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Castle River occurrence, Kupreanof Island, Petersburg Borough, Alaska, USAi
Regional Level Types
Castle River occurrenceOccurrence
Kupreanof IslandIsland
Petersburg BoroughBorough
AlaskaState
USACountry

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Latitude & Longitude (WGS84):
56° 39' 59'' North , 133° 15' 35'' West
Latitude & Longitude (decimal):
Nearest Settlements:
PlacePopulationDistance
Petersburg2,948 (2017)24.7km
Mindat Locality ID:
201488
Long-form identifier:
mindat:1:2:201488:6
GUID (UUID V4):
0
Other/historical names associated with this locality:
ARDF - PE024


Location: The coordinates are at the center of an area of mineralized outcrops that occur discontinuously just above the high tide line for about a half mile along the west shore of the large shallow bay at the mouth of the Castle River. The site is locality 29 of Grybeck, Berg, and Karl (1984) and this may be a continuation of the mineral occurrence at PE025 just to the northeast.

Geology: Outcrops of phyllitic, light greenish gray to cream, felsic metatuff intercalated with muscovite-rich siliceous phyllite occur discontinuously just above the high tide line for about a half mile along the edge of a large shallow bay. The metatuff locally contains massive-sulfide layers up to 6 feet thick with abundant pyrite and sparse sphalerite(?) (Grybeck, Karl, and Berg, 1984). Grab samples of the massive sulfide layers and felsic metatuff show up to 700 parts per million (ppm) lead, 350 ppm zinc, 10 ppm silver, and 2,000 ppm barium. These outcrops may be a continuation of the mineralized occurrence at PE025 just to the northeast. This is probably the locality noted by Buddington (1923) that he described as a pyrite layer about 4 feet wide exposed for 50 feet. Recent mapping by Karl and others (1999) indicates that these outcrops are part of the Hyd Group of Triassic age. This occurrence was covered by a large block of claims staked by Pacific Alaska Resources Co in the late 1980's and early 1990's; the company planned to drill to test several geochemical anomalies in copper, zinc, and silver but apparently did not follow through. Still and others (2002) sampled several of these lenses; their samples contained up to 31.8 ppm silver, 1,304 ppm lead, 1.7 percent zinc, and 1,268 ppm arsenic.

Workings: In 1979, nine lode claims were staked in the area that probably covered this deposit. By 1995, a considerable block of ground several square miles in area was staked on and northwest of this site and PE025. Informal discussions with industry geologists who worked in the area indicate that they found several to numerous additional occurrences of similar deposits on these claims (D.J. Grybeck, oral communication, 1996). An aerial examination of the area in 1996 indicated no obvious signs of surface exploration. In 1998, there was renewed interest in the area encouraged by the geophysical surveys the State of Alaska had flown over the area.

Age: Late Triassic based on the age of the host rock.

Commodities (Major) - Ag, Ba, Cu, Pb, Zn
Development Status: None

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


2 valid minerals.

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 2 - Sulphides and Sulfosalts
ⓘSphalerite2.CB.05aZnS
ⓘPyrite2.EB.05aFeS2

List of minerals for each chemical element

SSulfur
Sⓘ PyriteFeS2
Sⓘ SphaleriteZnS
FeIron
Feⓘ PyriteFeS2
ZnZinc
Znⓘ SphaleriteZnS

Other Databases

Link to USGS - Alaska:PE024

Other Regions, Features and Areas containing this locality

North America PlateTectonic Plate
USA

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