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Ruby Hill Gold Mine

Producer in Eureka county in Nevada, United States with commodities Gold, Silver, Arsenic, Mercury, Antimony, Barium-Barite, Zinc
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Geologic structures
  13. Ore body information
  14. Controls for ore emplacement
  15. Economic information about the deposit and operations
  16. Mining district
  17. Land status
  18. Ownership information
  19. Links to other databases
  20. Bibliographic references
  21. General comments
  22. Reporter information

Geologic information

Identification information

Deposit ID 10310484
MRDS ID MP90056
Record type Site
Current site name Ruby Hill Gold Mine
Alternate or previous names West Archimedes Deposit, East Archimedes resource, Archimedes Gold deposit

Comments on the site identification

  • The names Ruby Hill Gold Mine and Archimedes Gold Deposit refer to the same operation. This record supersedes the incomplete Archimedes MRDS record MP90056 which should be deleted. All data from the MP90056 record has been incorporated into this new record.

Geographic coordinates

Point of reference Pit
Geographic coordinates: -115.9843, 39.526 (WGS84)
Elevation 1950
Relative position The mine lies just 1.5 miles northwest of the town of Eureka

Site location context

Political divisions (FIPS codes)

Eureka(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Eureka(quadrangle 1:24,000 scale)

Newark Lake(quadrangle 1:100,000 scale)

Ely(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Diamond-Monitor Valleys(hydrologic unit)

Central Nevada Desert Basins(hydrologic accounting unit)

Central Nevada Desert Basins(hydrologic subregion)

Great Basin(hydrologic region)

Geographic areas

Country State County
United States Nevada Eureka

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 019 053 10,11 Nevada

Comments on the location information

  • The east edge of the Archimedes deposit is on the east flank of Mineral Point, between the old Holly and Holly Extension mine workings less than one mile northwest of downtown Eureka.

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Arsenic Critical Tertiary
Mercury Tertiary
Antimony Critical Tertiary
Barium-Barite Critical Tertiary
Zinc Critical Tertiary

Comments on the commodity information

  • Commodity Info: Mercury is retorted from process metal sludge.
  • Ore Materials: gold, electrum
  • Gangue Materials: quartz, limonite, hematite, pyrite, cinnabar, barite, various sulfide minerals

Materials information

Materials Type of material
Gold Ore
Electrum Ore
Limonite Ore
Hematite Ore
Pyrite Ore
Cinnabar Ore
Barite Ore
Quartz Gangue

Alteration

  • (Local) Zones of silicification, jasperoid development, and limestone decalcification (decarbonization) guided ore formation.

Mineral occurrence model information

Model code 173
USGS model code 26a.1
Deposit model name Sediment-hosted Au
Mark3 model number 17

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock type qualifier cherty
    Rock unit name Goodwin Limestone, Pogonip Group
    Stratigraphic age (youngest) Early Ordovician
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock type qualifier micritic to shaley
    Rock unit name Ninemile Formation, Pogonip Group
    Stratigraphic age (youngest) Early Ordovician
    Stratigraphic age (oldest) Middle Ordovician
  • Host or associated Host
    Rock type Plutonic Rock > Porphyry
    Rock type qualifier quartz-feldspar
    Rock unit name Graveyard Flat porphyry
    Stratigraphic age (youngest) Early Cretaceous
    Chronological age 110
    Dating method K-Ar
    Type of media whole rock
  • Host or associated Host
    Rock type Sedimentary Rock > Chemical Sediment > Chert
    Rock unit name Antelope Valley Limestone, Pogonip Group
    Stratigraphic age (youngest) Early Ordovician
    Stratigraphic age (oldest) Middle Ordovician
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock type qualifier fine to coarse
    Rock unit name Antelope Valley Limestone, Pogonip Group
    Stratigraphic age (youngest) Early Ordovician
    Stratigraphic age (oldest) Middle Ordovician

Nearby scientific data

Pit (1) -115.9843, 39.526
ListMap

Economic information

Geologic structures

Type of structure Regional
Structure description Roberts Mountains Thrust; Central Nevada Fold Belt; Hoosac Thrust
Type of structure Local
Structure description 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.

Ore body information

  • General form The 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.

Controls for ore emplacement

  • Mineralized 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.

Comments on the geologic information

  • The primary host rock of the Archimedes deposit is thin to thick bedded cherty limestone of the early Ordovician Goodwin Limestone of the Pogonip Group. minor hosts are micritic to shaley limestone of the early Ordovician Ninemile Formation also of the Pogonip Group, and early Cretaceous quartz porphyry. Archimedes satellite deposits are hosted by fine- to coarse early to middle Ordovician limestone and chert of the Antelope Valley Limestone, also of the Pogonip Group. The West Archimedes deposit is a more stratigraphically controlled offshoot of the East Archimedes deposit, a steeply-plunging, oxidized, gold-bearing jasperoid breccia adjoining the quartz-feldspar porphyry intrusive.

