Mine detail: Sleeper Mine

Previously called 'Sleeper PitWood PitWest WoodBedrock CasinoNortheast areas'

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Location

Lat / long: 41.3338, -118.0524

Resource(B)

Primary: Gold, Silver
Tertiary: Barium-Barite, Bismuth, Copper, Lead, Tellurium, Zinc, Cobalt, Nickel, Molybdenum, Sulfur, Arsenic, Selenium, Antimony, Mercury, Thallium, Potassium
Ore: Gold
Gangue: Quartz, Adularia, Stibnite, Pyrite, Marcasite, Opal, Cristobalite, Sericite, Alunite, Kaolinite, Barite, Illite, Jarosite
Orebody form: tabular to disseminated to irregular
Discovery year: 1982

Production

Operation type: Surface
Deposit type: hydrothermal -vein, -stockwork/stringers, -breccia filling
Production size: Medium
Development status: Producer
Production years: 1986 - 1996
First production started: 1986
Last production ended: 1996

Geology

Host rock:Auld Lang Syne Group
Host type:Rhyolite,Porphyry,Andesite,Phyllite,Slate,Quartzite
Structure:In the northern Slumbering Hills, Triassic sedimentary rocks are weakly folded and form a N20E-trending monocline that dips 45 east., The Sleeper Deposit occurs within a N20E-striking range front fault zone that dips 45-85 and terminates the NW side of the range. This fault zone hosted extensive hydrothermal alteration and mineralization and localized the Sleeper Gold Deposit. A normal fault which strikes N50W and dips 72 south intersects the range front fault zone in the vicinity of the Sleeper Deposit.
Alteration processes:Alteration of rhyolitic host rock consists predominantly of silicification, argillic alteration, acid leaching, and supergene alteration. Replacement and open-space filling by silica minerals are the most prominent and diagnostic alteration styles at Sleeper. Early silicification, accompanied by pyrite, resulted in pervasive replacement of plagioclase phenocrysts and groundmass by opaline silica. Alunite occurs in some early silicified rocks, but possibly was a later addition. Silicification of several types accompanied ore stages. Late-stage silicification in the form of opal is controlled by post-ore faults and fractures and is barren of gold. This late opal typically contains abundant light-colored alunite, kaolinite, or jarosite. Small amounts of native sulfur are enclosed in the late silica. Hypogene argillic alteration occurs peripheral to zones of early silicification; commonly there is a transition zone from 3 to 50 m wide of clay-altered plagioclase in silicified groundmass. The broad argillized zones are barren of Ag and Au, and contain little sulfide and no silica veinlets. Feldspar phenocrysts and aphanitic groundmass in argillized zones commonly are altered to clay minerals, most commonly kaolinite, smectite, and illite. Plagiocalse phenocrysts have been replaced by fine-grained clay minerals and alunite. Sanidine is locally altered to sericite or kaolinite. Groundmass is generally altered to very fine grained silica-clay mixtures. Thoroughly acid-leached rocks with sponge-like texture of more than 90% silica occur in local zones along post-ore faults. Subsequently, opal, alunite, and jarosite were deposited in the porous rocks. The prominent red coloration of upper pit walls reflects supergene destruction of sulfides and local redistribution of iron into fractures. Pyritic tuffs have been oxidized to tan alunite+jarosite+limonite-bearing mixtures. Feldspars are altered to white clays along open fractures and voids later filled by phases of unusual composition, some rich in Cl (as NaCl and AgCl), and various combinations of Al, Mn, and Co As oxides or sulfates. Propylitically altered tuffaceous sediments, andesitic lava flows, and metasedimentary basement rocks underlie the rhyolitic host rock.

