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Easy Junior Mine

Producer in White Pine county in Nevada, United States with commodities Gold, Silver, Mercury, Thallium, Antimony, Barium-Barite
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Geologic information

Identification information

Deposit ID 10310554
Record type Site
Current site name Easy Junior Mine
Alternate or previous names Nighthawk Ridge Mine
Related records 10047584, 10310405

Geographic coordinates

Geographic coordinates: -115.67422, 39.18104 (WGS84)
Elevation 1990
Relative position The mine is located about 30 miles SE of Eureka, Nevada.
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Geographic areas

Country State County
United States Nevada White Pine

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 15N 56E 9 (UNSURVEYED) Nevada

Comments on the location information

  • The mine is located at the northern end of Railroad Valley at the southeast end of the Cortez Trend.

Commodities

Commodity Importance
Gold Primary
Silver Secondary
Mercury Tertiary
Thallium Tertiary
Antimony Tertiary
Barium-Barite Tertiary

Comments on the commodity information

  • Commodity Info: AU:AG ratios are generally > 50:1.
  • Ore Materials: micron-sized gold grains
  • Gangue Materials: hematite, limonite, opal, barite, scorodite

Materials information

Materials Type of material
Gold Ore
Hematite Gangue
Limonite Gangue
Opal Gangue
Barite Gangue
Scorodite Gangue

Alteration

  • (Local) Silicification is the most common alteration within the orebody. Jasperization, argillization, and decarbonization have also affected the rocks. Chainman Shale and Pilot Shale are argillized and silicified adjacent to the Nighthawk Fault.

Mineral occurrence model information

Model code 172
USGS model code 26a
BC deposit profile E03
Deposit model name Carbonate-hosted Au-Ag
Mark3 model number 15

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Shale
    Rock unit name Chainman Shale
    Stratigraphic age (youngest) Late Mississippian
    Stratigraphic age (oldest) Early Mississippian
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock unit name Joana Limestone
    Stratigraphic age (youngest) Early Mississippian

Nearby scientific data

(1) -115.67422, 39.18104
ListMap

Geologic structures

Type Description Terms
Local Nighthawk Fault
Regional Rocks in the mine area have been affected by low amplitude, open folds with axes that strike between N-S and N15E.

Controls for ore emplacement

  • The Nighthawk Fault strikes northeast, dips 80 degrees west and serves as the primary conduit for mineralizing fluids. The ore is thickest where the Nighthawk Fault is offset by WNW-trending en echelon faulting, as a result of secondary porosity tat developed in the Chainman Shale at the fault intersections. The Joana Limestone acted as a porous host since gold mineralization appears stratabound and closely emulates the fold pattern.

Comments on the geologic information

  • All mineralized intercepts were at the contact of the Chainman Shale and Joana Limestone.

Economic information

Economic information about the deposit and operations

Operation type Surface
Development status Producer
Commodity type Both metallic and non-metallic
Deposit size Small
Significant Yes
Discovery year 1986
Discoverer Tenneco Minerals Co.
Year of first production 1989

Mining district

District name White Pine District

Land status

Ownership category BLM Administrative Area
Area name BLM Ely Administration District

Ownership information

  • Type Owner
    Owner ALTA BAY JOINT VENTURE: ALTA GOLD CO.
    Interest 60
    Year 1999
  • Type Owner
    Owner ALTA BAY JOINT VENTURE: ECHO BAY, LTD.
    Interest 40
    Year 1999
  • Type Operator
    Owner ALTA GOLD CO.
    Home office 2319 FOOTHILL DRIVE #140, SALT LAKE CITY, UTAH, 84109
    Year 1999

Comments on the workings information

  • The mine has been developed by open pits and other surface workings.

Comments on other economic factors

  • 'Reserves in 1989 were estimated to be apporximately 5.68Mt of ore grading 0.031 opt Au. In 1991, reserves and resources of 137,000 oz Au were estimated to remain. The cash cost of production was $240/oz. gold.

Comments on development

  • The original Easy Junior claims were staked in 1979 by Earth Resources Company on the basis of prominent jasperoid outcrops. These claims were acquired by Houston International Minerals Company (HIMCO) in 1980. HIMCO drilled eight holes totaling 1810 ft in 1980, but only one hole contained anomalous gold mineralization. Himco subleased Easy Junior to Consolidated Mineral Resources from 1981 to 1983, during which eight holes totaling 2620 ft. were drilled. Drill results were discouraging. In 1984, Consolidated Minerals conveyed interest in Easy Junior to AAMINEX for stock, and AAMINEX sub-leased the property to Santa Fe Pacific Mining Co. During 1984-1985, Santa Fe completed geologic mapping, a VLF survey and 16 drill holes totaling 9295 ft. Several of these holes intersected narrow zones of gold mineralization, the best being a 45 ft intercept grading 0.059 opt gold. All mineralized intercepts were at the contact of the Chainman Shale and Joana Limestone. Santa Fe terminated the lease in 1985, after which AAMINEX returned the claims back to Tenneco Minerals Co, which had since acquired HIMCO. All drilling up to this time had been completed in the vicinity of the outcropping jasperoids. In 1986, Tenneco extended the claim block north to include what would become the Nighthawk Ridge deposit. A soil geochemistry grid identified two linear gold anomalies which led to the discovery of outcrop of folded and silicified Chainman Shale with abundant barite and minor scorodite along fractures. 36 samples from this outcrop assayed as high as 2.33 ppm gold, but averaged 0.5 ppm gold, with anomalous Hg, Tl, As, and Sb. A 41 drill hole program was initiated in September, 1986. The discovery hole was the 39th hole, intersecting 320 feet grading 0.066 opt gold.

Reference information

Bibliographic references

  • Deposit

    Carden, J.R., 1991, The Discovery and Geology of the Nighthawk Ridge Deposit at Easy Junior, White Pine County, Nevada, in Geology and Ore Deposits of the Great Basin, Raines, G.L., et al., eds., The Geological Society of Nevada, Reno, p. 665-676.

  • Deposit

    NBMG, 1991, The Nevada Mineral Industry 1990, NBMG Special Publication MI-1990, p.25.

  • 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.

General comments

Subject category Comment text
Deposit Sediment-hosted disseminated gold

Reporter information

Type Date Name Affiliation Comment
Reporter 14-NOV-2002 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.