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Silver Star prospect, Kupreanof Island, Petersburg Borough, Alaska, USAi
| Regional Level Types | |
|---|---|
| Silver Star prospect | Prospect |
| Kupreanof Island | Island |
| Petersburg Borough | Borough |
| Alaska | State |
| USA | Country |
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Latitude & Longitude (WGS84):
56° 50' 53'' North , 133° 15' 50'' West
Latitude & Longitude (decimal):
Type:
Köppen climate type:
Nearest Settlements:
| Place | Population | Distance |
|---|---|---|
| Petersburg | 2,948 (2017) | 19.2km |
Other/historical names associated with this locality:
Silver King prospect
This prospect is now in the Petersburg Creek-Duncan Salt Chuck Wilderness, which is closed to mineral exploration and mining.
Location: This prospect is about 1.6 miles west-southwest of Duncan Peak at an elevation of about 400 feet. It is about 0.5 south-southeast of the center of section 10, T. 58 S., R. 77 E. There is some confusion in the old literature about the location and geology of two prospects in the area. For example, Cobb (1972 and 1978) or Berg and Cobb (1967), and an earlier generation of ARDF almost certainly combine two different prospects on the west side of Portage Mountain. Still and others (2002) spent considerable time in the field and library trying to decipher their locations and descriptions; this record is based on their location for the Silver Star prospect. The other prospect--XXX PE New A1028--which is about 2 miles to the north-northeast is a different type of deposit.
Geology: The rocks in the vicinity of this prospect are mafic intrusions of late Cretaceous age (Brew and others, 1984). Between an elevation of 360 and 480 feet along a creek, there are outcrops of hornblendite and hornblende diorite that were examined by Still and others (2002). Disseminated pyrrhotite, pyrite, and chalcopyrite are common and there are veinlets up to 1 inch thick in the hornblendite with pyrite and pyrrhotite. Copper staining is locally prominent. Still and others (2002) took 17 samples. The maximum copper content was 4,666 parts per million but most samples contained much less. The highest platinum value was 39 parts per billion (ppb) and the highest palladium value was was 59 ppb; all other metals were in the background range. Buddington (1923) reports that the only workings were several cuts. Still and others (2002) suggest that the prospect is a magmatic segregation deposit.
Workings: The only workings were several open cuts.
Age: Late Cretaceous or younger based on the age of the host rocks.
Commodities (Major) - Cu; (Minor) - Pd, Pt
Development Status: None
Deposit Model: Magmatic segregation with copper?
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
3 valid minerals.
Detailed Mineral List:
| ⓘ Chalcopyrite Formula: CuFeS2 |
| ⓘ Pyrite Formula: FeS2 |
| ⓘ Pyrrhotite Formula: Fe1-xS |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 2 - Sulphides and Sulfosalts | |||
|---|---|---|---|
| ⓘ | Chalcopyrite | 2.CB.10a | CuFeS2 |
| ⓘ | Pyrrhotite | 2.CC.10 | Fe1-xS |
| ⓘ | Pyrite | 2.EB.05a | FeS2 |
List of minerals for each chemical element
| S | Sulfur | |
|---|---|---|
| S | ⓘ Chalcopyrite | CuFeS2 |
| S | ⓘ Pyrite | FeS2 |
| S | ⓘ Pyrrhotite | Fe1-xS |
| Fe | Iron | |
| Fe | ⓘ Chalcopyrite | CuFeS2 |
| Fe | ⓘ Pyrite | FeS2 |
| Fe | ⓘ Pyrrhotite | Fe1-xS |
| Cu | Copper | |
| Cu | ⓘ Chalcopyrite | CuFeS2 |
Other Databases
| Link to USGS - Alaska: | PE009 |
|---|
Other Regions, Features and Areas containing this locality
North America
- Coast MountainsMountain Range
North America PlateTectonic Plate
- Alexander DomainDomain
- Alexander TerraneVolcanic Arc
USA
- Alaska
- Petersburg Borough
- Kupreanof Mining DistrictMining District
- ⭔Wrangell-Petersburg Census AreaBorough
- Petersburg Borough
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References
Berg, Henry C.; Cobb, E.H. (1967) Metalliferous Lode Deposits of Alaska. Geological Survey Bulletin 1246. US Geological Survey 254 pp.
Grybeck, Donald J.; Berg, Henry C.; Karl, Susan M. (1984) Map and description of the mineral deposits in the Petersburg and eastern Port Alexander quadrangles, southeastern Alaska. Open-File Report 84-837. US Geological Survey 87 pp. doi:10.3133/ofr84837
