Ruby Hill Gold Mine

Eureka County, Nevada, United States

GoldSilverBarium-BariteArsenicMercuryAntimonyZinc

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Description

Homestake

Commodities

PrimaryGold

SecondarySilver

TertiaryBarium-Barite, Arsenic, Mercury, Antimony, Zinc

Commodity typeB

Deposit

Deposit typesediment-hosted gold

Model173: Sediment-hosted Au

Deposit sizeS

Orebody formThe deposit shape is complex and irregular, but generally has a central elongate, subtabular body with ovate cross section. From this core, similar shaped lithologically controlled lobes branch and flare out along structural intersections.

Ore controlMineralized bodies are coincident with zones of iron-stained jasperoid and decalcified limestone formed in response to both structural and stratigraphic controls: ore is primarily controlled by WNW- and NE- to NNE-trending faults, with secondary control by open folds and faulted fold limbs. Stratigraphic traps formed by contacts between limey mudstone and wackestone host rocks. Most of te West Archimedes deposit lies within the upper 200 feet of the upper cherty member of the Goodwin limestone. Archimedes is adjacent to a quartz porphyry stock of probable Cretaceous age to which it may be genetically linked.

Materials

Ore mineralsGold, Electrum, Limonite, Hematite, Pyrite, Cinnabar, Barite

GangueQuartz

Geology

Host rockLimestone,Porphyry,Chert · "Goodwin Limestone, Pogonip Group", "Ninemile Formation, Pogonip Group", "Graveyard Flat porphyry", "Antelope Valley Limestone, Pogonip Group"

StructureRoberts Mountains Thrust; Central Nevada Fold Belt; Hoosac Thrust, The oldest identified structures within the deposit are the high-angle NNE-trending Bowman, ?271?, and Jackson pre-mineral faults that were important in localizing some gold mineralization. More common within the deposit are WNW-trending high angle structures including the Blanchard fault system, which largely controlled emplacement of the West Archimedes deposit, and the Molly fault system, which localized some gold mineralization and had up to 100m of post-mineral offset. E-W-trending normal faults localized base metal mineralization, and NNW-trending faults (such as the Holly and the ?150?) show significant post-mineral offsets, and may be associated with regional basin-and-range development.

Tectonic settingCentral Nevada Fold Belt

AlterationZones of silicification, jasperoid development, and limestone decalcification (decarbonization) guided ore formation.

Economic & production

Development statusProducer

First production1997

Discovery year1991

Identification

Deposit ID10310484

MRDS IDMP90056

Alternate namesWest Archimedes Deposit, East Archimedes resource, Archimedes Gold deposit

RegionNA

Data scoreB

Coordinates39.526, -115.9843

References

Dilles, P.A., Wright, W.A., Monteleone, S.E., Russell, K.D., Marlowe, K.E., Wood, R.A., and Margolis, J., 1996, The geology of the West Archimedes deposit: a new discovery in the Eureka mining district, Eureka County, Nevada, in Coyner, A.R., and Fahey, P.L., eds., Geology and Ore Deposits of the American Cordillera: Geological Society of Nevada Symposium Proceedings, 1995, Reno/Sparks, Nevada, v. 1, p. 159-171.Russell, K., 1996, West Archimedes Gold Deposit, in Green, S.M., and Struhsacker, E., eds., Geology and Ore Deposits of the American Cordillera: Geological Society of Nevada Field Trip Guidebook Compendium, 1995, Reno/Sparks, NV, p. 316-319.Sediment-hosted Gold Deposits of the Eureka (Ruby Hill Mine) and Gold Bar Districts, East-Central Nevada, Geological Society of Nevada Special Publication No., 27, 1998 Spring Field Trip Guidebook.NBMG MI-97Mining Engineering, Dec., 1994, Society for Mining, Metallurgy, and Exploration, Littleton, Co, vol. 46, p. 1320.Final Environmental Impact Statement for the Ruby Hill Project of Homestake Mining Company, January 1997.Homestake press release, 2/19/98Denver Mining Record, 12/3/97Northern Miner, 11/23/97Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Significant deposits of gold, silver, copper, lead, and zinc in the United States: U.S. Geological Survey Open-File Report 90-206A, 33 p.; 98-206B. one 3.5 inch diskette.