 40. 28 RitaniumydioxiGdeCLiO;) ciistusrr aye 2s Jaa aod ents »L2 PS TMUPRTEY EEA) gee en Ve Ge ee ge ene ee SAO Herniesironedbe;@s) sek os etre GE ed a ie, ed = 29. 76 Herroisnnonn (he) esac m ets 2h ceess A URh ALEC eth ees Ye g) Meee Lime (CaO oe a 2 EO eR eek eee 3. 00 Winwnesia C(ViCO ys nae eR eS oe 10. 36 Water (HoOjabovertlUrsC sees sa Lee oe ails ele 5. 28 WielerrCEGOy below TkU;t@ =e 2 = eee owe ee Se 12 BO Gea) ene See | eg an Serre ae acs eS Doty S52 ot 100. 08 The iddingsite is dark reddish brown in thin section and occurs as pseudomorphs after olivine. The larger grains are completely al- 10 Waldemar Lindgren. 18th Ann. Rept., U. S. Geol. Survey, pt. 3, p. 669, 1898. 400 BULLETIN 131, UNITED STATES NATIONAL MUSEUM tered to iddingsite, but some of the smaller ones show outer borders of iddingsite around cores of olivine. The iddingsite has very per- fect cleavage which, however, is masked by the extreme brittleness of the mineral. Cleavages parallel to the three pinacoids are well developed and there is probably a fourth cleavage parallel to a dome face. The optical orientation is X=a, Y=b, Z=c. The indices of refraction are: a=1.710+0.005, B=1.722+0.005, y=1.754+0.005. The optic axial angle varies from 20° to 65°, with an average of about 50°. The optical character is negative, dispersion strong; color red- brown; pleochroism shght. As has been noted from other localities, there occurs with this iddingsite an amorphous or cryptocrystalline substance derived from the olivine in the same manner as the deeper-colored crystalline material. In some specimens this forms at the core and in others occurs as a border around the crystalline material. A sample of this material, separated from the iddingsite, was analyzed with the fol- lowing results: Analysis of cryptocrystalline material associated with iddingsite (E. V. Shannon, analyst) Per cent SHicae(SiOs) ios eee ele Meo Seek wea Oe PPL ee eat eae ete 44, 40 Titanium dioxide: (is) =a eee ee de ee ho pee ee 216 Alumina; (ALO3)22 aha gait) omer ah Cee ae 2:28 Merric inom Ciies Oia) oe ee ee oe ce ee ae ir ena Im ee ee 29. 00 Parr (CaO) Seve ea i Se sca Te eg ee es 9 e ne g 2. 20 Magnesia (Mg) 20) perder Poe Tye a ee we goers ehD Weaterj(HsO) laboverdlO? Ge sic csi sec eee ee 6. 96 Waiter iGH>sO) below ailOss Cee Ss eta A a a eee 8. 40 otal 2/0 shan encys dt + fee le Biya 4 she aed as ae ps Seas, 100. 52 This is apparently an amorphous equivalent of the crystalline iddingsite. TITANITE (510) Calcium titano-silicate, CaO.TiO;.SiO». Monoclinic. Titanite has been noted at several places in Idaho as crystals in placer concentrates and as small crystals in rocks, but no locality of consequence as a source for mineralogical specimens of the mineral is yet known. The following occurrences have been noted: ADAMS COUNTY Titanite is listed by Livingston and Laney" as a mineral of the contact deposits of the Seven Devils district. BOISE COUNTY Titanite is common as an accessory mineral in rock from the Silver Wreath mine in the Willow Creek district.” 11D. C. Livingston and F. B. Laney. Idaho Bur. Geol. and Mines., Bull. 1, p. 62. 12 Waldemar Lindgren. U.S. Geol. Survey, 18th. Ann. Rept., pt. 3, p. 709. 1898. THE MINERALS OF IDAHO 401 CAMAS COUNTY Titanite occurs prominently in a black sand placer concentrate from Bear Creek, Camas County. The crystals, which are minute vary from pale yellow to greenish in color and show the familiar “envelope” habit bounded by the forms ¢(001), a(100) and n(111). CLEARWATER COUNTY Small yellow crystals similar to the last occur commonly in a placer sand concentrate from Cow Creek in the Pierce district. VALLEY COUNTY Titanite is present in numerous crystals in a coarse-grained red granitic rock sent from West Mountain in Valley County by I. W. Phillips, of Pocatello. The crystals reach an extreme diameter of 4 mm. and range from honey yellow or reddish yellow to black. They have the usual envelope habit, but show smaller modifying faces of a number of other and less common forms. BRANNERITE (519a) Hydrated metatitanate of Uranium, etc. Orthorhombic or tetragonal. CUSTER COUNTY The new mineral brannerite has recently been described as material from a gold placer worked by Henry Sturkey 1 in Stanley Basin in the central part of Idaho.’ The placer f from which the mineral came is near the head of Kelly Gulch in western Custer County. The bed- rock in the gulch is said to be granite cut by pegmatite. The branner- ite is probably derived from one or more dikes of the pegmatite. The mineral occurs in the form of grains part of which are prisms and most of which show a prismatic tendency (see pl. 13). They are brownish yellow on the outside but the visible weathering has ex- tended to a depth not exceeding the thickness of paper. Inside they are a brilliant black, with a conchoidal fracture and no sign of cleavage Polished specimens examined under reflected light show the mineral to be remarkably homogeneous. It is, however, traversed by minute eracks which are in part filled with quartz that undoubtedly accounts for the silica shown in the analysis. Although to the eye the mineral is opaque black, under the microscope very thin chips allow sufficient yellowish-green light to pass to make possible optical measurements. The streak is a dark greenish-brown. The hardness is about 4.5, as the mineral will scratch apatite but will not scratch orthoclase. The crystals are not perfect enough to allow a determination of the erystal form but their shapes suggest that they may be orthorhombic or tetragonal. mOwovery E. S. ‘Larsen determined it to be isotropic 13 Frank L. Hess and Roger C. Wells. Journ. Franklin Inst. Philadelphia,vol. 189, pp. 225-237, February, 1920. 