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D. GEORGE, State Geologist BULLETIN 14 MOLYBDENUM DEPOSITS OF COLORADO WITH GENERAL NOTES ON THE MOLYBDENUM INDUSTRY By P. G. WORCESTER DENVE EAMES BROS., STATE PRINTERS GEOLOGICAL BOARD, His EXcELLENGcY, JULIUS C. GUNTER............ Governor of Colorado CHORGE NOR RN sises aaa eee President University of Colorado VierTor, 1G) AT DBRSON 22. 82.) eee President State School of Mines CHARUNS 24 J MORY 2. Seas ee President State Agricultural College LETTER OF TRANSMITTAL StTaTE GEOLOGICAL SURVEY, UNIVERSITY OF COLORADO, NOVEMBFR 27, 1918 Governor Julius C. Gunter, Chairman, and Members of the Advisory Board of the State Geological Survey. GENTLEMEN? {I have the honor to transmit herewith Bulletin 14 of the Colorado Geological Survey. \ Very respectfully, R. D. GrorRGE, State Geologist. CONTENTS CET ONG TE VOUPTO NTL, 50 EE a os tg Seek poe oo ee eS Oe Introductory statement __.............. BAe Secs wae eee 82s cn: ae ee ee TIMES CMO les U Oar ODOL Geo cre. — oe i coee eee e nadt seeeeace eek , SA CELE TO ONLY EG SS CON SY TT BS] NO a ee er te ee ee Re ete ee CHaAptTeR I. Molybdenum ...................... So at CdS See. Sa re Se eee CRSTIOIEAY ag ek Se eS a oe Som TRI A i ae OS ey ne oe [PLEAS IVERUL TORR OY NST MYSNEP OY. Ty et OO Ere MS wee) ea Ae ee Ane reese SHEE CAI DCOPCE LLC Sta eae eee ee te tenes ee ee ee ei oon CuAprern tl Molybdenum minerals and. OPCS. -- 2 ancicc Seeccc ence ceee eee oe NLU Al oy WEVA Sy 5 SSD a ES NY 5a Sgn nec ae Se aa Se ae ae, ee eee EREAVASTCAl aU LODELUICS a Sante, geen nas foe Set ne te ea eee Ce eee M1 -ENSHL AS Woe 0 Son ee ere oe eee 2 Shee ees Weal A eh nye festa (CG EIIT EE DTNOEY RR ee a een a Ps eee eee igh Rt WO DULRS TONNE: ~ Magee 8 08 cele Seog ae OSG ae ei sens Bane Pan eee Be Ee [PiLG PANES KEY Ae SS ale ot Ree ee ae aS ne ae “TR SHEA IS pol ea Ae ee i ee Oe te Nae re EY Sa eso ee ee ONGC EEU CI EY a G(s te Sak Se ee ite SR a Se AR ae eae te ae BR A oe Se ee AIVICGS LSS 0) CIM Go temeeese Saee vet aes re ee ee ELLEN 8 Seen eee oer ee eS 2 COMPOSITION ete 2 ens ns fe Ree eee tee ares ae LETE(O% BYSI GE) ISIS has eS Sa ea a en Be Se A eS CEES ES a eed nie Sr 8 aa SE 9. oe ON ES AE SE DOE ee TE Onell ies, ee eee ee OS aie g NE en Fert We ae et ede ee reed oe ee TEED OXSTCLKETSY ce Sey ee cr A ane ee nee ee Raa Leas Oa ee eee De De ee ee oe COXGCGIS TEEN OU GUE ge Se a RO i ARE A eee Sim RE SOB lees a gh ae eee a ea eM aN ee ae pele ee Cg Joh kot PORE GO nt DURE. TD ool tae Ake ‘Properties and occurrence.................. er enn eee 1 Soh oa react eee EVES Ghat silt Creat eae aetna ears a Dien AG eters ep eee LEIS NUE WILE) oe Sais 8 ae at a ee are aster OF: «8 ae ee IDIOMS) 2c eh eee ea i Aaa Ce to bs A a CUSLLUEEL Sorell Sy Se gS Eroguchonmor moby bDaeniimis =) se ee ee Hea ae eS CHAPTER III. Foreign molybdenum deposits:....................... Peta is 2. «| Oe AUISGralianrteCDOSILS =~ eee ee a eee a 8 Eroduction of molybdenitein Australias ee ee CGeology< of the depOSits2 ek oere eee ees es ne ee aes Woncentrationy o©-the) Oreset.< oe ee eee oe ee ee EN OMaWicl Ver CLD OSLES | 4! a%tesci cick. TEA. cot Pee eS oa ae en Re tore Production of molybdenite in Norway..............2.---2..2 pate: Sc: Gecologyzob-thesdeposits a Ba eee eee eee ee Costeote productions. 2h Se 2 ei re es Be ht ei en Paes Ganadiane Molybdenite deposits... i220 Se we BritishaColumbia ade DOSiUSs2<— =r ens eee yg ee on Alice Arm sIniING! tr. se. eee ee ieee rt ea ene pe MEO) vermin erm See a eT ete bean ee ManitobardeDOSItS y= =n eee ee 22 SEs ee ee od ee Bal Gon Wake ms te 25 2S See es eee CMe eS oe EE ees eS Obani ORME DOSULS a. Meee ei toh ee ionmenie Mae eet e Peeeee eon i Ventre wee COUN tye CG CDOSIUS 2 wee aes netrer ee ree eee ee pe e OUMEDEC ad CDOS TUS ies tet ee ee ee eS en ee ee BIVIGSS sin Gitta cee eee eee, Ero Sei Dee ey vee oe IV CONTENTS PAGE Cuapter IV. United States molybdenum deposits, except Colorado. 24 States in) which molybdenum occurs] 24 Operatine scompanies ge eae be 24 Production in ‘915... 8 a ee ee ee eee 24 Arizona molybdenite: deposits. = ee 25 Leviathan -miness As ask ween eee ee See eee i i 25 California “molybdenite deposits 26 Ramonagde posits... = eee aR MNND Rs SR ER Pata oS 5 26 Maine molybdenite deposits.232 a eee 26 - Cooper deposit}... ee eee 26 American Molybdenum Gone LS Ae ee eee ee 26 CHAPTER V. The Molybdenum deposits of Colorado. (A list of claims by counties showing locations and owners’ names.) _.... ante 2h eee 29 Boulder County: 22-3 29 Chaffee County: -2.:2.5..4. 4. ee 29 Clear:Creek County. ..50 {20 2 eS ee eee 30 Conejos (County 222... eee eee 30 Custer County 2.5.0... 4 eee eee 30 Wasle County. 20 ei ee 30 Fremont County? ..2.2..22 22. eee 30 Gilpin. County “2... 2 eee 30 Grand ‘County’ .12...2.04020 3 te bk Se eee 30 Gunnison County -:.2.-455.53- 53 30 Hinsdale. County 2:22:38. kee 31 Huerfano ‘County: 2... 23 ee ee 31 La. Plata’ ‘County 2.2......22.00 2. eS eee 31 Larimer: County: 2... ee eee 31 Mesa: ‘County S252 Re ee eee 31 Montezuma, County -:.,2....22-.... See 31 Ouray County. 2-2... Se ee 31 Park =Coumty 2.220 oo ae 31 Pitkin “County <...2:00)-.. 38. ee ee 31 Routt County «......2. ee eee 31 Saguache”’ County | 22..4.-24 eee 32 San Juan;County..2222020 2 es ee 32 San Miguel County:2:..22.202) 5.22 eee 32 Summit? Countysoe 2. ee ee eee coast ee 32 Teller ‘County... 20 ee vaoneuviventacnctn ee 32 Boulderi@ ountiyge eee Lotdidee ena lie 32 Mountain - Lion: mine:=....... eee 32 Jamestown ‘deposit: 2... ee eee 33 Caribou ‘Ge@posit: <2 eee eee 33 Other deposits:<..:...2 2 Ae eee 34 Chaffee” County 2223 ee ee eee 34 California smine..2 3 eee eee ee See 34 Development. 2... 2.04... oS Se eee 35 Geolozy 2. Scie ee eR ee a) Treatment of the-ore:c23.. 22 eee 37 Improvements. \.:5.....05 232 = A eee 37 Future development veecitutntsai Le ee 37 Huffman “Park. »:..3 2228s ee ee 38 Royal: ‘Purple: claimi-.. 2 eS a eae eee 38 The Nest Dee... ti. oe ee ee 39 Winfielddistrictsdeposits. 32.22.) = eee 40 North Pointsand’ Hastern:Star claims) s= ee 40 Wintah “lode: 2.22225 Se ee enon 4l Banker. mine. -22.2...4-- 2 S20 eee ee eee 41 CON'TEN'TS 7 Vv PAGE (QU Mee ACOA IMENT) yee Say eae She Sy a ee Oy nk eee Ae Ae Wee Ae 43 Dwin akes district ideposits:..0.:...2.2.-2.. Rain Ae ph daa tary Cree 43 Mo kybidemuirie Od Gier mere. Seca aS 6 ee a at pee 43 GeEOlO Sygate eres eh ee OE ns: Lee: See 43 (CHOU, (CUTE, 2A at es SR eae ele ee eee aie one ee Nee 44 eivavar alee VW WalOmGlalmS! 2 222. sc tee ee A (CIMA Ee. 5 Ae Re ee Sen a ee ee 45 Simi ENED, AE a yah RS A, Se eS ae ene se a ee oe oe ne a 46 Ge OlO yar eee nee pu eee eM eS 46 NDING SOISbGC Ty CODOSIiSs ee ean trek cee. eee et 47 TB edNY Led BS eC) FEI ro 01a eee a ae AEE De Sc ee ae ee a a 47 STRUNG eet CLAS BRN Creme ea hee at le kre ee ce 47 CON GEE IEP 2 CTEM ee aC CON Wasa a eS es Sn a ree ele Se Ne es em 47 Primoss Chemicals Companys ammine.- eee ee 47 WEVELOPUMCT tyes wee sen Oe ee el Dee ele ee eae 48 (CONC iy ee cee ns corel ty UE ee De ee pe 49 IPLOGUCTIONNS 42s. pe ere eat Oe 50 (Cui aiorital Teoh aS)" es Sea a a ee ee Bene te ee ee coil 51 CON ENPONSS C CHOU EDIN A A aA Ree cele ER se mere eae ee oe 52 1 PNG ROW Gea Se ahs oe sae 8 Sa de rece eee ait Rene er 0 8 Bee es SO em ee 52 INAS rere tomes elv COE aa eS eS eee ee ene ae eee ee ee ee ae 52 (CEU TP” CCR ONT ae ae a ee ES oS One ee ee 52 Kenia Gye Cleat ni eee ene feck erev ieee Bee Penns Sa Nona 52 (Garay oy, CUE al, et ae ease 2 GR ONE ele a a Oa ia, Sa es er ee 53 SuacyeDISSmOTemClaiM” cx ee ee ae 53 TEDPE WERT A CCH a E57 a Orr ee ee eee 54 CLEOSSenlinin SAG StLICERC CDOSIUS Geet ee ee 54 PDT TTT OTN (eae OUT Uy ag eee ee ee Re oe a re ok ese 55 Coppers Gin leit r eee es a ee ne ees SA iB DD (OST KON DAA? CIE hc ihn ety A tle a A A Ete le 55 WEVEOP MICH tem nee reat eae ae et pS I Deere ee 55 LEAT ASN ed B10) 00 Lay) 213 0 0 Vera Ree eee EEE Eee 57 CG RNa OLN bya eee cn ee ee EE te ee eA 58 Circa ia ple aGla ieee ws a cae eee oes ee. Une, Bet ok ia 58 ’ SUC we LO Geel OMe eee tet ee ae I ee 2 2 te 59 GUT SOM nC OU ye eee le ee eceree k e klt eeae ere aa ee Sra) Quartz. andeelincupymininesdistriets:. 0. eee 59 Bone Non ser Ouse ces Saree teat A's Eatin. 2 i 67 Lee PU OG) NR ee oor Pear eee sa ere 67 I. D. A. claim 67 VI CONTENTS PAGE Huerfano County:~.2...5) 3 Se eee 68 Mosca: -Pagsicis 22 200 3s te a 68 Grand. County. (222-2223 2 5.2 ee ee eee 68 RVG ry ee eg eh a oe a 68 Iba Plata Coumbtyese ye ee ee ee 68 Kast: ‘Silver -mesa:2 2 A ee ee ee eee 68 Vallecito: -basinses<...0 2 eee ee 69 Larimer : County 2225)... 3.22 = ee ee ee 69 St? Cloud -Gistrict...22: 5-2 ee 69 Mesa. ‘County... ...--2-6..55:.. 22. ata eee 70 Gavette. claim: 1:0... .5) a ee 70 Collinson. claim \s.3...3) 2 eee Tal Montezuma County.-...4..5.2-3...2242 2 eee 12 Giles, Mountain: deposit: 22 = 2 eee psd 72 Ouray ‘County =345.5-25--3 ee 72 Ironton deposits: .2 2528 ee eae 72 Trene@* 3.022.080 a ee eee 12 Jumbo NO: 2s ee eee 12 Other “regions: ...-=.-: 23S ee 73 Ouray and Hinsda’e\ counties: comer ol 73 Engineer’ Mountain deposits]. = ee 73 Park County 2.23222 22 ee ee 73 VEC Siksine mine pera Rare tS eee Ss ai 3 Van: Epps claim 2.23.2... we 2 eee 74 White Swan claims.......2°3... SS eee 75 Humbug. claims. 2220.00. ee ee 76 Crescent. Mine .......2n eS eee 76 Geology. ..2...:2.58.53 te ee hihi Pitkin County 2.2022. 2255 3 sc 5 ee ecscceescec ce ee ret Green Horn Claims... 2282. Se Be heae. i) Routt. County -2253 nc 3 ee ee tS Farwell Mountain deposit== = = eee 78 Geology 2. enn Re ee ee Eee 79 Development ii ee eee 79 Slavonia. district <2... 053) 2 See 80 Saguache County {22.00.0220 oi eee 81 Merideth’s Claims ....00 3. eee 81 Other) deposits! near Alder =e 81 San Juan County 238 ee ee 82 Chattanooga deposits)... 3. 82 Hidden Treasure and Gold Finch mines. = 82 Development}. ee een 82 Geology (is. 22s e202 eee 82 Future,development ...-2....2....- 3 ee 83 Liberty Bond) Claims=—.2.....4..2.2..2i2...0 a 83 Black Diamond -claim. 2... ee 84 Head. of South® Mineralccreek 3 ee 84 Bear Mountain deposits, near Silverton. ee 84 Cascade Basin ©...22-2:22000.2 SS ee 85 San Miguel County2 ....).222.22222 a2 85 Molybdenum_Queen- claim ==] ee 85 Colorado, Molybdenum) MinineCol 85 Summit County: <....22.c525-3i 2 87 Climax (Premont (Pass) deposits=.—. ere 87 Geology - 22.000. n ce ee 87 Development} 2222-2 Se ee ee eee 90 CONTENTS Vil Pinteney vines and Ore Reduction '©o.....cc.----cecec-ess-c-e ee 90 Chinas Mol ypd enumC Ole ose ee ee 91 Molybdentim) Products: Corporation.<....25--. 2 ee 93 OK OM Om CIS tL C laa een erent ek. toe red er de 94 BE yanbeClalin Sipe ares ne Se PEEL PO eS OE. en 95 KMokomorvilline2@o Claim Soe en ee ee 95 Omani evo umualneoIsyrlCtes ra. series feos Di eee ere ee oe => 96 salamander and Blue: Valley. claims =... -.-2).42. 96 GCOl Ops eaten ten een ee apa te Ree. kato 96 MEVeLO DNC ite ree ee ee ee ar ea a 97 IOS ZU as GIES UTE Gta nee tee ee eee ee On Glaciers Mountainecl alms 2222 ee See ee eS OUIETeOCAIIGIC ST eater Rees Sones eee ees Coe REE Ae ee, 98 LUPE ERED WEM cere(e bts (oO) ee ee nee Se ce Bete ae ee eee eee ee 98 TEMS, ACTOR Bae e™ See pe ea ee aoa ee ee San eS aS 98 Areassn Colorado that Showld be: prospected a. cce oon eee cee aes 98 Cuaprrer VI. Concentration, reduction, and analysis of molybdenite OCS ee a eel ee eae eae a Ste Ec Pie CPR AGE EN 101 COM SUMO T= eee ee see sere an eS ese ere tk ae ipa SON Boe ls es 101 AUT SCL ATI MAIN CEMOGS ae tert Sat ee es en ee ee Le thee 101 INOIAWENV ane UNOd Si 4 eas oo ee ee Ro eee ae oreo 102 CanatianmIinetnodsy, 2548.2 ee ee CEA See 102 linitedsStatesmethous: 2. sien = ere Pe oe ee 104 Reduction of molybdenite, concentrates: -- 106 Quantitative analysis of molybdenum ores.........................22222222-222022---- 107 Cuapter VII. The uses, supply and demand, market and prices of THO NY GLC MUTT geet a te so a eg i ee epee I et tS Hots! WSGSHOLSINOLYOCONUI se = ee. tn er Seen er en Ce a eA 111 STUNTS hye cuTl esl TIN ATT sce aee een eee nt ent oe Doe ad SS ns ee 114 WWE EGS ae oC ee Ss AE RR I ee ook ye Mie fa al RS a fa U3) TEATHEIS ce Se ea ace BRE ke ne Sa See oh Oe EIR se Sn oes Se 116 Tce mOre th Caan US yse. cen oe te Oe a ae Se 8 on ee eee ee Pa 9 LBS Ap UAN OPE TCI ON IN 8 Lee oe ee ae ee eee ener Rana nase 120 BEARE ele PLATE II. ILLUSTRATIONS Index map showing Colorado molybdenum deposits.............. Map showing areas in Colorado that should be prospected for.molybdenunt 222-5 eee Leet eee Molybdenum Deposits of Colorado With General Notes on the Molybdenum Industry INTRODUCTION Soon after it was declared that a state of war existed between the United States and Germany, the Colorado Geo- logical Survey was asked to cooperate with Federal officials in determining the extent of the undeveloped molybdenum re- sources of Colorado. A notice was at once sent to all the papers of the state, in which information was asked for concerning molybdenite and other minerals which were then, or might later be, needed for war purposes. A questionnaire was mailed to prospectors, mine owners, assayers and others, who would be lkely to know about the required minerals, and the writer spent approximately three months in the field during the summer and autumn of 1917 examining molybdenite properties that were reported to the Survey through various mediums of information. It seemed necessary to get certain data with as little delay as possible, and the examination of the various prospects was, therefore, brief and of a reconnaissance nature, but it was suf- ficient to show that Colorado has very large molybdenum re- sources, although all the ores are low grade. Many reports of molybdenite prospects were received at the Survey office after the field work was finished in 1917, and those properties which seemed to be the most promising. were exam. ined during the summer of 1918. Purpose of the Report It is the purpose of this report to present a brief statement of the occurrence of molybdenum; to show the present condition of the molybdenum industry; to describe the molybdenite prop- erties of Colorado so far as they are now known; and to indicate the areas in this state that should be prospected. 2 MOLYBDENUM DEPOSITS OF COLORADO Acknowledgments To acknowledge individually all who have given informa- tion, or who have extended courtesies of one sort or another, would be a pleasure, but it is one which the writer must, with reluctance, forego, for more than 100 people have responded to requests for information, and it is obviously out of keeping with this report to specifically mention each one. To all who have in any way contributed to this report, the author is extremely grate- ful. To acknowledge all the sources of material from which the statements regarding the occurrence, properties, uses, ete., of molybdenite are derived, is also too great an undertaking for this report. Standard works like Dana’s Mineralogy are there- fore not referred to in the statements that follow. However, when material has been drawn from special articles, whose dis. tribution may be limited, they are acknowledged in the footnotes or in the text. Dr. Horton’s bulletin, Molybdenum: Its ores and _ their concentration, U. S. Bureau of Mines Bull. 111, 1916, has been drawn upon freely in the preparation of this report. CHAPTER I MOLYBDENUM History Molybdenum was discovered in 1778 by the Swedish chemist Scheele, and Bergman described its isolation by Hjelm four years later. Until recently it was regarded as a ‘‘rare metal,’’ and as such it was little used for industrial purposes. A small amount has long been used for various purposes in chemical laboratories, and ammonium molybdate has been widely used to detect phos- phorus in steel works. During the past 10 or 15 years many experiments have been made with molybdenum, for industrial purposes, and partic- ular attention has been given to various mixtures that would give tougher, harder, and acid or heat-resisting steels. These experi- ments have apparently advanced further in Europe than in America. It was not until the present war was imminent that the demand for molybdenum was at all strong on either conti- nent. Almost as soon as the demand quickened slightly, the production was largely increased and at the present time the supply greatly exceeds the demand. c¢ Physical Properties Pure molybdenum is a heavy, silvery white metal, which is ductile, malleable, and may be both polished and welded. Its hardness is about 5; its atomic weight is 96.0; and its melting point as given by the Bureau of Standards’ in cireular 35 is equaled by only 4 or 5 elements. The following table gives extracts from this circular to show the melting points of molybdenum and some of the other elements: 1Bureau of Standards Circular 35, 2nd ed., p. 2, revised Jan. 1, 1915. 4 MOLYBDENUM DEPOSITS OF COLORADO MELTING POINT OF VARIOUS ELEMENTS Boron Molybdenum Osmium Tantalum Tungsten Carbon C: F. ee 1083 1981.5 ae 1530 2786 oe 1755 3191 2200-2500 4000-4500 2500(%) 4500 2700(%) 4900 elt 2850 5160 see 3000 5430 3600 6500 The specific gravity of molybdenum is usually given as 9 or 9.01, but Fink’ gives it as 10.02, and shows that after it has been worked, like zine, copper, tungsten and other metals, its specific gravity increases. Thus the specific gravity of molybdenum, be- fore drawing, was 10.02. After drawing a wire of 3.75 mm. di- ameter it was 10.04, and when drawn to 0.038 mm. it was 10.32. In common with the inerease in specific gravity with working, it is shown by Fink? that the tensile strength of molybdenum and other metals is increased the more they are worked. COMPARATIVE TENSILE STRENGTH OF MOLYBDENUM, STEEL WIRE ee Wire Ge 8 ooo AE Ege ES aon Se ass As = 15.(0) 0.125 Molybdenum’ <-....... ! 2.8 0.070 l 1.5 0.038 { 5.0 0.125 Munesten. 26 G fesse J 2.8 0.070 [ 1.5 0.038 Hard-drawn piano wire. 3.0 0.075 Pounds per square inch 200,000 to 230,000 to 270,000 to 460,000 to 480,000 to 550,000 to 1Fink, C. G., Ductile tungsten and molybdenum. chemical Soc., vol. 17, 1910, pp. 229-233. 2Fink, C. G., loc. cit. 260,000 270,000 310,000 490,000 530,000 600,000 507,000 TUNGSTEN AND Kilograms per square mm. 140 to 161 to 189 to 322 to 336 to 385 to 182 189 217 343 371 420 356 Trans. Am. Electro- Or MOLYBDENUM Chemical Properties: Molybdenum is insoluble in dilute acids except nitric acid. It is soluble in concentrated sulphuric acid. Under ordinary conditions of temperature and humidity, pure molybdenum does not tarnish. If heated for a long time in air to dull-red heat molybdic oxide appears on the surface of the metal in the form of a white coating. At a temperature of 1,500 C. the metal takes up carbon and becomes very hard. When in the form of a coarse powder, molybdenum is readily attacked by fluorine at ordinary temperatures, by chlorine at dull-red and by bromine at cherry-red heat. Molybdenum unites. with varying proportions of oxygen to form oxides; with sulphur to form sulphides; with oxygen and sodium, potassium, lead, ammonium, calcium, barium, ete.,. ete., to form molybdates of these elements. Bromides, iodides, chlorides, ete., of molybdenum are formed under certain conditions, and more complex compounds formed from these simpler ones, such as bromolybdie chloride, are known. Molybdenum also unites with boron, carbon, phosphorus and silicon, and with many other elements. 1For a full discussion see Roscoe and Schorlemmer, A Treatise on Chem- istry, vol. 2, ‘“Molybdenum.” CHAPTER II MOLYBDENUM MINERALS AND ORES In the following list are the names of the known minerals that contain molybdenum, with the composition of each and the per- centage of metallic elements of those that have been thoroughly studied. The first three are common; the others are rare. MOLYBDENUM MINERALS Mineral Composition Percentage of Metals Molybdenite MoSe Mo. 59.95 Wulfenite PbpMoO, , Mo. 26.16 Pb. 56.4 Molybdite Fe,0,.8Mo00,;.714H,O Mo. 39.60 Fe. 15.40 Powellite CaMoO. Mo. 48.00 Ilsemannite MoO,.4Mo0O, (?) Mo. 68.18 Belonesite MgMo0Os (?) Mo. 52.08 Pateraite CoMoO.: Mo. 43.84 Co. 26.94 Achrematite 3(3PbsAs2Os.PbCl:), 4(PbsMoOs) Mo. 3.40 Pb. 78.58 Eosite Vanado-molybdate of lead Not determined. MINERALS IN DOUBT" Molybdurane UOc. UOs. 2M 00; Knightite Phosphate of molybdenum Molybdoferrite FeMoO: MOLYBDENITE Molybdenite, molybdenum sulphide (MoS,) is the most im- portant ore of molybdenum. It is a primary constituent of many granites” and other acidic rocks.® Molybdenite looks very much like crystalline graphite, for which it is often mistaken. It is also rather easily confused with lead, or gray copper, by one who is uninformed. In some in- stances when it occurs in small flakes it has been mistaken for silvery mica, with which it is quite commonly associated. uELonton, F. W., Molybdenum, etc., U. S. Bureau of Mines Bull. 111, 1916; p.) 16. : 2Clark, F. W., The Data of Geochemistry. U. S. Geol. Survey Bull. 330, 1908, p. 273. 8Hillebrand, W. F., Distribution and quantitative occurrence of vanadium and molybdenum in rocks of the United States. U. S. Geol. Survey Bull. 167, 1900, pp. 49-55. TESTS {i The color of molybdenite is typically blue or lead gray, but it varies somewhat. Some flakes are a bright silvery gray, while in very fine-grained aggregates which coat fractures it is almost black. In distinct crystals molybdenite has a metallic luster, but in fine-grained or amorphous aggregates the luster is sub-metallic to earthy. It is soft, has a greasy feel, soils the fingers when handled and marks paper readily. On white paper it leaves a blue-gray mark, which if rubbed thin has a distinctly greenish tinge. This is a very distinctive test, and usually is all that is needed to identify the mineral. Its specific gravity is about 4.8. Molybdenite crystallizes in the hexagonal system. ‘The crys- tals are often horizontally striated. A radiated structure is also common. The crystals have one nearly perfect cleavage (basal). Laminae produced by this cleavage are flexible, but not elastic. The size of the flakes varies from a small fraction of an inch to several inches in diameter. Tests There are many tests for molybdenite, but only a few of the simpler ones will be given here. 1. The physical test given above, viz., rubbing a streak thin and getting a green tinge on pure white paper, is usually sufficient, if flakes one-fourth of an inch or more in diameter can be procured for the test. 2. Powder some of the mineral and heat it strongly in an. open glass tube. Sulphur fumes (detected by the edor) will be given off and a pale yellow finely crystalline residue of molyb- denum trioxide will be left. 3. Heat some of the powdered mineral on charcoal with a blowpipe in an oxidizing flame. Sulphur fumes are given off and a coating of molybdenum oxide, yellow when hot and white when cold, is left. If this coating is touched with the reducing flame a beautiful azure-blue color appears. 4. Dissolve some of the powdered mineral in nitric acid, evaporate to dryness, add a drop or two of sulphuric acid, again evaporate to dryness, let the residue stand and a deep blue color will finally appear. 5. Powder some of the mineral, dissolve in nitric acid, evapo- rate to dryness, cool, add a drop of ammonium hydroxide (ammonia 8 MOLYBDENUM DEPOSITS OF COLORADO water) and then a drop of hydrogen peroxide. If molybdenum is present a cherry-red to pinkish-yellow color will appear, depending upon the amount of molybdenum there is present.? Occurrence of Molybdemte Molybdenite is found chiefly in quartz veins in granite, pegma- tite, acidic intrusives, gneisses and schists. It is much less com- monly associated with intermediate and basic intrusives which cut granites or other acidic rocks. Crook? gives the following rocks in which -molybdenite is found: Conglomerate (Switzerland), granular limestone (Hessen, Ungarn), contact of marble and pyroxenite (California), serpen- tine (Tirol), garnetite (Hessen), amphibolite schist (Finland), chlorite schist (Switzerland, Sweden), gneiss (Baden, Mahren, France, Norway, Connecticut), basalt (Sardinia), pyroxenite (Canada), gabbro (Harz), syenite (Norway), granite (Schlosien, Bohmen, Bayern, England, Norway, Ceylon, Tasmania, New South Wales, Victoria, Canada, United States). In the same reference Crook also gives a list of minerals with which molybdenite is associated. These are: apatite, arsenopyrite, barite, bornite, biotite, cassiterite, chalcopyrite, fluorite, garnet, gold, hornblende, magnetite, muscovite, oligoclase, orthoclase, pyrite, pyroxenite, pyrrhotite, rutile, scapolite, scheelite, silver, sphalerite, tourmaline, tremolite, wolframite, zircon. To this list Umpleby*® adds the following: Chalcocite, cuprite, hubnerite, manganese oxides. . Heintze* records these additional minerals: Beryl, dolomite, lollingite, phlogopite, tale. Several additional minerals are recorded by Horton.’ These are azurite, bismuthinite, chrysocolla, native copper, epidote, lim- onite, malachite. Hess® notes that erythrite, autunite and vanadium and several other of the minerals mentioned above, occur with molybdenite and molybdite in a vein near Placerville. an AY ce ae gaat! reaction for molybdenum. Eng. and Mining Jour- 2Crook, A. R., Molybdenite at Crown Point, Washington. Bull. Geol. Soc. America, vol. 15, 1904, pp. 283-288. 3Umpleby, J. H., Geology and ore deposits of Lemhi County, Idaho. U. S. Geol. Survey Bull. 528, 1913, p. 73. 4Heintze, Carl, Handbuch der Mineralogie, Bd. 1, pp. 410-418. F 5Horton, F. W., Molybdenum: Its ores and their concentration. Bureau of Mines Bull. 111, 1916, p. 9. ; 6Hess, F. L., Vanadium deposit near Placerville, Colo. U. S. Geol. Survey Bulle GSO; Alle. elon. MOLYBDENUM ORES 9 WULFENITE Wuifenite, lead molybdate (PbMo0O,) is second in importance to molybdenite as an ore of molybdenum, but its occurrence is very much more limited, and it is found in commercial quantities in comparatively few localities, none of which are in Colorado. It is always associated with ores of lead, and is especially likely to be associated with vanadinite and pyromorphite. Wulfenite usually occurs as a yellow, orange or orange-red mineral, in thin square plates. Sometimes its color is greenish, brown, or gray. Its erystals may be thick pyramids or almost cubes, rather than thin plates. It has a bright resinous or adaman- tine luster. In thin pieces it is translucent. The hardness is slightly less than 3. It is easily scratched with a knife but not by the thumb nail. The streak is white, and the specific gravity is 6.7-7. It occurs usually in more or less perfect crystals, or erystal crusts, but sometimes in massive, or granular forms. Tests Fuse with sodium carbonate (soda) or chareoal. A globule of metallic lead appears. The addition of strong hydrochloric acid to the powdered min- eral gives a green solution. If this solution is much diluted and tin is added, it becomes deep blue and finally brown. Occurrence Wulfenite occurs in commercial quantities in Mexico, Spain, Arizona, New Mexico, and California. It is reported from many other regions, where it is associated with lead ores. MOLYBDITE For many years molybdite was regarded as synonymous with molybdie trioxide (MoO,) which is obtained artificially by oxidiz- ing molybdenite. Schaller’ demonstrated that natural molybdite contained iron and water and that it has the composition Fe,O,. 3Mo0,. 714H,0. Schaller? also showed that the analyses of various samples of pure molybdite agreed very closely with the theoretical composi- tion derived from this formula. The theoretical composition is: MoO, 59.42 per cent, Fe,O, 22.01 per cent, H,O 18.57 per cent. 1Schaller, W. T., Mineralogical notes. Series 1, U. S. Geol. Survey Bull. 490, 1911, pp. 84, 87 and 88. 2Schaller, W. T., loc. cit., pp. 87-88. 10 MOLYBDENUM DEPOSITS -OF COLORADO Molybdite is an alteration product of molybdenite, with which it is very commonly associated near the surface of the ground. It is also found in open fractures, where ground water has been active in molybdenite deposits. It occurs as a yellow powder or as yellow, silky, fibrous or radiated crystals. When in the powder form it resembles carnotite, or tungstic oxide. Its luster is silky, pearly or earthy. Its streak is yellow, and its specific gravity is 4.5. Tests When heated on charcoal it fuses and leaves a coating of minute yellowish crystals. If this coating is heated for an instant in the reducing flame it turns deep blue, and with continued heat- ing it becomes dark red. On heating the mineral in a closed tube water is given off and the mineral takes a dark-blue color, which becomes lighter upon further heating. For further tests see Schaller’ or Horton? who gives Schaller’s tests. POWELLITE Powellite is a calcium molybdate with the formula CaMoQ,. It is a white or grayish mineral, which breaks into small glistening scales. These are soft, and adhere to the skin like tale when crum- bled between the fingers. The mineral is formed by the weathering of molybdenite, after which it is a pseudomorph. Scheelite may occur with the mineral, but Schaller* believes that the mixture is mechanical, and not a chemical combination. The specifie gravity of powellite is about 4.25.4 It has a resin- ous luster, and an uneven fracture. It is decomposed by nitric and hydrochloric acids. It has been reported in the United States from Texas and Nevada. ILSEMANNITE The composition of ilsemannite is believed to be MoO,.4Mo0,. It is a blue-black ecryptocrystalline mineral which is soluble in water, giving a deep blue solution. Upon evaporating the solu- tion, dark blue crystals appear. The mineral is reported from the Cripple Creek district, and from Idaho Springs.® 1Schaller, W. T., loc. cit., pp. 85-86. 2Horton, F. W., Molybdenum: A ores and their concentration. U. S. Bureau of Mines Bull. Wall, sisal. Ser 3Schaller, W. T., loc. cit., pp. $1. 83. 4Schaller, W. T., loc. cit., p. 83. 5Lindgren, Waldemar, and Ransome. F. L., Geology and gold deposits of the Criprle Creek district, Colo.: U.S. Geol. Survey Prof. Paper No. 54, 19 Pp. oa F. W., loc, cit., pp. 15-16. MOLYBDENUM ORES ial BELONESITE This mineral is believed to be a magnesian molybdate (MgMoO,). It is white, and is transparent in thin flakes. It is insoluble in acids but fuses readily in salt of phosphorus, and less easily in borax. It has been reported only from Italy, where it occurs in rock fragments, enveloped in the lava flow from Vesuvius of 1872. PATERAITE Pateraite is an impure black mineral reported from the Elias mine, Joachimsthal, Austria, where it is associated with ura- nium. Its composition is CoMoQ,. ACHREMATITE Achrematite is a complex mineral having the composition rep- resented by the formula 3(3Pb,As,0,.PbCl,)4(Pb,MoO.). It has a sulphur-yellow to orange, or red color, when fresh, but in mass is liver-brown due to the presence of limonite. If heated on charcoal it fuses, gives arsenic fumes and odor, and finally yields a lead coating on the charcoal and globules of lead. It is reported from the mines of Guanacere, Chihuahua, Mexico. EOSITE Hosite is supposed to be a vanado-molybdate of lead, of the composition and formula Pb,V,MoO,, although its exact composi- tion has not, according to Horton,’ been definitely established. It occurs as minute octahedral crystals of the tetragonal system on pyromorphite and cerussite at Leadhills, Scotland. Its hardness is 3 or 4. Its color is deep aurora-red and its streak is a brownish orange-yellow. Tests When heated in a closed tube the mineral darkens, but regains its color on cooling. When fused with potassium bisulphate it gives a slightly yellow color to the mass, while hot, but on cooling it turns first reddish brown and finally brownish orange-yellow. The fused mass, when dissolved in water and boiled with metallic tin, colors the solution a faint greenish-blue. If a small fragment of the mineral is placed on a glass plate and treated with hydrochloric acid, followed by the addition of alcohol, and then evaporated, a " 4Horton, F. W., loc. cit., pp. 14-15. IY MOLYBDENUM DEPOSITS OF COLORADO blue or bluish-green coating is formed with a green precipitate on the edges. DOUBTFUL SPECIES Horton! cites molybdurane, molybdoferrite and knightite as doubtful minerals, whose ‘‘existence as distinct species is prob- lematical.’’ The provisional formula of molybdurane is given as UO,.U0O,.2Mo00,, and that of molybdoferrite, FeMoO,. Knightite is said to be a phosphate of molybdenum. PRODUCTION OF MOLYBDENUM The following countries have considerable quantities of molyb- denum ores, and most of them have produced concentrates in com- mercial amounts: Australia (New South Wales, Queensland, and Tasmania), Bolivia, Canada, Chile, German East Africa, Germany, Japan, Mexico, Norway, Peru, New Zealand, Rhodesia, Spain, Sweden, United States. Of these, Australia, Canada, Norway, Spain, the United States, and possibly Germany, are the chief producers. 1Horton, F. W., Molybdenum: Its ores and their concentration. U. S. Bureau of Mines Bull. 111, 1916, pp. 16-17. , CHAPTER III FOREIGN MOLYBDENUM DEPOSITS AUSTRALIAN DEPOSITS For many years Australia, from the two states Queensland and New South Wales, was the world’s largest producer of molybdenum. Queensland is the larger producer of the two. The following table shows the production of these two states: PRODUCTION OF MOLYBDENITE IN AUSTRALIA’ Year 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 LOTS 1914 11S) 5055 Queensland Tons ilal *26 39 10 ra 63 106.25 66.75 89 CBG) 106 9925 102.66 66.33 17.15 97.50 New South Wales Tons 15 29 25.25 19.40 32.65 21.65 8.45 28.15 47.50 20.65 56.55 78.80 61.40 31.70 1916 (estimated) for the two states 140 tons. *Includes some wolfram and bismuth. Andrews? states that, in Queensland, wolfram, molybdenite and bismuth occur together in all the mines, although the main tin deposits of north Queensland do not have the other minerals present. He further states that: ‘‘All the important deposits of the mineral in question (molybdenite) occur in northern Queens- land.’’ 1Andrews, E. C., The molybdenum industry of New South Wales. New South Wales Geol. Survey, Bureau of Mines, Min. Res. No. 24, 1916, p. 22. 2Andrews, EC. loc: cit., p. 17. 14 MOLYBDENUM DEPOSITS OF COLORADO Mr. Andrews quotes Mr. Ball in describing the geology of these deposits as follows: All these deposits occur on or within a few hundred feet of the con- tact of the granite and the rock it intruded, exceptions to this rule being only apparent. Thus, when a deposit is found in the granite distant from a covering rock, it is easy to show that the intruded rock has formerly existed at no great elevation above the present surface; and when the deposit is found in sediments unassociated with the granite, it can mostly be shown that the latter lies at comparatively shallow depths below the surface. The deposits when occurring in granite are peculiar in shape, being typically bent and contorted tubes or pipes, the origin of which is not per- fectly clear, beyond that they have been produced in the solidifying magma by the escaping gases and solutions. He notes further in the same reference that the veins of molyb- denite in southern Australia, which produce negligible amounts of molybdenite, are believed to be of igneous origin. Andrews! summarizes the geology of the New South Wales deposits as follows: The greater portion of the molybdenite from this Australian state is won from New England, in the northeast, and from Whipstick, in the southeast. The deposits occur as follows: A. Pipes or cylindrical masses of tortuous form. (a) Quartz pipes. (b) Pegmatite pipes. (c) Granite pipes. (d) ‘“Mica-garnet” pipes. (e) “Garnet” pipes. Aplitic segregations. Pegmatitic veins. Quartz veins containing feldspar. Quartz veins. (a) In greisen within the peripheral areas of coarse, sandy granite. (b) In aplites or tin-granites of fine texture. (c) In coarse basic granites. (d) In sandy granites, fine and coarse in texture. (e) Networks of veins in quartz-porphyry. F. Contact deposits, containing abundant garnet, wollastonite, amphi- bole, actinolite, quartz, with a little pyrrhotite and pyrites. BOOP As late as the beginning of 1916 only a little work had been done on the problems of concentrating the low-grade ores of Australia, and the lack of modern plants has kept down the produc- 1Andrews, E. CG., loc. cit. p. 16. MOLYBDENUM DEPOSITS OF NORWAY 145 tion. Hand picking, crude methods of crushing and saving the coarse flakes by hand picking and sieving, are the methods in use at the smaller mines. Small plants, with a capacity of from 5 to 25 tons a day of 3 shifts each, are described by Andrews.’ These are based on some form of oil or water flotation. The same author,” in discussing the outlook for the industry in New South Wales, states that many of the owners of small proper- ties, which have no large showings of ore, are not pushing their production, but are waiting for concentration methods to be per- fected which shall be both cheap and efficient. He estimates that eventually it will ‘‘be possible for New South Wales to produce hundreds of tons a year of high-grade molybdenite concentrate from the pipes, seams, and veins above mentioned.”’ MOLYBDENUM DEPOSITS OF NORWAY Norway has produced about the same amount of ore as has New South Wales. The average annual production of molybdenite concentrates (probably about 75 per cent MoS,) between 1902 and 1913 was about 30 tons.2 About 75 tons of concentrates of similar grade were produced in 1914, and 87 tons in 1915.* Extracts by Mr. Claudet® from the translation of a paper pub- lished by Dr. Otto Falkenberg give the main facts of the geology of the Norway deposits. The most important discoveries in Norway are at Knabeheien near Kvinas Valley, north of Flekkefjord. The occurrences are associated with granite and partly granite-gneiss. They appear to some extent in intimate association with massive pegmatite, and specially-at the boundary. of the pegmatite with the surrounding granite. In other places one can best speak of molybdenite-bearing quartz-rock, and finally there are occurrences of ore direct in the granite without any accompanying kind of vein mat- ter. This last is, however, usually of little extension and seems to be confined to small veins which intersect the granite. Owing to its intimate association with the pegmatite, the want of a distinct line between the vein and the surrounding granite, together with the appearance of fluor- spar, the author considers these occurrences to be formed, at any rate ' partly, from pneumatolytic origin in connection with the ascending ore- bearing solutions. Their formation is to be considered as the last effect of the granite eruptions. * * * The ore-bearing zones are intersected by several diabase dykes, running approximately H-W, having a width up 1Andrews, E. C., loc. cit., pp. 10-13. 2Andrews, E. C., loc. cit., pp. 190-191. 3Horton, F. W., loc. cit. p. 29. 4Claudet, H. H, Notes on molybdenite operations in Norway. Can. Min. Inst. Bull. 51, July, 1916, p. 610. 5Claudet, H. H., loc. cit., p. 611. 16 MOLYBDENUM DEPOSITS OF COLORADO to five meters. They do not appear to have any special influence on the ore’s occurrence. The diabase dykes can be followed for several kilo- meters. This ore-bearing zone is about one kilometer broad and has a longitudinal extension from north to south of about twenty kilometers. A further continuation is not out of the question as the same granite con- tinues also beyond the present known ore-bearing zone, but is little ex- plored. A red granite variety, whose red colour is owing to large ortho- clase crystals, must be considered as quite unmetallic. Claudet' states that the deepest workings are only about 100 feet, vertically, in depth, and that in many places the ore has dis- appeared at shallow depths. In some cases the veins themselves disappear ; in others, they simply become barren. He further notes* that, although there are considerable amounts of mica, pyrite, and chaleopyrite, and some pyrrhotite with the molybdenite, the concentration of the ores has not been a particu- larly difficult matter, and that by the Elmore process, molybdenite ores as low grade as 0.4 per cent to 0.5 per cent MosS,, containing other sulphides and mica, have been concentrated up to from 70 per cent to 75 per cent Mos, in one operation. ‘With an ore containing 0.8 per cent. to 1.0 per cent. MoS, over 80 per cent. recovery and a concentrate varying from 75 per cent. to 85 per cent. MoS, is obtained in practice, but when the mill feed is very low the results will correspondingly suffer.’’ Mr. E. R. Woakes* states that the war demand, coupled with unrestricted prices, has caused an abnormal expansion of the molybdenite industry in Norway. He gives a list of 18 promising deposits, all in southern Norway. Of these 5 are undeveloped, 5 are producing, but have no concentrating plants, and 8 have mills, all of which use the Elmore vaccum process. According to Mr. Woakes, the cost of producing a ton of 75 per cent concentrates is $2,500. He believes that Norway ean pro- duce 100 tons a year of the metal molybdenum for many years, if the price stays above $19.00 a unit for the concentrates. Norway has an abundance of undeveloped water power, which is soon to be utilized in the manufacture of ferro-molybdenum. 1@laudet, H. H., loc: cit., p. 612. 2Claudet, H. H., loc. cit., pp. 610, 612-614. 3Woakes, HE. R., Molybdenum industry in Norway. (Extracts from a paper in Bull. 160, I. M. M.) Eng. and Min. Journal, vol. 105, No. 11, 1918, pp. 499- 502. CANADIAN MOLYBDENITE DEPOSITS 17 CANADIAN MOLYBDENITE DEPOSITS In 1911, Dr. T. L. Walker’ stated that up to that time there had been no regular production of molybdenum ore in Canada. He also stated® that the recorded production of Canadian ore between 1886 and 1909 was only 90 tons. Between 1909 and the first of the year 1915 there seems to have been no commercial production. In the latter year, however, due to the European demand, 28,600 pounds of molybdenite was produced. The next year 159,000 pounds of molybdenite was produced,* while in 1917 the production had increased to 271,530 pounds.° These figures show the stimulus on the industry caused by the war. Dr. Walker,® in 1911, cited 12 localities in Canada that appeared promising. Since that time a large amount of prospecting has been done and many important locations have been made, especially in Quebec, Ontario, Manitoba, and in British Columbia. Drysdale’ states that Mr. Johnston, mineralogist of the Geolog- ical Survey, gives a list of 60 different localities in Canada where molybdenite occurs. ‘‘Of these 20 are in British Columbia, 18 in Ontario, 15 in Quebec, 3 in Nova Scotia, 3 in New Brunswick.’’ Of these, 2 in British Columbia, at least 1 in Manitoba, 1 in Quebee and 3 in Ontario, appear to be particularly promising, and will be briefly described in order to present some idea of the character of the deposits and the probable Canadian production. British Columbia Deposits The Canadian Mining Journal for August 1, 1916, p: 361, quotes a Spokane newspaper report of a statement by Mr. Arthur Lakes, Jr., as follows: About 13 miles from Anyox, on Alice Arm, the Stilwells, of Seattle, Washington, are equipping a molybdenum mine with a 50-ton flotation plant, which is expected to begin operations on August 1. This is prob- ably the largest known deposit of molybdenum in the world, and as the ore occurs in quartz its metallurgy presents no problems. The owners 1Walker, T. L., Molybdenum ores of Canada. Canada Department of Mines. 1911, p. 57. 7 2ANiaikersiois. lOc. Clit... ps dD. 2McLeish, J. S., Preliminary report on the mineral production of Canada during the calendar yvear 1915. Mines Branch, Ottawa, p. 15, 1916. 4McLeish, J. S., Can. Min. Journal, vol. 38, No. 6, 1917, p. 122. 5McLeish, J. S., Can. Min. Journal, vol. 39, No. 5, 1918, p. 72. SiWealkenr.ls alee LOC: Clit., "Ds.0.t- 7Drysdale, C. W., Notes on the geology of the “Molly” molybdenite mine, ea Nelson Mining Division. Can. Min. Inst. Bull., Nov., 1915, pp. 18 MOLYBDENUM DEPOSITS OF COLORADO have been awarded a contract by the Munitions Board for one hundred tons of the metal in concentrate containing not less than 60 per cent mo- lybdenum at $1.00 a pound, or $20.00 a unit. From what I have seen of the ore, I believe they will not experience any difficulty in producing the grade of concentrate required, and they should clean up $200,000 on the contract. Another British Columbia deposit which shows considerable promise was described by Drysdale’ in 1915. The following quota- tions will show his conception of the geology and the value of the deposit : The Molly mine is situated on Lost Creek, on the old Dewdney Trail, about 15 miles by wagon road from Salmo. It is at present being opened by a Vancouver syndicate. The property includes a group of four Crown Granted claims—‘Molybdenum No. 1,” “Molybdenite,”’ ‘Bromyrite,’ and “Bromyrite King.” The claims were located July 15, 1913, by S. N. Ross, H. E. Bennett, and J. A. Benson. PRODUCTION.—‘Since discovery, 50 tons of molybdenite ore have been shipped from the property. The first car of 24 tons was shipped by the owners to Denver, Colorado, on October 1, 1914. The average run of the shipment was 16.586 percent molybdenite and 822 pounds of the ore averaged as high as 30.175 percent MoSe. Specimens of ore of this grade assayed 2% ounces in silver with a trace of copper and gold. Selected samples assayed from 52 percent to 80 percent MoS. At that time the shippers were paid for 85 percent of the MoS:2 contents at the low rate of 20 cents per pound. On March 10, 1914, the property was leased to G. H. and J. P. Bell of Salmo, who proceeded to actively develop it; and on April 9, 1915, shipped one car of 24 tons to Denver, Colorado. The shipment ran 12.26 percent MoSse, and 90 percent of the MoS:z content was paid for at the rate of 50 cents per pound. In addition, two tons of ore samples, which assayed 9.5 percent. MoS:2 and sold for $1.00 per pound of MoS: content, were shipped by the owners to New York. Several thousand tons of milling ore of about probably 4 percent MoSz lie on the mine dumps. During the spring of 1915 the property was bonded for $100,000 by a Vancouver syndicate, which continued the de- velopment of the mine, intending, should conditions warrant, to presently install a small concentrating plant on the property. GEOLOGY OF THE ORE DEPOSIT.—Like so many Cordilleran ore deposits, that of the Molly mine is associated with the upper border of a large intrusive mass or batholith of granitic rocks which have been laid bare by erosion. * * * ‘The ore zone appears to be about 10 feet thick, as exposed in the main open cut at the west border of the cupola stock. The granite below the ore zone becomes more massive, blocky, and coarser in grain. Whether the molybdenite ore persists into the diagonally jointed granite or is only confined to the platy jointing still remains to 1Drysdale, C. W., loc, cit., pp. 876, 877, 879. ONTARIO DEPOSITS 19 be seen. The granite, however, for considerable distances from the ore zone is impregnated with molybdenite and much of it might be milled profitably. . Hy VSO ee Ee The geological structure, the small amount of mica in the ore, which contains also only traces of copper, and the existence of a sufficiently ample water supply, are factors favorable to the provision of a mill to treat the lower grades of molybdenite ore. By thus raising the per- centage of molybdenite through concentration to, say, 95 percent Mos:, not only the highest prices would be obtainable, but also a more wide- spread market and sale for the product made possible. Mamtoba Deposits There are several undeveloped deposits in Manitoba. One, at Falcon Lake, has been described by J. S. De Lury.' At the time he wrote there had been no commercial development of the deposit. The mineral occurs in large crystals and masses, in dikes of pegmatite, which lie in the Keewatin schists parallel to and adjacent to the contact of the schist and masses of intrusive red granite. In describing the occurrence and value of the molybdenite, Mr. De Lury says: The showings were much better in some openings than others. At one point, where a shot had been put in exposing about one square yard of fresh pegmatite, the crystals of molybdenite were exposed, which taken together, it was judged, would weigh from one-half to one pound. In the blasting out of seven or eight cubic yards of the dyke-rock, twenty or twenty-five pounds of loose crystals and masses were gathered, while in the large unbroken blocks of rock piled on the dump, could be seen many more. The prominent type of occurrence of the molybdenite is in large crystals and lamellar masses, which could be readily hand-picked into ‘an almost pure product. There is another type which, if found in suffi- cient quantity, would be of economic importance: the fine-grained variety as found in aplite. Mr. De Lury believes that the content of the ore is from one or two-tenths of one per cent to one per cent of molybdenite, but that better values may be uncovered with further prospecting. Ontario Deposits Mr. A. L. Parsons,’ in a preliminary report on the molybdenite deposits of Ontario, thus summarizes the geology of the deposits in Ontario: 1De Lury, J. S., Molybdenite at Falcon Lake, Manitoba. Can. Min. Jour- nal, vol. 38, No. 23, 1917, pp. 460-462. 2Parsons, A. L., Molybdenite deposits of Ontario. Can. Min, Journal, vol. 38, No. 11, 1917; pi 231. 20 MOLYBDENUM DEPOSITS OF COLORADO With but few apparent exceptions to the rule, the molybdenite of eastern Ontario is intimately associated with pegmatite dikes in the gneisses and crystalline limestone, probably of Grenville age. In case limestone is present, it is usual to find that the pegmatite is not directly in contact with the limestone, but is separated from it by a band of pyroxenite, which is presumably due to a chemical reaction between the pegmatite and the limestone. Where this pyroxenite is present it usually carries the greater part of the molybdenite, and with it considerable quantities of pyrite and pyrrhotite. In certain instances brown and black mica replace part of the pyroxene. When limestone is absent and the pegmatite has introduced gneissic rocks, the pyroxenite band is seldom present and the molybdenite is in the normal pegmatite, but in only one case did the writer find an outcrop where no trace of pyroxene was to be seen. In the more normal pegmatite deposits tourmaline is fre- quently associated with molybdenite, and in certain instances the pegma- tite becomes more siliceous until it appears to be an ordinary quartz vein. The deposits at Net Lake, near Timagami, District of Nipissing, appear to be an exception to the pegmatitic origin of the deposits. At this place the molybdenite is present in a series of gash veins of quartz, which contain in addition small quantities of gold and Gopper, the latter being in the form of chalcopyrite. Whether these veins are pegmatitic in origin is not definitely known, though such an origin has been suggested for some of the gold veins at Porcupine. In case the pegmatitic origin for this deposit can be shown, the deposits of eastern Ontario may all be grouped together as being associated with pegmatite. Renfrew County seems to be the most promising. The Inter- national Molybdenum Company, Limited, and the Renfrew Molyb- denum Mines Company, Limited, as well as some individual oper- ators, are developing certain deposits, as indicated by the following extracts from Mr. Parsons’ report :* Brougham Township.—Lots 35 and 36, con. XIV. An open cut about 10 by 70 feet has been excavated by Legree Bros., Dacre, in a micaceous pyroxenite. About 8 tons of ore, running possibly 3 percent: Mos, together with possibly 400 pounds of pure flake, had been taken out and laid aside for shipment. The property merits further prospect- ing, and the ore should be shipped to prevent loss by oxidation. Lots 76 and 17, con. XI., and Lot 17, con. X. Owners of mineral rights, International Molybdenum Company, Limited. Development work is being carried on under the superintendence of J. C. Murray. From 20 to 30 men are employed. The molybdenite is in a series of parallel pegmatite-pyroxenite dikes, and at the time of the writer’s visit the work had all been by stripping and open cuts. More than 200 tons of con- centrating ore have been shipped from this property. The writer was informed that a shaft was started after his visit. Lots 7, 8 and 9, con. XI., and lot 8, con. XII. The Renfrew Molybde- num Mines, Limited, under the superintendence of Charles Spearman, are working on a low-grade pyroxenite, which lies between Grenville 1Parsons, A. L., loc. cit., pp. 231-232. QUEBEC DEPOSITS 21 limestone and pegmatite. Several carloads of concentrating ore have been shipped from this property. A drift about 60 feet long and a cross- cut about 90 feet in length have been driven into this deposit and two holes have been put in with a core drill. The deposit as exposed is about 600 feet long and 40 feet wide, and apparently offers a large tonnage of concentrating ore. Preparations were in progress for the erection of a mill, and two more boilers were being installed. It is pro- posed to use the Elmore (flotation) concentrator in the mill. Preparations were being made for the sinking of a shaft. Lot 15, con. XI., known as the Connelly-Chown property. Two pits have been sunk on a couple of narrow pegmatite dikes of apparently the same character as those on the adjoining claims, which are worked by Mr. Murray. Griffith Township.—Lots 31 and 32, con. V., and lot 31, con. IV. Owner, W. J. Spain, New York City. Manager, George R. Gray, Dacre. The molybdenite is in two dikes of pegmatite and pyroxenite in gneiss and crystalline limestone, separated by about 10 feet of gneiss. The two dikes together give a width of about 25 feet of working ore. The molyb- denite occurs in extremely large flakes, some of them being more than a foot across. Masses of nearly pure molybdenite, weighing as much as 50 pounds, have been taken out. A mill has been erected and was nearly ready for work. As much of the flake molybdenite as possible will be picked out on picking belts, and the remainder, after passing through the rolls, will go to a Hooper pneumatic concentrator. Lyndoch Township.—Lot 5 and 6, con. VII. Jamieson mine, operated by the International Molybdenum Company, Limited. Idle at the time of the writer’s visit and workings filled with water. There were 57 sacks of low-grade ore ready for shipment and a few small piles of ore to be cobbed. This is looked upon as one of the promising properties. , Quebec Deposits There are important deposits of molybdenite in the Ottawa Valley, north and west of Ottawa. Of these the ‘‘Moss”’ mine, in Onslow Township, 3 miles from Quyon and 35 miles from Ottawa, has become a large producer. The property was located in 1915, and purchased by the Canadian Wood Molybdenite Company, in March, 1916. During the remainder of 1916 and 1917 the mine is said to have produced about 300,000 pounds of molybdenite. In 1916 it was probably the largest producing molybdenite mine in the world. In 1917 the property was purchased by an American syndi- cate, the Dominion Molybdenite Company. This company has done a large amount of prospecting with the diamond drill, and has enlarged the mill at the mine from a capacity of 50 tons a day to 200 tons a day. The Wood water flotation machines, which are said to have given fair satisfaction, have been replaced by the Callow oil flotation cells. ae MOLYBDENUM DEPOSITS OF COLORADO The geology of the Ottawa Valley, and particularly the ‘‘ Moss’”’ mine deposits, has been described by M. E. Wilson’ and E. Thompson.’ It is peculiarly interesting that pyroxenite in considerable quantities is intimately associated with the molybdenite. Thompson? divides the deposits of the region into three types, as follows: 1. Associated with slightly more basic segregations in the granites, syenites, or gneisses of the Laurentian. 2. In intimate association with pyroxene in the ‘‘contact pyroxenite’’ of the Grenville series, or in the partially digested rock of this process of silicification. 3. In pegmatite dikes. The articles are too long to quote here, but the authors show that in spite of the seemingly unusual occurrence of the ‘*Moss”’ mine ore with pyroxene, it is probably not so unusual after all, when all the conditions have been studied, and that the molyb- denite was deposited by pneumatolytic action in one of three ways: (a) accompanying the formation of pegmatite dikes; (b) the intru- sion of acidic rocks, granite, or syenite, into sedimentary or meta- morphic rocks; or (¢c) the segregation of slightly more basic rocks from their parent masses, accompanied by fracturing and possibly followed by pegmatitie action. The ‘‘Moss’’ mine deposit seems to be of the latter type. CONCENTRATION The ore is being concentrated at the mines mentioned above in British Columbia and Quebec, also at Hull, Quebec, and at Ren- frew and Mt. St. Patrick, Ontario. The Mines Branch at Ottawa has for some time been conducting a custom concentrating plant for the convenience of prospectors and small mine owners, but this was to be discontinued July 31, 1918.* The concentrates are being reduced, and molybdenum powder, ferro-molybdenum, and ammonium molybdate are being manufac- tured at the plant of the International Molybdenum Company at Orillia, Ontario. 1Wilson, M. E., Molybdenite deposits of Quyon District, Quebec. Can. Min. Journal, vol. 29, No. 5, 1918, pp. 78-80. 2Thompson, E., A pegmatitic origin for molybdenite ores. Economic Ueology, vol. 18, No. 4, 1918, pp. 302-313. 3Thompson, E., loc. cit., pp. 305-313. 4Can. Min. Journal, vol. 29) Now SeHlOLs: Wpheos- QUEBEC DEPOSITS 23 It is apparent, from a review of the literature of the subject, that Canada has very large molybdenite resources, and it is evident that this country will be an important factor in furnishing the world’s supply of molybdenum. GERMAN DEPOSITS There is little information at hand concerning the German molybdenite deposits. A note in Engineering and Mining Journal, volume 100, October 9, 1915, page 589, states that the German mines near Halle, on the Saale, have been enlarged and improved and will be able to supply the whole European steel industry, when peace is restored. CHAPTER IV UNITED STATES MOLYBDENUM DEPOSITS—EXCEPT COLORADO Horton’ gives a list of the following states from which one or more deposits of molybdenite have been reported : Alaska, Arizona, California, Colorado, Connecticut, Idaho, Maine, Massachusetts, Minnesota, Montana, Nevada, New Hamp- shire, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Utah, Vermont, Washington and Wyoming. Wulfenite® is reported from: Arizona, California, Colorado, Massachusetts, Montana, New Mexico, Nevada, New York, South Dakota and Utah. Six western states,’ namely, Arizona, California, Colorado, Montana, New Mexico and Washington, have many molybdenite deposits, some of which are now producing, In addition there are deposits of considerable promise in Utah, Nevada and Maine. In 1915* the United States produced 91.0 short tons of mo- lybdenum, most of which came from Arizona and Colorado, but small lots were shipped from Texas and Utah. The larger operating companies or individuals in 1915 are given by Hess’ as: The Arizona Rare Metals Co., Col. Epes Randolph, The Duquesne Mining and Reduction Co., The Levi- athan Mines Co. and the American Molybdenum Co., all working in Arizona; The Pingrey Mines and Ore Reduction Co. and the Primos Chemieal Co., of Colorado. The Arizona Rare Metals Co. and Col. Epes Randolph produced wulfenite concentrates from the Mammoth Mine 48 miles northeast of Tucson, and from the Yuma Mine 14 miles northwest of Tucson, respectively. All the others produced molybdenite ore. In 1917 Hess® reported that: 1Horton. F. W., Molybdenum: Its ores and their concentration. U. S. Bureau of Mines Bull. 111, 1916, pp. 86-88. 2Horton, F. W., loc. cit., pp. 89-90. 3Horton. F. W., loc. cit., pp. 44-85. ; 4Hess, F. L., Molybdenum. U. S. Geol. Survey, Mineral Resources of the United States for 1915, part 1, pp. 807-812. 5Hess, F. L., loc. cit., pp. 807-808. 6Hess. F. L., Our Mineral Supplies. The Rarer Metals. U. S. Geol. Sur- vey Bull. 666-U, p. 10. 2 Cn ARIZONA*MOLYBDENITE DEPOSITS Pe The principal deposits of molybdenum ores known are on Chalk and Bartlett mountains and Quandary Peak, in Summit County, and near Empire, on the east side of Red Mountain, Colorado; in Copper Canyon, on the east slope of the Hualpai Mountains, Mohave County; at the old Yuma mine, Pima County, and at the Mammoth and Collins mines, Pinal County, Arizona; and near Emigrant and at other places in Montana. Many smaller deposits on which less development work has been done, occur in practically all the Rocky Mountain and Pacific slope states. Some of the deposits, such as the wulfenite-bearing veins at the Yuma, Mammoth and Collins mines and the molybdenite deposits in Copper Canyon, Arizona, are now (1917) being actively exploited. It has been impossible for the writer to get reliable statis- ties of production since 1915, but it is understood that in 1916 and 1917 Arizona produced large amounts of wulfenite and mo- lybdenite concentrates, and that early in 1918 some of the com- panies were holding thousands of pounds of concentrates that could not be marketed at what was regarded as a fair price. Colorado, as shown in another part of this report, is capable of producing large quantities of ore, and it would therefore appear that for the present the demand is likely to be exceeded by the immediately available supply, in this country. For purposes of comparison with Colorado deposits, brief extracts of reports on the geology of several molybdenite de- posits of the United States will be given. Since Colorado does not now have, and is not likely to have, commercial wulfenite deposits, no mention of the geology of those deposits will be made. ARIZONA MOLYBDENITE DEPOSITS Dr. Horton’ deseribes the occurrence a the Leviathan mines, Copper Canyon, Mohave County, as follows: The Leviathan properties consist of a group of six claims located on two approximately parallel veins knowns as the “Whale” and the ‘‘Cop- per Wonder.” These veins traverse a granite country rock and consist of white quartz carrying molybdenite and chalcopyrite as the principal ore-forming minerals. * * * The “Whale” vein, which is the larger of the two, varies in width from 6 to 40 feet, and the “Copper Wonder” vein from about 2 to 20 feet. The molybdenite occurs in amorphous and finely crystalline form in thin veinlets and irregular masses throughout the quartz, and as a fine crystalline powder and as nuggets in vugs and cavities in the veins. Much of it is somewhat intimately associated with chalcopyrite, and in only a few places could the writer obtain specimens that were free from copper: os 1Horton, EF. W., loc. cit., pp. 52-54. 26 MOLYBDENUM DEPOSITS OF COLORADO The country rock is a medium-grained gray granite consisting of quartz, feldspar (orthoclase, microcline and plagioclases varying from albite to labradorite), biotite, muscovite and small amounts of the usual accessory minerals, zircon and apatite. * * * The analyses of 22 samples of the ore are given as 2.73 per cent Mos, and 1.71 per cent copper, and the writer concludes : The outcrop of the “Whale” vein is so exceptionally well defined and so wide and the molybdenite and copper contents of the vein, as indicated by sampling of the outcrop and workings, are so regular and persistent that the writer considers the property a most promising one notwith- standing the unfortunate association of copper with the molybdenite. CALIFORNIA DEPOSITS Mr. F. C. Calkinst has described an occurrence of molybdenite near Ramona, San Diego County, California, as follows: The dominant rock about Ramona, as well as westward to the foot of the mountain range, is one that would commonly be called a biotite granite. * * * Microscopic study shows that the rock is not a typi- cal granite, inasmuch as the alkali feldspar is very subordinate to the soda-lime feldspar. This granitic country rock is cut by many dikes of aplite. * * * The molybdenite occurs in one of the aplite dikes, which trends north-northwest and has been traced about 1,500 feet southward from the brink of the gorge of Santa Maria Creek, on whose south wall it is exposed. Its width varies from less than 50 to about 200 feet. The molybdenite is very unevenly distributed through the rock. The greater part of the dike is barren or nearly so. * * #* The molybdenite is clearly an original constituent of the aplite, to which it is confined. Its occurrence in the coarser parts of the rock indicates that the coarse crystallization and the mineralization were both due to local concentration in the magma of the more mobile constituents. To its mode of origin is due its uneven distribution. MAINE MOLYBDENITE DEPOSITS The following is an extract from Hess’s* description of the geology at the property of the American Molybdenum Co., at Cooper, Maine: The prevailing rock is a comparatively fine-grained light-gray biotite granite, which weathers to a pinkish color. It is much broken by three prominent sets of joints. Two of these strike about northeast, one dipping 45° or less to the northwest, the other from 45° southeastward to vertical. The third set is older than the other two and runs nearly north and south with an almost vertical dip. Many of the joints of this third set have been filled with thin dikes of rather quartzose pegmatite 1Calkins, F. C., Molybdenite near Ramona, San Diego County, California. U. S. Geol. Survey Bull. 640-D, 1916, pp. 74-75. “Hess, F. L., Some molybdenum deposits of Maine, Utah and California. U. S. Geol. Survey Bull. 340, 1907, p. 232. MAINE MOLYBDENITE DEPOSITS Pf) from one-half inch to three inches thick. Ordinarily the most quart- zose phases occur where the dike has narrowed to its smallest pro- portions, and at many such places molybdenite forms crusts in which the flakes lie in radical groups of considerable beauty. Between the molybde- nite and the walls of the dike there is a thin layer of quartz and feldspar, ‘the latter on the wall itself, but at some places in crystals so small as to escape casual examination. In width the molybdenite flakes commonly range between one-sixteenth inch and an inch, but may fall short of or exceed these limits. It is said that segregations occur weighing 10 to 12 pounds. In wider parts of the dikes feldspar is a conspicuous constituent, but molybdenite is more sparsely distributed and seems inclined to segregate in the middle of the dike. From this list of occurrences of molybdenite in the United States and in other countries it is evident that the majority of the richest known deposits are associated with granitic rocks, particularly pegmatites. Aueul uy ‘I9quUINU 9UO JapUuN pepnNy{oUt sie s}IsOdep [e19AeS sesBod ‘poonpoid useq sey 910 YOIYM WOIJ S}Isodep Se}voIpUT Se[D110 papeYys eyYL ‘Ssand00 Wnuap ‘yout 94} 0} SeTIut 9g ATeyeuTxordde o[vog ‘ JIM9035—— (a | T 238Id ‘FT UljeyiIng yf m OQ a > Y Ps > a” AVAING [BOISO[OV5) OPVIOl[OD OdGVuOTOO HO SLISOdHC NWONHCEA ION CHAPTER V THE MOLYBDENUM DEPOSITS OF COLORADO The following list includes all the molybdenum deposits in Colorado that have been reported to the Survey. This list is followed by descriptions of the larger deposits. The numbers in the first column of this list agree with the location numbers on the accompanying map. It should be noted that several deposits may be included under one location number. BOULDER COUNTY No. Location Name of Property 1—Magnolia Mountain Lion 2—Jamestown 3—Caribou Red Warrior Group 4—HEldora Mogul Tunnel 5—Cardinal Boulder County Owner Robert Kermack, Boulder. Chas. Mohr and others, Jamestown. W. C. Bryant, M. B. Wray and Geo. Bartels, Nederland. Spencer Mtn. Tunnel Co., Eldora. Cardinal Co., Cardinal. CHAFFEE COUNTY 6—Brown’s Gulch California 7—Huffman Park near Garfield Nest Egg _ Same Location Royal Purple 8—Winfield Dist. Banker Winfield Dist. Uintah Winfield Dist. North Point Winfield Dist. 9—Twin Lakes Molybdenum Dist. 10—Twin Lakes X Ray and Whale Dist. Twin Lakes Climax Dist. 11—So. Cotton- Geneva wood Creek 12—Turret Independence 13—Alpine D. M. D. Molybdenum Mines Co., Denver. C. M. Morgan and G. M. Hendricks, Garfield. J. and E. A, Huffman, Poncha. Lessees W. B. Brooks, Leadville, P: S. Smith, Denver, Horace Hop- kins, Greeley. Same (Owners). R. T. Matthews, Granite. R. T. Matthews and J. W. Ady, Granite. Wm. Frederick and Fred Olson, Twin Lakes. Wm. Mock, Leadville. Earle Whited and C. G. Bilt, Twin Lakes. G. K. Hartenstein and H. C. Mc- Lean, Buena Vista. R. S. Stratton, Lessee, Turret. J. H. Dermitt, Buena Vista. 30 MOLYBDENUM DEPOSITS OF COLORADO CLEAR CREEK COUNTY No. Location Name of Property 14—Dailey Dist. Urad 15—Near Central Clifford City Owner Primos Chemical Co., Boulder. Leopold Sternberger, Central City. CONEJOS COUNTY 16—Platora Merrimac A. E. Reynolds, Denver. CUSTER COUNTY 17—Rito Alto Peak Grab Rito Alto Peak 18—Hillside J. M. Duckett, Hillside. E. F. Stacy, Hillside, R. J. Knight, Canon City. E. F. Stacy, R. A. Dissmore, Hill- side. EAGLE COUNTY 19—Mount Whit- ney W. 'G. McKay and John Popovitch, Red Cliff. FREMONT COUNTY 20—9 mi. S. Park- Copper Girl dale 21—12 mi. N. E. Liberty Bond Westcliffe Greenhorn Mtn. Copper Mining Co., Canon City. K. L. Eldred and B. F. Young, Canon City. GILPIN COUNTY 22—Apex Gray Eagle Apex John Goldberg, Apex, Eugene Ste- vens and Geo. Holland, Boulder. John Smith and Will Converse, Apex. GRAND COUNTY 23—Radium isl HSh Porter, Radium. GUNNISON COUNTY 24—Treasury Mtn. 25—Lamphere Lakes 26—Gold Hill Molybdenum Gold Hill Bon Ton Gold Hill Emma H. Gold Hill New Discovery 27—Cross Moun- tain 28—Spencer 29—Paradise Pass John O’Toole, 410 Ideal Building, Denver. Geo. Carter and Herman Hudler, Ohio. Wm. McKinley and A. L. Pearson, Pitkin. Lessee, Penn. Rare Metals M. and D. Co., Pitkin. H. Stephens Ehrman, Pitkin. A. L. Pearson, Pitkin, and Mr. Carpenter, Tin Cup. William Waugh, Gunnison. Pat Trainer, Iola. Charles Daniels, Salida MOLYBDENUM DEPOSITS OF COLORADO on HINSDALE COUNTY No. Location Name of Property Owner 30—4 mi. North I. D. A. Robert Wagner, Lake City. of Lake City 31—Sherman John Gavin, Lake City. HUERFANO COUNTY 32—Mosca Pass Not Located. LA PLATA COUNTY 33—East Silver Oregon CG. M. Ayers, Durango. Mesa 34—Vallecito John Bloom, Durango. Basin LARIMER COUNTY 35—St. Cloud Dist. Iron King E. F. Bartlett, Cherokee Park. MESA COUNTY 36—Unaweep R. U. Gavette, Grand Junction. Canyon Unaweep R. Collinson, Whitewater. Canyon MONTEZUMA COUNTY 37—Near Mancos Allard Mining Co., La Plata. OURAY COUNTY 38—Engineer Mtn. Fred Richter, Ouray. 