| Main commodities | Au |
|---|---|
| Other commodities | Ag; Pb; Zn |
| Ore minerals | arsenopyrite; galena; gold; pyrite; sphalerite |
| Gangue minerals | carbonate minerals; chlorite; quartz; sericite |
| Quadrangle map, 1:250,000-scale | VA |
|---|---|
| Quadrangle map, 1:63,360-scale | A-8 |
| Latitude | 61.2052 |
| Longitude | -146.6668 |
| Nearby scientific data | Find additional scientific data near this location |
| Location and accuracy | This mine is one-third of a mile south of the summit of Mount Cameron; it is at an elevation of about 5,100 feet on the ridge crest near the center of section 4, T. 8 S., R. 8 W., of the Copper River Meridian. This mine is located to within one-quarter mile. It is locality 3 of Cobb and Matson (1972) and locality 3 of Winkler and others (1981 [OFR 80-892-B]). |
Geologic descriptionSeveral gold-bearing quartz-carbonate veins as much as 11.5 feet thick, cut metaflysch of the Valdez Group (Johnson, 1915). The veins strike northwest and dip steeply to the north. The largest veins were traceable for as much as 300 feet. The veins carry about 3 percent sulfide minerals that include pyrite, galena, sphalerite, and arsenopyrite. The deposits are exposed from about 2,400 to 4,500 feet in elevation and were explored with eight adits and about 2,000 feet of underground workings (Cobb, 1979 [OFR 79-1241]; Jansons and others, 1984). A mill was installed on the property, and some ore was processed most years from 1913 to 1921. Total reported production from these veins was 585 ounces of gold and 18 ounces of silver (Jansons and others, 1984). The U.S. Bureau of Mines collected 25 chip samples that contained 0.06 to 21.0 ppm gold and 0.1 to 8.5 ppm silver; 12 grab samples contained as much as 15.3 ounces of gold and 4.3 ounces of silver per ton (Jansons and others, 1984). These veins 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 | (-146.66886061167, 61.2046777974395) |
|---|---|
| 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). |
| Workings or exploration | The deposits are exposed from about 2,400 to 4,500 feet in elevation and were explored with eight adits and about 2,000 feet of underground workings (Cobb, 1979, OFR 79-1241; Jansons and others, 1984). |
|---|---|
| Indication of production | Yes; small |
| Production notes | A mill was installed on the property, and some ore was processed most years from 1913 to 1921. Total reported production from these veins was 585 ounces of gold and 18 ounces of silver (Jansons and others, 1984). |
| MRDS Number | A011444 |
|---|---|
ReferencesGoldfarb, 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.
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| Reporters | Travis L. Hudson |
| Last report date | 12/14/2001 |