Main commodities | Au |
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Other commodities | Ag; Pb; Zn |
Ore minerals | arsenopyrite; galena; gold; pyrite; sphalerite |
Gangue minerals | quartz |
Quadrangle map, 1:250,000-scale | VA |
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Quadrangle map, 1:63,360-scale | C-2 |
Latitude | 61.5371 |
Longitude | -144.6462 |
Nearby scientific data | Find additional scientific data near this location |
Location and accuracy | This prospect is located in the cirque at the southwest head of Liberty Creek. It is in the southeast headwall of this cirque, about nine-tenths of a mile north of elevation 5,285. It is at an elevation of 4,400 feet in the NW1/4 section 11, T. 4 S, R. 4 E., of the Copper River Meridian. This prospect is approximately located, perhaps to within one-half mile. It is locality 54 of of Cobb and Matson (1972) and locality 45 of Winkler and others (1981 [OFR 80-892-B]). The location used in this report is that shown by Winkler and others (1981 [OFR 80-892-B]); it is nine-tenths of a mile north of the location shown by Cobb and Matson (1972). |
Geologic descriptionWidely spaced quartz veins as much as 1 meter wide cut the schist of both the Liberty Creek terrane and Eocene tonalite (Winkler and others, 1981 [OFR 80-892-B]; Winkler and others, 1981 [OFR 80-892-A]). The veins contain arsenopyrite, pyrite, galena, and sphalerite. The Opal prospect, being evaluated by Ben Porterfield, contains gold-bearing, polymetallic quartz veins hosted in a white mica-altered, 52 million-year-old tonalite sill. In 2016, exploration was conducted on high-angle shear zones cutting the sill and on pods at the wall-rock contact at the top of the sill (Athey and Werdon, 2017). | |
Geologic map unit | (-144.648297056383, 61.5366218787844) |
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Mineral deposit model | Polymetallic veins (Cox and Singer, 1986; model 22c) |
Mineral deposit model number | 22c |
Age of mineralization | Tertiary; the quartz veins cut tonalite with a K/Ar age of 52.4 +/- 2.6 m.y. (Winkler and others, 1981 [OFR 80-892-A]). |
Workings or exploration | The Opal prospect, being evaluated by Ben Porterfield, contains gold-bearing, polymetallic quartz veins hosted in a white mica-altered, 52 million-year-old tonalite sill. High gold grades, up to 4 ounces of gold per ton, are present, visible gold is common, and it is associated with galena, sphalerite, pyrite, and arsenopyrite. In 2016, exploration was conducted on high-angle shear zones cutting the sill and on pods at the wall-rock contact at the top of the sill (Athey and Werdon, 2017). |
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Indication of production | Yes; small |
MRDS Number | A011496 |
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References | |
Reporters | Travis L. Hudson; M.B. Werdon (DGGS) |
Last report date | 8/26/2017 |