Latitude & Longitude (WGS84):
61° 27' 36'' North , 149° 11' 24'' West
Latitude & Longitude (decimal):
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Mindat Locality ID:
199396
Long-form identifier:
mindat:1:2:199396:0
Bjorklund and Wright (1948) considered the deposit to be too small and too low grade to be mineable under conditions prevailing in 1940's.
Location: Along Pioneer Creek, 1/2 mile south of Pioneer Creek bridge on the Old Glenn Highway, between 800- and 1,500 ft elevation. Accurate within 1,000 feet. This is locality 'Pioneer Creek Area' of Rose (1966), locality 43 of Cobb (1972), and locality 32 of MacKevett and Holloway (1977).
Geology: Jurassic dunite of the Eklutna Sequence containing two mineralized zones about 400 ft apart containing chromite in stringers, small pods, and disseminations. These are separated by olivine and minor clinopyroxene (Bjorklund and Wright, 1948). The lower zone strikes N 50 W, and dips 37 to 78 NE, and can be traced for 50 ft in outcrops and trenches. The upper zone strikes N 10 W, and dips 35 NE, can be traced for 30 ft in trenches, and has a maximum width of 30 ft. There is evidence in the upper zone that indicates some of the dunite may be slumped talus blocks rather than in place (Rose, 1966). Calculated grades based on weighted average analysis was 6.8 percent chromite for the lower zone and 6.9 percent chromite for the upper zone (Bjorklund and Wright, 1948). The best exposure assayed 7.5 percent chromite across a 13.5 ft zone (Rose, 1966).
Workings: Trenched by the U.S. Bureau of Mines in 1942. Calculated grades based on weighted average analysis for the lower zone was 6.8 percent chromite and 6.9 percent chromite for the upper zone (Bjorklund and Wright, 1948). The best exposure assayed 7.5 percent chromite across a 13.5 ft zone (Rose, 1966).
Age: Lower to Middle Jurassic
Alteration: Slight serpentinization of olivine.
Commodities (Major) - Cr
Development Status: None
Deposit Model: Podiform chromite or Alaskan PGE (Cox and Singer, 1986; models 8a or 9)
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
1 valid mineral.
Gallery:
List of minerals arranged by Strunz 10th Edition classification
| Group 4 - Oxides and Hydroxides |
|---|
| ⓘ | Chromite | 4.BB.05 | Fe2+Cr3+2O4 |
List of minerals for each chemical element
Other Databases
| Link to USGS - Alaska: | AN094 |
|---|
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References
Barnes, F.F., 1948, Preliminary report on the geology along the route of a proposed tunnel to develop hydroelectric power from Eklutna Lake, Alaska: U.S. Geological Survey Open-File Report 54, 9 p. Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p. Bjorklund, Stuart and Wright, W.S., 1948, Investigation of Knik Valley chromite deposits, Palmer, Alaska: U.S. Bureau of Mines Report of Investigation 4356, 5 p. Clark, S.H.B., and Bartsch, S.R., 1971, Reconnaissance geologic map and geochemical analyses of stream sediment and rock samples of the Anchorage B-6 quadrangle, Alaska: U.S. Geological Survey Open-File Report 475, 63 p., 2 sheets, scale 1:36,360. Clark, S.H.B., 1972, Reconnaissance bedrock geologic map of the Chugach Mountains near Anchorage, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-350, 1 sheet, scale 1:250,000. Cobb, E.H., 1972, Metallic mineral resources map of the Anchorage quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-409, 1 sheet, scale 1:250,000. Cobb, E.H., 1979, Summary of references to mineral occurrences (other than mineral fuels and construction materials in the Anchorage quadrangle, Alaska: U.S. Geological Survey Open-File Report 79-1095, 184 p. MacKevett, E.M., Jr., and Holloway, C.D., 1977, Map showing metalliferous and selected non-metalliferous mineral deposits in the eastern part of southern Alaska: U.S. Geological Survey Open-File Report 77-169-A, 99 p., 1 sheet, scale 1:1,000,000. Rose, A.W., 1966, Geology and chromite-bearing ultramafic rocks near Eklutna, Anchorage quadrangle, Alaska: Alaska Division of Mines and Minerals Geologic Report 18, 25 p., 1 sheet, scale 1:42,000.
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