Koby; Shepard Prospect, Chichagof Mining District (Chicagof Mining District), Sitka, Alaska, USAi
Regional Level Types | |
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Koby; Shepard Prospect | Prospect |
Chichagof Mining District (Chicagof Mining District) | Mining District |
Sitka | City Borough |
Alaska | State |
USA | Country |
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Latitude & Longitude (WGS84):
57° 48' 53'' North , 135° 56' 38'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Mindat Locality ID:
198393
Long-form identifier:
mindat:1:2:198393:0
GUID (UUID V4):
b5c856a0-9f4a-4aa2-ba25-95d0bf839729
Location: The Koby prospect is at an elevation of about 100 feet on a trail along the southwest side of Lisianski River, about 3.5 miles from the head of Lisianski Inlet. The prospect is 0.5 mile north of the center of sec. 12, T. 47 S., R. 58 E. It is location P-31 of Bittenbender and others (1999); location 23 of Cobb (1972, 1978), who calls it Koby (and Shepard); and MAS no. 0021140051 (U.S. Bureau of Land Management, 2002). The location is accurate within 0.2 mile.
Geology: Johnson and Karl (1985) map the rocks in the area of this prospect as part of a batholith of Cretaceous or Jurassic tonalite and gabbro. The rocks are cut by numerous high-angle faults of varying, but mainly northwest, strike. The most prominent of these is the regional-scale Peril Strait Fault that follows the Lisianski River. The prospect is on or near this fault. Cobb (1972, 1978), citing Reed and Coats (1941) and Rossman (1959), reports that the prospect consists of quartz lenses as much as 7 feet thick along a fault zone in quartz-chlorite schist. The quartz contains about one percent sulfides, including arsenopyrite, pyrite, sphalerite, and galena; in 1959, the owners claimed that it also carries free gold. The deposit was explored by pits, trenches, and a 280-foot adit and crosscut that did not intersect mineralization. Bittenbender and others (1999), mainly citing Kimball (1982), describe the prospect as a quartz vein in greenstone schist. It was explored by a 300-foot adit, and by surface cuts for about 300 feet along strike. Samples across 3- to 6-foot widths of the vein assayed up to 0.02 ounce of gold per ton and 0.5-0.9 ounce of silver per ton. Selected dump samples contained up to 2.96 ounces of gold per ton, 52.5 ounces of silver per ton, and 1 percent lead. They report that the deposit also contains copper, bismuth, and cadmium. There is no record of any production, but the extent of the workings suggests that some gold may have been produced.
Workings: According to Cobb (1978), the deposit was explored by pits, trenches, and a 280-foot adit and crosscut that did not intersect mineralization. Bittenbender and others (1999) report that it was explored by a 300-foot adit and by surface cuts for about 300 feet along the strike of the vein.
Production: There is no record of any production, but the extent of the workings suggests that some gold may have been produced.
Commodities (Major) - Au, Pb, Zn; (Minor) - Bi, Cd, Cu
Development Status: Undetermined.
Deposit Model: Polymetallic vein (Cox and Singer, 1986; model 22c).
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
6 valid minerals.
Detailed Mineral List:
ⓘ Arsenopyrite Formula: FeAsS |
ⓘ Galena Formula: PbS |
ⓘ Gold Formula: Au |
ⓘ Pyrite Formula: FeS2 |
ⓘ Quartz Formula: SiO2 |
ⓘ Sphalerite Formula: ZnS |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 1 - Elements | |||
---|---|---|---|
ⓘ | Gold | 1.AA.05 | Au |
Group 2 - Sulphides and Sulfosalts | |||
ⓘ | Sphalerite | 2.CB.05a | ZnS |
ⓘ | Galena | 2.CD.10 | PbS |
ⓘ | Pyrite | 2.EB.05a | FeS2 |
ⓘ | Arsenopyrite | 2.EB.20 | FeAsS |
Group 4 - Oxides and Hydroxides | |||
ⓘ | Quartz | 4.DA.05 | SiO2 |
List of minerals for each chemical element
O | Oxygen | |
---|---|---|
O | ⓘ Quartz | SiO2 |
Si | Silicon | |
Si | ⓘ Quartz | SiO2 |
S | Sulfur | |
S | ⓘ Arsenopyrite | FeAsS |
S | ⓘ Galena | PbS |
S | ⓘ Pyrite | FeS2 |
S | ⓘ Sphalerite | ZnS |
Fe | Iron | |
Fe | ⓘ Arsenopyrite | FeAsS |
Fe | ⓘ Pyrite | FeS2 |
Zn | Zinc | |
Zn | ⓘ Sphalerite | ZnS |
As | Arsenic | |
As | ⓘ Arsenopyrite | FeAsS |
Au | Gold | |
Au | ⓘ Gold | Au |
Pb | Lead | |
Pb | ⓘ Galena | PbS |
Other Databases
Link to USGS - Alaska: | SI049 |
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Other Regions, Features and Areas containing this locality
North America PlateTectonic Plate
- Alexander DomainDomain
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