39—Ironton Irene G. C. McGee, Ironton. Ironton Jumbo J. Davis and Gus Bruner, Ouray. PARK COUNTY 40—Lake George Red Skin Lessee, U. S. Rare Minerals Co., Denver. Lake George Apex * J. O’Driscoll and associates, Colo. ~ Ke “ Springs. 41—Guffey = ~— Crescent Alfred Dell, Guffey, and F. M. Woods Iny. Co., Colo. Springs. 42—West of Alma EK. E. Van Epps, Red Cliff. West of Alma White Swan EK. O. Nippert, Alma. 43—West of Alma Humbug Geo. W. Shelton, Alma. PITKIN COUNTY 44—-Near Red Mtn. Greenhorn F. E. Kendrick and associates, Leadville. ROUTT COUNTY 45—Farwell Mtn. Farwell Mtn. Cu. Co., Montreal. 46—Slavonia Dist. G. H. Frantz, Clark. Slavonia Dist. D. M. Wilt, Clark. Slavonia Dist. M. A. Hoskinson, Oak ‘Creek. on MOLYBDENUM DEPOSITS OF COLORADO SAGUACHE COUNTY No. Location Name of Property Owner 47—-Near Alder Wm. Merideth, Alder. SAN JUAN COUNTY 48-—Chattanooga Gold Finch and WLee Tinsley and Taylor McGrew, Hidden Treasure Chattanooga. 4'9——?) mi. S. of Liberty Bond E. J. Holman, A. D. Malchus and R. Chattanooga J. Hoffman, Silverton. 50—Near mouth Black Diamond J. P. Eaker, Silverton. S. Mineral Creek Bear Mountain Edward Hollingsworth, Silverton. 51—Head of S. . Not Located. Mineral Cr. 52—Cascade Basin Not Located. SAN MIGUEL COUNTY 53—Ophir Molybdenite Colo. Molybdenum Mining Co., Queen Ophir. 54—Placerville Evans Claims SUMMIT COUNTY 55—Climax Many Claims Climax Molybdenum Co., Climax. Climax Denver No. 2 Molybdenum Products Cor., Denver. Climax Rare Metal Group Pingrey Mines and O. R. Co., Lead- ville. Climax Molybdenum ©. J. Senter, Leadville. Group 56—Kokomo Bryant Claims Joe Bryant, Kokomo. Kokomo Kokomo Milling Co., Kokomo. 57—Quandry Mtn. Salamander and R. J. A. Widmar and A. C. Howard, Blue Valley Breckenridge. 58—Uneva Lake 59—Montezuma Clyde Drolsdraugh and John Sulli- van, Montezuma. TELLER COUNTY 60—Near Dome Lafe Fyfe, Cripple Creek. Rock 61—North of Wm. Smith, Cripple Creek. Pike’s Peak BOULDER COUNTY The Mountain Lion Mine The Mountain Lion Mine at Magnolia, Boulder County, is owned by Robert R. Kermack, and leased to M. A. Long, both of Boulder. It is situated about seven miles from Boulder. The BOULDER COUNTY DEPOSITS 33 property is close to the Keystone Mine, and within the limits of the village of Magnolia. The mine is 350 feet deep and has drifts at the 100, 200, 300 and 350-foot levels. At the time it was visited no work was being done, and the shaft was partly full of water. The country rocks are pre-Cambrian eneiss and schist cut by many masses of intrusive granite, and by pegmatite dikes. Messrs. J. H. Horry and M. A. Long, both of whom have worked in the mine, say that molybdenite occurs only on the lower lev- els, where it is associated with massive white quartz and small amounts of chalcopyrite and is found in and on the borders of a large pegmatite dike. The best showing is on the 350-foot level, where the dike, which has been cross-cut for 16 feet, shows small amounts of molybdenite all the way along. Wher- ever it occurs, the ore is very pockety and no safe estimate of the available supply can be made. In 1916 Mr. Horry shipped about 1,200 pounds to Denver for sampling and treatment. This ore was hand sorted, and selected from what was regarded as a rich streak, 10 feet long and 20 inches wide. The ore assayed 2 per cent Mos,. Most of the molybdenite is coarsely granular. Some individual flakes are an inch in diameter and from one-half to three-quarters of an inch thick. Most of the mineral, however, oceurs as small thin flakes, sparsely seattered through the quartz gangue. The probabilities for developing a commercial body of mo- lybdenite here are not regarded as good. No other molybdenite deposits are known in this region. JAMESTOWN DEPOSIT Mr. Charles J. Mohr, of Jamestown, Colorado, reports that he and associates have molybdenite claims near Jamestown, which show a large vein of low-grade ore. There is said to be a 60-foot tunnel on the property, which is all the development that has been done. No ore has yet been shipped. Samples and assay returns were requested but have not been received. CARIBOU DEPOSIT . Messrs. W. C. Bryant, M. B. Ray and George Bartels, all of Nederland, have molybdenite in the Bighorn Shaft, which is on one of the ten claims of the Red Warrier Group, situated about two miles north of Caribou on the northeast slope of Haystack Mountain. 34 MOLYBDENUM DEPOSITS OF COLORADO The property can be reached by a poor but passable road from Caribou, or by a trail about three-quarters of a mile long from the Silver Lake Mine, which may be reached by a fairly good wagon road from Hill, a station on the Denver, Boulder & Western Railroad. The Bighorn Shaft is 90 feet deep. At the bottom = are two drifts on the vein, each about 30 feet long. The country rock is garnetiferous quartz mica schist into which have been intruded many masses of coarse, gray biotite granite. A strong quartz vein cuts the country rock. It is said to vary from 114 to 7 feet in width. It dips vertically and strikes N. 45° E. The vein carries a great deal of pyrite. In fact, if it were near the railroad it might be successfully worked for pyrite. There are also said to be small values in gold and silver. At the time the mine was visited the vein could not be ex- amined in place, for there was a good deal of water in the shaft, which had accumulated during several months’ time when the mine had been standing idle. The vein material on the dump was carefully studied. Molybdenite, in very fine grains, is dis- seminated all through the quartz. In some fractures the mo- lybdenite content is high. and rich specimens ean be obtained, but the average of all the molybdenite-bearing quartz is from one-half to three-fourths of one per cent. The mine is well equipped with a 15-horsepower wood-burn- ing boiler, a double 4 by 6 eylinder hoist, and a good shaft house. There are comfortable log cabins near. Plenty of fire wood is close at hand, and water is not far distant. OTHER LOCALITIES Lindgren! has noted the oceurrence of molybdenite in the Boulder County Mine, and also in the Mogul Tunnel, Spencer Mountain, near Eldorado. On the dump of the Mogul Tunnel he found deep blue stains, believed by him to be ilsemannite. CHAFFEE COUNTY The California Mine The California Mine is owned by The Molybdenum Mines Co., whose office is in the Evans Block, Denver, Colorado. The mine is situated near the head of Brown’s Gulch, on the north side of the creek, at an elevation of 12,500 feet. It is iLindgren, Waldouan, Gold and tungsten deposits of Colorado. Eco- nomic Geology, vol, , 1907, pp. 456-458. CHAFFEE COUNTY DEPOSITS 35 19 miles from Nathrop, which is the nearest station on the Denver & Rio Grande Railroad, and it is 5 or 6 miles south of Alpine, a station on the McElmo-Buena Vista division of the Colorado & Southern Railroad. From Nathrop or Salida the property is reached by a good wagon road as far as Centerville, thence a poor wagon road 5 miles to the Beaver dams in Brown’s Gulch, and from there by a rough mountain trail 6 miles long. At present there is neither road nor trail all the way to the mine from Alpine, but a road 4 or 5 miles long follows a guleh south from Chalk Creek to a point within 1 or 2 miles of the camp. This road now reaches almost to the vein, where it outcrops in the first valley north of Brown’s Gulch, and it may be of importance if the mine is finally developed, as it is likely to be, from the Chalk Creek side. In July, 1917, the company owned four claims, namely, the California, California No. 2, Nevada and Nevada No. 2. DEVELOPMENT All the development work, with the exception of some shal- low surface cuts and location shafts, has been done on the Cali- fornia Claim. In the summer of 1917 the workings consisted of: an open eut with a 50-foot drift on the vein; an inclined shaft 50 feet deep, near the open cut, but apparently not on the vein; a cross-cut tunnel, that was started 50 feet vertically below the open cut and was run 98 feet to the vein; and drifts from this tunnel, one 30 feet westerly on the vein and another 126 feet to the east. Small stopes, only 2 or 3 feet above the normal roof of the tunnel, have been run for 75 feet, on the east drift. Mr. W. B. Lowry reported in June, 1918, that since July, 1917, the drift has been continued on to the east 15 feet to a fault, and 130 feet beyond, where the vein was recovered. GEOLOGY The ore occurs in a fissure vein in Pomeroy quartz monzo- nite. This rock has been described by Professor Crawford,! as follows: The rock is pinkish-gray to bluish-gray, and carries a great number of small, bluish-gray plagoclase crystals which frequently show twin striations on lustrous cleavage faces. In the hand specimen may also be seen pinkish to white orthoclase, chloritized hornblende, a few biotite _ 1Crawford, R. D., Geology and ore deposits of the Monarch and Tomichi Districts, Colorado. Colorado Geol. Survey Bull. 4, 1913, pp. 79-80. 36 MOLYBDENUM DEPOSITS OF COLORADO crystals, and occasional pyrite grains. With the aid of a strong lens quartz may be seen intergrown with the orthoclase. Near the east border of the larger area the rock is finer in texture, decidedly por- phyritic, and carries a larger proportion of quartz. Along the east bor- der also, wherever this porphyry is exposed on the ridges, as at Pom- eroy Pass, it is much stained by red and brown oxides of iron. The gangue minerals are quartz, beryl, some white mica and a little pyrite. The vein varies from 18 inches to 3 feet in width. Its average dip is 80° N. 18° W., but it straightens up in many places to almost 90°. It seems to be a strong vein. It holds its course well and according to Mr. W. W. Rogers, superintendent at the mine, it has been followed by float on the surface for a mile or more. Work done since the writer’s visit to the property in 1917 shows that at a distance of 141 feet from the cross-cut the vein is faulted, and that the east side is displaced 30 feet to the north. Two ores of molybdenum, molybdenite and molybdite, occur in the vein. The latter is more abundant in the upper workings, but is found in considerable quantities at the main tunnel level. Molybdenite is found everywhere that the vein has been opened. The richest ore is near the walls, but there are rich streaks and vugs scattered all through the vein. In these rich streaks, and along the walls, chunks of solid molybdenite from 1 to 2 inches thick, and from 6 inches to 2 feet in length, are of common oeccur- rence. The molybdenite is entirely crystalline, the flakes being as a rule from one-eighth to one-half an inch in diameter. The intimate association of pure white quartz crystals, some of which are 12 inches long, with opaque or clear beryl (aqua marine) erystals, and molybdenite is an interesting phase of the occurrence of this ore. Much of the richest ore is found with beautiful specimens of beryl. In many places pockets are found between masses of beryl and quartz crystals from which it is possible to dig out with a candle- stick 20 or 30 pounds of practically pure molybdenite and molybdite. While the vein as a whole is strong, there are rich and lean streaks all through it. On this account it is very difficult to get fair average samples without shooting down, and sampling a large amount of ore. The difficulty of proper sampling is increased by the facet that the country rock is mineralized for several inches more or less from the vein proper. It is noticeable that there is consider- ably more pyrite with molybdenite in the country rock than in the vein. CALIFORNIA MINE or TREATMENT The ore taken from the mine is trammed by hand to the sorting room at the entrance of the tunnel, where it is cobbed, hand sorted, screened and sacked. The value of the hand sorted material varies, but is said to average between 20 and 30 per cent MoS,. The screenings which pass a 10-mesh sieve run from 2 per cent MoS, up. The sacks of ore, which weigh from 75 to 100 pounds each, are packed on burros from the mine to the wagon road at the Beaver dams. From there they are hauled by wagon to Nathrop, and shipped by rail to Denver. The company, for a time, conducted a small chemical plant in which they reduced the ore to molybdenum trioxidé and ammonium molybdate. Only test lots of ore were so treated and the work was not resumed after a fire in the fall of 1917 destroyed the company’s mill equipment. - IMPROVEMENTS, TIMBER AND WATER There is a comfortable log cabin near the mine, which ac- commodates 8 or 10 men, and a log shop and sorting room at the entrance of the tunnel. Timber line in Brown’s Gulch is at 12,000 feet. There is plenty of timber suitable for mine use and building purposes within three-fourths of a mile of the camp. There are springs within 100 yards of the camp, which furnish all the water needed for ordinary living and mine use. Half a mile away and 300 to 400 feet below the mine there is a strong, permanent stream. FUTURE DEVELOPMENT Stoping ground above the present tunnel level is limited to a maximum of 200 feet east of the cross-cut. In the west the drift will run out of the hill to the surface within 200 feet of the cross- eut. While the writer has not been over all the ground, it is his belief that the property could best be worked by going in from Alpine and drifting on the vein from the northeast. It would give more stoping ground, and the distance to a railroad would be much less than from the present camp. It is of course evident that this property is not likely to become a large producer, but it should be an attractive proposi- 38 MOLYBDENUM DEPOSITS OF COLORADO tion to some one who wishes to mine and mill a small quantity of relatively high-grade ore which is free from copper and other injurious impurities. HUFFMAN PARK DEPOSITS Huffman Park lies just at the foot of the east slope of Mount Etna, in the Monarch Mining District, about 4 miles northwest of Garfield. Garfield is on the Monarch-Salida branch of the Denver & Rio Grande Railroad, and is 20 miles west of Salida. The train service is irregular, but averages 2 or 3 times a week from Salida, during the summer. An automobile stage makes the round: trip daily, between Monarch or Garfield and Salida. There is a good road between Salida and Garfield. From Garfield to the head of Huffman Park the road is rough and steep, but ordinarily passable for wagons. In the Park there are two molybdenite claims, the Royal Purple and the Nest Egg The Royal Purple Claim About one-fourth of a mile N. 25° E..of the cabin farthest up the gulch is the Royal Purple Claim which is owned by J. and E. A. Huffman of Poncha Springs. There are two veins here which are nearly parallel and which strike N. 55° E. There is an open cut and shallow shaft on the east one of these veins. The country rock is Princeton quartz monzonite’—a light gray, or nearly white rock, which contains considerable pale pink or white orthoclase, bluish gray plagioclase, and small amounts of quartz. A 6-foot vein is exposed which contains considerable molyb- denite in a 6 or 8-inch streak on the hanging wall. Most of the min- eral is found as distinct grains, from one-tenth to one-fourth of an inch in diameter, scattered through the vein. Some, however, occurs as facings in-cracks in the vein and in the country rock. A little molybdite is found in the vein. Much pyrite is associated with the molybdenite, but no copper is present. The vein could not be fully studied on account of the large amount of snow in the cut, but judging by what could be seen and by the ore on the dump, the grade of the ore is too low to allow its being mined and milled at a profit. 1Crawford, R. D., Geology and ore deposits of the Monarch and Tomichi Districts, Colorado. Colorado Geol. Survey Bull. 4, 19138, p. 138. NEST EGG CLAIM 39 A short distance northwest of the first vein, at an elevation of 11,850 feet, is a second quartz vein in the same country rock. This vein is three feet wide. It contains many thin facings of molybdenite and some that is rather coarsely granular. An average sample of ore from the dump assayed 0.96 per cent MoS,. Pyrite, but no copper, occurs in this vein. There is plenty of water near this property, and there is good wood and timber not more than half a mile away. The Nest Egg The Nest Egg Claim, owned by C. M. Morgan and G. M. Hen- dricks, both of Garfield, is situated on the east slope of Mount Etna, above Huffman Park, at an elevation of 12,150 feet. A rough, poor trail leads up from the Park to this claim. The country rock is Princeton quartz monzonite’ and Pomeroy quartz monzonite.* There are several small open cuts on the Nest Egg ground. At the main opening two faults cross. One dips 27° N. 20° E., and the other 85° N. 35 E. Along the junction of these faults, and on the hanging walls of both, there are bunches of molyb- denite, which are entirely crystalline and occur in bright, silver- gray, thin, radiating flakes. These flakes impregnate the country rock for a distance of two feet or more from the fault planes, and fill many vugs which cannot be detected until the rock is broken open. Some work has been done at and near the junction of the faults, and at a distance apart of ten feet the country rock is mineralized from one fault to the other. The ore is entirely free from all other metallic minerals, and can be concentrated easily. It is probable that a 1 or 2 per cent erade of ore could be sorted out without difficulty. The extent of the deposit, however, is in doubt. There is a great deal of slide rock in the region, and the veins have been exposed, only locally in the shallow cuts. If more work near the surface proves that the veins are continuous for some distance, it would probably be desirable to start a cross-cut tunnel considerably lower down the slope of the mountain where it would be easier to get timber and water. The relief is high, and more extensive development would be a com- paratively easy matter. 1Crawford, R. D., loc. cit., p. 138. 2Crawford, R. D., loc. cit., p. 134. 40 MOLYBDENUM DEPOSITS OF COLORADO WINFIELD DISTRICT In the Winfield District only a little development has been done, but there are several deposits of molybdenite worthy of further investigation. Winfield is an old, almost deserted mining camp situated at the forks of Clear Creek, about 14 miles west of Granite, which is the nearest town on the railroad. There is a fairly good automobile road all the way from Granite. Clear Creek furnishes an amount of water sufficient for extensive mining or milling oper- ations. There is also a large amount of timber close at hand. The topography is mountainous and the relief is high. Altogether the environment is entirely favorable for mining and milling, pro- vided that further prospecting proves the existence of ore bedies of sufficient size and value. There are two regions in this distriet where there are. very good surface indications of molybdenite. These are on the moun- tains immediately east and west of the south branch of Clear Creek, within two miles of Winfield. Four groups of claims have been located and they will be described in order, beginning with those farthest west. North Point and Eastern Star Claims These claims are owned by R. T. Mathews of Granite. They le on the ridge which extends east from Virginia Peak, between Fortune Basin and the north branch of Clear Creek. Both are 600 by 1,500-foot claims. They trend northeast and southwest and lie side by side. The slopes of the ridge both to the north and south are steep. The elevation at about the center of the ridge is 12,200 feet. . Coarse gray biotite granite is the only country rock in the region. It is cut on this ridge by not less than 14 quartz veins, the smallest of which are 6 inches, and the largest about 2 feet, in width. All the veins run nearly north and south, and are prac- tically vertical. Four of them, each about 1 foot wide, lie close together and show some very good-looking float. Samples broken from surface outcrops assayed 1.22 per cent MoS,. The average molybdenite content of the four veins is estimated to be not less than 1 per cent and probably 1.5 per cent. There is some pyrite and a little molybdite with the molybdenite, but no copper. This property is wholly undeveloped. The opportunities for tunneling at a considerable depth are very good and it is believed that the ground should be thoroughly prospected. BANKER MINE 41 The Uintah Lode, and Others Messrs. Horace Hopkins of Greeley, W. B. Brooks of Leadville, ; and Philip S. Smith of Denver, have located a group of 13 or more claims just northeast of the Mathews ground. Several veins outcrop on this ground. The country rock and the occurrence of the ore are the same as just described, except that the ore does not seem to be so high grade in these veins as in the Mathews deposit. Since there has been no work done on this ground, one cannot, with assurance, predict what the values will be. As in the case of the Mathews claims, there are good tunnel sites on the claims, and prospecting would be easy and should be done. The Banker Mine This mine is situated about two miles south of Winfield, on the south fork of Clear Creek, at an altitude of 10,400 feet. It is owned by a corporation consisting largely of Pennsylvania people, and is ‘now leased by Messrs. Hopkins, Brooks, and Smith. The mine has not been worked for several years. There is a good deal of water in it, and in 1917 the air was so bad that no examination could be made by the writer. There are said to be 44 claims in the Banker group. Most of the development work has been done through one big tunnel, but there are several shafts and small tunnels which have been used for surface prospecting. There was at one time a splendid equipment at the mine. It included two 100-horsepower boilers, a large compressor, machine drills, ete., ete., with good buildings for offices, and bunk houses, and small cabins for the married employees. Some of the machin- ery has been dismantled by looters, but it would not be a very expensive matter to refit it if operations at the property should be resumed. There is plenty of water only a few yards from the tunnel and wood for mine timbers and fuel is close at hand. The main tunnel is 3,700 feet long and has cut several veins. One vein 19 feet wide was cut at a depth below the surface of 1,200 feet and at a distance of 2,400 feet from the entrance of the tunnel. This was drifted on for 1,200 feet to the northeast. A large amount of material said to have come from the vein in ques- tion was studied on the dump. The gangue is pure white massive quartz. Scattered irregularly through it, but chiefly in layers near the walls, is molybdenite, most of which occurs as fine, dark lead- 42 MOLYBDENUM DEPOSITS OF COLORADO gray grains, and aggregates sheet-like in form. The richest streaks are on the vein walls and in the country rock near the walls, where with silvery mica and pyrite there is some very high-grade ore. Considerable bismuthinite was found on the dump in a white quartz exactly like that which contains the molybdenite, and in one instance bismuthinite and molybdenite were found together. It is not known whether or not such an association is common. It was, of course, impossible to get samples that would give any definite idea of the value of the ore that may be produced. Much of the vein undoubtedly carries practically no ore, but there are pockets and streaks on or near the contact of the vein and country rock, which will assay 10 or 15 per cent MoS,. It would, therefore, seem advisable to reopen the mine and prospect the vein. Ady and Mathews’ Claims About one mile northeast of the Banker Tunnel, on the east side of Winfield Peak, at an elevation of 12,200 feet, J. W. Ady and R. T. Mathews, of Granite, have located claims on what may be a continuation of the molybdenite vein in the Banker group. The country rocks are coarse gray feldspathic granite, and a finer even-grained gray granite, not so rich in mica as is the coarser one. A quartz vein outcrops for several hundred feet on the northeast side of Winfield Peak. Where the float is not cov- ered by mantle rock it shows a good deal of molybdenite. The dip of the vein cannot be accurately determined, but it seems to be practically vertical. The strike is N. 75° E. It is not possible to be sure of the width or length of the vein. It seems to split up more or less into stringers, with a rather well-defined mineral- ized zone 10 or 12 feet wide. According to Mr. Mathews it has been followed back to the southwest, half way to the Banker Tunnel, and northeast several hundred feet, but altogether it was not followed for more than 500 feet by the writer. Specimens which represent the average value of the ore exposed at the sur- face of the ground, assayed 2.037 per cent MoS,. No development work has been done. The situation of the claims, on top of the mountain, half a mile or more from wood and water, is not condu- cive to easy development. After more prospecting has been done to determine the length and width of the vein, if the results are suffi- ciently encouraging, the property should be developed through tun- nels started some distance down from the top of the ridge on which the claims are located. TWIN LAKES DISTRICT 43 Other Claims Several other occurrences of molybdenite have been reported from the Winfield District, but so far as is known none has been developed. Enough work has been done in this district to make it evident that there is considerable ore in the region, and the claims men- tioned above should be thoroughly prospected, in order to demon- strate the value of the various deposits. If sufficient bodies of ore are uncovered to make the project feasible, a concentrating mill should be built at or near Winfield to handle the product of the whole district. TWIN LAKES DISTRICT The Molybdenum Lode The Molybdenum Lode, which is owned by William Frederick and Fred Olson, of Twin Lakes, is situated on Hope Mountain, at the head of Little Willis Gulch, at an elevation of 12,500 feet. It is reached by a rough, steep pack trail 5 miles long, from Twin Lakes postoffice. The nearest railroad station is at Granite which is 12 miles from Twin Lakes by wagon road. Granite is on both the Denver & Rio Grande and the Colorado Midland railroads. The discovery shaft on this claim is located well up on the side of Hope Mountain, about 1,000 feet above the valley floor. The topography of the region is rough and mountainous. The maximum relief is not less than 2,000 feet. The high relief is advantageous for tunnel sites, but, at present, mining at the discovery shaft is difficult, for the shaft is 1,000 feet above, and three-fourths of a mile away from wood and a perma- nent supply of water. GEOLOGY Not enough work has been done on this ground to permit an accurate estimate of the value of the deposit. Molybdenite occurs in many small quartz veins which are in a fractured granite zone, evidently on a fault. This mineralized zone is 10 to 15 feet wide. It strikes N. 50° E. Where the rock in place is not covered with talus and mantle rock molybdenite can be found on the surface of the ground for a distance of 30 or 40 feet. One opening 10 by 10 feet in length and breadth and 20 feet deep has been made in the deposit. Ore is shown on the walls and in the bottom of this cut, 44 MOLYBDENUM DEPOSITS OF COLORADO and apparently the best ore is at the bottom. It impregnates both the granite and, the quartz veins, and occurs extensively as thick solid facings on the vein walls. According to Mr. Frederick, a sample clear across the best 5-foot mineralized zone assayed 2.5 per cent MoS,. The writer’s sample, which represents a grade of ore that could be cobbed out in considerable quantities, assayed 2.18 per cent MoS,. It would be an easy matter to sort the ore more carefully and procure a 5 per cent grade, although the whole vein would probably not average more than one-half of 1 per cent. As is to be expected, so near the surface of the ground, there is a good deal of molybdite associated with the molybdenite. Pyrite, in considerable amounts, also is found all through the mineralized zone. Since this property is relatively inaccessible, it is not likely that it will be developed at present. If the demand for molyb- denum increases, however, it would be advisable to prospect this ground thoroughly, for there are very good surface indications of ore. Collins Claim George Collins, who lives 10 miles up Lake Creek from Twin Lakes postoffice, has a prospect on the north side of and 100 feet from the stream about 300 yards above the junction of the creeks at the mouth of Sayre Gulch. The only development so far is a hole 10 feet long and 6 feet deep. A 214-foot quartz vein is exposed which carries a little molybdenite with considerable pyrite. The country rock is granite and gneiss. The vein dips 60° N. 37° W. The showing is not at all promising. . X-Ray and Whale Claims Messrs. William Mock and Fred St. Clair, of Leadville, have claims on the crest of the continental divide on the west side of west Sayre Gulch, about 14 miles from Twin Lakes postoffice. The X-Ray Claim crosses the divide at an altitude of 12,300 feet and is about one mile from the head of the gulch. The country rock is medium-grained gray granite. Molyb- denite occurs with pyrite in a quartz vein which is 6 to 8 feet wide. The vein stands vertically and strikes S. 65° W. The ore is very pockety. Occasional rich bunches are found, but most of the vein is barren. About 400 feet below the top of the divide, on the west CLIMAX CLAIM 45 side, a prospect tunnel, now caved, was driven in a distance of 20 feet. At the breast, according to Mr. Mock, the ore was of a very good grade. — The Whale vein crosses the divide 400 feet north of the X-Ray. This is also a white quartz vein in granite, which carries more or less molybdenite. The vein is 30 feet wide, strikes S. 45° W. and is vertical. Most of the vein appears to be barren, but in some places there is ore which runs 1 per cent or more MoS,. The Whale vein has been followed down in Sayre Gulch and up on the east side, through a distance of more than 1,500 feet. Both these properties are at present relatively inaccessible, although they could be easily developed by tunnels from Sayre Gulch. There is plenty of timber and water in the gulch. The vertical range from the creek in the bottom of the gulch to the top of the saddle where the Whale crosses the divide is about nine hundred feet. There is a poor wagon road half way up Sayre Gulch from Lake Creek, and it would not be a difficult matter to continue it to the head of the gulch. The surface showings on these claims are not good enough to make them attractive prospects at this time. Climax Claim The Climax Claim, owned by Earl Whited and C. G. Bilt, of Twin Lakes, is located on the east side of South Lake Fork on Mount Ewing. The altitude at the discovery shaft is 11,650 feet, which is just the elevation of timber line in this gulch. The claim is about 12 miles from Twin Lakes postoffice, and is not far from ““Three Cabins.’’ There is a good road from Twin Lakes to within a mile of the property and an old wood road goes up from the valley nearly to the vein. The country is mountainous, with beautiful glaciated valleys and high relief. The claim is about 850 feet vertically above the valley bottom, and a still greater distance below the top of the mountain. There is plenty of wood and water near at hand. The country rock is gneissoid granite cut by a dark gray felsite porphyry rich in quartz phenocrysts. Small amounts of molybdenite, with much pyrite, occur in an 18-inch quartz vein which dips 55° N. 50° E. The vein is on the porphyry-granite contact and seems to be due to the intrusion. Only a small amount of work has been done here. There are several shallow surface cuts and one opening that is 10 feet deep, 46 MOLYBDENUM DEPOSITS OF COLORADO about 6 feet wide and 15 feet long. The present development does not indicate that the vein is a strong one and it is not probable that it will ever be developed. The Geneva Claim Messrs. G. K. Hartenstein and H. C. McLean, of Buena Vista, own this claim, which is situated about 18 miles southwest of Buena Vista on the north side of South Cottonwood Canyon. The property is reached from Buena Vista by a good wagon road to Cottonwood Lake, a poorer road for the next 2 or 3 miles and a trail the rest of the way. The relief is high, and the topography of the region is ex- tremely rough and mountainous. The claim is located 400 or 500 feet above the bottom of the valley on the south side of Jones Moun- tain, at an elevation of 11,750 feet. GEOLOGY There is a great fault here which strikes approximately N. 20° E. A block of dolomitice limestone has been tilted up into a vertical position and is held between granite walls. The limestone block is about one-eighth of a mile wide and more than a mile long. The limestone is everywhere much brecciated and metamorphosed, but is most altered near the granite contacts. Secondary mica, serpentine, asbestos and calcite are found in the brecciated parts of the limestone. There are many small calcite veins which cross the fault block, and in these veins are considerable quantities of pyrite and very small amounts of molybdenite. Varying but rather small amounts of chalcopyrite accompany the other sulphides. The molybdenite is very pockety. Some of the richer streaks are a foot or more across, but these are not common. There seem to be no continuous veins, and the grade of the ore that has been found is so low that it is doubtful if there will be much work done on this claim. Plenty of water and good wood are close at hand, and cabins have been built on the ground to accommodate miners who took out considerable silver ore from a higher shaft on this claim, The ore is said to have been worth $100.00 a ton. It soon played out, however, and no work has been done on the property for some time. There are altogether 800 or 1,000 feet of workings at the main tunnel level. CLEAR CREEK COUNTY 47 ALPINE D. M. D. Claim The D. M. D. Claim is located about three-fourths of a mile in an air line north of Alpine, a station on the Buena Vista & McElmo branch of the Colorado & Southern Railroad. The claim is owned by J. H. Dermitt and Maud Davis, of Buena Vista. The property is on the south slope of a very steep side hill at an elevation of 10,500 feet. It is reached by a good trail from Alpine. : A tunnel 200 feet long crosses two quartz veins, both of which are small. The country rock is Princeton quartz monzonite. In the veins are chalcopyrite, pyrite and a little galena. Mr. Dermitt states that the vein can be followed for nearly half a mile and that it carries an average value of 114 per cent molybdenite. The writer’s samples, which were carefully taken from the only veins exposed, failed to show more than traces of molybdenite. TURRET DISTRICT Molybdenite has been reported by Mr. A. E. Moynahan, former deputy state mine inspector, from the Independence Tun- nel in the Turret District. The ore is said to oceur in mica schist and gneiss. It is understood that the deposit is of small extent and that the ore is low grade. CLEAR CREEK COUNTY The Primos Chemical Company’s Mine This property is in the Dailey Mining District on the south- ‘east slope of Red Mountain, about 14 miles from Empire Station. It is reached from Empire by a good wagon or auto road which follows the Berthoud Pass road along West Creek for about one-half the distance, and continues along the creek valley after the Berthoud Pass road turns off to the north. The property was visited by the writer in June, 1917. At this time no work was being done, operations having been sus- pended in the autumn of 1915. The camp buildings are well situated on the side of the val- ley at the foot of the mountain, near abundant supplies of wood and water, at an elevation of about 10,200 feet. At the time the property was examined there were only two buildings at the lower camp. These were a large house in which were combined 48. MOLYBDENUM DEPOSITS OF COLORADO the compressor room, offices and comfortable living quarters for about twenty men; and a stable for draft and pack animals. DEVELOPMENT The mine workings at this time were as follows: 1. A tunnel just above the camp at an elevation of about 10,600 feet. This tunnel was driven in a cross-cut for about 180 feet, nearly due west. Then it was turned to N. 60° W. and driven on for 370 feet, to the breast. In the latter direction it follows a fissure for about 150 feet. Several small quartz and pyrite veins were cut, but no molybdenite was seen by the writer. The country rock is mainly hard, gray, coarse-grained granite which carries a small amount of biotite. About 100 feet from the mouth of the tunnel a considerable body of garnetiferous quartz-mica schist was cut. 2. Going up the hill, the next work was done just east of the trail at an elevation of about 10,900 feet. Here a tunnel was run for 30 feet, N. 75° W., across a contact of granite, and granite porphyry or coarse rhyolite porphyry. The dike strikes N. 15° E. and dips 65° S. 75° E. It contains many small grains of pyrite, but no molybdenite was seen here. 3. The main tunnel, from which most of the ore so far has been taken, is at an elevation of about 11,300 feet. The tunnel was started on the south side of a granite porphyry contact, and driven in a general westerly direction for about 600 feet, where it apparently cut the main vein, which is exposed high up the hill. From the 600-foot mark the tunnel becomes a drift for about 800 feet on the vein. Cross-cuts, most of which are from 10 to 20 feet long, have been driven out at short intervals from the main tunnel. There are also three stopes, each 50 or 60 feet long and about 100 feet high. Considerable molybdenite is shown in the tunnel and the stopes. It was not sampled, but is estimated to average 1 or 2 per cent MoS,. The vein varies greatly in width but averages perhaps three feet. 4. About 500 feet above the main tunnel there are several surface cuts where the original locations were made. The three largest cuts open on a line which runs about N. 45° E. The cut farthest to the southwest opened a vein which strikes S. 80° W., and dips 63° N. 10° W. The vein is 3 or 4 feet wide and has been opened up for 15 feet. Considerable molybdenite and molybdite are shown. The next cut, about 60 feet to the northeast, is on a PRIMOS CHEMICAL COMPANY’S MINE 49 vein which is nearly vertical and strikes N. 85° W. The vein has been opened for 40 feet, and a good grade of ore is exposed. The third cut, 40 feet northeast of the second, is about 20 feet long. Several quartz veins are exposed, but nothing so definite as in the middle cut. All these exposures seem to be part of one strongly mineralized zone, the richest part of which seems to center near Cut No. 2. GEOLOGY The country rock is chiefly coarse gray biotite granite which was intruded into pre-Cambrian garnetiferous quartz-miea schist. The granite in turn was cut by many dikes of a granite or rhyo- lite porphyry which apparently come from a large mass of the same rock that makes up the main part of Red Mountain. (This larger mass was not studied in detail, but the assumption is made, on the basis of the color, and the float washed down from above.) The porphyry consists of many large grains of colorless quartz and pale flesh-colored feldspar in a fine-grained light-green groundmass which is highly impregnated with small pyrite grains. The pyrite is present in such large amounts that the rock, when weathered, turns to a dark brownish or brick-red color, because of the oxidation of the iron. Horton’ deseribes the occurrence of the ore as follows: ‘‘The ore occurs in two forms—one consists of an alaskite (?) breccia in which the molybdenite occurs as occasional small flakes but more often in finely granular form associated with iron pyrite in the interstices of the breccia; in the other the molybdenite oceurs in small veinlets and stringers running off into the alaskite-porphyry (?) country rock. The brecciated type of ore constitutes the vein material proper, * * *.’’ According to the writer’s observations, which were some- what limited, the ore occurs chiefly in small quartz veins. in the shattered granite and on the borders of the porphyry dikes. Many fissures occur nearly parallel to or at right angles to the direction of the dikes. Both the dike rock and the country rock are in places much breeciated, and the molybdenite oceurs as fine separated grains or thick coatings with the quartz which has filled the fractures. The number of dikes which cut the granite, and their exact relationship to the ore bodies, were not learned, but there are at least three dikes exposed in the workings men- 1Horton, F. W., Molybdenum: Its ores and their concentration. U. S. Bureau of Mines Bull. 111, 1916, p. 65. : 50 MOLYBDENUM DEPOSITS OF COLORADO tioned above. In the upper surface cuts, all the ore seems to be northeast of a large porphyry dike which stands in a vertical position and strikes 8S. 25° E. In the main tunnel 500 feet below, the ore appears to he on the southwest side of a dike which is also vertical and strikes about S. 65° W. at the portal of the tunnel, but turns to nearly due west as it enters the hill. No ore was seen near the third dike, which is just east of the trail between the two tunnels. In the upper cuts considerable molybdite occurs with the molybdenite, but in the tunnels there has been no oxidation of the molybdenite and it is not present. Most of the molybdenite is very finely granular. It occurs as dark blue-gray coatings which vary in thickness from that of thin paper up to one-half an inch or a little more. Many veinlets of quartz which may or may not carry molybdenite run off roughly at right angles to the main veins. These stringers vary from a few inches to several feet in length. Pyrite occurs wher- ever molybdenite is found, but no other metallic mineral was observed. PRODUCTION The present owners took over this property in November, 1914, when the first real development work was done. Between January Ist and the end of August, 1915, nearly all the develop- ment work indicated above was done. Horton’ reports that dur- ing this time between 1,500 and 2,000 tons of ore, which averaged about 2 per cent MoS,, was mined, packed down to the creek on mules, hauled to Empire in wagons and shipped from there by rail to Pennsylvania. During the summer of 1917 the owners again began active work at the property. At the time of this writing, June, 1918, it is understood that an oil flotation concentrating mill with a rated capacity of 100 tons of ore a day has been completed and is in operation. An aerial tram has been built from the main tunnel to the mill and a new tunnel has been started at the foot of the mountain, which will open the veins at a depth of 1,600 or 1,800 feet below the upper surface cuts. : Rte hes) ois 1Horton, F. W., Molybdenum: Its ores and their concentration. U. S. Bureau of Mines Bull. 111, 1916, pp. 66-67. CLIFFORD MINE 51 Clifford Mine The Clifford Mine is located on the divide between Wood- pecker and York gulches about two and one-half miles west of Central City. Leopold Sternberger, of Central City, is the owner of the property. The country rocks belong to the Idaho Springs formation, which consists here of gneiss and biotite schist. The vein and its development are described by Bastin and Hill‘ as follows: The Clifford vein runs along the divide between Woodpecker and York guiches. About a mile south-southeast of Mount Pisgah it is opened by a shaft which could not be entered, but which is shown by mine maps to be an incline a little over 150 feet deep, with 300 feet of drifting on . the 100-foot and about 400 feet on the 150-foot level. The country rock belongs to the Idaho Springs formation, and biotite schist is the only rock seen on the dump. On the surface the vein is not well exposed, but appears to strike N. 60° E. The drifts shown on the mine map strike about N. 59° E., and the vein dips steeply southeast. The ore in the bins consisted of white quartz cut by seams and stringers of dark quartz carrying galena, light and dark sphalerite, chalcopyrite and some pyrite. Most-of the ore is siliceous, but some specimens carry barite, which is either embedded or implanted on the walls of vugs and which crystallized with the dark quartz and the lead and zinc minerals. Postmineral movement has crushed some of the ore, producing in some places a grayish gouge. No reference is made to molybdenite in this report, but the writer examined the material on the dump and found consider- able molybdenite with quartz. It occurs either as finely divided flakes or more commonly as amorphous coatings. It was of course impossible to judge the size of the vein from an examina- tion of the surface material, but it seems probable that the veins are small, and they may be only quartz stringers in the Idaho Springs formation. Specimens selected from the dump, which were probably of more than average value, assayed 1.87 per cent MoS,. Some pyrite and limonite were found with the molybdenite, but no other metal- le minerals were observed. As far as can be learned, no molyb- denite has ever been shipped from this property. There is not much good wood for mine timber nearby. Water is also scarce. The mine is easily accessible from Central City and it is hoped that when more work is done, some attention will 1Bastin, E. S., and Hill, James M., Economic geology of Gilpin County and adjacent parts of Clear Creek and Boulder Counties, Colorado. U. S. G. S. Professional Paper 94, 1917, pp. 317-318. 52 MOLYBDENUM DEPOSITS OF COLORADO be given to the molybdenite, although it seems unlikely that, if there were commercial deposits there, they would remain unde- veloped at this time. CONEJOS COUNTY PLATORA Mr. H. A. Aurand, of the Colorado Geological Survey, exam- ined this deposit in September, 1917, and the following statement is a résumé of his notes: Platora is reached by stage, either from Del Norte or Monte Vista. The distance is 26 miles from the latter town. A small quartz vein, which carries a little molybdenite, out- crops on the Merrimae Claim, between the Forest King and Mammoth mines. The vein is two inches wide, strikes N. 15°-17° W., and dips 90°. The wall rocks are granite and granite gneiss. On the surface the vein outcrops for 125 feet. It is believed that the same vein was cut by some of the upper drifts of the Merrimae, for ore of this character is found on the dump. The mine has not been worked for many years and the workings have caved badly. The deposit is too small to be of any commercial value. CUSTER COUNTY Knight-Stacy Claims R. J. Knight, of Canon City, and E. F. Stacey, of Hillside, have claims that are situated on the side of Rito Alto Peak, about 11 miles from Hillside, at an elevation of 11,600 feet. Hillside is a station, about 12 miles from Texas Creek, on the Texas Creek and Westcliffe branch of the Denver & Rio Grande Railroad. The property is reached by a good wagon road from Hillside to Stacy’s ranch, and by a poor road and rough trail the remaining six miles to the claims. The country rocks are fine-grained, gray diorite, and a coarser- grained, lighter-colored diorite or monzonite. A quartz vein, which averages about one foot in width and which dips nearly vertically, strikes N. 35° W. There are no deep openings on the vein, but it has been exposed for several hundred feet by surface cuts. The vein matter consists of honeycombed quartz, pyrite, and molybdenite. The latter occurs in small crystals and in amorphous aggregates one-eight to one-fourth of CUSTER COUNTY DEPOSITS 53 an inch in diameter. Molybdenite impregnates the country rock to a slight extent. Many of the crystals of molybdenite show a marked radiated structure. Specimens of selected ore assayed 3.47 per cent. MoS,. The whole vein, however, will probably not run 1 per cent. The ore is free from copper and from other un- desirable impurities except pyrite. Some molybdite is found near the surface, but it will probably disappear with depth. The claims are about 1,500 feet above the floor of the valley, and a corresponding distance above available wood and water. On this account development work will be expensive. The Grab Claim This claim is owned by J. M. Duckett, of Hillside. It adjoins the Knight-Stacy claims on the northwest. A shaft, 50 feet deep, has been driven on the vein, and some ore has been shipped by leasors. The shaft was nearly full of ice when the property was visited by the writer in 1918, and the vein could not be examined in place, but it is believed to be an extension of the Knight-Stacy vein. Judging by the material on the dump, the occurrence and values of the ore are essentially the same, with one important exception, namely, considerable chalcopyrite was found on the Grab dump, and it is said to be rather thoroughly mixed with the ore. This, of course, detracts from the value of the ore, in so far as its molybdenum content is concerned. Fine timber and abundant water for power or milling purposes are only about one-eighth of a mile away from the Duckett shaft. In connection with both the Knight-Stacy and the Duckett properties there are very good opportunities for driving cross-cut tunnels at considerable depth, if future surface and near-surface development makes such action seem desirable. It is believed, however, that, due to the difficulty of reaching the claims and to the present low-grade character of the ore, these properties will not be worked until the demand for molyb- denum is much greater than at present. The Stacy-Dissmore Claim Messrs. E. F. Stacy and R. A. Dissmore, of Hillside, have a molybdenite claim that is situated about two miles southeast of Hillside. 54 MOLYBDENUM DEPOSITS OF COLORADO The country rocks are coarse, pink biotite granite and an older quartz mica schist. On the contact of these rocks there are some rich patches of molybdenite which occurs in masses an inch or two across and half as thick. The absence of a vein and the irregular contact of the granite and schist are conditions adverse to the formation of workable ore bodies, and this deposit is not believed to be valuable. EAGLE COUNTY CROSS MINING DISTRICT John Popovitech and W. G. McKay, of Red Cliff, have two molybdenite claims on Mount Whitney, about 18 miles from Red Cliff and about 2 miles north of Cross City. The claims are reached by wagon road from Red Cliff, 12 miles long, to Gold Park; thence by the Cross City wagon road, now almost impassable, for 5 miles. There is neither road nor trail the rest of the way to the claim, but the grade is easy and the construction of a road would not be difficult. The elevation at the discovery tunnel is 11,250 feet. The country rocks are quartz mica schist and a micaceous eneissoid granite. Many quartz veins cut the schist, which is the dominant country rock. A quartz vein, which is from 12 to 16 inches wide and which has a general trend of N. 30° E., has been opened by a surface cut and tunnel for a distance of 30 feet. The dip is nearly vertical. Molybdenite in erystals and fine-grained coatings occurs in the vein and on the borders of the vein and the country rock. Some ore, which runs 5 or 6 per cent, is found in pockets, but the average of the vein is slightly less than 1 per cent. Pyrite in rather small amounts oceurs in the vein. No copper is present. The development work is too meagre to allow safe predictions as to the future value of this property. The vein is not straight, but winds around more or less. It has been followed up the hill, however, for several hundred feet, and a shallow hole, 150 feet higher on the hill, shows some ore. The relief is high and there is nearly 1,500 feet of stoping. eround above the present tunnel level. Wood and water are plentiful and are near at hand. On the whole, the property is regarded as unworthy of more prospecting unless other mines are opened in the neighborhood, so that road building and other costs of developing the property are materially reduced. FREMONT COUNTY DEPOSITS 55 FREMONT COUNTY The Copper Girl Mine The Copper Girl Mine is owned by the Green Horn Mountain Copper Mining Company, of which Ralph Fairchild, of Canon City, is the president and general manager. _ The property is situated about 9 miles south of Parkdale, Fremont County, Colorado, between Copper and Bear gulches. The main tunnel is at an elevation of about 7,700 feet. The mine is reached by a good road for the first 5 miles from Parkdale, then _a poor road which follows the bed of an intermittent creek for 2 or 3 miles, and a steep, difficult mountain road the last mile and a half to the mine. There are two patented claims in the property—the Copper Girl and the Valley View. The development work, all of which has been done in the Copper Girl Claim, consists of: (1) An upper surface cut, and a 30-foot incline, which extends down to the tunnel; (2) the main tunnel, which is 100 feet long; (3) a winze at the breast of the tun- nel, which is down about 75 feet on a 25-degree slope; (4) two or three short cross-cuts at the tunnel level. GEOLOGY The country rocks of this region consist of an undifferentiated pre-Cambrian complex of schists, gneiss and granite. The whole complex is cut by many pegmatite dikes. The ore in the Copper Girl occurs in strongly mineralized bands of quartz-mica schist. These bands contain a good deal of quartz whose origin was evidently contemporaneous with that of the metallic minerals which are associated with it. These mineral- ized bands conform to the dip and strike of the layers of schist. Near the breast of the tunnel two mineralized bands are exposed. Each band varies from 1 to 3 feet in thickness, and the individual bands are from 1 to 3 feet apart. Considerable chalcopyrite and some fine-grained flaky molybdenite occur in each band. Three carloads of ore are said to have been taken from this mineralized zone. The ore was sampled and assayed, and according to Mr. Fairchild, ran between 8 and 9 per cent copper. The main body of molybdenite in this property occurs between the chalcopyrite bands described above. It is found in fine-grained 56 MOLYBDENUM DEPOSITS OF COLORADO flakes, impregnating the schist. The width of the richest streak of molybdenite averages about ten inches. Some chalcopyrite is seattered all through the molybdenite-bearing schist, just as some molybdenite is found in the richer chalcopyrite streaks. According to Mr. Fairchild, two 100-pound samples of this ore from the molybdenite streak were sent to Henry E. Wood, Denver, Colorado, for analysis. One sample assayed 3.7 per cent MoS, and the other 4.3 per cent MoS,. The writer’s sample, sup- posedly of the same ore, ran 1.058 per cent MoS, and 3.54 per cent copper. This sample, however, was a small one and may not have correctly indicated the average value of the whole ore body. | DEVELOPMENT Comparatively little ore of any kind has ever been taken from the mine. Probably the amount is less than 400 tons altogether. All of this has been copper. The development work has not yet gone far enough to allow a careful estimate of the amount of molybdenum and copper that is available, but, judging by the limited exposures, it seems to be evident. that both are increasing in value as greater depths are reached. The elevation above the tunnel level is not great enough to allow more than 200 or 300 feet of stoping ground. However, if future development in the mine warrants such a procedure, a cross- eut tunnel can be run into the ore body from the bed of the creek. There is not much permanent equipment at the mine, but in July, 1917, when the property was examined, there was a-gas engine and compressor on the ground. There is plenty of good pinon pine timber within half a mile of the property. The nearest water available for any purpose is at the foot of the hill, in Bear Gulch, a mile and a half away. If processes are now available, as is now claimed by several manufacturers, for the economical concentration and separation of the molybdenite and chalcopyrite, it would seem that with the present, June, 1918, high price of molybdenum and copper, and with good management, the mine might be operated very profitably. Any separation process, however, must be very complete, for even a very small amount of copper is detrimental, when included with the molybdenum concentrates. If a mill should be built for the concentration of this ore it should be located at Parkdale, where there is plenty of water, and LIBERTY BOND CLAIM 57 where concentrates could be shipped via railroad directly from the mill. The Liberty Bond Claim The Liberty Bond Claim, owned by K. L. Eldred and B. F. Young, of Canon City, is situated about 12 miles north of West- cliffe and about the same distance nearly due east of Hillside, on the divide between Westfall Gulch and Grape Creek. The property is reached by a good wagon road for a distance of 10 miles from Westcliffe and a poor road the rest of the way. The topography near the property is rough and hilly. The relief is low to the west, but increases rapidly toward the east. The elevation at the claim is 7,500 feet. The country rocks of the region are pre-Cambrian gneiss and schist, and granite. In the immediately vicinity of the molybdenite prospect the rock is chiefly a more or less eneissoid, fine to medium- grained, gray or pink granite, which contains a little biotite. This rock is cut by a diabase dike, which strikes N. 10° W. and dips 85° N. 80° E. The dike is 6 or 8 feet wide and is highly brecciated, containing many granite and schist fragments, the largest of which are at least a foot long. A shaft, said to be 75 or 80 feet deep, was sunk on this dike about 30 years ago. The walls have caved and it was possible to examine only 8 or 10 feet of the rock which is exposed above the fallen timbers. There are no well-defined veins, but the ore oceurs in thin flakes, from one-eighth to one-half an inch in diameter, associated with calcite and pyrite, in lenses and small, irregularly distributed masses on and near the contact of the dike and the country rock. An occasional grain of chaleopyrite is found with the pyrite, but it is unimportant. The molybdenum is almost wholly unoxidized. It is impossible to fairly estimate the value of the ore from the limited exposure. Several tons of rock, which evidently came from the mineralized contact zone, was examined, as well as the rock in place. Samples were taken which were regarded as better than the average of the ore that could be sorted out from the dump, and the assays were not encouraging, for the tenure of the ore is less than one-half of 1 per cent of MoS,. It is possible that the ore increases in value with depth, but the general occurrence of the molybdenite, in such broad, thin flakes, irregularly distributed without well-defined veins, makes it seem improbable that this prop- erty will become a large producer. 58 MOLYBDENUM DEPOSITS OF COLORADO Timber, in the form of pinon wood, is available for mine pur- poses. There is no considerable body of water nearer than Grape Creek, which is 2 or 3 miles away. - GILPIN COUNTY Gray Eagle Claim The Gray Eagle Claim, owned by John Goldberg, of Apex, and Eugene Stevens and George Holland, of Boulder, is located about three-fourths of a mile northeast of the town of Apex, on the northwest side of Dakota Hill. The elevation at the claim is 10,500 feet, which is about 650 feet higher than the town. An old wood road extends almost up to the claim from Apex. The country is open and of high relief. The property is almost wholly undeveloped. There is one opening, 17 feet deep and 10 feet long, on the vein, and several shallow trenches have been dug in order to determine the course of the vein. The country rocks are coarse, gray granite and micaceous eneissoid granite, but only about 200 feet away these rocks are in contact with monzonite porphyry,’ and the intrusions of the latter may have been responsible for the occurrence of the ore. Little could be learned of the extent of the deposit, but the vein does not seem to be a strong one. The walls are poorly de- fined and the thickness is variable. In fact, the ore body is really a mass of quartz veinlets in gneiss and granite. These veinlets vary from 1 to 8 inches in thickness. They contain small amounts of molybdenite, which occur as distinet thin flakes, thick bunches of fine grains, and amorphous coatings on joint planes and fractured surfaces. Pyrite, muscovite, and molybdite are found with the molybdenite. No copper is present. Selected specimens of ore, which were better than average samples of the whole vein, but not better than could be easily hand sorted, assayed 2.13 per cent MoS... It is believed that more work should be done in order to de- termine the size and value of this deposit. There is plenty of wood near at hand. The nearest available water for mill purposes is at Apex, three-quarters of a mile away. 1Bastin, E. S., and Hill, J. M., Economic geology of Gilpin County and adjacent parts of Clear Creek and Boulder Counties. U. S. G. S. Professional Paper 94, 1917, p. 39. GUNNISON COUNTY DEPOSITS 59 Sure Shot Lode About 300 feet above the Gray Eagle is another quartz vein, which cuts the monzonite porphyry. This vein is 18 inches wide. It consists chiefly of pure white quartz, which contains very small quantities of molybdenite. The vein has been opened by 4 shallow cuts and one 20-foot shaft. It probably is of no value. GUNNISON COUNTY QUARTZ AND TINCUP MINING DISTRICTS In the vicinity of Gold Hill, 9 or 10 miles north of Pitkin, there are several veins which contain considerable molybdenite. One large fissure vein, which has been traced more or less con- tinuously for more than two miles, crosses Gold Hill in a north- westerly direction. Another vein is indicated by float in the tim- ber south of Gold Hill and the creek. On top of Gold Hill there are still other outcrops which indicate that there are several veins only imperfectly exposed. When the region was visited by the writer in the summer of 1917, his time was so limited that he was unable to work out the relationship of these various veins. His observations were sufficient, however, to allow the statement that there are several large bodies of low-grade ore in the Gold Hill region. In addition to the observations made in the field, notes have been furnished the writer by Mr. R. St. John Cleary, Mr. K. E. Tillotson, Major H. Stephens Ehrman and Senator Wm. J. Candlish. The principal development of the molybdenite veins has been done on the following claims: The Bon Ton, the Molybdenite Group, the Emma H., the Ida May, the Monitor, and the New Discovery. All these properties, with the exception of the New Discovery, are on the good wagon road from Pitkin to Tincup. The nearest ones are 5 or 6 miles, and those farthest away are 8 or 9 miles from Quartz, a station 3 miles from Pitkin on the Alpine branch of the Colorado & Southern Railroad. The part of that road between Quartz and Gunnison is now operated by the Denver & Rio Grande Railroad, and a bi- or tri-weekly train schedule is maintained. The total relief in this region, between Quartz Creek or the headwaters of Taylor River and the top of Gold Hill, is between 800 and 1,000 feet. Good timber in abundance is growing on all the claims, except parts of the New Discovery, Ida May and Moni- 60 MOLYBDENUM DEPOSITS OF COLORADO tor. Water is available within distances varying from a few hundred feet to one mile. All the groups of claims have good locations for tunnel sites. The Bon Ton Group There are 10 claims in this group which are owned by the Bon Ton Mine & Leasing Co., but now are under bond and lease to the Pennsylvania Rare Metals Mining & Development Co. Mr. K. E. Tillotson, of Pitkin, is the superintendent of the latter com- pany. DEVELOPMENT This property has been developed by two tunnels. The lower one was started only a short distance from Quartz Creek and has been driven in a northerly direction for 800 feet. Several veins have been cut and one has been followed to the west for 200 feet. The upper tunnel is about 300 feet long. Several veins, some of which have good showings of molybdenite, were crossed. A few years ago several tons of this ore was mined, hauled to Pitkin and then concentrated by oil-flotation in a remade mill. This ore is said to have assayed from 1 to 3 per cent MoSs,. GEOLOGY The country rock is quartz monzonite and granite. The veins are several feet across. They consist chiefly of massive white quartz and contain a good deal of chalcopyrite and gold-bearing pyrite. It is said by some people who are familiar with both properties that the Bon Ton vein is the same as the one which crosses the Molybdenite Group, just west of the Bon Ton ground. Others be- lieve that the veins are different. The writer did not have time to make the necessary examination, even if it had been possible to enter the Bon Ton tunnel. There is certainly a pronounced differ- ence, however, between the ore taken from the Bon Ton and the Molybdenite claims. The former consists of small crystals and thick facings of molybdenite, intimately associated with pyrite and chaleopyrite, in a white quartz gangue, while the ore from the Molybdenite claims contains less pyrite and chalcopyrite. Copper, with some gold and silver, have been, so far, the chief products of the mine. Molybdenite has not been regarded as of commercial importance until very recently and practically no work has been done on the molybdenum veins. MOLYBDENITE GROUP 61 EQUIPMENT The property is said to have a good working equipment, which consists of : cabins, ore house, blacksmith shop, boiler house, boiler, engine blower, compressor, machine drills, etc. A recent report states that the company is building a small concentrating mill near the mine. The Molybdemte Group The Molybdenite Group, owned by Wm. McKinley and A. L. Pearson, of Pitkin, consists of four full claims, each 600 by 1,500 feet, and a fraction. The property joins the Bon Ton on the west and the claims extend nearly to the top of Gold Hill. DEVELOPMENT In July, 1917, there were several shallow openings on the vein, and one 50-foot cut, 20 feet deep at the breast. Only specimen material had been taken out. During the autumn of 1917 and the following winter the property was worked under bond and lease by Messrs. W. J. Cand- lish, W. E. Kreamer, and C. W. Savery, of Denver. A tunnel was driven to cut the vein at a depth of 50 feet or more, and they drifted for 90 feet on the vein. Several carloads of ore were shipped to the Richardson-Candlish concentrating plant, 1610 Bryant Street, Denver. GEOLOGY The country rock is coarse gray quartz monzonite which weath- ers red or reddish brown due to the oxidation and hydration of the large amount of pyrite present. The vein seems to be a strong one. It averages 4 feet in width and dips 45° S. 10° W. In the exposures which were examined by the writer, molybdenite was found associated with a small amount of pyrite and considerable molybdite. The molybdenite occurs in two forms: first, as small flakes and crystals, fillmg vugs and impregnating the vein and country rock for several inches from the vein walls; and, second, as very fine-grained thick black facings which coat fracture planes in the vein. The latter form is the more important one of the two. This vein which looked so promising at the surface proved to be very disappointing when it was prospected at some depth. The molybdenite was found to be greatly diminished in quantity and the whole vein is so impregnated with copper that it is valueless for ordinary purposes. 62 MOLYBDENUM DEPOSITS OF COLORADO It may be desirable to do more work on this vein at another place to see if the copper is everywhere present in the same pro- portions, for it is possible that the valuable and detrimental metals are both pockety, although it is not probable that such pockets would continue through such a long distance as the copper seems to do where the drift was run on this vein. The New Discovery Claims The New Discovery Claims extend from near the top of Gold Hill diagonally down to the creek, at the foot of the north slope. They are believed to be on the Molybdenite and Bon Ton vein which crosses Gold Hill from the southeast. The property is said to be owned by A. L. Pearson, of Pitkin, and Mr. Carpenter, of Tincup, who have given an option on it to Messrs. Candlish, Rich- ardson and Savery, of Denver. The claims can be reached from either Pitkin or Tincup, but more easily from the latter town, for there is neither road nor trail on the Pitkin side beyond the top of Gold Hill, while from the north one can drive almost to the property. DEVELOPMENT The claims are, so far, almost wholly undeveloped. The vein has been exposed by shallow surface cuts for 200 feet, and one 25-foot drift has been made. In this region there are exceptionally good tunnel sites, and the development of the property without waste work will be an easy matter. If the vein proves to carry ore that is of the proper grade, it would undoubtedly pay to build a small concentrating plant near the creek at the foot of the hill. If this were done, the distance from the mine to the mill would be short. GEOLOGY The country rock here, as elsewhere in this region, is quartz monzonite which is like that already described. This is eut by a quartz vein 2 or 3 feet wide, which ean be followed on the surface of the ground for 600 feet. The writer was unable to find any copper in the vein. There is some pyrite and considerable molybdite with the molybdenite. The occurrence of the ore is noticeable in that it is found chiefly in bands which are parallel to the dip of the vein. Some of these bands of nearly pure molyb- denite are from one-eighth to one-fourth of an inch thick. Most of the ore occurs in this form, but considerable is found as small EMMA H. CLAIM 63 _ grains and erystals scattered through the vein. A sample which represents the grade that could be easily procured by rough sort- ing, assayed 1.05 per cent. molybdenite. It is understood that this property will be prospected more thoroughly during 1918. The Emma H. ~ On top of Gold Hill, at an elevation of 12,000 feet, about three-fourths of a mile west of the saddle where the road crosses the divide, Major H. 8. Ehrman and his associates have three claims: The Emma H., Emma H. No. 2, and the Cloverdale Consoli- dated No. 2. These claims run in a general north-south direction, the south ends extending down toward Quartz Creek, well below timber line. Most of the development work has been done on the Emma H, where there are a 45-foot inclined shaft, a 75-foot shaft and several open cuts. A quartz vein about three feet wide with well-defined walls is exposed in the 45-foot shaft and in a cross-cut from that shaft. The ore is associated with considerable pyrite, but there is said to be no chalcopyrite in the vein. Parallel with the molybdenite vein and about 25 feet away there is another quartz pyrite vein which earries gold, silver and some galena. No molybdenite has ever been shipped from this property, but it is probable that there is a considerable amount of low-grade ore available. The Ida May Claim This claim is now owned by Messrs. Peeters and O’Brien, of the Palace Grocery Company, Denver. It is situated right on top of Gold Hill near the saddle where the wagon road crosses the divide. This property has been developed for tungsten (hubnerite) rather than molybdenite, for hubnerite is found in considerable quantities in a large quartz vein which strikes S. 30° W. Some molybdenite is found in this vein, and more in another which crosses the hubnerite vein not far from the road. When the property was examined, in July, 1917, it was not sufficiently developed to give any idea of the extent of the molybdenite deposit. 