Ramsey-Rutherford

Mine, Probably inactive

Commodities and mineralogy

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

Geographic location

Quadrangle map, 1:250,000-scale VA
Quadrangle map, 1:63,360-scale A-6
Latitude 61.2043
Longitude -146.1032
Nearby scientific data Find additional scientific data near this location
Location and accuracy This mine is in a cirque valley, 1.5 miles west northwest of Prospector Peak. The mine location is shown on the USGS Valdez A-6 topographic map (1951; limited revisions, 1980). It is accurately located. This is locality 36 of Cobb and Matson (1972) and locality 28 of Winkler and others (1981 [OFR 80-892-B]).

Geologic setting

Geologic description

The Ramsey-Rutherford mine is one of the major mines in the Valdez area; it had a recorded production of 5,375 ounces of gold (Jansons and others, 1984). Two or more gold-bearing quartz veins cut metaflysch of the Valdez Group (Brooks, 1913; Johnson, 1915) at the mine. The main vein is steeply dipping and trends north-northwest. It varied in thickness from a few inches to about 6 feet; it averaged 2 to 3 feet in thickness over about 450 feet of strike length (Johnson, 1915; Jansons, 1984). The second vein, about 90 feet north of the main vein, varies from a few inches to a few feet in thickness; other small or cross-linked veins are present in the area (Hoekzema and others, 1986). Sulfide minerals are generally absent to sparsely distributed in the veins, but they also occur locally in semi-massive pods and lenses. The sulfide minerals reported at the mine include pyrrhotite, chalcopyrite, pyrite, arsenopyrite, galena, and sphalerite. In addition to quartz, calcite and siderite occur as gangue minerals (Hoekzema and others, 1986). The mine operated intermittently from 1912 to 1939 (Cobb, 1979 [OFR 79-1241]; Hoekzema and others, 1986). It was developed by at least 1,400 feet of underground workings by 1915; a 162-foot shaft was sunk in addition to adits, cross cuts, and drifts on four levels (Johnson, 1915; Hoekzema and others, 1986). Production began in 1914 after a mill was installed on site. The total recorded production of 5,375 ounces of gold and 1,194 ounces of silver was recovered from about 6,000 tons of ore (Hoekzema and others, 1986). The average grade of the produced ore is about 1 ounce of gold per ton. Selected grab samples from the area contained from 0.05 to 37.5 ppm gold (Hoekzema and others, 1986; Pickthorn, 1982).
The gold-bearing veins at the Ramsey-Rutherford mine 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 (-146.105276830433, 61.2037866861087)
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 mine operated intermittently from 1912 to 1939 (Cobb, 1979 [OFR 79-1241]; Hoekzema and others, 1986). It was developed by at least 1,400 feet of underground workings by 1915; a 162-foot shaft was sunk in addition to adits, cross cuts, and drifts on four levels (Johnson, 1915; Hoekzema and others, 1986).
Indication of production Yes; small
Production notes The total recorded production of 5,375 ounces of gold and 1,194 ounces of silver was recovered from about 6,000 tons of ore (Hoekzema and others, 1986). The average grade of the produced ore is about 1 ounce of gold per ton. Selected grab samples from the area contained from 0.05 to 37.5 ppm gold (Hoekzema and others, 1986; Pickthorn, 1982).

References

MRDS Number A011477

References

Goldfarb, R.J., Miller, L.D., Leach, D.L., and Snee, L.W, 1997, Gold deposits in metamorphic rocks in Alaska, in Goldfarb, R.J., and Miller, L.D., eds., Mineral Deposits of Alaska: Economic Geology Monograph 9, p. 151-190.
Hudson, T.L., 1994, Crustal melting events in Alaska, in Plafker, G., and Berg, H. C., eds., The Geology of Alaska: Geological Society of America, DNAG, The Geology of North America, Vol. G-1, p. 657-670.
Pickthorn, W.J., 1982, Stable isotope and fluid inclusion study of the Port Valdez district, southern Alaska: Los Angeles, University of California at Los Angeles, M.S. thesis, 66 p.
Reporters Travis L. Hudson
Last report date 12/14/2001