402 BULLETIN 181, UNITED STATES NATIONAL MUSEUM with an index of refraction for lithium light of 2.26+.02 and for sodium light, 2.30+.02. It seems probable that it is an isometric paramorph after either a tetragonal or an orthorhombic form as many of the complex pegmatite uranium minerals seem to be. Also like nearly all of the complex pegmatite minerals this mineral is variable in composition and the specific gravity of the specimens tested ranges from 4.50 to 5.43 as determined with the Joly bal- ance. The specimens analyzed had a specific gravity of 5.42 (by pycnometer). The radioactivity of specimens of different specific gravities showed slight differences as tested by the exposure of a photographic plate, those having the highest specific gravity appearing most active (pl. 14). The material was not tested with an electroscope. Pieces of like content of uranium and thorium were selected on the basis of comparative radioactivity. Two of the least active pieces from the seventh row (pl. 14) gave on analysis 35 per cent TiO, compared with 39 per cent in the best material. If available in quantity this mineral would be of value as a source of radium, but probably only a few pounds could be secured even at prohibitive cost. The analysis of such a complex mineral is so difficult that too much weight can not be attached to the percentage figures. The mineral is slowly decomposed by treatment with concentrated sulphuric acid or by hydrofluoric and sulphuric acids. It is more convenient, however, to bring it into solution by gentle fusion with acid sodium sulphate. On dissolving the melt in cold water or dilute sulphuric acid there remains a small residue consisting of silica, unattacked mineral, and sulphates of lead, barium, and strontium. The analysis gave the following results: Analysis of brannerite from Stanley Basin, Idaho [R. C. Wells, analyst] Per cent Moleauler Silical(Si@s) ts ee ee ee eee eee 0. 60 0. 010 (Ritanivmidioniade: (iOs) 2 ssa) es 2s eee eee ae a eee nee 39. 00 . 488 Ferrous oxide (FeO) ----......-----------------------------------------------=-- 2.90 . 040 Lime (Ca0) ee eee ae ee ee oases ere 2. 90 - 052 UWraniunt dioxide! (WiOs) 22222) 25 ees ee ne eee 10. 30 - 038 Granium' trioxide (UiOs) se sais Ce ea ee ee eee 33. 50 .116 ‘Thoria (TNOs) = seosse ee 2 a a ee cee 4.10 -015 @eriat(GerOs)i 5202 ft ees ELE Ee EE Se ee eee ee ewe None. | 22. eit Witirin earths GraOsnetc.) coesccne ote aa ee ee ee ae ee 3. 90 . O11 Firconiag (Zr Os) eee es ee EAT es ea SSE SES Cees BESS Se . 20 . OOL TeeRdvoxide. CED O) xe eee en ee oe ea ee ee oe ee . 20 . 001 ‘Berium/exide' (Ba) Le Raa ah ee ae Or PE ee eee oe . 30 . 002 Strontiumioxide;(SrO)) ee ae ee eee ee ee ee ee .10 . 001 Waters(Hs0)2fiu 2 ees NOR EEE “PEN ee PE SS Ee oe a8 Se AES 2. 00 Ld! @arbon\ dioxide: (@Os) 2-2 =. sae Sea a eee eee ee apes . 20 . 005 BULLETIN 131 PL. 13 U. S. NATIONAL MUSEUM IN ry, PITCHBLEND wood M CENTRAL CIT <1 /@%40% ) Sp.G. 5.2 >F@er3ese Sp.G.5.1 b 3 ) Sp.G. UNDET. BRANNERITE U. S. NATIONAL MUSEUM BULLETIN I3! PL. 14 RADIOGRAPH OF BRANNERITE FOR DESCRIPTION OF PLATE SEE PAGE 401 THE MINERALS OF IDAHO 403 In addition to the above constituents the analysis showed traces of ferric oxide, alumina, and phosphoric oxide. FEarlier tests did not definitely identify helium as a constituent of the mineral, but later tests made by more improved methods showed helium to be present in the mineral." The molecular ratios of the above analysis may be combined as “follows: Hee. 0. 040 ge a 2. 0, 038 CO one. 0. 005 Ca@el ns. 052 PROS oe . 015 BIOs sstou 010 BAO i961 002 //.< 0 aM 002 MOsVs Ut 488 po@es. o.t.2 001 5 Pues. 001 055 503 . 096 This leaves Yt,O,—0.011, UO,—0.116, and H,O—0.111 un- grouped. On this basis the mineral may be simplified to: Fuerst oa ase ae tlie Soe 0. 096 8. 7 TO etyneex acta tal teh s a) Uh) 7OLT 1 0 Eig eed eas vat eet ee . 055 5. O WOE eae. 2h ee eo ~ L16 10. 5 DIO ge 4 hicks 2 EE aed 2 ATS . 503 45. 7 DELO) mee ee meee hee AN al Ed 10. 1 Without any further combination this yields the approximate formula: The figures for RO and UO, are not very near whole numbers, but this need cause no disappointment, as the whole calculation rests on the assumption that the iron is in the ferrous condition. Although this assumption has certain analogies to support it and is given preference, it would not be entirely unreasonable to assume that part or all of the iron is in the ferric condition. The question can not be settled experimentally in the presence of uranium in two states of oxidation. If all of the iron is assumed to be present as ferric iron the following percentages and molecular values are ob- tained in place of those first given: Per cent Molecular values Bie One hes oe a tol OA io None. ier One eres ato a Sn 3. 20 0. 020 Oars ee save cere ten 18. 40 . 068 TOO Piety SEY POU PE TGS 25. 10 . 089 Appropriate grouping now leads to the approximate formula: 2RO.R203.3RO2.3U03.18Ti02.4H,0 The bases are apparently present as titanates, metatitanates, or uranotitanates, but an exact evaluation of the relative proportions 4 Wells, R. C. Note on brannerite, Journ. Franklin Inst., vol. 189, No. 6, pp. 779-780, June, 1920. 404 BULLETIN 181, UNITED STATES NATIONAL MUSEUM of these compounds is obviously very difficult and hardly appears practicable in view of the uncertainty concerning the stage of oxida- tion of the iron and uranium. There is more TiO, present than is required to form normal titanates of all the bases, but not enough to form metatitanates without taking some uranium as the basic radicals UO and UO,. To secure an exact balance any excess of TiO, may be reduced to the form of a titanyl metatitanate TiO.TiO,.” The mineral may berepresented asa hydrated metatitanate of various bases, thus: (Ca,Fe,UO, TiO) TiO;.(Th,Zr, UO) (Ti03)2.Yt2(TiO;).H20. Without implying exact molecular ratios the proportions of these four would be about 6:8:1:3, respectively. It is to be remembered, however, that the state of oxidation of the iron is unknown and this ignorance introduces uncertainty in these proportions. Nor is it known whether minerals of this kind should be considered as mixed crystals, solid solutions, or salts of complex acids. The brannerite contains more uranium than any similar mineral except pitch- blende. Unlike most others it contains no tantalum or columbium and is very high in titanium. THE NIOBATES-TANTALATES The minerals of the several groups included under the heading Niobates-Tantalates have been found in Idaho, with the exception of columbite, only as grains and larger masses in the concentrates from placer gravels, mainly in Boise County, but also in Custer and Clearwater Counties. ~The available information regarding these minerals has been, in part, previously presented in an earlier publication by the writer.