64 MOLYBDENUM DEPOSITS OF COLORADO The Momtor Claim About a mile from the top of Gold Hill on the road toward Tineup is the Monitor Claim which is owned by George Norwood and associates, of Pitkin. - Here, as in the other deposits on Gold Hill, the country rock is gray quartz monzonite. The Monitor Vein is probably the same as the Ida May. Hubnerite occurs in some rich streaks. One speci- men assayed 27.46 per cent Wo,. Small amounts of molybdenite, pyrite, and galena are also found in this vein. Very little development work has been done and most of the old work has caved, so it is impossible to make any accurate esti- mate of the strength of the vein and the character and extent of the ore. The occurrence of molybdenite with its associate minerals is, however, interesting and it is entirely possible that paying quan- tities of both hubnerite and molybdenite will be found in this region. Both will undoubtedly be low-grade ores, but if the molyb- denite is free from copper and the hubnerite free from phosphorus, as is the case with that tested by the writer, these minerals may be of considerable value to the owners of the claims. LAMPHERE LAKES DEPOSIT About seven miles due north of Ohio City there is a deposit of molybdenite, owned by Messrs. George H. Carter and Herman Hudler, of Ohio, Colo. This deposit is situated about 100 yards N. 60° E. of the outlet of upper Lamphere Lake at an elevation of 11,500 feet. It is reached by a wagon from Ohio, which is the near- est railroad station, or from Pitkin. From Ohio the road is very good as far as the foot of the mountain, a mile north of the Gold Links Mine. From this point on to the deposit the road is new and is rough, steep, and in many places on swampy ground. The surrounding country is mountginous with high relief and rough topography. GEOLOGY The country rock in the immediate vicinity of the deposit is a light-colored, fine-grained pre-Cambrian quartzite which cuts pre-Cambrian gneiss and schist. The granite in turn is cut by many large white quartz veins. These are very variable in size and are peculiarly distributed through the country rocks. One great vein 60 feet wide seems to be the center of mineraliza- fion. It has been exposed for 150 feet along the strike. Veins CROSS MOUNTAIN REGION 65 extend out in all directions from this main vein. Part of the sur- face has been covered with a thin coating of glacial debris, but in many places this has been removed by prospectors. Altogether at least an acre of ground is known to be ineluded in this net work of veins. Along the borders of large and smali veins alike, there are long, narrow, mineralized bands, which consist of iron-stained muscovite, molybdenite and molybdite. Most of the molybdenite occurs as crystals, but there are some fine-grained facings which cover an area of from 4 to 6 square inches. The erystals vary in size from the diameter of a common pin up to three-fourths of an inch across. There is a pronounced radiated structure in nearly all the erystals that have been examined. DEVELOPMENT To date, about a dozen surface cuts have been dug to show the nature and extent of the deposit. The largest of these is 40 feet long and nearly as wide. All are shallow. Since the ore is found almost entirely in pockets, which are separated by lean streaks, it is impossible to get average samples from the whole deposit. Small amounts of relatively high-grade (that is, 2 or 3 per cent) ore could be produced by careful sorting. It is doubtful if the whole deposit would run more than one-fourth, or possibly one-half, of one per cent. It seems evident that the deposit is in the form of a ‘‘pipe,”’ similar to deposits in Australia. These may have considerable depth, and it is possible that prospect shafts on some of the most promising-looking veins might uncover ore of more value than that which appears at the surface. A small amount of ore has been mined and shipped from this property, but apparently it was too low grade to pay. Un. less prospecting along the lines indicated in the preceding para- graph should reveal more and better ore, it is improbable that this deposit will become commercially important. There is plenty of wood close to the property, and the Lamphere Lakes make available enough water for any milling or mining operations that may be demanded in ease ore is found in large enough amounts to make the deposit workable. CROSS MOUNTAIN REGION Mr. William Waugh, of Gunnison, reports molybdenite from Cross Mountain, in Taylor Park between Gunnison and Tincup. 66 MOLYBDENUM DEPOSITS OF COLORADO Small specimens, said to come from this region, showed flaky molybdenite in quartz with no pyrite and no copper. The extent of the deposit and the grade of the ore are unknown. SPENCER DEPOSIT Mr. T. C. Moritz, of Paonia, has very kindly furnished the following notes regarding a deposit near Spencer: ‘‘Near the old town of Spencer is a lead showing from 3 to 5 per cent molybdenum in granite. There is also good tung- sten in this neighborhood. This deposit is about 12 miles south and west of Iola, on the east side of the Cebolla, in a gulch called Wild Cat Gulch. The molybdenum ore shows signs of copper.”’ This claim is said to be owned by Mr. Pat Trainer, of Iola. The writer has not been able to get further information regarding this deposit. PARADISE PASS DEPOSIT Mr. Charles Daniels, of Salida, has a molybdenite deposit on Paradise Pass, about 12 miles northwest of Crested Butte, and 7 miles from the Smith Hill Mine. The deposit was not visited by the writer, but according to Mr. Daniels there is a large deposit of low-grade ore here. A sample of the ore furnished by Mr. Daniels shows considerable very fine-grained molybdenite in a quartz vein. Considerable pyrite is found in the vein, but no copper. The country rock is said to be granite. No development work has been done on this deposit, but there are numerous outcrops within the limits of the two 600 by 1,500-foot claims, which have been ‘locatea by Mr. Daniels. The elevation at these claims’is about 11,500 feet. There is said to be plenty of timber and water near the property. THE TREASURY MOUNTAIN DEPOSIT On the southwest slope of Treasury Mountain, at an eleva. tion of 11.500 feet, there are molybdenite claims which are owned by John O’Toole, of Denver, and C. 8. Robinson, of Crested Butte. These claims are about nine miles southeast of Marble, and are reached by a poor trail that branches off from the electric rail- road near the Yule Marble Quarries. A trail also leads to these claims from Crested Butte. HINSDALE COUNTY DEPOSITS 67 The region is rough and mountainous. The maximum relief is about 2,000 feet. There is considerable water in Yule Creek, and there is plenty of good timber within a short distance of, but somewhat below, the property in question. GEOLOGY This region was visited by the writer in July, but little could be Jearned of the ore bodies, for they are exposed only in small open cuts which were fiiled with snow at the time. The country rock is pre-Cambrian gneiss, schist and granite. Molybdenite occurs as small flakes scattered through small white quartz veins, and also as thin seams or coatings in the fractured quartz. There are two veins here, one of which averages 10 inches and the other about 20 inches in width. Both strike nearly north and south. Specimens of the ore, which were furnished by Mr. Joe Barnes, of Marble, assayed 0.408 per cent MoS,. It is prob- able that the veins are too small and the grade of the ore is too low to allow the development of a workable body of ore in a deposit which is as inaccessible as this one is, for it would be a very expensive and difficult matter to build a road to the region from either Marble or Crested Butte. HINSDALE COUNTY The I. D. A. Claim Mr. Robert Wagner, of Lake City, has a molybdenum claim about 3 or 4 miles north of Lake City. The elevation of the claim is about 9,500 feet. It is situated about a mile west of the railroad. The country rock is a dark-gray, fine-grained rhyolite, which is eut by quartz veins. One vein which contains some molybde- nite strikes N. 55° E. and is vertical. Three open cuts aggregating 25 feet in length have been made on the vein. Small flakes of molybdenite and an occasional spot of molybdite are found, but the ore is not present in commercial quantities. Some pyrite is found in the vein. The country is rough and the relief is very high. There is no water which could be regarded as a permanent supply within half a mile of the deposit. There is fine timber in abundance, close at hand. On the whole the showing at this deposit is not at all en- couraging. 68 MOLYBDENUM DEPOSITS OF COLORADO SHERMAN DEPOSIT About 12 miles south of Lake City, near the old mining camp Sherman, there is an undeveloped molybdenite deposit owned by Mr. John Gavin, of Lake City. The deposit was not visited by the ariten. but it was de- seribed to him by Mr. Gavin. The country rock is granite. This is cut by a large peg- matite dike which carries occasional large flakes of molybdenite. The ore is pockety and does not occur in large enough amounts to be commercially valuable. HUERFANO COUNTY MOSCA PASS Mr. H. A. Aurand examined a molybdenite deposit at Mosea Pass and the substance of his notes follows: Mosca Pass can be reached from Hooper or Mosca, stations on the San Luis Valley division of the Denver & Rio Grande Railroad. The distance is about 25 miles from either station, and travel is very slow on account of the sand. About 300 yards east of the pass and on the north side of the road is a small quartz vein ten inches wide, in pegmatite, which contains some molybdenite. The vein strikes N. 27° W. The dip is 90°. Two small openings have been made on the vein, but no real development work has been done. The proposition is be- lieved to be too low grade to be of economic importance. GRAND COUNTY RADIUM It is understood that there is a deposit of molybdenite near Radium, which is owned by Mr. H. S. Porter, of that town. The extent and value of the deposit are not known. LA PLATA COUNTY EAST SILVER MESA Mr. C. M. Ayers, of Durango, reports molybdenite from his Oregon No. 1 and No. 2 claims, which are on East Silver Mesa, about nine miles from Needleton and within 2,000 feet of Lake Lillie. The claims join the Pittsburg Mine on the south. They are reached by a wagon road, five miles from Needleton, a station on the Durango- Silverton branch of the Denver & Rio Grande Railroad, to Chicago Basin, and by a good trail from there to the property. . LARIMER COUNTY DEPOSITS 69 The topography is mountainous, with high ridges and glaciated valleys. The relief is high. Timber-line in this region is at an altitude of about 12,000 feet, and the Oregon claims are 400 or 500 feet above timber-line. Very little work has been done on these claims, and that has been on veins which contain lead and zine. About a dozen shallow shafts have been sunk on quartz veins in the gray granite country rock, but the deepest one is 32 feet. Some four-inch quartz veins have been found which contain molybdenite. The mineral occurs in small bunches, facings, and single crystals. Assays of these four-inch veins gave an average of 2.1 per cent MoS., according to Mr. Ayers. Very small samples which he gave to the writer contained 1.156 per cent molybdenite. Mr. Ayers expects to do more development work on his ground during the summer of 1918. He already has a good cabin and a blacksmith shop on the property. VALLECITO BASIN About seven miles from Needleton, in Vallecito Basin, at an elevation of about 12,600 feet, there are said to be very good surface outcrops of veins which contain molybdenite on claims owned by John Bloom, of Durango. The vein is said to be entirely undevel- oped. It strikes nearly due north and stands nearly vertically. Specimens given the writer by Josiah Moore, of Rockwood, showed white quartz vein material in gray granite. Bunches of flaky molybdenite from one-fourth to one-half inch thick are scat- tered through the quartz. Considerable muscovite is associated with the molybdenite. There is no pyrite and no copper. The size of the vein is unknown. It is said that there is plenty of wood and water half a mile away. LARIMER COUNTY ST. CLOUD DISTRICT Small amounts of molybdenite have been found in the Iron King Mine, which is on Prairie Divide, about 4 miles south of Cherokee Park (St. Cloud) postoffice and about 40 miles north- west of Fort Collins. This property is owned by E. M. Bartlett, of Cherokee Park, and Mrs. L. M. Hill, of Denver. The relief here is very low. Prairie Divide is a broad, nearly level plateau, which lies between two of: the headwater branches of the Cache La Poudre River. The elevation above sea level is 8,000 feet. 70 MOLYBDENUM DEPOSITS OF COLORADO The property is reached by an auto road from Fort Collins. All but the last four miles of the road is very good. The country rock in this region is an even-textured, medium- grained biotite granite, which contains an abundance of pink orthoclase. There are two shafts on the property, but both were full of water. Consequently, only a superficial examination of the deposit could be made. According to Mr. Bartlett, one shaft is 35 feet deep. At the bottom there is a 10-foot drift, which runs N. 60° W. on the strike of the vein. Chalecopyrite, sphalerite, large quantities of magnetite and traces of molybdenite are found in the vein. A few feet west is a 45-foot shaft, with a 25-foot drift at the bottom. This is on the contact of granite and a coarse pegmatite dike. Molybdenite is found as small, irregular grains, and ageregates.in pockets in the pegmatite. Some of the individual flakes are half an inch in diameter, but most of them are much smaller. One hundred yards south of the Iron King is the Copper King group, owned by Mr. Bartlett, P. J. McIntyre, and associates, of Denver. This is a copper property, which contains some sphalerite and traces of molybdenite. The molybdenite in both of these properties occurs in too small amounts ‘to be of commercial value. MESA COUNTY In June, 1918, R. C. Coffin, of the Colorado Geological Survey, examined molybdenite claims in Unaweep Canyon, which are. owned by R. U. Gavette, of Grand Junction, and R. Collinson, of Whitewater. Mr. Coffin placed his notes and a complete set of specimens of the ore and the country rock at the disposal of the writer, and the following statements are based on these data: The Gavette Claim Mr. Gavette’s claim is located 29 miles from Whitewater, near the Casto ranch, on the north side of Unaweep Canyon, at an eleva-_ tion of 7,500 feet. The rocks in the immediate region of the deposit consist of pre-Cambrian schists, which carry considerable quartz and mica or , hornblende, hornblendite and pegmatite dikes of later, but unde- termined age that cut the pre-Cambrian complex in a general east- west direction. The hardness of these dikes is much greater than COLLINSON CLAIM (it that of the country rock and they form conspicuous geologic and topographic features. The dikes range from 1 to 50 feet in width, and some of them can be traced for 5 miles. Molybdenite is found in a dike of coarse, gray biotite granite, which runs at right angles to the general trend of the pegmatite dikes. The outcrop has been traced for 200 feet, but the condi- tions are such that the vein may extend for a much greater distance. The width of the dike varies from 2 to 5 feet. Short stringers leave the main dike and pinch out in the country rock. Most of the molybdenite is found near the contact of the dike and the country rock. The molybdenite occurs chiefly in isolated crystals and small masses, which range in size from one-fourth to one-half an inch in diameter. At the time Mr. Coffin examined the property there had been practically no work done on the deposit, and the samples, which were from the surface, showed only very low-grade ore. In a letter written soon after this examination, Mr. Gavette stated that he was down four feet on the vein and that he had uncovered some very good ore. The Collinson Claim The claim owned by Mr. Collinson is about two miles northeast of the Gavette property. This deposit is also on the north side of Unaweep Canyon, and is at’ an elevation of about 7,700 feet. It is about 1,200 feet above the bottom of the valley. The country rock here is essentially the same as that at the Gavette claims, except that there is rather more granite in the vicinity of the Collinson property. The vein is composed of coarsely granulated white quartz. Occasional flakes of molybdenite are found in the vein, but the surface showing is not at all encouraging. The vein strikes N. 30° W., and is vertical. It can be traced for more than one mile. Its width varies from 12 to 18 inches. Both of these claims are well situated, not far from the White- water-Gateway stage road. There is plenty of water near at hand, and the lateral streams that flow into Unaweep Canyon could be utilized for hydro-electric power purposes if there were a demand for the power. Timber is also available, and in general the natural conditions favor cheap development if ore bodies of sufficient size are found to warrant their exploitation. 72 MOLYBDENUM DEPOSITS OF COLORADO MONTEZUMA COUNTY Mr. H. H. Brown, of the Allard Mining Company, has reported molybdenite from Giles Mountain, near Mancos. The specimens he submitted show fine-grained molybdenite and molybdite in what appears to be a quartzite. The samples, it is estimated, will run 2 or 3 per cent MoS,. No work has been done on this deposit, and its extent and value are not known. OURAY COUNTY IRONTON DEPOSITS The lrene Messrs. G. C. McGee, of Ironton, and A. E..Ackerson, of Ouray, have a molybdenite claim, the Irene, which is situated about half a mile north of Ironton, 400 feet above and parallel to the creek. The country rock is the Silverton voleanic series. It is cut by a quartz vein, which is from one to two feet wide, and which carries pyrite, traces of gold and silver, 7 per cent lead and small amounts of molygdenite. The vein dips at a high angle to the west and strikes north and south. The molybdenite is fine-grained, and is intimately mixed with quartz. Considerable molybdite is found in soft streaks in the vein, especially along the walls. It is highly mixed with quartz. The vein has been opened by a tunnel for 50 feet. The vein is very variable in thickness and the ore in the vein is also variable in amount. Samples of the whole vein are said by Mr. McGee to have assayed 1 per cent molybdenite, but samples furnished by him to the Survey only assayed 0.364 per cent. MoS,. On account of so small a vein, and ore of this grade, it is probable that the vein can- not be successfully worked for the molybdenite alone. If the lead ore is rich enough and a suitable process devised for the economical separation of the lead and molybdenite, it may be that the property can be worked at a profit. The Jumbo No. 2 This claim is located near the creek, about one-fourth of a mile west of Ironton. There is a tunnel, 150 feet long, which runs S. 70° W., and 50 feet from the portal a drift 120 feet long has been run to the northwest along an alleged molybdenite vein. The streak which is supposed to carry the ore is only 2 or 3 inches wide, CORNER OF OURAY AND HINSDALE COUNTIES 73 and in it no molybdenite is to be seen. There is a little molybdite and probably some molybdenite that cannot be recognized inthe hand specimen, but the assay returns are only 0.338 per cent for the molybdenite present. Other Regions Molybdenite has been reported from Poughkeepsie Gulch and from Sneffels and other regions near Ouray, but, so far as is known, no active prospecting has been done for it, except at Ironton. CORNER OF OURAY AND HINSDALE COUNTIES ENGINEER MOUNTAIN DEPOSITS Near the junction of Ouray, San Juan, and Hinsdale counties, on Engineer Mountain, Fred Richter, of Ouray, has a claim in which there are traces of molybdenite. According to Mr. Aurand, who examined the property, there is not enough ore available to make the deposit worthy of further investigation. PARK COUNTY LAKE GEORGE DEPOSITS Molybdenite has been reported from several properties a few miles north of Lake George, the most important of which are the Boomer, the Apex, and the Redskin mines. The latter is the only one which has been developed for molybdenum. The others are said to have small amounts of molybdenite present with copper ores. The Redskin Mine This property is located near Tarryall Creek, about eight miles north of Lake George, a station on the Colorado Midland Railroad. The country is rough and the relief rather high. The elevation at the mine is about 8,600 feet. At the time the writer visited the property, in July, 1917, the mine was nearly full of water and no underground examination could be made. The following notes, therefore, are derived from data collected on the surface, and from statements made by officers of the U. S. Rare Minerals Company. This company, whose offices are in the Gas and Electric Build- ing, in Denver, has a three-year lease on the property. It took over the property in June, 1918, and immediately proceeded to put up 74 MOLYBDENUM DEPOSITS OF COLORADO cabins and mine buildings, and to install a compressor, hoist, and other necessary mine machinery. At this time there was one shaft, 150 feet deep, and a little drifting, which, with a small amount of surface work, represented the only development work done. The company has driven the shaft another 100 feet or more and has done some more drifting. The geology of the region could not be completely worked out from the surface, but the country rock seems to be coarse, pink, feldspathic granite, which has intruded gray biotite granite and quartz-mica schist. Along the borders of the intrusive pink gran- ite are deposits of molybdenite, which in some eases thoroughly impregnates the quartz-mica schist. The ore is very discontinuous, occurring in pockets and bunches, some of which are quite rich. Samples taken from the mine have assayed as high as 10 per cent MoS.,, but the average tenure is probably about 3 per cent. Only small commercial shipments have yet been made. It does not appear, from the recent prospecting that has been done, that a con- tinuous vein has been found, and the future of the property is in - doubt. Van Epps Claim KE. E. Van Epps, of Red Cliff, has a mclybdenite claim almost at the head of the South Platte River. In a direct line this claim is about 6 miles northwest of Alma, but by the road and trail which follow the river it is 10 or 11 miles. The Hoosier Pass road, which is a very good one, may be followed from either Breckenridge or Alma as far as the almost deserted mining camp Montgomery. From there on the road is almost impassable for a wagon, and it is better to use a saddle horse. . A tunnel on the property is one-eighth of a mile away from, and on the north side of, the creek, at an altitude of 12,400 feet. There is plenty of water in the creek, but there is no wood for timber or fuel within a distance of one or two miles. The country rocks are pre-Cambrian gneissoid granite and schist. These are crossed by large pegmatite dikes, some of which are considerably mineralized on their borders. Along a vein on the borders of one of these dikes « tunnel has been driven N. 80° W. for 150 feet, then northerly for 50 feet. Considerable pyrite, some chaleopyrite and traces of molybdenite are found in the vein. On the face of the cliff at the mouth of the tunnel near the contact of pegmatite and gneissoid granite, and not far WHITE SWAN CLAIMS io from a 2-foot black basic dike which cuts both the granite and pegmatite, there are considerable quantities of molybdenite which can be traced for 40 or 50 feet. It is not in a well-defined vein, but occurs only as grains and small aggregates impregnating the coun- try rock. The amount of mineral is surprisingly large. Half a dozen chunks 2 or 3 inches across were knocked off from the country rock, crushed and sampled. The molybdenite content was 1.703 per cent. The individual grains are rather large and thick, aver- aging perhaps one-third of an inch in diameter. There should be more prospecting done on this deposit to prove its extent. It may not amount to anything, but it is quite possible that a vein may be found which will be well worth developing. White Swan Claims E. O. Nippert, of Alma, has located a group of seven claims, near the saddle between Democrat and Cameron Mountains, on the divide between the head of Buckskin Gulch and the South Platte River. The claims can be reached either by following the South Platte River to its very head, or by going up Buckskin Gulch from Alma. The distance the latter way from Alma is about eight miles. There is a wagon road as far as the foot of the hill below the Kentucky Bell Mine, and a rough road on to the mine. A good trail leads from this mine to the claims. The topography is very rough. The relief is high and the elevation at the claims is about 13,200 feet. Only location work has been done here, and the ore bodies are not sufficiently developed to warrant positive statements regarding the extent and value of the ore. A large pegmatite dike, 20 feet or more wide, strikes N. 70° E. and cuts country rocks of gray granite and mica schist. In the quartz portions of this pegmatite dike and on the contacts of the dike and the country rock there are some very rich pockets of molybdenite. The mineral occurs in erystals and bunches of varying sizes up to an inch and a half in diameter. Much of the float on the side of the mountain contains molybdenite, and it is probable that there are ore bodies of considerable size in this region. On aceount of the high altitude and the distance (2 miles) from timber and (1,500 feet) from water, this property will be an expensive one to work, but the surface showing is favorable and it should be prospected further. 76 MOLYBDENUM DEPOSITS OF COLORADO The Humbug Claims George W. Shelton, of Alma, has located several claims near the head, on the west side, of Buckskin Gulch. These claims are about four miles from Alma, and are situated near the creek which flows from Lake Emma, at an elevation of 12,100 feet. The country rock is a coarse, white, mica-poor granite. This is cut by massive quartz veins which carry molybdenite and pyrite. ‘Three veins have been opened up by shallow surface cuts, tunnels and shafts. Two veins strike N. 75° E. and one, which is between the other two, strikes due east. All are nearly vertical. These veins are about 150 feet apart. They vary somewhat in width. The largest one is 5 feet wide, and the smallest is about 12 inches. All the veins are essentially alike in so far as their mineralization is concerned. All carry molybdenite in fine grains and facings irregularly scattered through the deposit. Considerable pyrite accompanies the molybdenite. Copper was seen in one vein, and some lead and zine occur in the vein farthest south. The grade of the ore when the whole vein is considered is in every case low, although rich streaks can be found. Assays of average samples taken from the vein yielded less than 1 per cent of MoS.,. It is possible that further prospecting would result in the discovery of larger deposits of molybdenite in this region, and it should be done, for the accessibility of the deposits, their near- ness to water and timber and the topographic conditions, with high relief, all favor economical development. The Crescent Mine This mine is owned by the F. M. Woods Investment Com- pany, of Colorado Springs, Jesse Robinson, of Cripple Creek, and Alfred B. Dell and his brother, of Guffey. There are three claims in the property, which is situated in the Freshwater Mining Dis- trict about three miles southwest of Guffey. Guffey is in the southern part of Park County, about 20 miles west of Cripple Creek and 14 miles south of Howbert, a station on the Colorado Midland Railroad. There are good roads to Guffey and to within half a mile of the property, from both Howbert and Cripple Creek. The relief of the region is rather high. The altitude at the mine is 9,100 feet, but the mine is nearly on top of a hill, so all the work must be below the present site of the shaft. The nearest PITKIN COUNTY DEPOSITS ii available water is nearly a mile away and 600 feet below the mine. Timber is rather scarce in this region and there is prac- tically none on the claims. GEOLOGY The country rock in this region 1s chiefly mica and fibrolite schist, into which have come intrusions of coarse, gray, horn- blende granite. These rocks are cut by felsite dikes, and at least by one basalt dike which does not appear at the surface. The shaft was nearly full of water when the property was visited, therefore information regarding the occurrence of the ore, ete., had to be obtained from an examination of the material on the dump, and from questioning men who have worked in the mine. The workings consist of a vertical shaft 300 feet deep, with a 40-foot drift at the bottom, another one about the same length at the 150-foot level and drifts 20 feet to the southwest and 17 feet to the northeast at the 100-foot level. On the dump there is considerable ore rich in sphalerite and galena, which is said to contain values in gold and silver. There is also some zine ore, without the other minerals, which is said to assay 15 per cent zine. Molybdenite is said to occur only in the drift at the bottom of the shaft. Apparently the amount present there is very small, for a careful search of the dump failed to show any considerable amount of this ore. What was found occurs as thin coatings in the fractures of quartz veins and in the gneiss and schist country rock. Chaleopyrite is associated with the molybdenite, and also with all the other minerals found on the dump. Judging by the information given by Mr. Dell and from the character of the ore on the dump, it seems improbable that mo- lybdenum will be found in commercial quantities in this prop- erty. PITKIN COUNTY The Green Horn Claim The Green Horn Claim is owned by F. E. Kendrick, Mrs. A. J. O’Leary and H. F. Foley, of Leadville. It is situated about 20 miles southeast of Aspen, on the north side of the creek, near the head of Lincoln Guleh, at an elevation of 11,600 feet. There is a good wagon road from Aspen as far as the mouth of Lincoln Gulch. The rest of the way the road is poor, but it could be improved at a comparatively small cost if there should 78 MOLYBDENUM DEPOSITS OF COLORADO be sufficient mining activity in the region to make such action desirable. | Only surface work has been done on this claim. There are several shallow cuts and one that is 20 feet long, 10 feet high and 10 feet wide. In this opening two veins, neither of which is more than a foot wide, are exposed. The larger vein dips 45° S. 35° W. The other is vertical and strikes N. 85° W. They join within the limits of the cut. A third small vein, which has been exposed in two or three shallow cuts, strikes 8. 