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Aurora Mine Area

Producer in Mineral county in Nevada, United States with commodities Gold, Silver
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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. Bibliographic references
  20. General comments
  21. Reporter information

Geologic information

Identification information

Deposit ID 10310395
MRDS ID W002908
Record type Site
Current site name Aurora Mine Area
Alternate or previous names Esmeralda, Cambridge, Old Humboldt Mine area, Humboldt West claim, Humboldt East claim, Humboldt vein, Prospectus vein, Martinez, Juniata Mine, Del Monte Mine, Wide West Mine, Johnson Mine, Pond Mine, Chihuahua Mine, Garibaldi Mine, Antelope Mine, Utah Mine, Silver Hill, Middle Hill, Last Chance Hill, Aurora Mine, Aurora Partnership Mine, Chesca Mine
Related records 60001663

Comments on the site identification

  • This is a new record for the Aurora Mine area significant deposit. It incorporates all pertinent material from earlier records #W002908, M035801, M242411, and M233145, which may be kept in the databases as describing historic workings.

Geographic coordinates

Geographic coordinates: -118.90179, 38.28631 (WGS84)
Elevation 2290
Relative position The Aurora Mine area is located about 25 miles SW of Hawthorne; 3 miles east of the Nevada-California state line; and 15 miles north of Mono Lake.

Site location context

Political divisions (FIPS codes)

Mineral(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Aurora(quadrangle 1:24,000 scale)

Excelsior Mountains(quadrangle 1:100,000 scale)

Walker Lake(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

East Walker(hydrologic unit)

Walker(hydrologic accounting unit)

Central Lahontan(hydrologic subregion)

Great Basin(hydrologic region)

Federal lands

Humboldt-Toiyabe National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State County
United States Nevada Mineral

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 005N 028E 10, 17,18,19,20 Nevada

Comments on the location information

  • The Aurora mines are scattered over an area that covers more than a square mile and include several historic mines as well as recently mined areas in the district.

Commodities

Commodity Importance
Gold Primary
Silver Primary

Comments on the commodity information

  • Commodity Info: Average. Au:Ag ratio of 1:5. Higher gold values found near surface decreased as silver values increased with depth.
  • Ore Materials: native gold, argentiferous tetrahedrite, electrum, acanthite, naumannite, bromargyrite, chalcopyrite, pyrite.
  • Gangue Materials: quartz, adularia, calcite

Materials information

Materials Type of material
Gold Ore
Tetrahedrite Ore
Electrum Ore
Acanthite Ore
Naumannite Ore
Bromargyrite Ore
Chalcopyrite Ore
Pyrite Ore
Quartz Gangue
Adularia Gangue
Calcite Gangue

Alteration

  • (Local) Progressive weak to strong propylitic alteration with quartz-illite alteration surrounding silicification in the mineralized faults.

Mineral occurrence model information

Model code 150
USGS model code 25c
Deposit model name Epithermal vein, Comstock
Mark3 model number 16

Host and associated rocks

  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite
    Rock type qualifier agglomerates and flows
    Stratigraphic age (youngest) Middle Miocene
    Chronological age 13.5
    Stratigraphic age (youngest) Middle Miocene
    Chronological age 15.4
  • Host or associated Host
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Latite
    Rock type qualifier agglomerates and flows
    Stratigraphic age (youngest) Middle Miocene
    Chronological age 15.4
    Stratigraphic age (youngest) Middle Miocene
    Chronological age 13.5
  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite
    Stratigraphic age (youngest) Tertiary
  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic) > Mafic Volcanic Rock > Basalt
    Stratigraphic age (youngest) Tertiary
  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid > Granite
    Stratigraphic age (youngest) Mesozoic

Nearby scientific data

(1) Alluvium, undifferentiated
ListMap

Economic information

Geologic structures

Type of structure Regional
Structure description A young, less than 3 Ma old, broad regional upwarp extends form the southwest of the Bodie Hills through the Bodie District to the area of the Aurora District. This upwarp may continue to the northeast, south of the Borealis mine.
Type of structure Local
Structure description Steep N-S striking faults offset the mineralized NE-striking faults.

Ore body information

  • General form lenses and stringers

Controls for ore emplacement

  • NE-striking faults are occupied by quartz-adularia-gold-silver veins. Three stages of veining are recognized. Precious metal deposition is associated with the second stage of veining, probably during boiling of the hydrothermal fluid. Ore was deposited by hydrothermal fluids in open space fillings.

Comments on the geologic information

  • Aurora has been is the most productive district in Mineral County in historic times, accounting for 40% of the total county production. In general the ore was of low grade, though some shoots ran as high as $1000/ton. The gold: silver ratio may have been as low as 1:14. The mineralized area of the district is approximately 2 miles long. Host rocks are pre-Esmeralda andesitic to latitic agglomerates and flows.