* The minerals mentioned below as tentatively identified in these sands include fergusonite, columbite, polycrase, hjelmite, aeschynite, samarskite, pyrochlore, and euxenite. Of these, columbite is de- finitely identified and brannerite, a new mineral, has been described in detail above. The identifications of polycrase and samarskite are partially established by crystal form while the other identifica- tions are little better than mere surmises. The mineral listed and described as polycrase is available in amount sufficient for chemical analysis but the other minerals are present only as small grains and their isolation in pure form in amount sufficient for analysis would be a matter of difficulty. The identification of minerals of this class is difficult, since most of them are isotropic, many of them are opaque, and all have very high indices of refraction. Furthermore none have characteristic blowpipe reactions or chemical peculiariarities of diagnostic value. The analysis of any mineral of the group is a 18 Karl V. Shannon. Mineralogy of some black sands from Idaho, ete. Proc. U. S. Nat. Mus., vol. 60, art. 3, pp. 1-33. THE MINERALS OF IDAHO 405 task only to be undertaken by a chemist experienced in this particular work and requires much time and a large amount of material. The rare-earth minerals are associated in the heavy sands with abundant monazite and their source has not been proven by the find- ing of any of them in place in matrix, although the fact that they sometimes contain embedded mica and other minerals suggests that they came from the granitic rock. The source is quite probably in pegmatitic phases of the granite and a careful examination of peg- matitic streaks and segregations in the bedrock would doubtless _ reveal them in place. FERGUSONITE (523) Columbate and tantalate of yttrium, Tetragonal. erbium, cerium, etc., approximates the formula (Y, Er, Ce),03 .(Cb, Ta)20s5. BOISE COUNTY Rare brown resinous grains observed under the microscope in a concentrate from a placer sand from the Idaho City dredge, Idaho City may be fergusonite. In one case a crystal was seen which appeared to have the tetragonal form and pyramidal hemihedrism of fergusonite. When crushed and examined under the microscope the material of these grains is transparent, light brown in color and perceptibly isotropic with very high refractive index. COLUMBITE (525) Iron columbate, FeO.Cb20;. Orthorhombic. Columbite has been obtained only in Boise County where it occurs as small crystals in heavy sands and also as larger masses probably in pegmatites. BOISE COUNTY A separation product from a concentrate from placer gravels worked by the Idaho City dredge at Idaho City, consisting largely of samarskite, contains important amounts of a black mineral in crystals, which proved, upon measurement, to have the angles of columbite. Aside from the difference in form, which is not always manifest, this mineral greatly resembles ilmenite, which occurs com- monly in the sands. The columbite makes up about 10 per cent of the samarskite concentrate and is more abundant than samarskite in another concentrate from the same locality which consists largely of garnet. The columbite crystals vary considerably in habit, ranging from tabular parallel to the pinacoid 6(010) to square prismatic. The common forms and habits are illustrated in the drawings, Figures 122 to 125, inclusive. ‘The color is black and the luster is more vitre- ous than metallic. The prismatic planes are usually very brilliant, but the terminal faces are frequently more or less dull or pitted. 406 BULLETIN 131, UNITED STATES NATIONAL MUSEUM This is especially true of the unit pyramid u(111), the faces of which are most frequently dull and often show rounded depressions." Under Figs. 122-125.—COLUMBITE CRYSTALS FROM BLACK SAND. IDAHO City, BOISE COUNTY the microscope the powdered mineral is translucent on thin edges with a brown color. Frequently several crystals of similar habit are grown together in parallel position and many crystals are_attached THE MINERALS OF IDAHO 407 to small masses of quartz and muscovite. In the coarse, polycrase- bearing sand from Centerville crystals up to 1 cm. in length occur sparingly, which have the form and appearance of columbite. These are invariably dull with a grayish-black color and somewhat metallic luster. These are more opaque than the small crystals described above. Judging from appearance alone it seems probable that these crystals from Centerville are ordinary columbite while the brilliant black crystals from Idaho City are probably higher in their content of tantalic acid and possibly contain some manganese. The forms and angles measured on crystals from Idaho City are given in the, following table: Measurements of columbite crystals from Idaho City Form Symbol Measured Calculated ; = Quality, description ; ce No.| Letter Gdt. | Miller e | Pp g p | | ° , ° , | ° / | ° / te Ware co0 | 100 WVICEY 2000s ee ea eee | 90 00) 90 00 / 90 00! 90 6O 2eUee oe Qoo | O10. 5 -|2e 2 COS ee ee ee eee SNS 0 00/980 00}; O 00; 90 00 Sale eee 0 | 001 (POOL ee eee a ee eee nek Saeoe eee O: (06° |Seee 2 0 00 Aa gees ©O | 110 MCE Y: POOG 253 ee ens ce a eee | 68 14) 90 00] 68 05 | 90 00 Somes ses cs | SOc Sa aee COs ne ee eee ee | 39 32/90 00); 39 38] 90 00 Geen cose Cooper 150 IP OO sn ne ER OI eee ene 28 20/90 00 | 26 26) 90 00 ae Cee ee Ta Pee Ted Ai pene na me Ae foe eA Sy 68 23| 43 23 | 68 05} 43 48 Sulack 21 | 211 GOO ds cee a ea ese 78 35 | 61 16 78 387) 61 O09 OE Beers 12 121 OO Yet eee oie ey eee ern ae ese 52 04] 48 36] 51 11 | 48 48 10 | eb nse 2 20 201 Goode =e wt a on seek eS | 90 00/| 60 29} 90 00) 60 39 | In addition to the occurrences of columbite in the heavy sands, the mineral has been found in place in larger masses in this county but the locality is not known. A number of pieces of columbite in the National Museum are labeled as from near Boise. The mineral is typical heavy iron-black columbite, some of the pieces showing crystal faces. The largest fragments in this lot are about 2.5 em. in diam- eter and are partly coated with a scaly fine micaceous material. Another specimen of columbite has recently been received from Boise County. This is a mass of columbite 5 by 7 cm. in size, and Frank L. Hess writes that a much larger mass was received from the same locality by the United States Geological Survey. The speci- men consists of an aggregate of crystals, some of which show a few good faces. The columbite shows attached portions of large mica crystals and is obviously from a pegmatite. 408 BULLETIN 181, UNITED STATES NATIONAL MUSEUM SAMARSKITE (529) Variable complex columbate and tan- Orthorhombic. talate of various bases approximat- ing the formula 3(Fe,Ca,UO,)0. (Ce, Yt)203.3(Cb, Ta)20s. BOISE COUNTY A sample of a heavy concentrate from a sand from Idaho City labeled ‘‘ P654, olivine,” was found to be strongly radioactive. Care- ful microscopic examination showed this material to be composed in large part of a coal-black glassy mineral with a brown streak and conchoidal fracture. The mineral occurs in rounded grains and in dull pitted square prismatic crystals which are either broken at the ends or are terminated by a chisel-shaped dome. All of the grains and crystals are very much corroded and are dull and brownish in color on the outside. One of the smooth- est of the crystals was measured by light reflected from the faces and gave approximate measurements of 90° between the pinacoids and 86° between the faces of the dome, which compares well with the angle e(101) : e’(101) =87° for samarskite. The radioactivity of the mineral, its crystal form, and its physical properties suggest that it is samarskite. The identity is by no means definitely established, however, and it is to be understood that this and several other of the rare Fia. 126.