Unnamed Occurrence (ARDF - MG072; near West Fork of Post River), McGrath Mining District, Bethel Census Area, Alaska, USAi
| Regional Level Types | |
|---|---|
| Unnamed Occurrence (ARDF - MG072; near West Fork of Post River) | - not defined - |
| McGrath Mining District | Mining District |
| Bethel Census Area | Census Area |
| Alaska | State |
| USA | Country |
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Latitude & Longitude (WGS84):
62° 1' 44'' North , 153° 49' 26'' West
Latitude & Longitude (decimal):
Köppen climate type:
See other shale-hosted deposits in McGrath quadrangle such as MG049, MG029, MG051, MG071, MG064, and MG074.
Location: This unnamed occurrence is located on a steep, southeasterly slope adjacent to the west fork of Post River at an elevation of 4,900 feet (1,494 m) in the NE1/4 sec. 3, T. 22 N., R. 25 W., of the Seward Meridian. The reporter sampled the site in 1982.
Geology: This unnamed occurrence is shale-hosted Ag-Cu-Zn mineralization in the Lower Ordovician-to-Lower Silurian Post River Formation, a unit of the Dillinger subterrane (Bundtzen and others, 1988). Graptolites of the Monograptus spiralus zone were found in the shale at the occurrence. A distinctive yellowish, sulfur bloom occurs in the mineralized zone, which is estimated to be about 2 meters thick. Disseminated pyrite was observed in one outcrop. Although isotopic data is lacking, Bundtzen, Harris, and Gilbert (1997) classified the occurrence as a sedimentary exhalitive lead-zinc deposit. Two random chip-channel samples collected across the zone contained up to 1.37 percent zinc, 0.12 percent copper, 13.6 grams/tonne silver, and 196 ppm nickel.
Workings: The reporter sampled the occurrence in 1982. Two random chip-channel samples taken across the mineralized zone contained up to 1.37 percent zinc, 0.12 percent copper, 13.6 grams/tonne silver, and 196 ppm nickel.
Age: Inferred to be Lower Silurian, based on graptolite identifications (Bundtzen and others, 1988).
Alteration: Sulfides oxidized to free sulfur.
Reserves: None.
Commodities (Major) - Ag, Cu, Zn; (Minor) - Ni
Development Status: No
Deposit Model: Sedimentary exhalitive lead-zinc(?) (Cox and Singer, 1986; model 31b).
Select Mineral List Type
Standard Detailed Gallery Strunz Chemical ElementsCommodity List
This is a list of exploitable or exploited mineral commodities recorded at this locality.Mineral List
1 valid mineral.
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 2 - Sulphides and Sulfosalts | |||
|---|---|---|---|
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
Other Databases
| Link to USGS - Alaska: | MG072 |
|---|
Other Regions, Features and Areas containing this locality
North AmericaContinent
North America PlateTectonic Plate
- Farewell-McGrath DomainDomain
- Farewell TerranePassive Margin
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