|Quadrangle map, 1:250,000-scale||SV|
|Quadrangle map, 1:63,360-scale||A-5|
|Nearby scientific data||Find additional scientific data near this location|
|Location and accuracy||These chromite deposits occur on a small peninsula on the northern shore of Port Chatham in the SW1/4 of section 21, T. 11 S., R. 15 W., of the Seward Meridian. Most of the chromite lens and layers are found on the northeast side of the peninsula near the old mill and wharf. This is location 1 of Cobb (1972, MF-397) and is accurate to within half a mile.|
The chromite at Claim Point occurs in dunite that is part of the informally named Border Ranges ultramafic and mafic complex of Burns (1985). The Border Ranges complex is at least Jurassic in age. The complex is faulted at the base and there are many small northeast-trending, high-angle faults which offset the chromite layers. In general, the chromite layers strike northeast and dip nearly vertical.
Most of the production in the area has occurred from the Reef mine where the ore body strikes N76E with a near vertical dip. Its length is about 135 feet and the width ranges from three to 35 feet. The chromic oxide content of the ore as shipped, ranged from 42 to 49 percent (Guild, 1942).Foley and Barker (1985) estimates there is 82,000 metric tons of ore that grades from 5 to 30% chromic oxide.
|Geologic map unit||(-151.822115387555, 59.2093292959436)|
|Mineral deposit model||Podiform chromite (Cox and Singer, 1986; model 8a)|
|Mineral deposit model number||8a|
|Age of mineralization||Early Jurassic.|
|Alteration of deposit||Serpentinization and spillitic alteration is common.|
|Workings or exploration||Production totaled 2,000 metric tons from the Reef and Bluff mines from 1916 to 1918; development included a wharf and camp. Some drilling was done during WW II by the U.S. Bureau of Mines. Anaconda Minerals flew regional airborne geophysics in the early 1980s which showed a major magnetic high underlying the outer part of Port Chatham bay (Foley, 1992).|
|Indication of production||Yes; small|
|Reserve estimates||There are conflicting estimates of the remaining reserves for this property. Foley (1992, p. 38) estimates a total resource of 82,000 metric tons of ore that grades 17.8% chromic oxide, while MacKevett and others (1978, p. 17) estimate a resource of 260,000 tons at 17.8% chromic oxide.|
|Production notes||Two thousand metric tons of chromite ore was produced in 1917 and 1918 (Foley, 1992, p. 38).|
Bain, H.F., 1946, Alaska's minerals as a basis for industry: U. S. Bureau of Mines Information Circular 7379, 89 p.
Berg, H.C., and Cobb, E.H., 1967, Metalliferous lode deposits of Alaska: U.S. Geological Survey Bulletin 1246, 254 p.
Bird, M.L., 1977, Electron-microprobe analyses of chromite and olivine from alpine ultramafic complexes: U.S. Geological Survey Open-File Report 77-236, 66 p.
Brooks, A.H., 1921, The future of Alaska mining, in Martin, G.C., and others, Mineral resources of Alaska, 1917: U.S. Geological Survey Bulletin 714-A, p. 5-57.
Burns, L.E., 1985, The Border Ranges ultramafic and mafic complex, south-central Alaska; Cumlative fractionates of island-arc volcanics: Canadian Journal of Earth Science, v. 22, p.1020-1038.
Cobb, E.H., 1972, Metallic mineral resources map of the Seldovia quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-397, 1 sheet, scale 1:250,000.
Cobb, E.H., 1979, Summary of references to mineral occurrences (other than minerals fuels and construction materials) in the Seldovia quadrangle, Alaska: U.S. Geological Survey Open-file Report 80-87, 47 p.
Foley, J.Y., 1992, Ophiolite and other ultramafic metallogenic provinces in Alaska (west of the 141th meridian): U.S. Geological Survey Open-File Report 92-20-B, 55 p.
Foley, J.Y., and Barker, J.C., 1985, Chromite deposits along the Border Ranges fault; Part 1 -- Field investigations and descriptions of chromite deposits: U.S. Bureau of Mines Information Circular 8990, 57 p.
Gill, A.C., 1920, Preliminary report on the chromite of Kenai Peninsula: U.S. Geological Survey Bulletin 712-D, p. 99-129.
Grant, U.S., and Higgins, D.F., Jr., 1910, Preliminary report on the mineral resources of the southern part of Kenai Peninsula: U.S. Geological Survey Bulletin 442-D, p. 166-178.
Guild, P.W., 1942, Chromite deposits of Kenai Peninsula, Alaska: U.S. Geological Survey Bulletin 931-G, p. 139-175.
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.
Martin, G.C., 1920, The Alaska mining industry in 1918: U.S. Geological Survey Bulletin 712-A, p. 1-52.
Martin G.C., Johnson, B.L., and Grant, U.S., 1915, Geology and mineral resources of Kenai Peninsula, Alaska: U.S. Geological Survey Bulletin 587, 243 p.
Mertie, J.B., Jr., 1919, Chromite deposits in Alaska, in Martin, G.C., and others, Mineral resources of Alaska, report on progress of investigations in 1917: U.S. Geological Survey Bulletin 692, p. 265-267.
Nokleberg, W.J., Bundtzen, T.K., Berg, H.C., Brew, D.A., Grybeck, D.J., Robinson, M.S., Smith, T.E., and Yeend, W., 1987, Significant metalliferous lode deposits and placer districts of Alaska: U.S. Geological Survey Bulletin 1786, 104 p., 2 plates, scale 1:5,000,000.
Sanford, R.S., and Cole, J.W., 1949, Investigation of Claim Point chromite deposits, Kenai Peninsula, Alaska: U.S. Bureau of Mines Report of Investigations 4419, 11 p.
|Reporters||Jeff A. Huber (Anchorage)|
|Last report date||2/25/1999|