—SAMAR- s 3 sxite rrom earth minerals of these sands are but tentatively as- BLACK SAND, sioned to the species under which they are described. IpaHo CITY, mn . ‘ Bose County. ‘Lhe hardness of the samarskite is 5-6. The streak Drawn witt js dark brown. When powdered and examined under b(010) IN FRONT : : : the microscope the mineral is found to have a dark- brown color and to be transparent only on very thin edges. It is isotropic throughout as are most such rare earth minerals. The form and appearance of the crystals are as shown in Figure 126, which also shows the tendency of two or more crystals to occur in parallel position. The samarskite makes up about 60 per cent of this material, which apparently is the heaviest fraction of a concentrate from a sand obtained from a dredge operating at Idaho City. In addition to the 60 per cent of samarskite, this concentrate contains about 10 per cent of columbite in sharp crystals, the remaining 30 per cent consisting of various other unidentified rare earth minerals, zircon, monazite, garnet, and much metallic lead, the latter evidently being artificial and fragments of solder, shot, or something of the sort whose source is not known. Several other samples labeled ‘“P654, chromite,” “P654, garnet,” etc., are apparently other frac- tional concentrates from the same original lot of sand. The one labeled garnet consists of about 50 per cent by volume of brownish- THE MINERALS OF IDAHO 409 red almandite in sharp trapezohedral crystals, the remaining 50 per cent being largely samarskite and columbite. The columbite is relatively more abundant than in the first sample examined. The samarskite is entirely like that already described, showing rounded pitted grains and rough crystals. Some of these have grains of quartz and crystals of muscovite attached to them, while others seem to show either two minerals or two generations of samarskite, some of the grains, where broken, showing an inner crystal surrounded by an outer shell of a similar substance. The sample labeled “chromite’’ contains a little samarskite but is, for the most part, composed of ilmenite. HIELMITE (531) Stanno-columbate and _ tantalate of Orthorhombic. yttrium, iron, manganese, calcium, ete. Formula doubtful. CLEARWATER COUNTY Out of a concentrate from a placer mine at Pierce, Clearwater County, labeled ‘‘ Rutile and aeschynite,” there was selected a small waterworn pebble, less than a centimeter in diameter, which was very tough when broken and had conchoidal fracture and very brilliant submetallic to resinous luster. Under the microscope the material of this small mass was doubly refracting with a mean index of refraction between 2.31 and 2.40. The birefringence was 0.02, color very dark brown; pleochroic. Hardness 4.5, specific gravity 6.18; streak red-brown. These properties are nearer those of hielmite than any other of the rare earth minerals. The mass was lost without any chemical tests having been made. AESCHYNITE (532) Chiefly a columbate and titanate of the Orthorhombic. cerium metals. CLEARWATER COUNTY A lot of waterworn grains and small black pebbles received by the National Museum from Pierce in Clearwater County is labeled ‘Rutile and aeschynite.’”’? Presumably aeschynite has been identi- fied in this material by someone, although most of the pebbles examined by the writer proved to be rutile of unusual colors. One piece was tentatively identified as hielmite and a crystal was meas- ured which could not be identified. Aeschynite may occur, since only a small proportion of the masses, all of which look alike, could be examined. 54347—267-—27 410 BULLETIN 1381, UNITED STATES NATIONAL MUSEUM EUXENITE (534) Columbate and titanate of yttrium, Orthorhombie. erbium, cerium, and uranium. For- mula doubtful. CUSTER COUNTY | Euxenite has been reported to occur in heavy black rolled pebbles and masses devoid of cleavage or crystal outline in goid-bearing gravels at the head of Kelly Gulch on a claim which is only 300 feet from the low divide between Kelly Gulch and Stanly Basin. The mineral, which is strongly radioactive, has not been quantitatively analyzed.'® The locality is the same as that which furnished bran- nerite and the so-called euxenite may have been brannerite. POLYCRASE (535) Columbate and titanate of yttrium, erbium, cerium, and uranium. For- Orthorhombie. mula doubtful. BOISE COUNTY A sample of “oversize” coarse sand from a placer concentrate from Centerville contains abundant grains and rough crystals of a dark brownish or greenish-black mineral not very dif- ferent in appearance from the samarskite. The crystals, which reach 1 cm. in diameter, are or- thorhombic in aspect and vary from square- prismatic to thin tabular. They are all coated with a thin exterior crust of a pale-yellow altera- Hn tion product. Within this shell the crystals and ~ Go Z 33 grains consist of a brownish-black glassy ma- terial having a conchoidal fracture and a brown streak. Under the microscope the fragments are Fic. 127—Porycrase transparent, isotropic, and brown in color. The FROM BLACK saNv. ynineral is intensely radioactive. Several lots of aan Crry, Boss this material have been received and it seems to be common, especially in the Poncia placer tract. A lot of the fragments of the mineral are shown in natural size in Plate 15, while in Plate 16 is shown a radioactivity photograph made from the same lot of pieces. F. L. Hess has turned a rather large sample of this mineral over to the Museum for investigation which has not yet been undertaken. The properties and appearance of the mineral are identical in most respects with the polycrase of Marietta County, N. C., and for the present it will be referred to that mineral. This mineral, recognizable by its light-colored coating, occurs sparingly also in the samarskite and columbite-bearing concentrates from Idaho City. A crystal from this lot gave measurements on the 16 Robert N. Bell. 16th Ann. Rept. Mining Industry of Idaho for 1914, p. 29. U. S. NATIONAL MUSEUM .