Rose Johnson

Mine, Probably inactive

Commodities and mineralogy

Main commodities Au
Other commodities Cu; Pb; Zn
Ore minerals arsenopyrite; chalcopyrite; galena; gold; pyrite; sphalerite
Gangue minerals carbonate minerals; chlorite; quartz; white mica

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale A-6
Latitude 61.1837
Longitude -146.1632
Nearby scientific data Find additional scientific data near this location
Location and accuracy This prospect is along the east side of Valdez Glacier at an elevation of about 1,300 feet; it is near the center of the south boundary of section 8, T. 8 S., R. 5 W., of the Copper River Meridian. This prospect is probably located to within one-half mile. It is locality 34 of Cobb and Matson (1972) and locality 26 of Winkler and others (1981 [OFR 80-892-B]).

Geologic setting

Geologic description

Gold-bearing quartz veins from a few inches to a few feet thick cut metaflysch of the Valdez Group at this locality (Johnson, 1915). A small mill was installed in 1914 but was only operated for a short time. About 50 ounces of gold were reported to have been produced (Jansons and others, 1984). The vein observed by Johnson (1915) was a few inches wide; it trended east-west and was vertical. Specimens said to have come from this property contained gold, pyrite, chalcopyrite, galena, and sphalerite(?). The gold-bearing veins at this locality are probably similar to others that are widespread 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 (-146.165266279226, 61.1831854749062)
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 Open cuts, short adits, and a 20-foot shaft explored this property by 1915 (Johnson, 1915).
Indication of production Yes; small
Production notes About 50 ounces of gold were reported to have been produced from this property (Jansons and others, 1984).

References

MRDS Number A011475

References

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