Economic information about the deposit and operations

Operation type Surface
Development status Producer
Commodity type Both
Deposit size Medium
Significant Yes
Discovery year 1991
Discoverer Homestake
Year of first production 1997

Mining district

District name Eureka District

Land status

Ownership category BLM Administrative Area
Area name Battle Mountain BLM District

Ownership information

  • Type Owner-Operator
    Owner Barrick Gold Corp
    Year 2006

Comments on the workings information

  • The West Archimedes deposit of the Ruby Hill Gold Mine is developed by an open pit in an area previously mined for polymetallic deposits by underground methods. A mill, haul roads, leach pads, and waste dumps are also present on the property

Comments on other economic factors

  • Ruby Hill production for 1997 was 16,600 ounces of gold. Total production through April, 1998 was about 57,000 ounces of gold. Recent dore has contained less than 10% silver. In early 1998, reserves stand at 7.028 million tons proven and probable ore grading 0.098 opt gold plus 7.173 million tons mineralized material grading 0.073 opt gold.
    IN 2006, Barrick reports reserves of 1.0 million ounces for the East Archimedes deposit, scheduled to begin production in 2007.

Comments on development

  • The initial discovery sample was collected in 1991 by a geologist working under contract to Homestake from a pit north of the old Holly Extension mine dump. The first hole was drilled in the orebody in 1992, and an economic deposit was indicated by mid-1993. The Archimedes orebody was discovered by rock-chip sampling and subsequent geochemical soil anomaly and drilling. Stripping of the Archimedes deposit began in early 1997, and the first gold was poured on November 6,1997. By year?s end, the mine had reached expected production of 3,500 tons per day, of which about 2,600 tons of lower-grade ore is heap leached, while 900 tons of higher-grade material is sent to the mill. The stripping ratio is 7-to-1 and anticipated production is between 105,000 and 110,000 troy ounces of gold annually. Exploration in 1998 continued in the immediate area to identify other shallow oxide deposits as well as a deep drilling program designed to further define a zone of high grade sulfide mineralization discovered 1,500 feet below the West Archimedes open pit.
    By 2005, Barrick reported that thecurrent project will be an open-pit, heap leach operation exploiting the East Archimedes deposit, a deeper continuation of the ore mined previously at Ruby Hill. Permitting has been secured and the two-year, approximately $75-million construction phase is underway. The project is expected to enter production in early 2007 and has reserves of 1.0 million ounces at December 31, 2005.

Reference information

Bibliographic references

  • Deposit

    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.

  • Deposit

    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.

  • Deposit

    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.

  • Deposit

    NBMG MI-97

  • Deposit

    Mining Engineering, Dec., 1994, Society for Mining, Metallurgy, and Exploration, Littleton, Co, vol. 46, p. 1320.

  • Deposit

    Final Environmental Impact Statement for the Ruby Hill Project of Homestake Mining Company, January 1997.

  • Deposit

    Homestake press release, 2/19/98

  • Deposit

    Denver Mining Record, 12/3/97

  • Deposit

    Northern Miner, 11/23/97

  • Deposit

    Long, 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.

General comments

Subject category Comment text
Deposit Archimedes is a Carlin-style sediment-hosted gold deposit in carbonate rocks. The ore is a mixture of jasperoid and decalcified limestone exhibiting strong structural controls. Micron-size gold is associated with oxidized pyrite sites and is strongly fracture controlled. Deeper portions of the east Archimedes resource are sulfidic, and root-zones include retrograde-altered base metal skarn and marble hosts. The mineralized area closely adjoins a Cretaceous porphyry intrusive and may be genetically linked to it, as both base metal-related adularia and the intrusive yield similar radiometric ages. Some evidence suggests the presence of a younger cross-cutting Au-As-Hg system superimposed on the earlier base-metal system and associated with Oligocene magmatism. The West Archimedes deposit is about 780 m long, plunging gently S60?E and covered by 15 to 150 m of partially cemented calcareous alluvium. The deposit is subtabular to ovate in cross section, branching locally at structural intersections. The orebody has a central elongated lens of higher grade jasperoid ore enclosed by a more tabular envelope of lower grade decalcified limestone ore.

Reporter information

Type Date Name Affiliation Comment
Reporter 18-AUG-1995 Sachiko Tanikawa U.S. Geological Survey
Reporter 08-JUL-1998 La Pointe, D.D. Nevada Bureau of Mines and Geology
Editor 01-SEP-2007 Schruben, Paul G. U.S. Geological Survey Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

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Authoritative Nevada resources

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