Unnamed Occurrence (ARDF - PE079; near head of Portage Bay), Kupreanof Mining District, Petersburg Borough, Alaska, USAi
Regional Level Types | |
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Unnamed Occurrence (ARDF - PE079; near head of Portage Bay) | - not defined - |
Kupreanof Mining District | Mining District |
Petersburg Borough | Borough |
Alaska | State |
USA | Country |
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Latitude & Longitude (WGS84):
56° 54' 52'' North , 133° 16' 8'' West
Latitude & Longitude (decimal):
KΓΆppen climate type:
Nearest Settlements:
Place | Population | Distance |
---|---|---|
Petersburg | 2,948 (2017) | 22.2km |
Mindat Locality ID:
201491
Long-form identifier:
mindat:1:2:201491:6
GUID (UUID V4):
f9193546-565d-4183-89e7-b4894a4c6139
Location: This occurrence is in a borrow pit about 0.5 mile south of the head of Portage Bay; it is near the center of section 22, T. 57 S., R. 77 E. The location is accurate.
Geology: This mineralization was discovered by Still and others (2002). The rocks in this borrow pit consist mainly of fine- to medium-grained gray to dark green diorite. Intrusive rocks were previously unknown at this site although intermediate intrusive rocks of Cretaceous age have been mapped to the north and south of the pit (Brew and others, 1984). Pyrrhotite makes up 1-2 percent of the diorite and fine-grained chalcopyrite is common in the pit. The sulfides occurs as thin coatings along fractures. Rare molybdenite was also identified. The intrusive in the pit is cut by several faults and the sulfides are commonly localized along them. One of the faults contains bands of sulfides, mainly pyrrhotite with chalcopyrite, sphalerite, galena, arsenopyrite, and pyrite. Hornfels, probably metamorphosed from Cretaceous phyllite, is exposed north of the pit (Brew and others, 1984). Still and others (2002) collected 12 samples from 8 to 20 feet long in the pit. They averaged 163 parts per million (ppm) copper. A select sample of sulfide-rich material contained 3,271 parts per billion (ppb) gold, 12.9 ppm silver, 3.025 ppm copper, 4,708 ppm lead, 1.4 percent zinc, and 9,762 ppm arsenic. Other samples contained up to 855 ppm molybdenum and 1,365 ppm nickel.
Workings: Sampling by Bureau of Land Management geologist in borrow pit.
Age: Cretaceous(?) or younger based on the age of nearby intrusive rocks.
Commodities (Major) - Au, Ag, Cu, Mo, Ni, Pb, Zn
Development Status: None
Deposit Model: Porphyry 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
8 valid minerals.
Detailed Mineral List:
β Arsenopyrite Formula: FeAsS |
β Chalcopyrite Formula: CuFeS2 |
β Galena Formula: PbS |
β Molybdenite Formula: MoS2 |
β Pyrite Formula: FeS2 |
β Pyrrhotite Formula: Fe1-xS |
β Quartz Formula: SiO2 |
β Sphalerite Formula: ZnS |
Gallery:
List of minerals arranged by Strunz 10th Edition classification
Group 2 - Sulphides and Sulfosalts | |||
---|---|---|---|
β | Sphalerite | 2.CB.05a | ZnS |
β | Chalcopyrite | 2.CB.10a | CuFeS2 |
β | Pyrrhotite | 2.CC.10 | Fe1-xS |
β | Galena | 2.CD.10 | PbS |
β | Molybdenite | 2.EA.30 | MoS2 |
β | Pyrite | 2.EB.05a | FeS2 |
β | Arsenopyrite | 2.EB.20 | FeAsS |
Group 4 - Oxides and Hydroxides | |||
β | Quartz | 4.DA.05 | SiO2 |
List of minerals for each chemical element
O | Oxygen | |
---|---|---|
O | β Quartz | SiO2 |
Si | Silicon | |
Si | β Quartz | SiO2 |
S | Sulfur | |
S | β Arsenopyrite | FeAsS |
S | β Chalcopyrite | CuFeS2 |
S | β Galena | PbS |
S | β Molybdenite | MoS2 |
S | β Pyrite | FeS2 |
S | β Pyrrhotite | Fe1-xS |
S | β Sphalerite | ZnS |
Fe | Iron | |
Fe | β Arsenopyrite | FeAsS |
Fe | β Chalcopyrite | CuFeS2 |
Fe | β Pyrite | FeS2 |
Fe | β Pyrrhotite | Fe1-xS |
Cu | Copper | |
Cu | β Chalcopyrite | CuFeS2 |
Zn | Zinc | |
Zn | β Sphalerite | ZnS |
As | Arsenic | |
As | β Arsenopyrite | FeAsS |
Mo | Molybdenum | |
Mo | β Molybdenite | MoS2 |
Pb | Lead | |
Pb | β Galena | PbS |
Other Databases
Link to USGS - Alaska: | PE079 |
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Other Regions, Features and Areas containing this locality
North America
- Coast MountainsMountain Range
North America PlateTectonic Plate
- Taku DomainDomain
USA
- Alaska
- ⭔Wrangell-Petersburg Census AreaBorough
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