References

MRDSW700408
DEP10310319
Reference{Deposit:: Quade, Jack, 1985 - Attempted field examination report (locked gate, guard).}{Deposit:: Nash, J.T., Utterback, W.C., and Saunders, J.A., 1991, Geology and Geochemistry of the Sleeper Gold Deposits, Humboldt County, Nevada, an interim report, in Raines, G.L., et al., eds., Geology and Ore Deposits of the Great Basin, The Geological Society of Nevada, Reno, p. 1063-1084.}{Deposit:: Amax Annual Corporate Report for 1990, p. 18-19.}{Deposit:: Wood, J.D., 1988, Geology of the Sleeper Gold Deposit, Humboldt County, Nevada, in Schafer, R., et al., eds., Bulk Mineable Precious Metal Deposits of the Western United States, The Geological Society of Nevada, Reno, p. 293-302.}{Deposit:: Wood, J.D., 1987, Technical Aspects of the Sleeper Gold Discovery, Nevada, in Mining Technology and Policy Issues: 1986 International Mining Show, Las Vegas, Nevada, American Mining Congress, Washington, D.C., 3 pp.}{Deposit:: Mining Magazine, January, 1989, p. 44.}{Deposit:: Staff, 1988, Directory of Nevada Mine Operations Active During Calendar Year 1987: Nevada Division Of Mine Inspection, 84 p}{Deposit:: Metal Market Consultants, Inc., 1987, Gold Situation Map.}{Deposit:: Minesearch Annual, 1984-1985, Vol. VII, p. 418-420; Metals Economics Group, Boulder, Co.}{Deposit:: Bonham, H.F., 1986, NBMG Field Examination Report, 5/86, and sample analyses.}{Deposit:: Bonham, H.F., 1986, NBMG Map 91.}{Deposit:: Bonham, H.F., 1988, in NBMG MI-1987.}{Deposit:: NBMG Mining District File 123, Numerous Press Clippings and news releases}{Deposit:: NBMG, 1994, MI-1993-2002}{Deposit:: Nevada Division of Minerals, 1994}{Deposit:: Mining Record, March 24, 1993}{Deposit:: Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Database of significant deposits of gold, silver, copper, lead, and zinc in the United States; Part A, Database description and analysis; part B, Digital database: U.S. Geological Survey Open-File Report 98-206, 33 p., one 3.5 inch diskette.}{Deposit:: Saunders, James, 1994, Silica and gold textures in Bonanza Ores of the Sleeper Deposit, Humboldt County, Nevada: Econ. Geol. vol 89, pp. 628-638.}{Deposit:: http://www.x-cal.com/sleeper.htm}{Deposit:: Crafford, A.E.J. (ed.), 2003, GSN Road Log 2, Interstate 80 Eastbound, Fernley (Exit 48) to Golconda (Exit 194).}{Deposit:: AMAX GOLD INC FORM 10K, 3/29/90}{Deposit:: AMAX GOLD INC FORM 10K, 3/30/89}{Deposit:: AMAX GOLD INC PROSPECTUS, 7/87}{Deposit:: DEMULL, THOMAS J. ORE PROCESSING AT AMAX GOL* SLEEPER MINE, 12/87.}{Deposit:: NEV. DIV. MINE INSPECTION, 1991, DIRECTORY OF NEVADA MINE OPERATIONS ACTIVE DURING CALENDAR YEAR 1990, P. 45.}{Deposit:: HAMILTON, S. K. AND J. D. WOOD. THE SLEEPER GOLD-SILVER DEPOSIT DISCOVERY THROUGH FEASIBILITY, IN ASSAYS TO ASSETS RECENT FEASIBILITY CASE HISTORIES. NORTHWEST MIN. ASSOC., SPOKANE, WA, DEC. 1987.}{Deposit:: POOLER, A. F. ENGINEERING AND OPERATIONS AT AMAX GOL* SLEEPER MINE, IN ASSAYS TO ASSETS RECENT FEASIBILITY CASE HISTORIES. NORTHWEST MIN. ASSOC., SPOKANE, WA, DEC. 1987.}{Deposit:: STANFORD, W. D., AND T. J. DEMULL. AMAX GOL* SLEEPER MINE DEVELOPMENT AND CONSTRUCTION, IN ASSAYS TO ASSETS}{Deposit:: UTTERBACK, W. C. GEOLOGY OF THE SLEEPER GOLD DEPOSIT, IN ASSAYS TO ASSETS RECENT FEASIBILITY CASE HISTORIES.}{Deposit:: AMERICAN MINES HANDBOOK, 1996, PP. 19, 20, 21.}{Deposit:: RANDOL MINING DIRECTORY, 1994/95, U.S. MINES & MINING COMPANIES, P351.}{Deposit:: RANDOL MINING DIRECTORY, 1996/97, U.S. MINES & MINING COMPANIES, P272.}{Deposit:: 1995/96, NEVADA MINES DIRECTORY, PP. 2, 25.}{Deposit:: THE NORTHERN MINER, VOL., #9, APRIL 28, 1997, P10.}{Deposit:: AMAX GOLD INC., 1996 FORM 10-K, P8, AND ANNUAL REPORT.}{Reserve-Resource:: AMAX GOLD INC., 1995 ANNUAL REPORT; & FORM 10-K REPROT.}
ReporterLa Pointe, D.D. (Tingley, J.V.), Beougher, Delilah J. (Spanski, Gregory T.), Phinisey, J. D. (Marcus, S.), Li, Zhiping (Moyer, Lorre A.), Buckingham, David A., LaPointe, D.D., Schruben, Paul G., Paidakovich, Matthew E.