Minnie

Mine, Probably inactive

Alternative names

Olson
Bald Mountain Group

Commodities and mineralogy

Main commodities Au
Other commodities Pb; Zn
Ore minerals arsenopyrite; galena; gold; pyrite; sphalerite
Gangue minerals carbonate minerals; chlorite; quartz; sericite

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale A-8
Latitude 61.2007
Longitude -146.6469
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is eight-tenths of a mile southeast of Mount Cameron at an elevation of about 3,000 feet in the SW1/4 section 3, T. 8 S., R. 8 W., of the Copper River Meridian. This mine is located to within one-half mile. It is locality 4 of Cobb and Matson (1972).

Geologic setting

Geologic description

Gold-bearing quartz veins as much as 2 feet wide cut metaflysch of the Valdez Group (Johnson, 1915). The veins strike northwest and dip steeply to both the north and south. The quartz veins also contain pyrite, sphalerite, galena, and a brown-weathering carbonate mineral. The Minnie deposit was explored by three or four short adits, and the Olson deposit was explored by an adit and drifts that totaled about 250 feet in length (Johnson, 1915). Open cuts explored the deposits on the surface. A few tons of ore were processed from each deposit. The U.S. Bureau of Mines collected three chip samples from the Minnie deposit that contained as much as 12.0 ppm gold and 7.0 ppm silver; a grab sample contained 45 ppm gold and 12.5 ppm silver (Jansons and others, 1984).
These deposits are probably similar to other gold-bearing quartz veins cutting metaflysch of the Valdez Group in the southern Valdez quadrangle. Data summarized by Goldfarb and others (1997) show that gold-bearing quartz veins in the Valdez Group commonly contain pyrite, arsenopyrite, carbonate minerals, chlorite, and white mica and formed from water-rich fluids with 5 to 15 mole percent CO2 and significant amounts of CH4, N2, and H2S. The vein-forming fluid salinities were less than 8 percent, vein formation temperatures ranged from 225 to 375 degrees centigrade, and emplacement depths varied from 3 to 10 kilometers. The vein-forming fluids were produced by metamorphic devolatilization reactions. Radiometric dating indicates that the veins formed from 57 to 49 Ma (Goldfarb and others, 1997, p. 171), when deep parts of the accreted Valdez Group flysch underwent high-grade metamorphism and partial melting (Hudson, 1994).
Geologic map unit (-146.648955933122, 61.2001781728034)
Mineral deposit model Low-sulfide Au-quartz veins (Cox and Singer, 1986; model 36a)
Mineral deposit model number 36a
Age of mineralization Radiometric dating indicates that the gold-bearing quartz veins in the Valdez Group formed from 57 to 49 Ma (Goldfarb and others, 1997, p. 171), when deep parts of the accreted Valdez Group flysch underwent high-grade metamorphism and partial melting (Hudson, 1994).
Alteration of deposit Country rocks to gold-bearing quartz veins in Valdez Group metaflysch can be variably silicified, carbonitized, and sericitized (Goldfarb and others, 1997).

Production and reserves

Workings or exploration The Minnie deposit was explored by three or four short adits, and the Olson deposit was explored by an adit and drifts that totaled about 250 feet in length (Johnson, 1915). Open cuts explored the deposits on the surface.
Indication of production Yes; small
Production notes A few tons of ore were processed from each deposit (Johnson, 1915).

References

MRDS Number A011445

References

Reporters Travis L. Hudson
Last report date 12/14/2001