Red Mountain Creek

Site Name

Primary: Red Mountain Creek
Secondary: WTF (Western Tundra Flats)
Secondary: Dry Creek

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Commodity

Primary: Gold
Primary: Silver
Primary: Zinc
Primary: Zinc
Primary: Copper
Primary: Lead

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Location

State: Alaska

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Land Status

Not available

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Unknown
Years of Production:
Organization:
Significant:

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Physiography

Not available

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Mineral Deposit Model

Model Name: Massive sulfide, kuroko, (Precambrian)
Model Name: Massive sulfide, kuroko
Model Name: Massive sulfide, kuroko (Phanerozoic)

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Not available

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Materials

Ore: Galena
Ore: Sphalerite
Ore: Chalcopyrite
Gangue: Chlorite
Gangue: Feldspar
Gangue: Quartz

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Comments

Comment (Deposit): Model Name = Kuroko massive sulfide (Cox and Singer, 1986; model 28a)

Comment (Reserve-Resource): Reserves = 178.2 grams silver per tonne (The Northern Miner, 1998 and 1999: v. 84, nos. 26 and 52).

Comment (Reserve-Resource): Reserves = Reserves for part of this deposit have been estimated at 1.10 million tonnes grading 0.15 percent copper, 2.5 percent lead, 7.9 percent zinc, and 270 grams silver, and 1.9 grams of gold per tonne (Nokleberg and others, 1987). An estimate based on 38 of 60 holes drilled to test the southern limb of the syncline gave an inferred resource of 2.9 million tonnes grading 4.4 percent zinc, 1.9 percent lead, 0.2 percent copper, and 0.55 gram gold and 93.6 grams silver per tonne. Included in this estimate is a higher-grade core of 1.5 million tonnes grading 6.4 percent zinc, 2.9 percent lead, 0.3 percent copper, and 0.79 gram gold and 123.8 grams silver per tonne. The bulk of the resource is in the Fosters Creek and Discovery zones, respectively in pyritic sedimentary rocks and intensely altered rhyolite. On the north limb of the syncline, the WTF resource currently (1999) stands at 2.8 million tonnes grading 6 percent zinc, 2.5 percent lead, 0.1percent copper, and 0.9 gram gold and

Comment (Exploration): Status = Active

Comment (Workings): Workings / Exploration = Exploration of the area includes an EM geophysical survey and extensive drilling. Press releases indicate that over 60 drill holes totaling approximately 7600 m have been drilled to date (Robertson, 1998; The Northern Miner, 1998 and 1999: v. 84, nos. 26 and 52).

Comment (Geology): Age = Mineralization was syngenetic with the Lower Mississippian to Middle Devonian host rocks.

Comment (Commodity): Gangue = white mica

Comment (Reference): Primary Reference = Nokleberg and others, 1994

Comment (Geology): Geologic Description = The country rocks in the area of this prospect are mapped as the Lower Mississippian to Middle Devonian Totatlanika Schist, composed predominantly of metavolcanic and metavolcaniclastic rocks, and subordinate amounts of intercalated metasedimentary rocks (Wilson and others, 1998). The dominant structural fabric on the property is a strong mylonitic foliation, and there is a consistent east-northeasterly lineation that plunges at about 20-30 degrees. The deposit is in greenschist-grade metasedimentary rocks and altered rhyolite schist, and consists of stratiform bodies of massive sulfides that occur on the northern and southern limbs of an east-trending synclinal fold. The southern limb of the syncline contains three ore horizons that dip to the north at about 70 to 80 degrees (Schuster, 1998). These are referred to as the DC zones, which have been subdivided into the DC-North, DC-South, and DC-17 zones. The DC-North zone is defined by a 2-kilometer-long EM conductor. This zone has been further subdivided into three areas: Discovery, which roughly bisects the EM anomaly; Lago Creek, which is 200-400 meters west of the Discovery area; and Fosters Creek, about 800 meters west of the Discovery area. In the Fosters Creek area, drilling has intercepted a 29-meter interval (true width) grading 6.22 percent zinc, 2.56 percent lead and 0.22 percent copper, as well as 182.8 grams silver and 1.03 grams gold per tonne. A 3.7-meter intercept in the hole produced assay results as high as 23.58 percent zinc, 8.46 percent lead, 1.02 percent copper, and 531.5 grams silver and 2.24 grams gold (Schuster, 1998). The DC-South zone is virtually unexplored except for a few reconnaissance drill holes. The DC-17 zone is a 15-meter-thick bed of pyrite (with minor amounts of lead and zinc) that is believed to be genetically related to other zones. The northern limb of the syncline dips gently to the south and hosts the WTF zone, a layer of massive sulfides 0.3 to 5 meters thick that has been tested by 26 widely-spaced drill holes (Schuster, 1998).

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References

Reference (Deposit): The Northern Miner, 1999, v. 84, nos. 52

Reference (Deposit): The Northern Miner, 1998, v. 84, nos. 26

Reference (Deposit): Schuster, T., 1998, Grayd advances Alaskan properties: The Northern Miner, v. 84, no. 18, p. 2.

Reference (Deposit): Robertson, R, 1998, Grayd hits massive sulphide: The Northern Miner, v. 84, no. 17, p. 3.

Reference (Deposit): Cox, D.P., Light, T.D., Csejtey, Bela, Jr., and Campbell, D.L., 1989, Mineral resource assessment map of the Healy quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map, MF-2058-A, scale 1:250,000.

Reference (Deposit): Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p.

Reference (Deposit): Wilson, F.H., Dover, J.H., Bradley, D.C., Weber, F.R., Bundtzen, T.K., and Haeussler, P.J., 1998, Geologic map of central (interior) Alaska: U.S. Geological Survey Open-File Report 98-133, 17 p., 2 sheetsm, scale 1:500,000.

Reference (Deposit): Nokleberg, W.J., and others, 1994, Metallogeny and major mineral deposits of Alaska and Metallogenic map of significant metalliferous lode deposits and placer districts of Alaska, in Plafker, G. and Berg, H.C., eds., The Geology of Alaska: Boulder, Colorado, Geological Society of America: The Geology of North America, v. G1, p. 855-904 and v. G1, Plate 11, scale 1:2,500,000.

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