Nevada · Humboldt County
Producer

Hycroft Gold Mine

Humboldt County, Nevada, United States
GoldSilverMercurySulfurAntimony
⌖ Show on mapUSGS source ↗
Description

Homestake

Commodities
PrimaryGold, Silver
SecondaryMercury
TertiarySulfur, Antimony
Commodity typeB
Deposit
Deposit typevolcanic-hosted epithermal deposit; hot springs gold-silver
Model150: Epithermal vein, Comstock
Deposit sizeS
WorkingsSurface
Orebody formdisseminated, blanket
Ore controlMineralization is controlled by structure and host-rock permeability. The NNE-trending central fault zone and related splays are mineralized continuously over a distance of 2.5 miles.
Materials
Ore mineralsGold
GanguePyrite, Silica, Jarosite, Sulfur, Alunite, Stibnite, Stibiconite, Barite
Geology
Host rockVolcanic Rock (Aphanitic),Volcanic Breccia (Agglomerate),Mixed Clastic/Volcanic Rock,Conglomerate · "Sulphur Group", "Camel Conglomerate"
Associated rockVolcanic Rock (Aphanitic) · Kamma Mountains Group
StructureThe mine area is cut by NNE-trending faults; and by the western, central and eastern fault zones., The area is affected by N-S-trending Basin and Range structures.
AlterationThere are two major types of alteration recognized at Sulphur: solfataric-near surface alteration by hot water, gases, acids; and silica-pyrite-(silica-alunite) characterized by dense siliceous flooding accompanied by fine-grained sulfides, formed at moderate depth. Alteration varies from intense silica-adularia-pyrite to weak propylitic with a widespread cap of late "acid-leach alteration," which appears to have descended along pre-existing structures.
Economic & production
Development statusProducer
Production years1988-2002
First production1988
Discovery year1980
Identification
Deposit ID10310408
MRDS IDW700587
Alternate namesCrofoot/Lewis Gold Mine, Standard Slag Mine, Crofoot Gold Project, Crofoot Project, Crofoot Mine, Lewis Mine, Hycroft-Lewis Mine, Brimstone, Gap, Graveyard (Boneyard), North Pit, South Central Pit, South Extension pit, Peninsula
RegionNA
Data scoreA
Coordinates40.8691, -118.688
References
Tingley, J.V., 6 Sep 85, Field Examination and Sample Analysis.Unpublished Report, 1983, Homestake Mining Co.NBMG Mining District File 143, Item 11-Unpub. Report for Cordex, 1980, by Andy Wallace. also NBMG File 143 Press ClippingsA.E.G. Field Trip Guidebook, 1984, Sulphur Mining-DistrictTooker, E.W., 1986, USGS Bull 1646, P.142-143State Inspector of Mines, 1985, Directory of Nevada Mine Operations Active in Calendar Year 1984.Pay Dirt, April, 1984Bonham, H.F. 1986; NBMG Map 91Bonham, H. F. 1988 in NBMG MI-1987.Mine Search Annual, 1984-85, Vol. V11, P. 111, Metals Economics Group, Boulder Co.Mining Journal, 6/21/85Doebrich, Jeff, USGS Written Communication 1991.NBMG, 1994, MI-1993Nevada Division of Minerals, 1994Ebert, Shane W; Groves, David I; Jones, J Kenneth, 1995 Geology, alteration, and ore controls of the Crofoot/Lewis Mine, Sulphur, Nevada; a well-preserved hot-spring gold-silver deposit, in Geology and Ore Deposits of the American Cordillera; symposium proceedings, Geological Society of Nevada.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.D.A. Davis and J. V. Tingley, 1999, Gold and silver resources in Nevada, NBMG Map 120Wallace, Andy; Friberg, Robert S., 1996, Geology and mineral deposits of the Sulphur mining district, Humboldt County and Pershing County, Nevada; in Gold and silver deposits of western Nevada, Geological Society of Nevada, Special Publication vol.18, pp.67-76.2004 Report by Mine Development Associates, on website.Vista Gold Corp. press release, 9/22/2004.Crafford, A.E.J. (ed.), 2003, GSN Road Log 2, Interstate 80 Eastbound, Fernley (Exit 48) to Golconda (Exit 194).MILLER, M.S. 1993, EMIGRANT TRAIL STUDY AREA, US BUREAU OF MINES, OPEN FILE RPT, MLA 7-93, P89.ANNUAL REPORT GRANGES EXPLORATION LTD.,VANCOUVER BC, 1985DUNCAN, D. AND B. WIGGLESWORTH. CROFOOT'S PROJECT JOINS NEVADA'S FORMIDABLE LIST OF GOLD PRODUCERS. MIN. AND ENG. J., JUNE 1988, PP. 40-41. (NOTE: DUNCAN IS THE DIRECTOR AND PROJECT MANAGER AND WIGGLESWORTH THE SENIOR STAFF ENGINEER, BOTH OF HYCROFT RESOURCES AND DEVELOPMENT CO., RENO, NV.)BELING, D. C., J. HARRINGTON, AND B. WIGGLESWORTH, TREATING LOW GRADE SOLUTIONS AT THE CROFOOT MINE. CH. 22 IN GOLD '90, ED. BY D. M. HAUSEN. SOC. MIN. ENG. AIME, 1991, PP. 231-234.NEVADA DEPARTMENT OF TAXATION, MINING DIVISION. HYCROFT RESOURCE AND DEVELOPMENT NET PROCEEDS TAX RECORDS. CARSON CITY, NV, FEB. 1991.GRANGES INC, 1995 ANNUAL REPORT, 52 PP.THE MINING RECORD, VOL., 107, #42, OCT., 16, 1996, P1.THE MINING RECORD, VOL., 107, #47, NOV., 20, 1996, P1.THE MINING RECORD, VOL., 108, #13, MAR. 26, 1997, P1.THE NORTHERN MINER, 1996.SKILLINGS MINING REVIEW, SEPT 27, 1997, V86, #39, P14.GRANGES INC, 1995 FORM 10-K, PP. 7-8.THE MINING RECORD, FEBRUARY 22, 1995, PAGE 7, "1994 PRODUCTION AT CROFOOT/LEWIS MINE".RANDOL, MINING DIRECTORY, 1996/97, U.S. MINES & MINING COMPANIES, P238.1995/95 NEVADA MINES DIRECTORY, PP. 11, 24.GRANGES INC. FORM 10-K REPORT, P17.