10° W. and presumably crosses the other veins, although it is not known to do so. Molybdenite occurs with considerable pyrite and with small amounts of molybdite in all of these quartz veins. Its main occurrence is as black amorphous facings, but erystalline ma- - terial is sparingly found scattered through the veins. Specimens which represent the average of the veins assayed 0.947 per cent MoS,. The country rock is granite which has been much fractured. Higher up on the mountain side float of mica schist and an in- trusive, which is probably trachyte, were found. It is quite pos- sible that there is some connection between the intrusion and the molybdenite veins, but not enough work has been done to demon- strate this point. There is plenty of timber near, and Lincoln Creek furnishes a large permanent supply of water. The topography is such that there are good tunnel and mill sites. Altogether the condi- tions are very favorable for mining and milling if future develop- ment discloses the necessary amount of ore of high enough grade to be economically handled. The veins are so small and the ore now exposed is so low grade that the deposit is not regarded as a promising one. It is believed, however, that it would be desirable to sink prospect shafts on the junctions of the veins, where there is the greatest likelihood of striking richer ore. ROUTT COUNTY FARWELL MOUNTAIN A property which contains some molybdenite is owned by the Farwell Mountain Copper Company, whose home office is at 712 St. James Street, Montreal, Quebec. The property is located on the northwest side of Little Farwell Mountain, near the head FARWELL MOUNTAIN DEPOSITS 719 of Middle Beaver Creek. It is about five miles northeast of the town of Hahn’s Peak. The elevation at the tunnel is 9,600 feet, At one time there was a good wagon road all the way from the main Steamboat Springs-Hahn’s Peak road to the mine, but. it has not been used for several years and has become so badly washed that the last mile to the mine is now impassable to wagons. DEVELOPMENT The property has been developed by a 1,000-foot tunnel which has been driven N. 17° E. into the hill, and by several pros- pect shafts which were sunk higher up on the mountain. All the prospecting done so far has been for copper, veins of chalcopyrite _ having been found, which outcrop at the surface in a number of places. No important veins were found as the tunnel was driven. GEOLOGY The country rocks are pre-Cambrian granite, gneiss and schist, with the latter predominant. Many strong pegmatite dikes cut these rocks. They were formed before the processes which caused the metamorphism of the country rocks were com- pleted, and in consequence the pegmatites show evidence of considerable movement. One large pegmatite dike was crossed by the tunnel about 200 feet from the portal. Molybdenite occurs on both sides of this dike, and it impregnates the country rock for several inches. The mineral occurs almost entirely in grains which are from one- fourth of an inch up to more than an inch in diameter. Some grains are an inch thick, but most of them are very thin when compared with their surface area. Considerable muscovite occurs with the molybdenite, and it will interfere more or less with the concentration of the ore if it is ever milled. The ore is entirely free from molybdite, pyrite and copper minerals. The molybdenite occurs entirely in pockets which are separated by barren rock. The value of the whole dike would be very low, but because of the occurrence of the mineral in large grains it can be easily cobbed out and separated from the gangue and the country rock. Assays of roughly sorted material yielded 1.56 per cent MoS,. It would be possible to sort the ore and get a product which would run from 5 to 10 per cent MoS,, and whenever the value of 60 per 80 MOLYBDENUM DEPOSITS OF COLORADO cent MoS, concentrates are $2.00 a pound or more, it is believed that this ore might be broken out and handled at a profit. Absolutely no attempt has been made to develop this deposit, therefore its extent is unknown. A fault cuts through the peg- matite dike, which causes it to appear to pinch out in the roof of the tunnel. The fault could not be traced, on account of the lack of development work, and its effect on the deposit is not known. The presence of several small surface outerops which con- tain molybdenite, coupled with the rather pronounced miner- alization along the walls of the dike mentioned above, lead to the opinion that there may be a larger bedy of ore in this neigh- borhood, which might be found if strict search were made. Near the breast of the tunnel there are said to be several small quartz veins which show some molybdenite with chal- copyrite. None of these veins are of commercial size and their mineral content is low. Both wood and water are fairly accessible. There are com- fortable living quarters near the tunnel fcr a small force of men. SLAVONIA MINING DISTRICT Several occurrences of molybdenite have been reported from this district, but no deposits have yet been developed on a com- mercial seale. Mr. G. H. Franz, of Clark, reports a promising occurrence of molybdenite on Gilpin Creek. This property is about 15 miles from Clark and is situated on the east side of a spur of the Sawtooth Range at an elevation of about 10,000 feet. There are said to be several veins in this region. One quartz vein 8 feet wide contains considerable low-grade ore. Another 18-inch vein has rich pockets of molybdenite. No other metallic minerals occur in these veins, according to Mr. Franz. Altogether there are at least 5 claims within a distance of 2 or 3 miles which show molybdenite. The country rock is granite. Part of these claims are said to be readily accessible to the auto road from Clark. Others are 3 or 4 miles from the road. Mr. M. A. Hoskinson, of Oak Creek, has a molybdenite claim in the Slavonia District, situated 10 or 12 miles from Clark on a branch of the middle fork of Elk River. It is said that one can drive almost to the property with a team or an automobile. SAGUACHE COUNTY DEPOSITS 81 On this claim there is a quartz vein which has been opened up by a tunnel for a distance of 30 feet. The width of the vein was not given in Mr. Hoskinson’s report. The country rocks are granite and mica schist. According to the report from Mr. Hoskinson, average samples of the ore assayed 1.5 per cent Mos,. There is said to be a large amount of timber on and near this claim, also plenty of water power and water for mining and milling. Mr. D. M. Wilt, of Clark, Colorado, also has molybdenite claims in the Slavonia District, but they are wholly undeveloped. SAGUACHE COUNTY Merideth’s Claim About seven miles northeast of Alder there is a small molyb- denite deposit owned by William Merideth, of Alder, which is under bond and lease to Messrs. W. J. Candlish, J. E. Richardson, and C. W. Savery, of Denver. The property is reached by a good wagon road which goes from Alder to within about one mile of the claim. A poor wood road and rough trail lead from the end of the wagon road to the property. The property is located on the west side of the Sangre de Christo Range, at an elevation of 10,200 feet. The relief is high, and the topography rough and mountainous. The ore occurs very sparingly in a small quartz vein which cuts the quartz mica schist and biotite granite country rocks. A 10-foot shaft has been sunk on the vein, and a cross-cut tun- nel 25 feet long, at the time of the writer’s visit to the property, has been started near the creek 200 feet below the shaft. The vein strikes N. 60° E. It is practically vertical, and can be followed by surface outcrops for 200 or 300 feet. The ore exposed in the shaft is low grade, and as the vein is small, the deposit is probably not of commercial value. Other Deposits Near Alder - Several other deposits of molybdenite have been reported from the region, but none has been developed, and all are said to be very low-grade propositions. 82 MOLYBDENUM DEPOSITS OF COLORADO SAN JUAN COUNTY CHATTANOOGA DEPOSITS About half a mile south of Chattanooga, a station on the Silverton-Red Mountain branch of the Denver & Rio Grande Rail- road, there are two groups of claims in which there is considerable molybdenite. These are the Hidden Treasure and the Gold Finch groups owned by Taylor McGrew and Lee Tinsley, of Chattanooga. The Gold Finch group consists of six 300 by 1,500-foot claims, all of which le just west of Mineral Creek. There are eight claims of the same size in the Hidden Treasure group and they are situ- ated a short distance east of the wagon road. DEVELOPMENT The Gold Finch group has been developed by a cross-cut tunnel driven west 275 feet to the vein; drifts 30 feet north and the same distance south on the vein; an upraise 100 feet to the surface from the intersection of the cross-cut and drifts; and surface euts which proved the occurrence of the vein for 750 feet west of the creek. There is a combined shop and an ore-sorting room at the en- trance of the tunnel. On the Hidden Treasure ground there are several tunnels and drifts with a total length of about 1,000 feet. The vein has been opened for 600 feet, and it is said to outcrop for an additional distanee of 200 feet. GEOLOGY In the Silverton Folio, U. 8S. G. S. Folio No. 120, the geologic map shows San Juan tuff on the west side of the creek and the Silverton series, of undifferentiated andesite and rhyolite flows and flow breccias on the east side. These rocks are eut by dikes of medium to coarse-grained dark-gray andesite, in which the ore bodies are found. The veins on the two sides of the creek are very much alike. In the Gold Finch claims the whole vein is four feet wide. It is vertical and strikes nearly due north. The minerals in the vein are chalcedony, quartz, pyrite, molybdenite and some gold and silver. In many places the chaleedony, quartz and molybdenite are beautifully banded. The molybdenite is found chiefly in nar- row strips in the quartz and chalcedony bands, 6 or 8 inches wide. In such cases the rest of the vein is barren. These molyb- CHATTANOOGA DEPOSITS 83 denite strips are very discontinuous, widening to 20 inches and pinching out entirely within afew feet. Most of the molybdenite is in exceedingly fine grains which are very dark gray, or entirely black. These grains are so thoroughly mixed with quartz that where they occur together the bands of the mixture have a bluish- black or black color. Pyrite is widely disseminated through the bands of quartz and molybdenite, but is not commonly found with the chaleedony. Mr. McGrew reports assays as high as 10 per cent MoS, from rich bands in this vein. Average samples of the molybdenite por- tions of the vein (not the whole vein), taken by the writer, assayed 2.22 per cent of molybdenite. The Hidden Treasure vein strikes N. 60° W. and is vertical. The whole vein averages about 4 feet between the walls, but the molybdenite streaks are only from 6 to 20 inches wide, including ° the quartz bands which alternate with the ore. The ore is very pockety. Samples from the molybdenite portions of the vein as- sayed 3.739 per cent molybdenite. FUTURE DEVELOPMENT On the Hidden Treasure vein there are good opportunities for development, for the relief is such that there is more than 1,000 feet of stoping ground. The Gold Finch Vein does not offer so desirable conditions, because of the lack of stoping ground above the tunnel level. It is probable that, at first, there will be difficulties encountered in concentrating the ore, but it is not believed that they will prove permanent. There is an abundant supply of both wood and water close at hand. The transportation facilities are good and if the ore proves to be in large enough bodies, these properties should become ‘ producers. Inberty Bond Claims About two and one-half miles south of Chattanooga, on the east side of Mineral Creek, nearly opposite the mouth of the middle fork of the Mineral Creek, there are three claims; the Liberty Bond, Liberty Bond No. 1 and No. 2. These claims are owned by E. J. Holman, A. D. Malchus, and R. H. Hoffman, of Silverton. The topography is rough and mountainous with high relief. The claims are situated at an elevation of 11,150 feet, about 1,100 feet above the road, on a very steep slope. 84 MOLYBDENUM DEPOSITS OF COLORADO There is no single well-defined vein exposed here, but there are stririgers of quartz in the Silverton series of voleanic rocks which have been uncovered for a distance of 300 feet by four shallow cuts and one 20-foot shaft. An occasional grain of flaky molybdenite with considerable pyrite occurs in these quartz stringers. Not much development work has been done, and only in the 20-foot shaft has solid rock been reached, but from present indications the ore is too much scattered and too low grade to be of commercial value. Black Diamond Claim Mr. J. P. Eaker, of Silverton, has located this claim on the north side of South Mineral Creek, about a mile from the mouth of the gulch, at an elevation of 10,500 feet. There is a poorly defined quartz vein here in voleanic breccia. The vein dips 65° S. 27° W. It varies in width from 2 to 12 inches. Thin flakes of molybdenite from a small fraction up to one-eight of an inch in diameter are scattered through the quartz. There is considerable pyrite, but no copper in the vein. Float has been found along the strike of the vein for 150 feet. Elsewhere the ground is so covered with slide rock that no indications of the vein have been found. Only 2 or 3 very shallow openings have been made on the vein, but the exposures of ore in these are not promising. The vein is so small and so vari- able, and the ore is so low grade, that there is little encouragement for further development work. HEAD OF SOUTH MINERAL CREEK There have been several reports of the occurrence of molyb- denite near the head of South Mineral Creek. One location is said to be near the trail right on the divide between South Mineral Creek and Routt Lake, where rich float has been found. Another body of ore has been reported from the Rico side of the divide just across from the head of the creek. The Rolling M. and M. Co. has placed samples of molybdenite in the Colorado State Museum which are, presumably, from this region. The writer has no personal knowledge of these deposits, but from all indications the ground should be thoroughly prospected. BEAR MOUNTAIN DEPOSITS, NEAR SILVERTON There is said to be a small deposit of molybdenite on the southwest slope of Bear Mountain about four miles west of Silver- ton. The deposit is owned by Edward Hollingsworth, of Silverton. SAN MIGUEL COUNTY DEPOSITS 85 It is wholly undeveloped, and judging from the samples, which were ‘said to have come from this property, it is too low grade to be important at this time. The samples showed thin radiated crystals of molybdenite, in a white quartz vein, but the amount of molybde- nite present seems to be very small. CASCADE BASIN Molybdenite float that looks very promising is reported from near Molas Lake in Cascade Basin. The mineral is said to occur in lenses in large white quartz veins. Frank Deputy and James Holden, of Rockwood, are said to know of this deposit. SAN MIGUEL COUNTY The Molybdenum Queen and the Molybdenum Lode Claims It is understood that until recently these claims were owned by Guy Knox, of Denver, Newton Sankey, of Ophir, and J. M. Belisle, of Norwood, Colorado. A short time ago these men organized the Colorado Molyb- ' denum Mining Company, and made Mr. Sankey president, Mr. Belisle vice-president, and Mr. Knox secretary and treasurer. The company is capitalized for $100,000.00, with 1,000,000 shares of a par value of 10 cents each. The company paid to the former own- ers 400,000 shares of stock which, valued at par, would amount to $40,000.00 for the two claims. On August 9th, 1917, the writer, accompanied by W. J. Hawkins, of Ophir, examined the Molybdenum Queen Claim and the surrounding country. The claim is situated on the west side of Nevada Gulch, about one mile southeast of Ophir, at an elevation of about 10,350 feet. Here there is an intrusion of granite porphyry, in which there is a more or less mineralized zone 35 feet wide, exposed on the steep face of the cliff that forms the west side of the gulch. The porphyry is cut by a great many small quartz veins which run in every direciion. A majority of the veins, however, seem to trend S. 70° W. There is no sharp line between the mineralized and the non-mineralized areas. The change from one to the other is a very gradual one, and it is not possible to accurately determine the dip and strike of the deposit. As nearly as it can be determined, however, the general dip of the mineralized zone is 50° N. 20° W. A tunnel has been started near the north side of the mineral- ized belt, and at the time the property was examined it had been 86 MOLYBDENUM DEPOSITS OF COLORADO driven for about 40 feet on a course S. 25° W. Several small, strongly pyritized quartz veins are exposed in the tunnel, but there is a striking absence of molybdenite after a point about 10 feet - from the mouth of the tunnel is reached. The molybdenite occurs in this deposit chiefly as grains and crystals which range in size from that of a common pin head up to half an inch in diameter. Most of the ore is near the sides of the mineral belt, where it occurs in quartz veins which vary in width from 1 inch to 2 feet. The veins do not seem to be all continuous and nearly all of them play out within a distance of 2 or 3 feet. There are many barren places in the veins, as well as, of course, some relatively rich ones. Pyrite is associated with molybdenite all through the deposit wherever the latter is found. Near the surface and along many fractures, molybdite is found as an altera- tion product of the molybdenite. No copper was seen, and no other metallic minerals are known to occur here. Although, it is possible to carefully sort out some of this ore, by hand, and get a product that may assay from 1 to 2 or even 3 per cent MoS,, there was no considerable amount of such ore available at the time the property was examined, and the geology of the de- posit does not warrant the assumption that better ore will oceur with depth. It is certainly wrong to think of the whole mineral zone as being one vein, which is the impression conveyed by the prospectus recently published by the company. If the face of the deposit were properly sampled through the whole vertical and horizontal distance, the ore would run only a very small fraction of 1 per cent of molybdenite. Both wood and water are near the property, and they would be important items if the property is to be developed. The situation of the deposit, well up on the side hill, also is favorable to easy development. It is, however, the writer’s opinion that the solicitation of funds, with which to build a mill and develop the property, is entirely unwarranted in view of the low grade and the unfavorable geological occurrence of the ore. Such solicitation could be justi- fied only by frankly stating that the money was to be used to prospect a deposit of unknown value. And no part of the funds so raised should be used to build a mill, until the extent and value of the deposit have been fully determined and are known to be sufficient to supply a mill with the HegeseinD quantity of ore of a workable grade. SUMMIT COUNTY DEPOSITS 87 SUMMIT COUNTY CLIMAX (FREMONT PASS) DEPOSITS The largest known molybdenum deposit in Colorado, and probably one of the largest in the world, is situated on the con- tinental divide, near Fremont Pass (Climax Station), about 15 miles northeast of Leadville on the South Park branch of the Colorado & Southern Railroad. This deposit occurs in a large mineralized zone, about one mile east of the pass near the head of Tenmile Creek, on the southwest slope of Bartlett Mountain and on the northwest side of Mount Ceresco. The full extent of the deposit has not yet been determined, but the surface area is known to be more than one-half a square mile, and the vertical range is 500 feet and probably very much more. The country is mountainous, and the relief is high. The elevation at the top of the pass is 11,300 feet and at the top of the range between 2 and 3 miles to the east it is over 14,000 feet. There is considerable timber near the pass. Tenmile Creek furnishes quite a large amount of water, but probably not enough to supply the requirements of the concentrating mills that are now in opera- tion, or under construction. GEOLOGY The geology of this region has not been thoroughly worked out and only general and tentative statements can be made at this time. The mineral zone is bounded on the west by the Mosquito fault, which occurs about two-thirds of the way from the pass to the top of Bartlett Mountain. The fault strikes approximately N. 15° E. On the north the boundary has not been determined. Float has been reported from points high up on the side of Bartlett Mountain and the ore is believed by some people to extend to the top of the mountain. The writer has not had the opportunity to study the geology of Bartlett Mountain, but he doubts the existence of large ore bodies far up on the mountain. It seems probable that the northern boundary is made by a strong fault that has been crossed by the main tunnel and the center drift of the Leal tunnel. It also is exposed by the drift on the Molybdenum No. 3 claim, and it’ appears plainly at the surface about 500 feet east of the Molyb- denum No. 2 workings. Where cut by the Leal main tunnel and to center drift, the fault strikes N. 25° W. and dips 60° N. 65° E. 88 MOLYBDENUM DEPOSITS OF COLORADO East of the workings of the Molybdenum No. 2 the strike is N. 40° W., and the dip is nearly vertical. So far as surface indications go, in the vicinity of the claims that are now being worked, this fault seems to mark the northern boundary of the ore. Judging by the topography, it seems probable that a third fault cuts off the ore bodies on the east. This fault probably crosses Tenmile Creek about one-third of a mile east of the Mos- quito fault. Its strike is thought to be approximately 8S. 50° W. If so, it intersects the Mosquito fault near Wortman, and the second fault described above, not far from the head of Tenmile Creek. If this conception is correct the ore zone is triangular-shaped. The base, represented by the Mosquito fault, is about a mile and a half long, the height represented by the distance east along Ten- mile Creek from the Mosquito fault to the junction of the other two is about one-third of a mile, while the other two sides of the triangle are represented by the faults which strike northwest and south- west respectively. It must be understood that this statement is subject to revision, when more work has been done, but it will at least suggest an hypothesis for future work. Within the fault block there are innumerable small faults and fractures, which on the surface do not seem to have any pro- nounced uniformity in their arrangement. In the tunnels and drifts of the Climax Molybdenum Company, however, there are two sets of fractures which seem to be arranged, one roughly normal, and one parallel to the big fault at the end of the main tunnel. The amount of fracturing varies greatly, but it is greater near this fault than elsewhere. Typical specimens taken from the Climax Molybdenum Company’s tunnel, 200 feet from the fault, show from 6 to 10 distinet fractures per linear inch of surface. ; On account of the large amount of fracturing followed by the formation of innumerable quartz veins, the original character of the country rock cannot in all places be determined. It seems to have been chiefly a white, even-grained granite, poor in muscovite and ferro-magnesium minerals. However, some of the country rock seems to be a very much fractured quartzite, which may be the Cambrian ‘‘Sawatch Quartzite,’’ faulted into the present position. Before much fracturing of the country rock occurred there were large intrusions of granite porphyry (nevadite). In some eases the porphyry is fractured and highly mineralized, but in general the country rock seems to have been much more fractured than the porphyry, and mineralization has been greatest where there was the most fracturing. CLIMAX DEPOSITS ~ 89 “he effect of the intrusion of the porphyry is problematical. Brown and Hayward? believe that the molybdenite is of magmatic origin and that-it is directly associated with the intrusion of the por- _phyry. This theory may be correct, but it is the writer’s belief that fracturing by the systems of faults described above is of primary importance in producing the situation favorable for the deposition of molybdenite. This inference is based on the geological conditions on Chalk Mountain just west of Climax, where there is a large intrusion of the same granite porphyry that is found on Bartlett Mountain, but no deposits of molybdenite have ‘yet been found there. It seems possible then that the order of events may have been: First, faulting on a great scale ; second, the intrusion of the granite porphyry, accompanied by fracturing, vein filling and ore deposi- tion; third, another period of minor fracturing and silicification. The ore occurs as molybdenite and molybdite. The latter is ‘found chiefly near the surface and along the larger fractures which extend down from the surface. The molybdenite occurs as exceed- ingly fine grains in veinlets of quartz. Mueh of it is so finely dis- seminated that it can hardly be seen with the unaided eye. It gives a blue tinge to the quartz veins which vary in intensity of color with the amount of molybdenite present. Where the rock is broken, partings are apt to occur along the veins which carry ore, thus leaving exposed their faces of nearly pure molybdenite. Most of such facings are very thin, approximately the thickness of aver- age writing paper, but occasionally much thicker layers are found. There seem to have been three periods of fracturing and vein fill- - ing; one preceded, one accompanied, and one followed the deposi- tion of the molybdenite. The whole mass of country rock is more or less mineralized, but certain regions, particularly those only a short distance from the larger faults, seem to be much richer than the others. There are, however, rich and lean streaks scattered all through the mineralized area. Pyrite in varying amounts occurs with the molybdenite. No copper minerals and no other metallic minerals are found. Many samples taken from various parts of the area indicate that the rock of the whole mineralized zone will run from three- fourths of one per cent to one and one-tenth per cent MoS,. Some rich streaks will assay as high as 2 per cent and large bodies of ore will run from 1 to 1.2 per cent. All proposed mill operations, 1Brown, H. Il. and Hayward, M. W., Molybdenum mining at Climax, Colo. Eng. and Min. Journal, vol. 105, No. 20, 1918, pp. 905-907. 90 MOLYBDENUM DEPOSITS OF COLORADO however, should be based on an ore with a MoS, content of from three-fourths of 1 per cent, to 1 per cent in order to insure a safe margin upon which to work. Mr. Brown, of the Climax Molyb- denum Company, states that the ore treated at the company’s mill averages almost exactly nine-tenths of 1 per cent MoS.,. DEVELOPMENT Three companies are now developing this deposit. They are: The Climax Molybdenum Company, The Molybdenum Products Corporation of Denver, and the Pingrey Mines & Ore Reduction Company of Leadville. These companies own, or control through leases, practically the whole mineralized zone. When the extent and value of the deposit became well known there was a great rush of people into the district, who desired to locate claims. Unfortunately there have been many charges and counter-charges of: False entry, failure to do assessment work, claim jumping, ete., which it will take the courts years probably to settle. In addition there has been and still is a dispute over the position of the Lake-Summit County boundary line. It is under- stood that at first the line was not surveyed, but was located by agreement. In 1917 it was surveyed by the proper officials of the counties concerned, and the line was declared to be correctly located and was not changed. This left all the richer molybdenite deposits in Summit County. The Lake County commissioners, however, have protested the survey, and it will take a court deci- sion and probably a re-survey to settle the matter. There is also some question regarding the ownership of the water in the upper part of Tenmile Creek. The Pingrey Mines and Ore Reduction Company Of the three companies on the ground, the Pingrey M. & O. R. Company of Leadville was the first to concentrate any large amounts of the Climax ore. In 1916 they treated nearly 1,000 tons of ore, about 600 tons of which came from the Molybdenum No. 2 claim owned by C. J. Senter, while the other 400 tons came from the dump of the Leal tunnel, which is now owned by the Chmax Molybdenum Company. The ore was treated in a modified zine concentrating mill at Leadville. The results of the treatment are not available for publication, but it is understood that the ore was CLIMAX MOLYBDENUM COMPANY 91 crushed to 60 mesh, concentrated by oil flotation, and a market- able product procured. The crude ore is said to have averaged. about 0.75 per cent Mos,. It is understood that this company will remodel the present mill, or build a new one at Leadville, if the court awards them the property which they claim. At the present time they are carrying on development work on the Rare Metal Claims Nos. 3 and 6, which are located south of Tenmile Creek, and are also developing the Molybdenum Claims Nos. 2 and 38, on Bart- lett Mountain. They have done the only important prospect- ing south of the creek, and have demonstrated beyond any question that the ore continues across from Bartlett Mountain to the west slope of Mount Ceresco. In March, 1918, their tunnel on the Rare Metals No. 6 claim was in 310 feet ; 250 feet was in mantle rock and the rest of the distance in granite. For the last 25 feet to the breast, the granite is fractured and shows some low-grade ore. About 500 feet north of No. 6 is the Rare Metal Claim No. 3. Here there was a tunnel 220 feet long, when the property was visited by the writer in March. About 145 feet from the portal the first ore is seen. This continues into the mountain and the value increases with depth. The country rock, fracturing, occurrence, and values of the ore seem to agree closely with those on Bartlett Mountain. The Climax Molybdenum Company The Climax Molybdenum Company owns more property in the district than does either of its competitors, and it is the first of the three companies to build and operate a concentrating mill on the ground. . This company has done a large amount of work on a group of five claims: the New Discovery, the New Discovery No. 2, Mountain Maid, Mountain Maid No. 2, and the Mountain Chief. They started work at the mine in August, 1917. At that time there was one small tunnel (the Leal) about 900 feet long. By the end of March, 1918, they had enlarged the original tunnel and had driven an addi- tional length of tunnels and drifts of more than 3,000 feet. They had under way an extensive system of shrinkage stopes and were mining 250 tons of ore a day with little effort. It is estimated that 6,000,000 tons of ore is now blocked out of this level. A new double- track tunnel has been started about 200 feet vertically below the main workings. Through it another large amount of ore will be blocked out. 92 MOLYBDENUM DEPOSITS OF COLORADO At the present time the ore is handled as follows: It is broken in the stopes, dropped to the tunnel level and trammed by man power to the mouth of the tunnel where it is dumped into large ore bins. From these bins it is carried by an aerial tram, down the hill about 400 feet to the crusher bin. It is then crushed by a Blake Crusher to pieces four inches or less in size. The crushed ore is carried 100 feet on a belt conveyor to another ore bin. This bin is 5,000 feet distant from, and 500 feet higher than, the mill which is located about 200 yards from the top of Fremont Pass. A Leschen tram is used to bring the ore to the mill. The buckets have a rated capacity of 1,000 pounds, but actually carry about 850 pounds of ore. The capacity of the tram is said to be 1,000 tons every 24 hours. . The ore is dumped by a tram tender into ore bins, from which it is fed automatically to a belt that carries it to a Chalmers 6 by 6 ball mill where it is ground to eight mesh. After leaving the ball mill it is automatically sampled, elevated, and classified in a Dorr classifier. The fines which pass a 60-mesh screen go directly to the oil flotation system. The middlings and oversizes go back to a 6 by 10 Chalmers ball mill. In this mill the ore is ground to 60 mesh. After leaving the mill it is again elevated and classified. The fines go to the flotation plant direct and the oversizes back to the mill that they just left. The flotation plant consists of 5 Janney and 5 Callow eells. The Janney machines are banked with about a 3-foot drop between each 2 cells. The whole feed goes into the upper machine. Tails from this form the heads for the second and so on through four machines. Tails from the fourth cell go out of the mill. The con- centrates from each of the first four machines flow to the fifth, where they are cleaned. From this cleaner the concentrates are pumped to the first of a three Callow cell series. The concentrates from the first go into a second, and from the second to the third eell. The tails from the fifth Janney machine, the cleaner, and from the three Callow cleaners form the middlings which are pumped back to the first Janney, where the process is repeated. The concentrates from the third Callow cell go to vanners to separate the pyrite from the molybdenite. The molybdenite con- centrates then go to large tanks where they are laundered and set- tled. From these tanks they are drawn off and dried on steam plates. Considerable water is left in the concentrates. After leav- ing the steam plates the concentrates are doubled-sacked and are then ready for shipment. : MOLYBDENUM PRODUCTS CORPORATION 93 When the mill is finally adjusted it can be handled by 4 or 5 men per shift, including the tram tender. Each machine in the mill has its own electric motor and the mill is designed for the addition of other units as required. The present plant can treat 250 tons a day, which is the capa- city of the ball mills. Another ball mill is soon to be added, which which will increase the capacity to 400 tons a day. It is said that the flotation system as now installed can probably successfully treat 700 tons a day. The savings on the ore, which, crude, assays nine-tenths of 1 per cent MoS,, are said to be more than 60 per cent and they are increasing as the mill is being adjusted. It is believed that at least a 70 per cent saving will eventually be made. The concentrates are said to assay 60 per cent MoS,. This statement was made be- fore vanners were used to reduce the amount of pyrite which is present in large amounts in the original ore and in considerable quantities in the concentrates that come from the last Callow cell. This company has a very fine equipment, and is thoroughly prepared to produce molybdenite concentrates on a very large scale. The power is electrical throughout. The mill, offices, board- ing house, hospital, ete., at Climax are steam-heated. A spur has been run in by the Colorado & Southern Railroad from the main line to the mill. Arrangements are made so that most of the sup- plies for the mine and the mine boarding house are carried up on the tram. The plans for developing the mines are extensive and the company is now one of the largest producers of molybdenum in the world. If the output is estimated on a basis of the daily treatment of 250 tons of ore which carries nine-tenths of 1 per cent MoS.,, and if the saving is 60 per cent., it is evident that 295.65 tons of metallic molybdenum would be produced annually. This amount is 73.05 tons greater than the world’s production in 1915, which was 222.6 tons.” The Molybdenum Products Corporation This company, whose offices are in Denver, owns one 150 by 1,500-foot claim, the Denver No. 2, in the molybdenite belt on Bart- lett Mountain. It has also located the Continental placer near the mill, and 14 claims, the Wolf, Nos. 1 to 14, on Chalk Mountain. All the Wolf claims are 300 by 1,500 feet in area. They have not 1Hess, F. L., Molybdenum. U. S. Geol. Survey, Mineral Resources for 1915, Pt. 1, 1917, p. 810. 