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Producer
Commodity type Metallic
Deposit size Large
Significant Yes
Discovery year 1860
Discoverer J.M. Brawley, J.M. Corey, E.R. Hicks
Year of first production 1860
Year of last production 1998
Production years 1860-1869; 1914-1918; 1930s, 1983, and 1988-1998 with minor production in intervening years

Mining district

District name Aurora District

Land status

Ownership category Private
Area name Carson City BLM Administrative District

Ownership information

  • Type Owner-Operator
    Owner Metallic Ventures
    Year 2004

Comments on the workings information

  • Historic development was underground. Total underground workings are estimated at about 20 miles. The deepest shaft, the Del Monte, was 900 feet deep and several others were 400-500 feet deep. Workings on Last Chance Hill seldom exceeded 125 feet in depth. Mine development since 1983 has been by open pit.

Comments on other economic factors

  • Historic Aurora mines having major production were: Del Monte, Wide West, Johnson, Pond, Chihuahua, Garibaldi, Antelope, Utah, and Juniata.
    Total recorded production from the 1930s, 1983, and 1988-1996 is estimated to have been at least 305,923 ounces of gold and more than 344,933 ounces of silver. This does not include an unknown but substantial amount of production pre-1930.

    A 2003 calculation reports: 30,710,500 tons grading 0.031 opt Au of bulk-minable measured and indicated resources plus 9,206,300 tons grading 0.025 opt Au bulk-minable inferred resources plus 192,152 tons grading 0.50 opt Au in underground-minable resources remaining in the Martinez & Prospectus zones.

Comments on development

  • The first camp in the early 1860s was at Esmeralda, but was soon relocated to Aurora, which reached a population of 10,000 by 1864. There were 17 active amalgamation mills in 1864, the largest of which had 30 stamps. The total amount of ore handled is estimated at 670,000 tons. From 1861 to 1869, nearly $29,500,000 in gold and silver were produced from the district, mostly by the Aurora Mines Co. and the Aurora Consolidated Mining Co. The district began to decline after 1869, although it was productive intermittently until the early 1900s. From 1914 to 1918 the district enjoyed a brief revival when $1,850,000 in gold and silver were produced, chiefly by the Goldfield Consolidated Mines Co. Much of this production was probably from reworking of tailings and dump material. As late as 1940 as small production was recorded from the district, but in 1956 there was no activity.
    In 1973-74, St. Joe explored for porphyry copper-moly deposits in the area and inferred possible deep (5,000-15,000 ft.) mineralization. In the late 1970s Homestake drilled the Prospectus and Humboldt veins and on Last Chance Hill but failed to find a large bulk tonnage deposit. In 1981 Hanna drilled the Juniata Mine area and the new Esmeralda area, identifying only small reserves. In 1983 Hanna drilled the Prospectus Vein, intersecting ore grades at depths of 50-100 ft. Follow-up drilling by Hanna and later by Nevada Goldfields outlined reserves of 350,000 tons of ore grading/0.185 opt gold.
    Electra Resources was drilling the property in 1980-1981 and in 1982, Electra combined with Pacific Northwest to form Electra Northwest Resources, Ltd. to develop the mine and conducted drilling and engineering programs. Plans were to process an initial 3000 tons of ore. Electra Northwest formed a joint venture with Centennial Minerals, and began production in July 1983 at 1000-1500 tpd at what was called the Aurora Partnership Mine, developed on the Humboldt Vein. Initial recoveries averaged 0.08 opt gold from material grading 0.12 opt gold. Full scale production was planned for 1984. Mine life projected at least five years. Production at the adjacent Aurora Mine (developed on the Prospectus Vein) began in 1987 by Nevada Goldfields. As the Aurora Mine production continued, Minerex Resources, Ltd. took over operation of the Aurora Partnership Mine in 1990, followed by Electra Mining Corp in 1994. The Aurora Partnership Mine appears to have ceased production in 1996, leaving just Nevada Goldfields mine in production, and it too closed by 1999.
    Precious metals exploration in the Aurora area has resumed with the recent increased gold prices. In January 2004, Metallic Ventures Gold Inc. reported the start-up of its 350 ton-per-day mill at its Esmeralda property at Aurora, and poured its first precious metal bullion on February 16. However, in the third quarter of 2004, Metallic Ventures suspended all production and exploration activities at this project in the Aurora district. The project was not providing consistent positive cash flow and, in order to ensure the company has adequatefunding for its other Nevada projects, Esmeralda was placed on care and maintenance status.

Comments on the environmental information

  • Oxidized subduction-related continental-margin arc along western North America.

Reference information

Bibliographic references

General comments

Subject category Comment text
Deposit The Aurora silver-gold deposits are for the most part epithermal fissure vein deposits. Veins consist mostly of finely granular white quartz, which in some places has a milky-white porcelain-like appearance. The veins are commonly composed of layers of quartz of different grain sizes, and all the veins contain cavities lined with clear quartz crystals. The veins are a series of NE-striking to east-striking anastomosing quartz-adularia veins in pre- Esmeralda volcanic rocks that are exposed in a window in an area of predominantly barren younger rocks. A few ounces of placer gold (.408 fine) were recovered from Bodie Creek in 1940-41.
Anastomosing quartz-adularia veins vary in width from less than an inch to as much as 60 feet (one reference states up to 130 feet). Average width is 4 feet. Most veins are wider at intersecting faults, with horsetailing of the veins at their extremes.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-DEC-2005 LaPointe, 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.

Maps centered on this site

Authoritative Nevada resources

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