@@® ae °e a= eS 2&2 42 2 @ (Same B&B 2 = la @wnr = ge «= a j 0&6 @ 9 o § - < &a @& —=— N 49 3 4 DQ a 4a Q 59 8 8 56 “> 3 BULLETIN 13! PL. 15 9 3 Ad os POLYCRASE oad) Z ) GE FOR DESCRIPTION OF PLATE SEE PA U. S. NATIONAL MUSEUM BULLETIN 131 PL. 16 PAGE 410 OF PLATE SEE Ww n < o oO > — Oo ou Ww ° ele a < o o Oo Q < x FOR DESCRIPTION THE MINERALS OF IDAHO 411 pinacoids and on two pyramid faces indicating roughly the form s(111) of polycrase. The remaining faces were coated. The form and appearance of this crystal, which is tabular, are shown in the drawing (fig. 127). There is, as shown in the figure, a smaller crystal in parallel position projecting from the face of the larger individual. The so-called Poncia tract, from which the most of this mineral has come, is worked by Carlos Poncia in Swede Gulch near the center of section 9, township 7 north, range 5 east, 114 miles southwest of Pioneerville. The polycrase is concentrated in the heavy sands with brilliant crystals of yellow monazite and colorless zircon. MONAZITE (537) Phosphate of the cerium metals Monoclinic. (Ce, La, Di}2,03.P20s. Monazite is abundant in a number of places in Idaho as a con- stituent of concentrates from the gold-placer deposits. The presence of this mineral in the State was first recognized by Lindgren " in the gold placers of the Boise Basin, where he found it as a resinous brown mineral in subangular grains in part exhibiting crystal faces. Roughly quantitative analyses by Hillebrand made upon the purified sand showed the principal constituents to be phosphoric acid and cerium earths, with a small amount of thorium. The absence of yttrium earths showed that xenotime probably was absent. Later, Day,'® in his work on the black sands of the Pacific slope, reported the mineral from 37 localities in 10 counties in Idaho. Some of these are in error, since several of the sands listed are from Snake River localities, and a reexamination of the same samples failed to detect any monazite. Schrader has recently * described the occurrence of monazite in Nez Perce County. BOISE COUNTY The monazite occurs most abundantly in the gold-placer region about Centerville, in Boise County, and preparations were made some years ago by the Centerville Mining & Milling Co. to recover and clean the sand for market. The plant which was built was burned before any important production was made and the commer- cial outlook was not sufficiently bright to encourage its rebuilding. At present the only value which attaches to monazite is dependent on its thorium content. The Idaho monazite is seemingly lower in its thorium content than similar sands from Brazil and North Caro- 17 Waldemar Lindgren. U.S. Geol. Survey, 18th Ann. Rept., pt. 3, pp. 677-679, 1898. 18 David T. Day and R. H. Richards. U.S. Geol. Survey, Mineral Resources of United States for 1905 pp. 1195-1201, 1906. 18 Frank C. Schrader. An occurrence of monazite in northern Idaho, U. S. Geol. Survey, Bull. 430, pp., 184-190, 1910. 412 BULLETIN 131, UNITED STATES NATIONAL MUSEUM lina, which are more cheaply mined, and the Idaho localities can not successfully compete in the limited market. The potential commer- cial value of the Idaho deposits is dependent upon the development of uses, which will create a market demand for the cerium metals which are the essential constituents of monazite. With the rapid advances of chemical and metallurgical industry this event will probably occur at no very distant date. The work of the several geologists who have examined the Idaho monazite-bearing area seems to indicate that the monazite is an orig- inal mineral present as an accessory constituent of the granitic rock of the great central Idaho batholith. Lindgren panned crys- Figs. 128-130.—MONAZITE CRYSTALS FROM PLACER CONCENTRATES. BOISE COUNTY tals of both monazite and zircon from angular granite soil formed by the disintegration of the granite on slopes where these minerals could have no other source. The nature of the mineral, monazite, its occurrence elsewhere throughout the world, and the fact that it is not invariably present in drainage basins in the granitic area probably indicate that it occurs, not in the normal granite, but in the small coarsened pegmatitic streaks and veins which are locally abundant in the granitic mass. The description of the monazite from the localities in Boise County will suffice for that from all of the other places where this mineral has been found in the State since they present no essential differ- ences. In color it is commonly resinous golden-yellow to amber or orange brown. Only a few crystals were found which had what — THE MINERALS OF IDAHO 413 could accurately be described as a greenish tinge, the associated green grains being usually augite, titanite, or olivine. v weak. The extinction is inclined and the data obtained make the optical orientation Z=b, Y: c=28°. These data do not agree entirely with the optical orientation and dispersion given for bayldonite, but they are approximate only, owing to the nature of the material, and may be incorrect. The mineral gives an arsenic mirror when heated with charcoal in a closed tube. EVANSITE (645) Hydrous aluminium phosphate, Amorphous. 3A1,03.P205.18H20O. Specimens sent to the United States Geological Survey by C. R. Potts from Goldburg in Custer County were identified as evansite and described by Dr. W. T. Schaller.*° 36 Waldemar T. Schaller. U.S. Geol. Survey, Bull. 490, p. 94, 1911. 434 BULLETIN 131, UNITED STATES NATIONAL MUSEUM CUSTER COUNTY The evansite from Goldburg is massive and amorphous and occurs in seams. It is brittle, with a conchoidal fracture and varies in color through shades of yellow, white, brown and dark red. The brown variety very much resembles common brown opal. An analysis of this brown variety gave the following results: Analysis of evansite from Goldburg, Idaho (W. T. Schaller, analyst) Per cent WV bert CEs ©) ee Sie eee te er US beep ee ae a el ee a aE ee 36. 96 POS PH CriCraelee Cha Os) mean ee tere ae apa apes an ee 19. 14 Perric Tron CHe5 Og) 2 koe Se ee RRR ep RSL Deel a tees 5. 49 Adamina 3:CA 13 Og ik ed A RAR Tp a Ue 34. 48 Ts inn GY © 3 Os ena BES ag ae ald dh ees lala N ale ee 4, 32 MVE aoriest a) (IVI gO) Ge nil a a UN i ae a Trace. Ferrous 1rOM CWEO) ee eee 5 seh La ANU i a aon ee nee ae None. TRO Gel oa barn 2 lors as 1 ee or Man evan alas on ne hat reed Ae a ee eR 100. 39 The temperatures at which the water content of the mineral is given off were determined and the following table shows the amount of water expelled at the several temperatures: Loss of water of evansite from Idaho Per cent AG LOTS IGE ee ae tee SGT eden Mls cites Pa Raia ah DI Pay Oe aR 20. 00 Ds Cee al cee aii ch see May a ae Nita ease ROOM DRE ee aN Ce ON Ce Tesle DS 1 a ar REA GP ae) EAL ad fer sea al SO ALL A oes AGIZ9 O° SC Lee TE OTN Pe et SEE NG . 