94 MOLYBDENUM DEPOSITS OF COLORADO been much developed. The company has leased a right of way for the tram, a distance of 8,400 feet on Bartlett Mountain to the mill at Buffehr’s Spur and has a perpetual lease on the Lake placer near the mill. Considerable development work has been done on the Denver No. 2 claim. A 550-foot tunnel has been driven, with several short drifts out on either side. The ore blocked out by this work is of a very satisfactory grade, and it is believed to be equal to the average of the ore from other parts of the district. It will be mined through shrinkage stopes. A large building at the mouth of the tunnel serves the com- bined purpose ©f a carpenter shop, crusher house, and also covers the ore bins at the head of the tram. The ore is handled as follows: It is broken in the mine, trammed by hand to ore bins in the crusher house, crushed by a Telsmith machine and classified by screens. All that does not pass a three- quarters mesh is returned to the crusher. The fines are carried by a belt conveyor to the bins at the head of the tram, thence by a Broderich and Bascom tram, which has a rated capacity of 1,000 tons every 8 hours, to the mill. Here it is ground in Marey ball mills, classified by a Dorr classifier and treated by K. and K. oil flotation machines. The concentrates are dried on special steam tables. The mill is designed for two 150-ton a day units. Each unit has its own crushing and flotation plant. One unit is in place and has been in operation part of the time since the first of May, 1918. The machinery for the second unit is on the ground, but has not been installed. The milling operations have not yet passed the experimental stage and figures of recovery values, operating costs, ete., are not available. : There are boarding houses at the mine and at the mill. The mine office is at the mill. Early in July the company suspended operations at both the mine and mill, giving as the reason for so doing that it was not possible to market molybdenite concentrates at that time. It in- tends to resume, operations when the demand for the product increases. ; KOKOMO DISTRICT This region is part of the Tenmile Mining District, which is situated in the southwest corner of Summit County. The town of Kokomo, the center of a zinc-mining region of considerable impor- KOKOMO DISTRICT 95 tance, is on Tenmile Creek, and is about 17 miles northeast of Leadville on the South Park division of the Colorado & Southern Railroad. | Joseph Bryant and the Kokomo Milling Company together control most of the molybdenite claims in this district. The original Bryant group consisted of 13 claims, 7 of which were patented. In 1917 these were leased to the Kokomo Milling Company, and more were located by this company. In July, 1917, considerable development work was being done in two tunnels which are situated about two miles northeast of the town of Kokomo. One tunnel is located right on the wagon road, only a few feet above Tenmile Creek. This tunnel is a cross-cut which has been driven for 540 feet through granite, gneiss, schist and quartzite. About 420 feet from the entrance, a large mineral- ized zone was encountered, which dips 43° N. 15° W. This zone is in a highly breecciated condition, due to faulting. The mineral- ization continues through a distance of 60 feet at right angles to the strike. On the borders of this zone are schist and quartzite. Within the zone the rock is chiefly quartzite and a very impure limestone. There are no large distinct veins, but the whole fractured mass is impregnated heavily with quartz veinlets, which contain consider- able pyrite and calcite. An occasional grain of chalcopyrite is found, and scattered through the veinlets there are small thin flakes of molybdenite. The ore is very low grade, and it is doubtful if it can be worked with profit at the present time. About half a mile southwest of this tunnel and 500 or 600 feet above it, is another claim belonging to the Bryant group. This is reached by a good trail, which winds up the hill from the wagon road. Here a drift has been run for 150-200 feet on a three- foot vein, which dips 45° N. 75° W. The vein is in quartzite and limestone, has distinet walls and is strongly mineralized. Calcite, garnet and quartz are the gangue minerals. Pyrite and small amounts of molybdenite occur in the vein, especially on and near the walls. Average samples from the walls of the vein assayed 1.08 per cent MoS,. Mr. George 8. Backus, superintendent of the Pingrey mill at Leadville, reports that 500 tons of ore was shipped to this mill from the vein last described. The molybdenite content of the ore averaged considerably less than one per cent. Because of the low grade and small body of the ore the possibilities for development are not believed to be good. 96 MOLYBDENUM DEPOSITS OF COLORADO There are both wood and water close to the property, however, and if larger bodies of higher-grade ore should be uncovered, and the price for concentrates increase somewhat, it might be possible to build a mill on Tenmile Creek and handle the concentrating ore at a small profit. The Salamander and Blue Valley Claims These claims are owned by R. J. A. Widmar and A. C. Howard, © of Breckenridge, Colorado, and are situated about 11 miles south- west of Breckenridge, on the south slope of Quandry Mountain, at an altitude of 12,000 feet. The property is reached from Breckenridge by a good wagon or automobile road for 9 miles up the Blue River Valley, a poor road for a mile and a half up Monte Christo Creek, and a rough, ill-defined trail the rest of the way. The best showing of molybdenite is in the Salamander vein. The Blue Valley vein is less than one foot wide and does not show much ore. GEOLOGY The country rocks are pre-Cambrian gneiss and quartz-mica schist, into which were intruded large, irregular masses of granite, before the metamorphism of the schist was completed. There are also many large pegmatite dikes, which differ from the granite masses just referred to, chiefly in that they do not conform to the gneissoid and schistose structure of the metamorphics. Both the granite and the pegmatite dikes are more or less mineralized, par- ticularly along their borders. The Salamander vein is in a large pegmatite dike, which dips 80° S. 80° W. Here there is an irregular quartz vein on the hang- ing wall of the dike, which is rather strongly mineralized. Right on the contact with the country rock there is considerable pyrite, with an occasional grain of chalcopyrite. Just below the pyrite, and in part mingling with it, is a two-foot quartz-muscovite band in which most of the molybdenite of the vein occurs. The molyb- denite is closely associated with bunches of very dark-colored mus- eovite, and the latter will undoubtedly be a drawback to the eco- nomical concentration of the ore. Nearly all the molybdenite is in large flakes or thick grains. The largest flake that the writer measured had a surface area about the size of a silver half-dollar: The grains are scattered very irregularly through the vein, giving a succession of rich pockets and barren places. On this account MONTEZUMA DISTRICT 97 it is impossible to get a fair sample of the ore without breaking and erushing a large amount. The whole vein will probably not assay more than 0.5 per cent MoS,. But by rought hand-sorting a 1 or 2 per cent product could easily be secured, and a better grade could be made if necessary. This vein has been followed for about 1,000 feet on the surface. There are several other small veins on the claim, but they do not amount to much. DEVELOPMENT There has been little work done on this ground. On the Sala- mander vein there is a 20-foot drift. About 100 feet west of the main vein another drift has been run 40 feet on a pegmatite dike, which strikes 7° 15’ EK. This is believed to cross the main vein. A few other shallow holes have been dug, but they are unimportant. There are very good opportunities for developing any veins that may be found, for there is a range in elevations of more than 2,000 feet on the slope of Quandry Mountain near these deposits. There is no serviceable timber within a distance of about a mile, and until a trail or road is completed to the property it would be a very difficult matter to get timber to the claims. An aburidanece of water can be had from Monte Christo Creek, a few hundred feet below the claims. Although the ore shows on the face of vertical cliffs, through which the veins have cut, it is not believed that the present out- erops and the exposed surfaces in the two short drifts allow a fair estimate of the extent and value of the ore bodies, and more work should be done to determine them. It is unfortunate that there is so much copper with the molyb- denite, for its presence undoubtedly will act against the sale and development of the property, although it can be removed chemically, and possibly mechanically, if the ore is ever concentrated and reduced. MONTEZUMA DISTRICT Messrs. John Sullivan and Clyde Drolsdraugh, of Montezuma, have a molybdenite property on Glacier Mountain, about two miles from Montezuma. The claim is reached by a trail from Montezuma. The altitude at the property is 11,700 feet. One 10-foot shaft, 10 feet wide, has been sunk on the deposit. The country rock is hornblende gneiss. This is cut by quartz vein- 98 MOLYBDENUM DEPOSITS OF COLORADO lets which contain serpentine stringers that run out into the gneiss. Some rich and some lean pockets of molybdenite occur in the quartz and serpentine stringers, but there is no regular occurrence of the ore. The vein walls are not well’marked and the deposit is not at all promising. The ore cannot be traced on the surface of the ground, and it has been found only at one exposure. Other Localities Molybdenite in very small amounts has been found on Lenawee Mountain, near Montezuma. It has been erroneously reported from the Arabella or Star Mine. UNEVA LAKE According to newspaper reports, molybdenite has been found near Uneva Lake, in Summit County. The Colorado Geological Survey has not yet been able to substantiate the report. TELLER COUNTY Mr. Lafe Fyfe, of Cripple Creek, has located molybdenite near Dome Rock, a few miles north of Cripple Creek. There are no well-defined veins here, but only occasional string- ers of quartz in the coarse-textured, red, ‘‘Pike’s Peak’’ granite, which contain some well-secattered flakes of molybdenite. The de- posit is not believed to be valuable. Mr. William Smith, of Cripple Creek, has a molybdenite claim 2 or 3 miles due north of Pike’s Peak, about 150 feet from the automobile road. Molybdenite occurs as coarse flakes in a small quartz vein, which cuts the ‘‘Pike’s Peak’’ granite. Samples of this ore assayed less than 1 per cent of MoS,, and as the size of the deposit is small, it is not regarded as valuable at this time. AREAS IN COLORADO WHICH SHOULD BE PROSPECTED Molybdenite is known to oceur in commercial quantities only in igneous and metamorphic rocks, or in contact deposits on the borders of igneous rocks. Therefore it is useless to look for this mineral in Colorado except in the areas indicated on the accom- paning map. AREAS IN COLORADO WHICH SHOULD BE PROSPECTED 99 Granite intrusions and pegmatite dikes are particularly likely to contain molybdenite, and the borders of all such masses should be prospected. Other intrusions of acidic igneous rocks, such as rhyolites, trachytes, acid porphyries, syenites, etc., may also con- tain deposits of molybdenite. Basalts and other basic rocks are not likely to contain molybdenite, except as there may be deposits on the contacts of these rocks and younger acidic intrusives. Sand- stones and other sedimentary rocks are unlikely to contain molyb- denite unless they are cut by acidie igneous rocks. There seems to be a rather widespread, erroneous impression among prospectors that molybdenite occurs only at high altitudes and that the ore does not extend to any considerable depth. There are no known grounds for such beliefs. It is true that many, although by no means all, molybdenite deposits in Colorado are located at high altitudes, but this is undoubtedly due to the fact that prospecting for molybdenite is a new industry, and it is much easier to find outcrops above timber-line than below. There are no very deep molybdenite mines yet, but, again, the industry is young. In the Winfield District a large quartz vein, which contained con- siderable molybdenite, was cut in the Banker tunnel at a depth below the surface of more than 1,000 feet. Pegmatite dikes are known to extend to a great depth, and there are good reasons to believe that molybdenite ‘‘goes down.’’ There are, of course, some deposits where the geological conditions indicate shallow depths of the ore, but usually they can be readily recognized by the geologist. The regions of acidic igneous and metamorphic rocks in Colorado should be thoroughly prospected, and particular attention should be given to old dumps and prospect holes, for until recently molybdenite has not been a well-known mineral, and doubtless it has escaped the attention of many prospectors and mine owners. + wWHWSvYYuGa3aINn Bulletin 14, Plate II aie ALE i HET Eg \) be prospected for molybdenite. pproximately 80 miles. 4 Gi a bs rai Te : ie i tt on Le oF a AT Scale, 1 inch equals a The shaded areas should TE te rae NY ee ' : 5 | i JS (" (Peis wae Colorado Geological Survey CHAPTER VI CONCENTRATION, REDUCTION, AND ANALYSIS OF MOLYBDENITE ORES CONCENTRATION For many years the problem of concentrating molybdenite ores was regarded as a difficult one. That it is not difficult for the modern mill man is well demonstrated by the processes now in operation. There are of course certain details yet to be over- come, such as the complete separation of molybdenite from the other metallic sulphides, pyrite and chalcopyrite, etc.; but the problem is by no means insurmountable and many mills are pro- ducing a good grade of concentrates, efficiently and econom- ically. Horton’ has discussed this subject fully and the reader is referred to his article or to others on the same subject in the bibliography. Only a brief account of some of the recent devel- opments in the industry will be given here. Australian Methods In Australia? most of the methods of concentrating the ore are crude and inefficient. The ore is hand picked; or crushed and sereened dry; or crushed, rolled and screened, and treated on Wilfley tables. Some of the larger mines now have oil flotation plants of small capacity, the largest reported by Mr. Andrews being that of the Whipstick? plant, which has a capacity of 25 tons of ore per day of 3 shifts. ‘*The ore at the Whipstick Mine contains bismuth. It is crushed by stamps to 20 mesh. The pulp is passed over Wilfley tables and the bismuth is recovered as a salable concentrate, while the molybdenite goes off as middlings and is carried by launders to a settling pit from which it is elevated 1Horton, F. W., Molybdenum: Its ores and their concentration. U. 8. eeu Se es Bull. 111, pp. 91-120. ws } outh Wales Department of Mines, Geol. Survey, Min. Res., No. 24, 1916, pp. 4-13. 2Andrews, Eee Cs 0c) cit.. pp. 110-11. 4Extracted freely from Mr. Andrews’ report. 102 MOLYBDENUM DEPOSITS OF COLORADO to a conical tank. The sand is drawn off from the bottom of the tank, and the molybdenite is carried by water to the mixer of a 12-inch unit of a mineral separation plant. The mixer has hori- zontal rotating blades which agitate the pulp. About three-quar- ters of a pound of oil per ton of ore is dropped by a drum into the mixer. The pulp passes from the mixer into Separator No. 1, in which part of the molybdenite rises as a froth and is washed out into setthng and dewatering tanks. The sands from No. 1 are. drawn by suction into Separator No. 2, where the frothing is con- tinued as in No. 1, and so on through 6 separators. The finished product varies from 82 to 90 per cent molybdenite. Methods Used in Norway In Norway the Elmore vacuum flotation process is the one universally used. This process’ is said to be very applicable to molybdenite ores and a 90 per cent MoS, extraction is made with one operation. Mr. Elmore?’ gives the principles on which the process is based, as follows: The process is based primarily upon the fact that, in a flowing pulp of crushed ore and water, oil has a selective action for the metallic mineral particles as distinct from the rocky particles or gangue. This selective action is materially increased in some cases by the presence of an acid; and secondly, upon the fact that the air or gases dissolved in water are liberated, partially or entirely, upon subjecting the same to a pressure less than that of the surrounding atmosphere. These liber- ated gases may be augmented by the generation of gases in the pulp or by introduction from an external sources. The gases attach them- selves to the greased mineral particles, and being largely increased in volume as a result of the partial vacuum applied, cause the greased par- ticles with their attendant bubbles of air or gas to float to the surface of the liquid. Canadian Methods In Canada several concentrating methods are in use. The Elmore vacuum flotation process is used by the Renfrew Molyb- denum Mines, Limited. They had in 1916 a single unit which treated 30 to 40 tons of 1 per cent ore daily and gave an 80 per cent concentrate. 1Elmore, A. S., Vacuum-flotation process for concentration. Eng. and Min. Journal, vol. 83, No. 19, 1917, pp. 908-909. 2Elmore, A. S., loc. cit., p. 908. 3Mackenzie, Ge C., The mining and metallurgical treatment of mmely boeg num ores in Canada. Trans. Royal Can. Inst., vol. XI, pt. 2, No. 26, p. 282. CANADIAN METHODS OF CONCENTRATION 103 The Dominion Molybdenite Company' at Quyon uses the Callow pneumatic flotation cells and is said to be making a very complete recovery from ore which carries between one-tenth of 1 per cent and 20 per cent of MoS,. There is much pyrite and. pyrrhotite in this ore. In 1916, 5,000 tons of this ore averaged 1.7 per cent Mos,. The International Molybdenum Company, at Orillia, Ont., mines, concentrates, reduces and refines its own ore, making ammonium molybdate, molybdenum trioxide and ferro-molyb- denum. The company has a water flotation® plant designed by Mr. G. P. Grant which is said to concentiate ore that carries less than 1 per cent MoS.,, and in one treatment make a 70-80 per cent molybdenite concentrate. The process is described as follows: The ore after passing through a gyratory crusher is ground by rolls. The crushed ore is fed dry to a drum revolving in water at the head of a float. A large percentage of the sulphides, including almost all the molybdenite, is thus floated. The stream passes down a gently inclined box 12 feet long. The iron sulphides are carried along with the molybde- nite until they strike baffle boards, which help to sink them. The baffles are vertically placed boards over the edge of which the water carries the molybdenite. They interfere very little with this mineral, but cause sink- ing of the other minerals. No acids or oils are used in the process. The sulphides float readily on water and the baffles sink the undesirable ores, leaving the molybde- nite. The plant can treat about 50 tons in 12 hours. The Mines Branch, Department of Mines, at Ottawa‘ has successfully used the Wood film water flotation machines. Between the time of installing the machines in 1916 and Oct. 2, 1917, the Mines Branch treated ‘‘3,612.9 tons of various mo- lybdenite ores containing an average of 2.125% of molybdenite,’’ and made a recovery of ‘‘82.8% of the original molybdenite con- tained in the ore.’’ This process is regarded by Mr. Mackenzie as particularly satisfactory when mixed sulphides such as pyrrhotite, pyrite, chalcopyrite and molybdenite are to be treated. However, the ore must be very carefully dried, in order to prevent oxidation and the consequent loss of molybdenite. 5, March 1, 2Mackenzie, GaGs, loc cits parc sis 3The concentration of molybdenite by flotation. Can. Min. Journal, vol. Bi NOw!o) Oct. 1 1906; po 460. 4Mackenzie, en c.. The concentration of molybdenite. Can. Min. Journal, vol. 38, No. 20, 1917, pp. 402-403. 1Molybdenite from Quebec. Can. Min. Journal, supplement vol. 39, No. 8. 104 MOLYBDENUM DEPOSITS OF COLORADO The staff of the Department of Mining Engineering of the University of Toronto’ has perfected a water flotation process for concentrating molybdenite. They crush the ore wet to 10 mesh or less and consider it advisable to split the pulp at 60 mesh, and treat the coarse and fine on separate machines. The machine consists mainly of a piece of sheet iron bent into a section of a cone. The lower edge dips into still water in a V-shaped tank. The pulp is fed from a small orifice on to the bent sheet iron and flows down and spreads out over it. The result is a gentle wave action. Between the crests of the waves the pulp layer is very thin and the surface film very much stretched. The result is that the less wetable minerals break through, are picked up by the crest of the next wave and are carried down to the still water, where they float. Here a gentle jet of air keeps them traveling towards the overflow and takes them out of the way of fresh comers. The thickness of the pulp, the steepness of the plate, the surface tension of the water as affected by modifying agents, are all easily con- trollable means of affecting the cleanliness of the float, and it is possible to make a very clean separation of different sulphides. Generally several trips have to be made over the plate, in order to make complete savings. Also it may be necessary to slightly roast the concentrates from the third and fourth trips, to oxidize the iron or copper pyrites, but the selective action of the flotation process is claimed to be so sensitive that this can be done without danger of losing the molybdenite. Mica, if present in considerable amounts, renders the ore very difficult to treat -by this process, although small amounts are said not to be harmful. The authors state that: The chief advantages of this system lie in its: extreme simplicity and the high grade of concentrates produced. In many cases no re- treatment of concentrates or middlings will be required. When this is necessary the amount to be so treated is very small and the operation simple and effective. The ore can and should be crushed wet, and fine screening is eliminated, so that the mill would be of the simplest type. In dry crushing molybdenite is smeared on other particles, causing them to float by reason of this partial coating. In wet crushing this apparently does not occur. : United States Methods In the United States as in Canada several methods are in use for concentrating molybdenite ores. Nearly all are now based on some form of oil flotation, although water flotation is used in some eases. 1Haultain, H. E. T., Dyer, F. C., King, J. T., The concentration of molyb- denite ores. Can. Min. Journal, vol. 38, No. 13, 1917, pp. 270-271. UNITED STATES METHODS OF CONCENTRATION Pat05 The Henry E. Wood Ore Testing Company, of Denver, con- tinues to use the Wood water flotation machine? with success. Mr. Wood stated in a conversation with the writer that he was consistently making better than a 90 per cent concentrate with this machine and that ores containing mica or pyrite were handled without difficulty. The Primos Chemical Company is using an oil flotation proc- ess in its mill at Urad, near Empire, Colorado. The Climax Molybdenum Company, the largest operator in Colorado at the present time, as stated in another part of this report, uses successfully both the Janney and Callow cells. For details of operations see pages 92 and 93 of this report. The Phoenix Works, of Denver, use a standard Ruth flota- tion cell, and a solution the composition of which is kept secret. The ore is crushed wet in a Denver Engineering Works ball mill, to 60 or 70 mesh, and fed directly to the Ruth cell. Mr. Candlish, the manager of the plant, states that practically all the iron and mica, in ores containing these minerals, are separated from the molybdenite, and that a high-grade concentrate is obtained. The capacity of a single unit of this machine is said to be approximately one ton per hour. The Molybdenum Products Corporation, whose property is at Climax, has operated a K. & K. oil flotation plant for about two months on the Bartlett Mountain ore. The work so far has been largely of an experimental nature and no figures of the sav- ings, cost of operation, etc., are yet available. The Pingrey Mines and Ore Reduction Company, of Lead- ville, treated 1,000 tons of the Bartlett Mountain ore by oil flota- tion, and this company contemplates the erection of a new oil flotation mill. Other companies in this state have milled some molybdenite ore, but not, so far as is known, on a commercial scale. The literature, in which the molybdenite concentrating plants of the United States are described, seems to be very meager. Hess? has described the method of treating molybdenite ore at Cooper, Maine, in use 10 years or more ago. 1For a full description of this process see: Wood, Henry E., The Wood flotation process. Trans. A. I. M. E., vol. 44, 1912, p. 684 et seq., or Agr. M. BE. Bull. 71, 1912, pp. 1227-1244. 2Hess F Fe Some molybdenite denosits of Maine, Utah and California. U. S. Geol. Survey Bull. 340, 1907, p. 233. 106 MOLYBDENUM DEPOSITS OF COLORADO It is understood'that a 50-ton flotation plant is in operation near San Diego, California, to treat the low-grade (1 per cent or less) ores of that region. Utah, Montana, Arizona and New Mexico are also said to have concentrating plants, but detailed information concerning them has not been available to the writer. The practices adopted in Norway, Canada and Colorado have been perfected to such an extent that it is safe to say that most molybdenite ores can be concentrated successfully. There are many details, however, still to be worked out. No single process is adapted to all ores, for each deposit has its own peculiar characteristics of gangue, country rock and ore. Oil flotation seems to be well suited to most finely granular molybdenite ores, although a special treatment of the concen- trates to eliminate iron, or iron and copper sulphides, will have to be undertaken in many eases. Probably all the larger low- gerade ore bodies in Colorado will be treated in this way. Where the ore bodies are small and relatively inaccessible, and particularly if such bodies contain coarse flakes of molybde- nite, it is probable that some simple form of water film flotation ean be used with success. Such methods are particularly: desir- able in cases where the size, or the state of development of the property, does not warrant the construction of a large, expensive mill, and yet on account of transportation difficulties it is desir- able to concentrate the ore. THE REDUCTION OF MOLYBDENITE CONCENTRATES Molybdenum is placed on the market, after being reduced from molybdenite concentrates, in four forms, ammonium molyb- date, molybdie oxide, metallic molybdenum, powdered of sin- tered, and ferro-molybdenum. Ammonium molybdate is produced by roasting the sulphide and leaching the mass with ammonium hydroxide. The oxide is produced by evaporating an ammonium molyb- date solution to dryness, and igniting the crystals to drive off the ammonia. Powdered molybdenum is produced by roasting the sulphide, and reducing the oxide, with carbon in an electric furnace. The metal takes up carbon, but by adding more molybdic oxide a very pure powder is obtained. 1Min. and Sci. Press, vol. 113, Nov. 4 ,1916, p. 667. ANALYSIS OF MOLYBDENUM ORES 107 Humphries: has described a method for making metallic mo- lybdenum rods. The following statements are extracts freely taken from his paper: Metallic molybdenum is produced in the electrie furnace from molybdenite or preferably from ammonium molybdate or molybdenum trioxide. The trioxide or molybdate is heated in an electric furnace in a hydrogen atmosphere and a erystalline product is produced. This is placed in a nickel or nickel-plated boat and heated in a gas furnace to 900 degrees or 1,000 de- grees C. ‘Then it is crushed, screened and reduced for several hours. It is examined for oxide, and if any is present it is again reduced, at a temperature of 1,400 degrees C. But there is danger of contamination with iron if a nickel-plated iron boat is used. After the oxide has been removed the metal is powdered, pressed in a steel mold and again heated in the electric furnace at a temperature of 1,200-1,300 degrees C. It is then placed in a furnace, the air is removed and a current of 100 amperes passed through the metal, which shrinks and forms a molybdenum rod. If it is to be used for rods, wire, filament, ete., it is swaged hot from the electric furnace by running the metal through dies of high-speed steel. The pure metal can be made gelass-hard by heating to 1,200 degrees C. and quenching several times. Ferro-molybdenum is made by heating the raw or roasted ore in the electric furnace with some fiuxing or desulphurizing agent such as lime. Ferric iron is added and the mixture heated in the furnace. Ordinarily the product contains from 5 to 10 per cent of carbon, which can be removed by adding the proper amount of molybdie oxide. Usually the marketable product contains about 80 per cent molybdenum, although in some cases the percentage is as low as 20. Formerly a 90 per cent MoS, concentrate was de- manded by the ferro-molybdenum manufacturers, but this is no longer required and a 70 or 80 per cent concentrate is more com- monly used. Ferro-molybdenum has a melting point several hun- dred degrees lower than that of metallic molybdenum, hence its demand for use in the steel industry. THE QUANTITATIVE ANALYSIS OF MOLYBDENUM ORES There are several good methods for the determination of molybdenum in ores. 1Humphries, C. H., Preparation of Pure Molybdenum. Min. and Sci. Press, vol. 114, 1917, p. 912. 108 MOLYBDENUM DEPOSITS OF COLORADO When vanadium, phosphorus and arsenic are absent and the molybdenum content is known to be low the following method has been found practicable: Fuse 2 grams of the sample with about 10 grams of Na2Os2 in an iron crucible (bring to quiet fusion). Cool and dissolve in cold water. ‘Trans- fer the mixture to a 500 c.c. flask, bring up to the mark, shake well and permit residue to settle (about 30 minutes). Decant 250 c.c. of the solution through a filter into a 250 c.c. flask and after bringing up to the mark transfer it to a 450 c.c. beaker. Add 30 c.c. dilute HeSO: (1-1) and run solution through a Jones zine reducer attached to a water pump. : Titrate reduced solution with KMnO:s. The Fe standard multiplied by .2871 equals Mo. The Davist method, which was devised for wulfenite ores, gives good results and it is also applicable to molybdenite by simply omitting the first two paragraphs of the process if lead is not present in the ore. A statement of this method follows: The wulfenite ores found in the southwestern states and Mexico usually contain more or less tungsten and vanadium, and as these ele- ments exert a decided infiuence on the metallurgical process of extrac- tion, a practical method of analysis of such ores was devised by the writer. Pb.Mo.V. Treat 1 gram of agate-ground sample with 10 ec. HCl and 5 c. c. HNO,, warm on hot plate and after the action has somewhat subsided add 10 ec.c. HeSO: and evaporate to strong sulphuric fumes. Cool somewhat, dilute and heat until all is in solution except the lead sulphate and silica. Filter into a pressure bottle (a citrate of magnesia bottle with patent clasp stopper is well adapted for this purpose), washing with HO containing a little HeSO:. Dissolve the lead sulphate in hot ammonium acetate and acetic acid, filter from SiO», washing well with hot ammonium acetate solution, and estimate the lead by titrating with ammonium molybdate. If desired, one may add a large excess of sul- phuric acid to the lead acetate solution, boil, add alcohol and determine the lead gravimetrically as PbSo:. Pass H2S into the filtrate in the pressure bottle for about 15 minutes, then stop the bottle, place in vessel of warm water and heat to boiling for about 20 minutes. If the amount of MoSe is small, and a preliminary test has shown copper to be absent, collect the precipitate in a Gooch crucible, dry and ignite gently until there is no more SOz odor, then heat to faint redness and weigh as MoO,, containing 66.57 per cent Mo. If this MoO; is not entirely soluble in ammonia the residue should be deducted. It is safer, however, especially if there is much Mo., to proceed as follows: Dissolve the MoSz in HNOs, evaporate in a casserole to dryness, then ~ heat over a wire gauze to remove all HeSO:. Add 5 ec. ec. ammonia and warm until the MoO, is all in solution (if copper is present use KOH in- 1Davis, R. S., Notes on technical analysis. Metallurgical and Chemical Engineering, vol. 9, No. 9, 1911, pp. 458-459. ANALYSIS OF MOLYBDENUM ORES 109 stead of NH:OHs, dilute, boil, filter off the cupric oxide and estimate the copper by any convenient method). Filter if necessary, acidify with acetic acid, boil and add excess of lead acetate. Filter and wash the precipi- tate with hot ammonium acetate solution to remove any trace of PbSO,, then with hot water, ignite gently and weigh as PbMoO: containing 26.15 per cent Mo. The writer has not had much success in estimating Mo. by the Zn. reduction processes excepting When very little Mo. is present. Boil the filtrate from the MoSe, which will be green or blue if vana- dium is present, to remove the HeS. Then add KMnO, to a pink color. The amount of standard permanganate used will give some indication of the amount of V. present plus Fe. Add an excess of KMnOs: and boil at least 5 minutes. Then add ferrous ammonium sulphate until the MnOz is dissolved and the liquor is clear and boil 5 minutes longer. Cool to about 70 degrees C., add KMnO: to a pink color, then run in ferrous ammonium sulphate until a ferri-cyanide spot shows an immediate blue color. Titrate back with standard KMnO: until the spot shows no color in 30 seconds, read the burette and run in permanganate until pink color is obtained which persists one minute. The iron value of the perman- ganate times 0.9159 gives the vanadium value. If the quantity of vana- dium is so small as to make its presence doubtful it is well to add H2O2 to the solution after titrating. This destroys the permanganate color and shows as little as .05 per cent. vanadium by the characteristic red- brown tint. The amount of iron present is approximately shown by deducting the permanganate used in the vanadium titration from the amount re- quired to oxidize the iron and vanadium above. WOs and SiO» are best determined in a separate sample. Treat one gram of ore with 20 c. c. HCl and evaporate to dryness. Add 10 e. ec. HCl and about 100 c. c. H2O and bring to boiling. Filter and wash by decantation with hot dilute HCl until all PbCl: is removed. Add 10 e. ec. dilute ammonia containing a little NH:Cl to the beaker containing the WOs and SiOz and allow to stand about five minutes, and pour on to the filter, receiving the filtrate in a platinum dish. Wash 4 or 5 times, using about 2 c. c. ammonia, wash solution each time. Evaporate to dryness, ignite gently until NH: salts are volatilized, then at moderate red heat. Do not heat excessively, as WO: can be slowly volatilized with a strong Bunsen flame. Add a few drops HF and a drop H:SO:, evaporate, ignite and weigh. Determine SiOz in the residue by loss with HF, and add to this any silica found with the WOs. The following is the U. S. Bureau of Mines method! which is used for ores that carry no tungsten and not more than traces of arsenic or antimony. Digest the sample of ore—from 0.2 gram to 5 grams, depending upon its seeming richness—with 25 to 35 ec. ec. of fuming nitric acid in an Erlenmeyer flask for three hours and finally evaporate to dryness. Add 1Horton, F. W., Molybdenum: Its ores and their concentration. U. S. Bureau of Mines Bull. 111, 1916, p. 44. 110 MOLYBDENUM DEPOSITS OF COLORADO 9 3c. e. of concentrated sulphuric acid to the residue and heat until dense white fumes are given off in quantity. Cool, dilute to 100 c. ec. and filter. Wash the residue with water, allowing the wash water to run into the filtrate. Wash the residue well with diluted ammonia, (1-3), and then with water. Make the filtrate alkaline with ammonia to precipitate the aluminum and any iron present in the original mineral. Heat, filter and wash well with hot water. Saturate this alkaline filtrate with hydrogen sulphide to a bright cherry-red color. Filter and wash with hot water. Acidify the filtrate with hydrochloric acid until slightly acid and digest until the precipitated sulphide and sulphur are well coagulated and the excess hydrogen sulphide expelled. Filter on a weighed Gooch crucible. Evaporate the filtrate to dryness in a casserole and drive off the ammo- nium salts at the lowest possible temperature, being careful not to heat the casserole to redness at any time. Take up the final residue with about 100 ¢c.c. of water to which 5 c.c. of ammonia has been added. Add 10 c.c. of ammonium sulphide, make faintly acid with hydrochloric acid and digest until the sulphide is coagulated. Filter this on the Gooch crucible used for the previous sulphide filtration. Add an amount of sulphur to the combined sulphides equal to about one-half their weight and ignite over a Bunsen burner at a dull-red heat in a stream of arsenic- free hydrogen for ten minutes. The ignition may be accomplished by using a Rose crucible cover and tube over the Gooch crucible. Weigh and repeat the ignition as before, until check weights are obtained. The weight obtained is the weight of molybdenum disulphide. CHAPTER VII THE USES, SUPPLY AND DEMAND, MARKET AND PRICES OF MOLYBDENUM THE USES OF MOLYBDENUM There is a wide difference of opinion, which finally resolves itself into a question of fact, regarding the uses of molybdenum. It seems evident that suggested uses, or uses that have been advocated after some experimentation, have been confused with actual com- mercially adopted practices in the use of this metal. In other words, molybdenum may be adopted for many purposes where it is not now used. It is extremely unfortunate that this confusion of state- ments has arisen, for it has already reacted, and probably will in the future react, to the disadvantage of many prospectors and investors, who have been led to believe that the uses of molybdenum are now so numerous and the demand is so great that the market can absorb all that is supplied, even at a relatively high price. The following lists indicate the commonly stated uses of molyb- denum. The authors of the papers in which these statements appear are given, not with the idea of drawing any individuals into the conflict of diverging opinions, but simply to give the authority and reference for each statement, in case anyone wishes to go into the matter further. Particular attention is called to the statement of Mr. Hess, which should probably be taken as an antidote for some of the ultra-optimistie statements of certain other writers. Mr. Horton’ gives the following uses of molybdenum : The principal use of molybdenum is in the manufacture of alloy steels, to which, particularly in conjunction with chromium, manganese, nickel, cobalt, tungsten, and vanadium, it imparts many desirable prop- erties. These steels are used for a large variety of purposes, such as for crank-shaft and propeller-shaft forgings, high-pressure boiler plate, guns of large bore, rifle barrels, armor plate, armor-piercing projectiles, permanent magnets, Wire, and for self-hardening and high-speed machine tools. Metallic molybdenum is used in various electrical contact-making 1Horton, F. W., Molybdenum: Its ores and their concentration. U. S. Bureau of Mines Bull. 111, 1916, p. 20. 112 MOLYBDENUM DEPOSITS OF COLORADO and breaking devices in X-ray tubes, and in voltage rectifiers, and in the form of wire for filament supports in incandescent electric lamps, and for winding electric resistance furnaces, and in dentistry. Molybdenum is also employed in the manufacture of chemical reagents, dyes, glazes, dis- infectants, etc. The following is an abstract of the list of ‘‘uses of molyb- denum’’ given by Mr. Andrews :! ‘“Blue pigment, used to color porcelain and as a dye for silk and woolen goods, and to color various leathers and rubbers.—To detect phosphorus in the manufacture of steel.—F or fire-proofing.— As a disinfectant for cloth used in passenger railway cars.—Molyb- denum compounds are used to form stabilizers for high explosives, to prevent deterioration and premature explosion. The great use, however, to which molybdenum is put is in the manufacture of certain steels, as a substitute for tungsten, especially in self-harden- ing steels, in armors, guns, and other steels needing tenacity and hardness. Molybdenum steel is also much used for rifle barrels, propeller shafts, heavy guns, armor plates, are-lamp electrodes, and in the production of other materials. Huropean armor plates are said to contain up to 2 per cent. molybdenum. If molybdenum could be procured in large quantities it would be much in demand for steel casting for railroad work.’’ Mr. Fleck? gives about the same list as is found above. The following is an abstract of his statement regarding the uses of molybdenum : Ammonium molybdate is used as a laboratory reagent in the deter- mination of phosphorus in iron ore, their products, and in fertilizers. Fire-proofing fabric, self-hardening steel, large castings, gun barrels, to prevent corrosive gas action; armor plate; armor-piercing shells (the last two uses contradicted in United States); motor-car steel; magnets; wire for electric furnaces, thermo-couples; coloring agents for leather, rubber and porcelain, preservative for smokeless powders. Mr. Hess* has the following to say about the uses of molyb- denum : The actual uses as now developed for the metal are small. In this country the use of molybdenum in tool steels, according to reports re- ceived by the Geological Survey from various sources, has decreased. A small quantity is used in electric work, for supports for tungsten fila- 1Andrews. E. C., The Molybdenum Industry in New South Wales. N. S. Wales Department of Mines, Geol. Survey, Mineral Resources No. 24, 1916, ae We ; 2Fleck, Herman, Molybdenum. Proceedings of the Colorado Scientific Soc., vol. XI, 1516, pp. 134-135. 3Hess, F L.. Molybdenum U. S. Geol. Survey, Mineral Resources for 1915, Pt. 1, Metals, 1917, pp. 808-809. . USES OF MOLYBDENUM 113 ments in incandescent lamps, in Roentgen ray apparatus, and in small resistance furnaces; a number of tons of ore is consumed in making am- monium molybdate for use in chemical work; and a little is used in some stellite; but outside of these practically no uses are known. Efforts have been made to use the blue oxide in dyes, but the process is not known to have been adopted on a commercial scale, although stated in certain papers as a prominent use. Statements that molybdenum is used in smokeless powder, gun steels, and armor plate are constantly reiterated and as positively denied. Abroad molybdenum is apparently used in steel much more than in this country, and it is commonly accepted that the decided rise in prices was caused by German buyers taking available supplies a few months before the beginning of the war. French and English steel makers are apparently now using the metal to some extent. It is probable that small amounts of molybdenum are used in the breech-blocks of large guns, in crank shafts of certain engines, in some stellite' and in certain parts of the new Liberty motors. It, is said that from 114 to 3 per cent molybdenum in steel is more beneficial than larger amounts. It is a common statement that from 3 to 5 per cent of molybdenum is used in the heavy German guns. But Howe? in a recent paper on the erosion of guns found no molyb- denum in the steel taken from two captured German guns, and he shows that the possibilities of reducing the erosion of guns by adding molybdenum are not encouraging. The substitution of molybdenum for platinum has been sug- gested, and Fahrenwald,’? in an extremely interesting paper, con- eludes the statement of his results respecting the experiments with molybdenum as follows: The second part (of the experimental work) develops the fact that, except in two respects, pure ductile tungsten, and, to a lesser degree, molybdenum, meet all of the specifications of a practical substitute for platinum and its alloys. These two defects are its ease of oxidation, and the difficulty with which it can be soldered, and they have been over- come by coating with a precious metal or alloy, the resulting material being in many ways far superior to platinum or its alloys. This material has met with instant demand, is in many cases replac- ing the best platinum-iridium alloys, and permits the performance of work which has been impossible with the materials hitherto available. He concludes his paper with the suggestion that the methods introduced for treating tungsten and molybdenum may be applied 1Haynes, Elwood, Alloys of Cobalt with Chromium and other metals. Trans. A. I. M. B., vol. 44; 1912, pp. 576-577. 2Howe, Henry M., The Erosion of Guns. Bull. of the A. I. M. E, No. 134, Feb., 1918, pp. 386-387. 3Fahrenwald, Frank Alfred, A development of practical substitutes for platinum and its alloys, with special reference to alloys of tungsten and molybdenum. Bull. A. I. M. EB. No. 109, Jan., 1916, p. 148, or Trans. A. I. M E., vol. 54, 1916, p. 586. 114 MOLYBDENUM DEPOSITS OF COLORADO to the “‘treatment of such metals as iridium, tantalum, rhodium, osmium, ete., in combination with each other, or with tungsten or molybdenum, which may result in the production of alloys possess- ing properties far superior to those of any material now available.”’ Haynes' states that if molybdenum is added to a cobalt- chromium alloy in which chromium forms 15 per cent of the whole mixture, the hardness of the alloy increases with the increasing amount of molybdenum, until the latter reaches 40 per cent. The resulting mixture scratches glass, takes a fine polish, and resists acids. An alloy composed of 25 per cent molybdenum, 15 per cent chromium, and 60 per cent cobalt has the properties just given; it ean be cast but not forged; it takes a strong, keen edge and makes fine cutlery. Tungsten also is used with chromium and cobalt. The stellite on the market is much used for “‘high-speed’’ tools. The experiments that have: been made with molybdenum and its alloys by Fink, Fahrenwald, Haynes, and many others are encouraging. It is persistently reported that two of the leading automobile manufacturers of this country are now buying large quantities of molybdenite concentrates, and that, if the tests they are now making prove satisfactory, they will require many thousand pounds of» molybdenum every year. In view of all the experiments that have been made, it seems probable that sooner or later a much greater demand for molyb- denum may be expected. But at the present time the experimental stage has not been passed and there are no commercial uses for very large amounts of molybdenum. SUPPLY AND DEMAND It is evident that no large tonnage of molybdenum can be absorbed by the world’s market, except as it is used in the manu- facture of molybdenum steel. Much has been written about the necessity of developing ade- quate supplies of molybdenum before the steel manufacturer would give serious attention to its use on a large scale, and it has often been definitely stated that if the molybdenum resources were devel- oped and reserve supplies assured, the increased use of the metal would also be assured. It now remains to be seen whether or not 1Haynes, Elwood, Alloys of cobalt with chromium and other metals. Trans. A. I. M. E., vol. 44, 1912, pp. 573-577. MARKET FOR MOLYBDENUM 115 this prophecy is correct, for the resources have been developed and already a very large tonnage of concentrates is being placed on the market. It is estimated that with the present equipment Colorado alone can produce annually not less than 800 short tons of metallic molybdenum from the mines at Climax and Empire. Other small properties in the state would add a considerable amount to this tonnage. The data for Arizona’s production are not available to the writer, but it is probably safe to estimate the annual possible production from that state as not less than 400 tons. The other states of the United States, Australia, Canada, and Norway can certainly furnish at least 800 tons a year if it is required, thus making an estimated minimum immediate total production of 2,000 tons a year of metallic molybdenum. This is equivalent to 3,000 tons of molybdenum trioxide (MoO,), which is nearly equal to one-fourth the amount of tungsten trioxide (WO,) produced in the world in 1915,’ and it is nearly ten times the amount of molyb- denum produced during that year,? which was 222.6 short tons. It should be borne in mind that these figures are intended to give estimates of what may be produced, not what will be produced in any year in the near future. It seems to the writer very doubt- ful if the demand will meet the available supply for some time to come. At the same time the potential uses of molybdenum are so varied that it is entirely possible that new demands may be made for the metal at any time. Certainly it is the wise and patriotic thing to do, at this time, to prospect for, and develop, all the sources of supply. But the organization of companies for the production of molybdenum ores and concentrates should be done most conservatively with the facts clearly in mind that, even with entirely favorable conditions of mining and milling, and low total cost of production, there may be no immediate market for the product, and the venture, therefore, may not be a financial success. MARKET Molybdenite concentrates are sold with the metal values based on the MoS, content. Wulfenite concentrates are sold either on the basis of the molybdenum trioxide (MoO,) or the metallic molyb- denum (Mo) content. One part of molybdenum sulphide (MoS,) by weight is equivalent to 0.9 part of MoO,, and 0.6 part of Mo. iHess, F. L., Tungsten. U. S. Geol. Survey, Mineral Resources of the U. S. for 1915, Part 1, Metals, p. 827. 2Hess, F. L., loc. cit., Molybdenum, p. 810. 116 MOLYBDENUM DEPOSITS OF COLORADO Or one part by weight of Mo is equivalent to 1.5 parts of MoO,, and 1.67 parts of MoS,. While 90 per cent. MoS. concentrates are desired, they are no longer demanded. It is reported that 20 per cent MoS, concen- trates are salable when the market is short, and it is probable that for ferro-molybdenum a 70-85 per cent MoS, concentrate will eventually become the standard. The presence of pyrite, arsenic, bismuth, antimony, tungsten or copper is objectionable, and if any of these except pyrite occur in amounts of more than 1 per cent the difficulty of marketing the concentrates is very greatly increased. As the percentage of unde- sirable minerals increases, penalties also increase until they may become so high that the product is entirely unsalable. The market for crude ores is uncertain. So far as is known, S. W. Shattuck and the Henry E. Wood Company, of Denver, are the only molybdenum ore buyers in Colorado. Wilson! gives the following list of consumers of molybdenum in the United States and Canada: Baker & Adamson Chemical Co., Easton, Pa. J. T. Baker Chemical Co., Phillipsburg, N. J. Electro Metallurgical Co., Niagara Falls, N. Y. Foote Mineral Co., Philadelphia, Pa. General Electric Co., Schenectady, N. Y. Goldschmidt Thermit Co., 90 West St., New York City, N. Y. Grasselli Chemical Co., Cleveland, Ohio. Imperial Munitions Board, Ottawa, Ont. International Molybdenum Co., Orillia and Renfrew, Ont. Pfanstiehl Co., N. Chicago, Ill. Primos Chemical Co., Primos, Pa. S. Schaaf-Regelman, New York City, N. Y. David Taylor, Boston Bldg., Salt Lake City, Utah. Tivani Steel Co., Belleville, Ont. Henry E. Wood & Co., Denver, Colo. York Metal & Alloys Co., York, Pa. There are new brokers and users constantly coming into the market, whose addresses can be learned from the Mining Journals. PRICES It is obvious that the price of molybdenum will continue to be controlled by the supply and demand. Unless the metal is more 1Wilson, A. W. G., Molybdenum. The Mineral Industry for 1916, vol. 25, Uhl (s joe. Ble PRICES 117 largely used in the steel industry than at present, the price will probably settle down to what it costs the largest producers, plus a small profit. If new uses are found so that there is a strong de- mand for the metal, the price will be higher, and will probably be somewhere nearly the same as that of tungsten. The writer does not wish to appear pessimistic, but it is his opinion that the price of concentrates containing 70-85 per cent MoS, will probably soon be not more than $10.00 or $12.00 a unit, and that those companies which cannot produce the ore and concen- trates on this basis will be forced out of business, until such a time as a largely increased demand causes an increase in price. If this opinion is correct, only two classes of properties will be successfully operated. These are, first, very large low-grade properties, where a large tonnage can be handled with relatively low overhead ex- penses and where a small profit on a large tonnage will pay the interest on the original investment; second, high-grade properties, most of which will be small, that can produce rich concentrates at a low cost. Those deposits which contain injurious minerals, and those which are disadvantageously situated, will be unable to stand competition at the present time. Ball’ says: ‘‘No molybdenite mine should be opened unless a 90 per cent. concentrate can be produced for from $800 to $1,000 per ton. If the world’s production should suddenly increase, the price might temporarily fall even below the former figure, but probably would eventually exceed it. Ore occurring in fair amounts and carrying 2 per cent or even 0.5 per cent MoS., if all factors are favorable, can be profitably treated.’’ The writer is entirely in accord with this view and believes it highly desirable that a conservative view of the molybdenum indus- try be held by investors and companies organized to develop molyb- denite properties. This does not mean that prospecting should not be continued or that good prospects should not be developed. But certainly there should be long-time contracts or other reliable assurance of a mar- ket for the product, before new companies should be organized and highly capitalized, for the production of molybdenum in Colorado. Before 1915, European nations furnished the largest market for molybdenum and Horton? gives the following table to show the scale of prices for an eight-year period: 1Ball, S. H., Molybdenite hare its occurrences. Eng. and Min. Journal, vol. 104, No. 8, ‘Aug. 2D, 191-7, 334, 2Horton, Fr. Ww. VRS Its ores and their concentration. U. S. Bureau of Mines Bull. 111, 1916., p. 38. 118 MOLYBDENUM DEPOSITS OF COLORADO PRICES OF HIGH-GRADE MOLYBDENITE CONCENTRATES (90 TO 95 PER CENT MOS,) IN EUROPEAN MARKETS, 1908 To 1915 " Prices per Unit Prices per Unit of 22.4 Pounds Year of 20 Pounds Shillings LG O Si.esre ccaeterer-s - $6.50 to $7.60 30 to 35 MOOSE exten eee 5.65 to 7.15 26 to .33 OW O Srarenetets fortes 6.30 to 6.75 29 to 3 ONE es waretena sae 6:95 como eLO 32 to 42 MO OT craves eueneleks 7.15 to 11.95 33 to 55 TGS Pears stonete ae 10.90 to 18.50 50 to 85 NO MAES Sreresaiciers ns 19.50 to 31.50 90 to 145 1S Use Bienes ee ic 23.90 to 36.90 110 to 170 The New York prices for 1917 are given by the Engineering and Mining Journal.! The price per pound multiplied by 20 gives the price per unit for comparison with Horton’s table. PRICES OF 90 PER CENT MOLYBDENITE CONCENTRATES 1917 Month Price per Pound Month Price per Pound January $1.81 July 2.16 February 1.80 August 2.14 March 1.90 September 2.18 April 2.10 October 2.20 May 2.95 November 2.20 June 2.15 December 2.20 Prices for the first 6 months of 1918 were quoted by the Engineering and Mining Journal as follows: PRICES OF 90 PER CENT MOLYBDENITE CONCENTRATES 1918 January 19 $2.25 per pound. February 16 $2.15 per pound. March 16 Market demoralized, no buyers. April 13 Very dull, Great Britain, France and Italy out of the market. May 18 After a long period of stagnation. Some business done on $1.25 pound basis. June 8 $1.25 nominal quotation only. For concentrates containing less than 90 per cent. MoS., the price decreases on a sliding seale, and the whole molybdenum con- tent is not paid for, but a margin is left to allow the buyer to raise the grade of the material by retreatment. iEng. and Min. Journal, vol, 105, No. 2, 1918, p. 92. FUTURE OF THE INDUSTRY 119 THE FUTURE OF THE INDUSTRY From what has been said in the preceding pages it is evident that, at the present time, the outlook for a rapidly expanding in- dustry is none too bright. What the future has in store no one can say. It is the writer’s belief that the demand will increase slowly as successful metallurgical experiments develop new uses or im- proved uses for the metal. The price for some time to come will probably be considerably less than that of tungsten, and only those properties from which molybdenite can be produced at a low cost will be worked. 120 MOLYBDENUM DEPOSITS OF COLORADO BIBLIOGRAPHY The following list gives a working molybdenum bibliography. It is not exhaustive: ANDREWS, E. C. The molybdenum industry of New South Wales. New South Wales Department of Mines, Geological Survey, Min. Res., No. 24, 1916. BALL, S. H. -Molybdenite and its occurrences. Eng. and Min. Jour., vol. 104, No. 8, 1917, pp. 333-338. Extracts from the same. Am. Inst. Min. Eng. Bull., Nov. 1917, pp. XIV-XV. BROWN, A. P. The crystallization of molybdenite. Proc. Acad. Nat Sci., Philadelphia, 1896, pt. I, pp. 210-211. BROWN, H. L. and HAYWARD, M. W. Molybdenum mining at Climax, Colorado. Eng. and Min. Jour., vol. 105, No. 20, 1918, pp. 905-907. CALKINS, F. C. Molybdenite near Ramona, San Diego County, Cali- fornia. U. S. Geol. Survey Bull. 640-D, 1916, pp. 73-76. CALLOW, J. M. Notes on flotation. Trans. Am. Inst. Min. Eng., vol. 54, 1916, pp. 3-25. CLAUDET, H. H. Notes on molybdenum operations in Norway. Can. Min. Inst. Bull. 51, 1916, pp. 609-616. CLENNELL, J. E. Molybdenum in cyanide solutions. Eng. and Min. Jour., vol. 97, 1914, pp. 363-364. COOLIDGE, W: D. Some applications of wrought tungsten and molybdenum. Jour. Ind. and Eng. Chem., vol. 4, 1912, pp. 2-4. CROOK, A. R. Molybdenite at Crown Point, Washington. Bull. Geol: Soc. Am., vol. 15, 1904, pp. 283-288. DAVIS, R. S. Notes on technical analysis—analysis of wulfenite ores. Met. and Chem. Eng., vol. 9, 1911, pp. 458-459. ; DE LURY, J. S. Molybdenite at Falcon Lake, Manitoba. Can. Min. Jour., vol. 38, No. 23, 1917, pp. 460-462. DRYSDALE, C. W. Notes on the geology of the “Molly” molybdenite mine, Lost Creek, Nelson Mining Division. Can. Min. Inst. Bull. 43, 1915, pp. 872-880. ELMORE, A. S. Vacuum flotation process for concentration. Eng. and Min. Jour., vol. 83, No. 19, 1907, pp. 908-909. EMMONS, W. H. Some ore deposits in Maine and the Milan mine, New Hampshire. U. S. Geol. Survey Bull. 432, 1910, pp. 21, 42, 47-49. FAHRENWALD, F. A. A development of practical substitutes for platinum and its alloys, with special reference to alloys of tungsten and molybdenum. Am. Inst. Min. Eng. Bull. No. 109, 1916, pp. 103-149. FINK, C. G. Ductile tungsten and molybdenum. Trans. Am. Electro- chem. Soc., vol. 17, 1910, pp. 229-234. BIBLIOGRAPHY 121 FLECK, HERMAN. Molybdenum. Proc. Colo. Sci. Soc., vol. XI, pp 119-136. FRIEND, N. J., and MARSHALL, C. W. The influence of molybdenum on the corrodibility of steel. Jour. Iron and Steel Inst., vol. 89, No. 1, 1914, pp. 503-507. GLEDHILL, J. M. The development and use of high-speed tool steel. Jour. Iron and Steel Inst., 1904, No. 2, pp. 127-182. HAYNES, ELWOOD. Alloys of cobalt with chromium and other metals. Trans. Am. Inst.. Min. Eng., vol. 44, 1912, pp. 573-577. HESS, F. L. Some molybdenum deposits of Maine, Utah, and Cali- fornia. U.S. Geol. Survey Bull. 340, 1908, pp. 231-240. —— Our mineral supplies. The rarer metals. U. S. Geol. Survey Bull. 666-U, 1917, pp. 9-11. Molybdenum. U. S. Geol. Survey Mineral Re- sources for years 1906-1915 inclusive. Vanadium deposits near Placerville, Colorado. U. S. Geol. Survey Bull. 530, 1913, p. 151. (Notes the occurrence of molyb- denite at Placerville.) HIBBARD, H. D. Manufacture and uses of alloy steels. U.S. Bureau of . Mines Bull. 100, 1915, pp. 58-59. HILLEBRAND, W. F. Distribution and quantitative occurrence of vana- dium and molybdenum in rocks of the United States. Am. Jour. Sci. ser. 4, vol. 6, 1898, pp. 209-216; U. S. Geol. Survey Bull. 167, 1900, pp. 49-55. HILLS, B. W. The molybdenite deposits of Tunk Pond, Maine. Min. World, vol. 31, 1909, pp. 323-324. ; HOLMAN, C. VEY. Molybdenum—Steel’s latest beneficiary. Mining American, vol. 74, May 19, 1917, pp. 8-9. HORTON, F. W. Molybdenum: Its ores and their concentration. U. S. Bureau of Mines Bull. 111, 1916. HOULTAIN, H. E. T., DYER, F. C., and KING, J. T. The concentration of molybdenite ores. Can. Min. Jour., vol. 38, No. 13, 1917, pp. 270-271. HOWE, H. M. The erosion of guns. Am. Inst. Min. Eng. Bull. No.. 184, pp. 335-390. KEENEY, R. M. The production of steels and ferroalloys directly from ore in the electric furnace. Jour. Iron and Steel Inst., Carnegie Scholarship Memoirs, vol. 4, 1912, pp. 108-184. Electric smelting of chromium, tungsten, molybde- num, and vanadium ores. Trans. Am. Electrochem. Soc., vol. 24, 1913, pp. 167-189. LYON, D. A., KEENEY, R. M., and CULLEN, J. F. The electric furnace in metallurgical work. U.S. Bureau of Mines Bull. 77, 1914, pp. 146- isi MACKENZIB, G. C. The mining and metallurgical treatment of molyb- denum ores in Canada. Trans. Royal Canadian Inst., vol. XI, pt. 2, No. 26, 1917, pp. 269-287. MELIKOFF, P. A new reaction for molybdenum. Eng. and Min. Jour., VO) 96; 19I3. pe 836. Mineral Industry. Molybdenum. Years 1905-1916. 122 MOLYBDENUM DEPOSITS OF COLORADO MOISSAN, HENRI. The electric furnace. Translated from the French by Victor Lehuer, 1904. , MOSES, A. J. The crystallization of molybdenite. Am. Jour. Sci., ser. 4, vol. 17, 1904, pp. 359-364. PARSONS, A. L. Molybdenite deposits of Ontario. Can. Min. Jour., vol. 38, No. 11, 1917,:pp. 231-233. —__——________________— Concentration of molybdenite ores sine Ontanion Eng. and Min. Jour., vol. 105, No. 19, 1918, pp. 880-881. PORTEVIN, A. M. Contribution to the study of special ternary steels. Carnegie Scholarship Memoirs, Iron and Steel Inst. (London), vol. 1, 1909, pp. 275-276, 330-333. PRATT, J. H. The steel and iron hardening metals. U. S. Geol. Survey, Mineral Resources for 1904, pp. 338-343. ROSCOE and SCHLORLEMMER. A treatise on chemistry. Vol. 2. Molybdenum. (Last edition.) ; RUDER, W. E. Solubility of wrought tungsten and molybdenum. Jour. Am. Chem. Soc., vol. 34, 1912, pp. 387-389. RUTH, J. P. Jr. The Ruth flotation machine. Eng. and Min. Jour., vol. 105, No: 1'6, 1/918) p: 752. SCHALLER, W. T. Notes on powellite and molybdite. Am Jour. Sci., ser. 4, vol. 25, 1908, pp. 71-75. — Mineralogical notes, ser. 1, U. S. Geol. Survey Bull. 490, 1911, pp. 80-92. (Discusses the occurrence, composition, etc., of powellite and molybdite.) SCHRADER, F. C., and HILL, J. M. Some occurrences of molybdenite in the Santa Rita and Patagonia mountains, Arizona. U. 8. Geol. Survey Bull. 430, 1910, pp. 154-1638. SMITH, G. O. A molybdenite deposit in eastern Maine. U. S. Geol. Survey Bull. 260, 1905, pp. 197-199. STEINHART, O. J. Metals and their ferroalloys used in the manu- facture of alloy steels. Trans. Inst. Min. and Met., vol. 15, 1905-1906, pp. 247-249. SWINDEN, THOMAS. A study of the constitution of the carbon-molyb- denum steels, with an appendix on the mechanical properties of some low molybdenum-alloy steels. Carnegie Scholarship Memoirs, Iron and Steel Inst. (London), vol. 5, 1913, pp. 100-168. Carbon molybdenum steels. Carnegie Scholarship Memoirs, Iron and Steel Inst. (London), vol. 3, 1911, pp. 66-124. TAYLOR, F. W. On the art of eutting metals. Trans. Am. Soc. Mech. Eng., vol. 28, 1907, pp. 31-350. THOMSON, E. A pegmatitic origin for molybdenite ores. Economic Geology, vol. 18, No. 4, 1918, pp. 302-313. UMPLEBY, J. B. Geology and ore deposits of Lemhi County, Idaho. U. S. Geol. Survey Bull. 528, 1913, p. 73. United States Bureau of Standards. Circular 35. 2nd ed. revised Jan. 1, 1915, p. 2. (Gives the melting point of many metals.) WALKER, T. L. Molybdenum ores of Canada. Canada Dept. of Mines, Mines Branch, 1911, No. 93, 64 pp. BIBLIOGRAPHY 123 WILSON, M. E. Molybdenite deposits of Quyon district, Quebec. Can. Min. Jour., vol. 39, No. 5, 1918, pp. 78-80. WINNE, R. Small electric furnace with heating element of ductile molybdenum. Trans. Am. Hlectrochem. Soc., vol. 20, 1911, pp. 287-292. WOAKES, E. R. Molybdenum industry in Norway. Eng. and Min. Jour., vol. 105, No. 11, 1918, pp. 499-502. WOOD, H. E. Concentration of molybdenite ores. Eng. and Min. Jour., vol. 93, 1912, pp. 227-228. The Wood flotation process. Trans. Am. Inst. Min. Eng., vol. 44, 1912, pp. 684-701, or Am. Inst. Min. Eng. Bull. 71, 1912, pp. 1227-1244. INDEX A Page PNCTIBOMAATLCG! “cnrancocecceceesncenecctterazecwezsesse al OND OSIEION: | coors oo. ccocestencdeccescus,ceesecene 11 COON TET NSS pe receeee eee eee See Atal TOEEO TOYS A HICSS) 0S eee ee 11 CKO WACHLIMECNES -..---2censc-ctecon-- nce 2 Ady and Mathews’ claims...............- 42 MIG Si CNET OCS SS Be ee see ere 81 PAC ao eATIN TOLION .cs.2.2-cccec-soaeaceseonance alt molyboaenite: Mine: -.-2_...------2-.-2-+-.:-- i Aliard: Minine’ Company:.---.------<<-:---- 72 ES POSIT REO Laas a i a er a ee eee 47 American Molybdenum Company.... 26 Analysis of molybdenum ores, Cen IMGs ENC tree see sees nee 107 Analysis of wulfenite ores................ 108 Andrews, E. C., quoted.......... 1G Iv be ta) RERCTOIMGE! GO) ata. co. cctenee ost eteowcswanes 15,101 ANTONE RS. oka sett ea OR Sie a a ae 58 PAA VO AD IMMITI tc ces aco 2a cn cosaaeoee tare -sonce 98 Areas in Colorado which should Hesprospected! stcs---- ee 98 Arizona molybdenite deposits......... 25 . Aurand, Harry A., reference to_.52, 73 Australian methods of concentrat- ing molybdenum ores................ 101 Australian molybdenum deposits... 13 concentration of ore BECO Sym OL, Ginc-cen- acco sone acee.d future production —_........ TOOT ETO setese neeee eee eea ce B iBT S48 obo) sic Eee mc 14, 117 [Rob PURE VE OFT g1LN Ge) eee aR ee Eo Se eR Ie 41 STURT ATO ot: ee a ee 42 Barvlett Mountain -.22.2...--.5..2.:.- 87, 91 Bastin, E. S., and Hill, J. M., GOOG ee eee as Se hen oii PEI OTE) 10 ee ee ee ee ee eae ne 58 Bear Mountain deposits.................... 84 EVESECRTUO SE Cate ft oars ke Sh nt a il GTA S OSGI (Gia Boe Ree a ie all ‘SVU ATEN EN TC ek eer en ee ioe ial RIOTS A eo eee oe ee 11 ISSUE Ges 0) 0 ee ee Se ee 120 EMIOMU Er Sha et 2.2. Mee ee Lo 33 Bigck Diamond Claim...-.::2::---:2-----<--- 84 PHeMVIDNLGY. CLAIM -/... 2.222. ccaccsaseceectevcte 96 Page LE-(ondvgels Dia) oY gees eee Spleen ee Sa a eee 59, 60 GAeVelOpnient) \sic.------------e- i eee 60 (s\o bby onaaVs\aq ey eaee eee ee eee eee 61 Ee Ta Kae eeepc soo ee erecta cee eec ree 60 Omi der. © Olin tyuee seca coos sass ee seeaeee sone 32 LCTIOSIE Sat LES UC Cee seee ee cece een eaevaeeeaene 29 Bowlder (County. MIN 62 c ess os. -deen-n2-< 34 British Columbia deposits................ 17 Brougham Township, Ontario.......... 20 molybdenite deposits -..-...............- 20 Brown, H. L., and Hayward, M. W., TOEKCT OIC Cpl Om ssa sees eee tea nde cenace 89 1Bi ON Aer (SHUN KET ies ees eee come sere reer 34 TEA CAS St oS AU OWE) of) eee eee eee eee mene eee 76 ES UPTV Ts SUS OU wet ee soe cae eee nece=enoeteces 94 BUnEaUOn meat OSs cose cease na ener eeceees 4 on melting point of molybdenum 4 @; Galo ray CLD ee eee nace ee eae 35 ING sec testes ea ee noc 35 C@aliformia deposits ee eee soos eee eee 26 @aihorniay Mie eee: ence eee 34 GEVETOP NTC TINE sae no ee eee 35 future development ...............-.....- 37 FCO ORY tase sae ce cc otenetnasenuck 35 AMD TOV.eMCTIES so 5a meee rs oas ee one 37 1h tia ols) peewee Set a aan A ne eee ae pee 37 tigate Saas) cll pa eae eee oe ee 37 DEM oh cht See a es ee ee a eee eee 37 CGailkeinshoh oe Gre CMOte deco euscn ee sarees 26 Canadian methods of concentrat- ing molybdenite ores__._._..... 22, 102 Canadian Mining Journal, quoted..103 reference to -... spuecE ac dereagies Pape ET, 22 Canadian molybdenite deposits_....... 17 ICOM OL MONT ese ae =e oe aes ale) DLOGUGHOMPORS coon se rece eeneeecee sean aeee ili GamribomimdenpOsitsy ec eee eo 233 WASCAMC SEAS UI ere ec eas cee ee naccceee 85 CO csi n eye Ofe) hire ee ae ee ee oe 34 CEPOSTUSMMISCC Oe a2 Coumt ys sete seseceosncseceee 47 GODOSITS PIISCO de cccccesecncecececoceceroserabese 30 126 INDEX Page Page (Gilitineoynl Tash OVS) Seen pees oss ae cee oes 51 Engineering and Mining Journal, @limasc claim) S22 45 quoted -.-4..-42 @llimiaxeed GPO SiS yeeenese eee 87, 115 Engineer Mountain deposits ss GevelopmMent, feces ee eee 90 DHosite +... COLO Sy ace tates see ee ne ee 87 composition. ==. Climax Molybdenum Company-91, 105 OCCUIYTeENCe (22.2) ee ee Cofine sRa Cs, Lekerentcestome. 70 properties... Collins elaine eee 44 testS: n2epc00.csseecee ee eee @ollinsonseia nine eset eens 71 Colorado Molybdenum Mining F COMPA iy, Feces 85 i ifs lybdenite a ee obtmol pene 101 Fahrenwald, Frank A., quoted____. 113 Bee cre Sarat a ee Falcon Lake molybdenite deposits 19 PARISt ra bias le ty OG see eee eens 101 g geology Of -:...2... 19 @anadian methods = 102 Norwegian methods 102 tenure of the ore... 19 A py ea a ie _, Falkenberg, Otto, reference to........ 16 United States methods......___.___....- 104 : : =i Karwell Mountain y= 78 Coneyoss Co minitiy ee eee ee 52 : ; development, =..2222 79 deposits, shisite dita ssee pes eeeeee eee 30 ns Z PeOlOLY aces Continental (Placer ys eee 93 E 2 : Ferro-molybdenum Cooper; Maine, (depositsh 2. 26 ¥ ; 3 manufacture of in Norway. Copper Girliclaim= 55 : Fink, C: Gi... eee Gewellopmile nity soe eee 56 RN to : : Evalere _ specific gravity and tensile > & Sindesostnocase seen eae serecersteeas se rose 99 : strength of molybdenum.......... 4 Grawhords ens, CMOue diese 535, 36 = cae 7 Fleck, Herman, quoted== === a TELereniGe: tO ae eee 38, 39 ae sh : xm Fremont County 2 === 55 GTRESCEMIE MIMIC ioe esac eee 76 ; : : ie 77 deposits, listed! .. = 30 FeolOsy oh =e kee obs auss Gest sscbonsace : Eremont Pass deposits=.--. = 2 87 Crook ates WeLChen@e tO issn 8 A } ie a see 5 ee A 5 Freshwater mining district... 76 Gross) mininic district see 54 Puture of the idiene 119 Cross) Mountain’ region® 222-22 = 65 aie ca SU shane rae Gusterei@ounty <4e2 2 sie Se 2 eee 52 Geposits, sistediaee= == ee B} G D Gavette claim. 32 70 Geneva claim Dailey: mM Ss) VNU WIRE Ct eeeee esate eee 47 geology —...2..-. [See N13) VALS see SCHL OE © Cl eee nee 108 German molybdenite deposits_._.....- 23 DelLury, J. S., reference to.............- 19 Giles Mountain) 72 TD) ONVET INO V2ecce cancer cease cetera eee ee 93 Gilpin County = 58 IB SNES IDS CUI 00 eee cee ee emcee scseseeoeeeoce i deposits! listed) = 30 IDXOS GANS ARON, Saeco eeeet ores ee eeeeeeen ae aoe 98 Silpin Creck =e 80 Dominion Molybdenite Company-...103 Glacier Mountain. eae 97 Drysdale, C. W., quoted....- #oscé sice I 1S) Gold Finch 2. == 82 IDA INS (Oh, 1RGbE diiboy eiarel development: ae 82 ee yONn em, 1 (ID As ce See cecesecenccess 104 future development -—.-2 83 weoloesy. --.1..-.8 Asses E Grab claim ; Grand (Countyie- Ha elie iC OUI E yea oe ee eee 54 deposits, listed GED OSTES Sec ieeee=- eee sree eee eens 30) (Gra ybagle claimie anes. 58 IDEISiKerga Shwve Olena oe ees ecetiee 40 Green Horn claim] {ir Mastr Siliviers WMiecam= sees Fe eee 68 Green Horn Mountain Copper Min- IDiboakoyden Ns PS hy CHUGH EG nee ose see cee 102 ing Company = 55 Elmore vacuum flotation process, Griffith Township, Ontario.........__..... 21 described) 245-2 eee 102 molybdenite deposits _............. 21 TERETSN CS iO! ee aseseeee ences ree ee ee 116. = Guifey, GepOSits) =e 76 LD pgah age Wed a hy ieee eee ee Ast be 59, 63 Gunnison ‘County, see eee 59 WOmpirey ces kee ese eee 47, 115 deposits, listed: 25:2 eeceeeeeeee 30 INDEX 127 H L Page Page riaiitcain, FH, He T, Dyer, FEF. C., Lake George deposits...............2..01..-- 73 and King, J. T., reference to....104 Wakes year tit dite, CULO te dese iareess 17 Hayward, M. W., and Brown, H. S., Lamphere Lakes deposit.................. 64 TEA ET REN OUCLS), 0 eo aes eae eee =e 89 GeEveloprnmenity esse. sc. chee ee 65 Haynes, Elwood, cited.............. ales, Wake! ECONO ype eee ee gen alee ea 64 Heintze, Carl, reference t0................ 8 bale gedeiicey, (Cfajoh Meni ieee ee eee jeoeeaacs 68 essen. Iz, \Clteds-:....-2.--..- Gos) Os akilp GE DOSES Ae lTS Ue Clupesess nee eee see CnuOted! “G.-.2....-..2 Pore ee by Ay, ll larimer ‘County... FE tee, Brees ei 69 TOBETOMC Gs CO: |