94 At low: med hep ter Epes Pid hing a raya ens es hE ced es BI re ya ae 3. 90 AT SET SES GEC te Breen eH A OED Za EOE US pe TO TO tell LOU POS) OR RV OPE Fe AES AO pe Eg ed Ege 36. 94 A density determination by means of Thoulet solution of the rela- tion of the density to the amount of iron present gave the following values: Relation of density to tron content Color of mineral “Fe?03 doe Limits Darkired leh 322 8. iE EON a EE ie Eee 6. 60 2.00 | 1. 990-2. 016 i 0)\,'9 ¢ Sean aS | a I eS Se Me SRA eed EB Oy Geta Te 5.49 1.98 {| 1. 972-1. 990 Yellow il t. 32D 0 Ee eS Res SSPE ee a 2.15 1.94 | 1. 927-1. 947 By plotting these values it was found that the density of the mineral free from iron should be between 1.88 and 1.91, though this value does not necessarily represent that of pure evansite as the material on which these determinations were made contains considerable calcium. A determination by F. E. Wright of the index of refraction of the colorless evansite from Idaho gave 1.485, the index for the colored varieties not varying more than 0.01 from this value. THE MINERALS OF IDAHO 435 BINDHEIMITE (670) Hydrous lead antimonate, approximates the formula 2PbO.Sb.0;.2H,0. Amorphous. Bindheimite is a common mineral formed by the oxidation of antimonial sulphides in lead-bearing ore bodies. It is most frequently some shade of yellow in color, although other colored varieties are known, and in texture it varies from a soft friable pulverulent ocher to compact opaline material. The bindheimite, in some cases is the result of alteration of lead sulphantimonites, as boulangerite and jamesonite and then usually has a fibrous structure inherited from the parent mineral. It commonly results from the alteration of tetrahedrite-galena ores in which the antimony is furnished by the tetrahedrite and the lead by the galena. Most of the Idaho occur- rences have had this origin. The occurrences which have been noted in the State are described separately below. It is noteworthy that bindheimite contains its antimony in a form very hard to reduce so that, by ordinary blowpipe methods, this element is very hard to detect and ocherous bindheimites from Idaho have previ- ously been called massicot, in error, by the present writer as well as others. Massicot is not definitely known from the State. The pulverulent yellow bindheimite is commonly called ‘chlorides’ by Idaho miners when yellow, or “bromides” when stained blue or green by copper. BLAINE COUNTY Bindheimite was probably common in oxidized lead-silver ores of the Wood River country and elsewhere in Blaine County. LEADHILLITE (734) Sulphate-carbonate of lead, 4PbO.SO3. Monoclinic. 2CO;.H20. Leadhillite has been identified in small amount in specimens from two mines in Shoshone County. It is probably present more fre- quently in the ores but has been overlooked because of its resemblance to cerusite. THE MINERALS OF IDAHO 451 SHOSHONE COUNTY A specimen from the Caledonia mine has previously been de- scribed ** as consisting chiefly of massive cerusite bearing on its surface ocherous limonite, drusy crusts of linarite, stains, and crusts of caledonite (?) and irregular masses of a greenish to brownish-white mineral. The latter mineral is altered and etched on the outside and resembles cerusite except that where broken open the masses 155 156 Figs. 155-156. —ANGLESITE. HYPOTHEEK MINE, SHOSHONE COUNTY show very perfect cleavage in one direction with pearly luster on the cleavage face. Before the blowpipe on charcoal with sodium carbonate the mineral gives a lead oxide coating and a button of metallic lead. It is soluble in hot hydrochloric acid with evolution of carbon dioxide and the solution reacts for sulphuric acid with barium chloride. The perfect basal cleavage makes it an easy 8 Earl V. Shannon. Linarite and Leadhillite from Idaho. American Mineralogist, vol. 4, p. 94, 1919. 452 BULLETIN 131, UNITED STATES NATIONAL MUSEUM matter to obtain thin oriented plates of the mineral by crushing a fragment on a slide when thin plates lying on the cleavage are. found to give a perfectly centered bi- axial negative figure with 2H very small. The index of re- fraction and birefringence are high. These properties defi- nitely identify the mineral as leadhillite. Leadhillite has also been iden- tified in minute tabular crystals in a specimen from the Look- out Mountain mine east of the Forks of Pine Creek. Thespeci- men is a residual lump of me- dium grained galena contain- ing a little chalcopyrite. It is crusted with alteration prod- ucts, which include cerusite, lim- onite, chrysocolla, copper pitch, linarite, caledonite, and the leadhillite. The leadhillite forms small tabular crystals of hexagonal aspect, most of which are now coated with or replaced by cerusite. A few were transpar- ent and unaltered and one of these which was measured had the development illustrated in the drawing (fig. 157) and gave the fol- lowing angles: 065 new? - 03) Fic. 157.—LEADHILLITE. LOOKOUT MOUNTAIN MINE, PINE CREEK, SHOSHONE COUNTY Measurements of Leadhillite, Lookout mine | Form Symbol Measured | Calculated a - Quality, description | No.| Letter Gdt. Miller ¢g Pas Vilewne p | ° , ° / ° , ° , PeiCeee coe 0 001 Dull; poor. Gos a eee Sees € Fis, =)- O20! estan ter O ean 2 Oa eS co0 100 TO hy i Te a a a 90 00} $90 00 | 90 00} 90 00 Di (MMA seco |} ©o2 120 Goods ee ee eee alee 29 48 /|90 00) 29 47/90 00 45 tee 10 101 Very Doors See eee 90 00 | 52 13 | 90 00} 52 18 Sale?) saeeee 03 O31?) | BRoorblurred 2 ees see Ree es 7 21 74 24 1) 0) 9.00: 7b 6 6| (?)-...--| 08 | 065(?)| Excellent sig_--_---.-----2----------- 6 00} 53 20/ 0 00) 53 04 vl eres 12 1D) «WG es ayes eats eee OAD 29 48/68 40/29 51 | 68 37 8 | Srssee2t 1% 212 Very: poor s3& 20J40..122. 52 Res 66 12) 53 30 66 27 | 54 12 The measured crystal was examined under the microscope and found to be biaxial negative with 2E very small, birefringence high. The axial plane is parallel to the face adopted as a(100) and the acute bisectrix perpendicular to (001) which makes the optical orientation Y=a, Z=b, X=c. Dispersion r - " . THE MINERALS OF IDAHO 473 close to those of scheelite as to make the two minerals almost insepa- rable, crystallographically. The forms observed are c(001), p(111), e(101). Small rudimentary planes appear on some crystals at the lower portion of the combination edge (111) A (101) suggesting hemihedrism as in scheelite, or these edges are rounded as if fused. The axial ratios derived for the mineral are compared with those of scheelite as follows: POwellitese=s 222552 a Bae eee eee ee eee oe es c= 1.5445 SCHeCClitG seats oe oa ee eee oe ee c= 1.5368 The angles measured on the one circle goniometer are compared with the calculated angles for powellite and scheelite below. Measurements of powellite from Seven Devils Powellite, Powellite, Scheelite, observed calculated calculated ° , ° / ° , (ESTEE: (COLD 3 te 49 12 | Fundamental. 49 27 CUD Sep rea) eens ew ee ee eS et oo een cece ec aee 65 24 65 24 65 16 (QTL) A 0) ag et om 5 ec me oe ae ea 79 57 80 01 79 56 (EOI LOU cee ob edn oe ce os eee ci cte corssn dzscches 65 55 65 51 66 06 CLOUD ry URT) ae eee eee ee eB A eee ee aan 40 02 40 O1 38 58 The powellite was analyzed with the following results: Analysis of powellite from Idaho (W. H. Melville, analyst) Per cent Molybdenum trioxide (MoQ3)_-.-.-..-.-.-......-_-.__- 58. 58 Tungsten trioxide:(W Os). +-=..--4-2-2¢-5- 5222. -5_6-. 10. 28 Silicag(Si Os) Sete oe ee ee eee Be ae ee 3:25 imo AO ees eos a ae IOP UIA oe eon 25. 55 MARTIGNIA IPO \icirs oe oo. oe oe so ee . 16 Herrichron oxide (he;O3)- 2 222 oe oa ek eee ee 165 ARETE Cg Og) on saa ic ees BUSES oe OTS lds Trace. Copperoxime (Ou@O)201 20 9. Civ ss 2 Ss gua 2 Trace. Ota eee ss oc UP Sooo oe eee Be 2 ee Daley 99. 47 Larsen * has determined the powellite from the original specimen to be uniaxial positive with the refractive indices: w=1.967 +0.005 e=1.978+ 0.005. Although powellite has since been found in a number of localities, no second specimen has ever been obtained from the original locality This is probably because no one familiar with the inconspicuous ap- pearance of the mineral has made a search. *? Esper S. Larsen. U.S. Geol. Survey, Bull. 679, p. 122, 1921. 543847—_26}——31 474 BULLETIN 131, UNITED STATES NATIONAL MUSEUM CUSTER COUNTY Powellite occurs as an alteration product of molybdenite in sev- eral specimens labeled as from the Bay Horse district in Custer County. The powellite forms dirty white pearly plates up to 1 cm. broad interleaved with molybdenite. A little molybdite is asso- ciated with the powellite. STOLZITE (817) Lead tungstate, PbO. WO; Tetragonal. Only one report of the existence of stolzite in Idaho has been received. SHOSHONE COUNTY Stolzite is reported to have been found with other oxidized lead minerals in the Hypotheek mine near Kingston in 1916.° No speci- mens of the mineral nor any detailed notes on its occurrence have been available. WULFENITE (818) Lead molybdate, PbO.Mo0Os3. Tetragonal Although nowhere abundant or in exceptionally large and fine crystals, the orange yellow lead molybdate has been examined or reported from the following localities: BEAR LAKE COUNTY Wulfenite occurs in the Blackstone claim, St. Charles district, in the Bear River Range, on the north side of St. Charles Creek, 34% miles west of the town of St. Charles. The mineral is in wax-yellow tabular crystals associated with cerusite.” BLAINE COUNTY A number of specimens collected by D. F. Hewett, of the United States Geological Survey, from the Golden Bell mine near the head of the ravine which contains the Minnie Moore mine, near Bellevue, contain small orange-yellow crystals of wulfenite abundantly dis- tributed in siliceous skeletal masses. The crystals vary considerably in development. Many of them are square tablets, showing only a single prism and basal pinacoid (fig. 165). Many are tabular com- binations of the base c(001) and the pyramid p(111) with the corners truncated by e(011), while in others the dominating form bounding the tables is ¢(011) and p(111) forms only small corner faces. In a few of the latter m(110) is present as narrow faces. Some of: the crystals appear hemimorphic with the pyramidal faces above and only the basal pinacoid below. The angles measured are as follows: 9% Ernest Leroy Adkins. Personal letter, 1917. 2 R. W. Richards. U.S. Geol. Survey, Bull. 470, p. 182, 1911. THE MINERALS OF IDAHO 475 Measurements of wulfenite from Blaine County l Symbol | Measured | Calculated | Quality, description I ee Gdt. | Miller ca ine | ° 0 001 "0 bn . 0 a co 110 08 | 90 00; 45 00 | 90 00 1 111 10 | 65 25 | 45° 00 | 65. 51 o1| 011 00 | 57 23] 0 00| 57 37 | FREMONT COUNTY In the Old Scott mine of the Birch Creek Mining Co., in the Birch Creek district, the principal minerals of the ore are cerusite, angle- site, and galena. Above the 100-foot level carbonates predominate Figs. 165-166.—165, WULFENITE. GOLDEN BELL MINE, BLAINE COUNTY. 166, WULFENITE. OLD ScCoTT MINE, FREMONT COUNTY and here wulfenite, though comparatively rare, is conspicuous be- cause of its orange color.” A number of specimens have been exam- ined from this mine and some crystals have been measured. ‘These are all tabular plates but they vary somewhat in habit. Small orange crystals in manganese-stained sand carbonate ore are tabular and bounded by 6(113) and narrow faces of p(111) with the corners bearing narrow line faces of + (013) (fig. 166). Specimens from the 150-foot level north of the shaft contain small orange-wulfenite crys- tals with cerusite on calcite and steel galena. These crystals, which are thick tabular, are bounded by well-developed faces of 0(012) J.B. Umpleby. U.S. Geol. Survey, Prof. Paper 97, p. 119, 1917. 476 BULLETIN 131, UNITED STATES NATIONAL MUSEUM and p(111) with narrow faces of e(011) and minute faces of the prisms 6(230) and q(120). Another specimen from the 150 foot level of the Old Scott mine contains larger pale yellow wulfenite crystals in pale yellow ocher associated with wad. The best of these was measured and found to show, in addition to c(001), p(111), and 06(113), faces indicating Fias. 167-168.—167, WULFENITE. OLD SCOTT MINE, FREMONT COUNTY. 168, WULFENITE. LENA DELTA MINE, LEMHI COUNTY new or vicinal forms giving the indices (117), (1.10.50), and (0.5.11) (fig. 164). Another crystal is bounded by 6(113) and narrow faces of p(111) with the corners beveled by a form giving the indices (038) (fig. 167). Still another crystal showing c(001), p(111), and e(011), has small faces of m(110), and another new form (121) (fig. 169). This makes a total of 5 forms on crystals from this locality which could not be correlated with established forms for the species. These may be stated, with their angles, as follows: @)HMorminmeastredit ae ae ral ree an ie hh g=26 14 p=74 15 (EDT) eal cur] Ge aaa aa DR e=26 34 p=74 10 QyeRorm Messurede ce. 6 eee pee alae eae pO aed p=30" 32 (038) caleulated’ ER Vio SiGe Wa OE EERE © g= 00 p=30 36 (3)) Form measuredsisiocwes blips Wai ei eee Tie g=45 00 p=17 00 (LL) cealeulated 22 fr kya) See Te hi yea eae ogy ¢=45 00 p=17 40 (4), Formiameasured «. 233) Joe pe ea es TAS oat 27 p=17 30 (1:10.50) ;caleulated..2~ 232 Soe a SR poesia y= 5 42 p=17 37 (Oy OTM MEAS UTE Cera ee ete Nee eter eae g= 0 00 pP—coee (0% .19)*ealctilatedge+ _ S12 19s ae g= 0 00 p=35 39 All of the forms noted on crystals from this locality with their angles are given in the following table: THE MINERALS OF IDAHO aa Measurements of wulfenite crystals from Old Scott Mine Calculated | | | Form | Symbol | Measured | EC eEea | ats se | Quality, description | . No. Letter | Gdt. | Miller | [Hera ys, guys | | | | eee tral overs | | ; o #4 |o , ° , o 87 Afonso | 0 O02. | Medium... <..-¢.22<2<--252--------- Wee eat 0) 00 tec 101 Oe BH abo cs. | co 110° || Poorwke 4% sai sacs Weer TT 45 03| 90 00| 45 00/90 00 Biigectetie | on2 HOO (ePnire nese ia See Oe Ne was | 25 53 | 90 00| 26 34/90 00 ll Bison, bs | 003 PAN sy aces RGM sere eeioeen ehceead 2 | 34 38/90 00| 33 41| 90 00 Bore tmers | eerie 2 es eripee oeeree 8 ater oem eats eee |o 00/57 23] 0 00| 57 37 Alionexe:- Oeil rOlGd i pod ane sin co fee tote ts | 0 00/37 32| 0 00) 38 16 ee Vee G13;. (POG ee ee | 0 02/25 37! 0 00/27 44 8 | New(?) 056 ti., -1088-r 1), Mediums. 5.94 ---aecasen esol. | 0 41/30 32] 0 00/30 36 9| New--_.- ees iia, ain ee en aes wrten eS / 0 00/35 42] 0 00/35 39 Hd pba: | Wi. j)iMediam.- 3 seca sercen pce ts (44 58/65 46/45 00| 65 51 ie Pe seeeiestenist SM Gunes. 5 oe aes ae eres UMASS (45 10 36 25) 45 00 | 36 38 12 | New(?) | Mf; J | POOre eaeeee ee oeeeee eo eee 45 00/17 00 | 45 00|17 40 13 New..__| 1__.| Fair...20 its, ays |26 14) 74 15| 26 34| 74 10 Tao Nawece}' Wei) 11050 | Good... 2. .caccsecccecse oo Suceaee | 5 27/17 30| 5 42|17 37 | | | Fias. 169-170.—WULFENITE. OLD SCOTT MINE, FREMONT COUNTY The material available is scanty and only a few crystals could be obtained which were suitable for measurement. Wulfenite also occurs in the Weimer copper mine in the Skull Canyon district as small orange crystals with anglesite and cerusite surrounding galena in barite and as pale yellow crystals on manganese oxide. IDAHO COUNTY Minute orange yellow films of wulfenite occur on cracks in a white rock from the Free Gold mine of W. C. Cooper and S. 'T. Muldrow in the Dixie district. 478 BULLETIN 1381, UNITED STATES NATIONAL MUSEUM LEMHI COUNTY An old specimen (Cat. No. 56532, U. S. N. M.) labeled as from the Lena Delta mine, Lemhi County, contains a few pale yellow tabu- lar wulfenite crystals in ocherous limonite. The crystals are bounded by e(011), 0(012), p(111), and 6(113) (fig. 168). MINERAL COAL Despite its practical value and importance coal is of little value or interest to the mineralogist and can scarcely be properly regarded as a mineral. The following abstracts merely include references to the most noteworthy occurrences of coal in Idaho. BOISE COUNTY Subbituminous or lignite coal occurs in Boise County at Horseshoe Bend and Jerusalem Valley on Payette River, 20 miles north of Boise and 40 miles southeast of Weiser. The field occupied by the coal-bearing formation is about 15 miles long in a northeast-south- west direction with an area of about 23 square miles. The beds of coal, which are mostly less than 14 inches thick, occur interstratified with unconsolidated sands and clays belonging to the Payette for- mation which is of Eocene age. The coal has a pitch-black color, vitreous luster, black streak, bedded structure, a tendency to pris- matic cleavage, an irregular to subconchoidal fracture and a dense texture. A typical analysis is as follows: ® Analysis of coal from Henry mine, Horseshoe Bend Per cent MFOTSHURE 2 SA chiar Saeco cNcia Ue only ra OM GE TE vice wee ieee Oe 5. 00 Molatile ama tter iia nets See ree aI Dt eet tre eee 40. 40 Fixed: carbon: 2.) Ste miele Berit | eMac Sea Silielae Ni tte ee ees Bee 38. 10 SED cs) RN a op IN I Aly De 16. 50 OUR Ep ur tess ee ere 54 TOCA: HOMO, LE IDeA NIG RI Ae sees 100. 54 Calories so 4G Mar 3h Ee CPYCLE MEE Ae SN Ee ee hae 6, 130 British thermal umltse 32sec ee sees Ee ae ee 11, 030 CASSIA COUNTY In Cassia County the Goose Creek coal-bearing district has an area of 156 square miles. Here lignite occurs in beds in sediments which are presumably of Eocene age and which greatly resemble the Payette formation. The lignite, which when fresh is black or very dark brown, weathers to flakes and scales, which show the presence of a considerable amount of earthy matter. There are two main lignitic coal beds, the lower of which is the best in quality and ranges % ©. F. Bowen. U.S. Geol. Survey, Bull. 531, p. 245, 1913. THE MINERALS OF IDAHO 479 from 3 feet to 5 feet in thickness. The upper bed varies from 14 inches to 9 teet in thickness but is very dirty and impure. The material is of no great value as fuel because of its high ash and moisture content. . =. ar gee See eee ee ere 425 Mrid'ymite--222 22-2255 eae eek eee ee 182 MpngPstitexe= tere cate sae. ee see eee 188 Torgiteiens po ee. eee 194 Turkey-(at, Of0sc202 ose sce e een e set ee esac anee 116 Walenclanitens 20. 22 oaoe oe oe eee eee 270° Walentinites 2258. ses st eee eeeee eae 187 Vanadinite = 2222242262222 se eee eee 424 Viesuivianite x. = 22 5222-2 tesa eo seeaeneeeeee 314 Witriol; blues. 2-2-2. sSncoocccee es Sast seeeee 462 WVAVIGNIGOS oe een eae oe See eee eee 427 Wiad ae Sn. A ee de eee 212 W olframite:..222.<2:2 5. s825. 220 aesenceee 467 Wiollastonites:-2- 24 ses ee ee 283 Wood opalics== 225225 22228 soon see esp eseeene 182° Wood silicified:- 22-7 22525. 2ess- See eee oe 182 Wood! tine22 26 fascia ska eee 200 Wrarlfenite. = oe. = ooo ot eee ee 474 WULtzite ssn. orc Sac as nese eee 116 Ranthoconite-.2. 2/032 2e ceo eee ese ese 160 Wellow:ocher :. 2.032 s222 eos eee eee 208 TEOlteSso-> scccnnd-cc oh usees easekee cascees 346-365 TinG Dlendes 2-5 ees aoe ceeese ecoeaeeeoe 106 FAT COD 22 eee a ca nae ee eee coe enaes 316 ZOISit@ nt =o cone oe een cee coe test oes e ea aeees 322 483 ADDITIONAL COPIES OF THIS PUBLICATION MAY BE PROCURED FROM THE SUPERINTENDENT OF DOCUMENTS GOVERNMENT PRINTING OFFICE WASHINGTON, D. C. AT 75 CENTS PER COPY Vv ae ee St aii a, [20 ty z sf bat _ Pr i 5 ; 7: nd aT _ = re e ma! _ ; / - 7 ’ 46 a! ae ee ie cae re i We _ oe . a= = 7g : > uy 7 > ’ a aay sie a ‘ / ee rr -7 , : Z Poy Wee; : i - , 7 t 7 ns se % i : . in 7 a : ' a AY pd y ri — 7 ny : > ; : : x i ee are > - oa a LMA yates ae wi a 0 ’ 7 is i) } ie ne p vr a Vee WE PE May " es 7 i y 7 Oe i in ir? ‘ 1 - e , Haat iG calle uy . . / e ee = ' \ a L - = 7 gis. . | 7 7 > i= ¢ ; : 0 os 7 + ; ; . . ¥) a . } ; HM ce - ss fl ay ri , a iy / a : c le ato wah oie. ow | iu | | ll | = N 2 xt = ™ 2 oO 2S] @ : © 9 © = o 2 oo Lateran eee pa eP an eee Soe oewn shaeees ee Sore pares koe oes Merete onows Sit emcatreetoele Mone Sed gone