Christophosen Creek Mine, Port Clarence District, Nome Borough, Alaska, USA
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Geology: Flake graphite occurs as disseminations and high-grade tabular lenses within amphibolite facies metasedimentary rocks (Coats, 1944). The metamorphic rocks are primarily biotite-quartz schist with some sillimanite and garnet (Sainsbury, 1972). Small granitic plugs, dikes, and sills locally intrude the metamorphic rocks. The graphite-bearing schists are sharply bound to the north by the recently active Kigluaik fault, the principal fault along which late Cenozoic uplift of the Kigluaik Mountains has taken place (Hudson and Plafker, 1978). The graphite-bearing schists strike approximately parallel to the mountain front and dip north between 25 and 65 degrees. They form a zone along the mountain front that is 200 to 400 feet thick and possibly 20,000 feet long (Hudson, 1981; also see Ruby Creek and Graphite Creek localities to the east). To the south, the graphite-bearing schists are in conformable contact with other amphibolite facies metasedimentary rocks. The latter appear to be feldspathic and contain much less graphite. The graphite-bearing schists make up two general sequences; (1) a heterogeneous sequence of garnet-sillimanite-biotite-quartz schist with disseminated graphite and graphite-rich lenses, and (2) a more evenly layered biotite-quartz schist with disseminated graphite. The latter contains disseminated pyrrhotite and commonly weathers orange. Claims were first staked on this deposit in 1900 but most of the work here appears to have taken place between 1912 and 1917 (Cobb, 1975). Coats (1944) describes 25-foot thick schist units with 10% disseminated graphite. Lenses in these schists, a few inches to 18 inches thick, can contain 50 to 90% coarse graphite by volume. The length of the lenses appears to be 10 to 15 times their widths. The graphite flakes are commonly 0.004 to 0.04 inches in diameter although some are greater than 0.1 inch across. Two samples (Coats, 1944) contained 24.9% and 56.6% graphite of which 76% and 82% was coarser than 30 meshes per inch. Samples of schist with disseminated graphite from this locality appeared to have a few to 15% graphite in thin section but laboratory analyses indicated only 4 to 6% (Wolgemuth, 1982).
Workings: Small surface pits are the principal wokings here. Exploration activity in the general area took place as recently as 1994 (Swainbank and others, 1995).
Age: The metamorphism that has developed coarse graphite in these rocks is Late Jurassic to Early Cretaceous in age.
Alteration: Some shearing and deformation of graphite-rich lenses has accompanied faulting and oxidation of disseminated pyrrhotite has led to orange-staining of graphite-bearing rocks but other types of alteration are not identified.
Production: 130 tons of hand-sorted high-grade material were shipped in 1916 (Mertie, 1918) and other small shipments of similar material may have occurred.
Reserves: A stock pile of hand-sorted material here is estimated to contain 50 tons and the few miles of strike between the area of the Christophosen Creek deposit and the Graphite Creek deposit to the east has been estimated to contain 65,000 tons averaging about 60% graphite (Coats, 1944). This zone has also been estimated to contain, overall, more than 10 million tons of 10% or more graphite (Weiss, 1973).
Commodities (Major) - Graphite
Development Status: Yes, small
Deposit Model: Flake graphite in disseminations and tabular lenses within amphibolite facies me
11 entries listed. 8 valid minerals.
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Coats, R.R., 1944, Graphite deposits on the north side of the Kigluaik Mountains, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 10, 8 p. Cobb, E.H., 1975, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Teller quadrangle, Alaska: U.S. Geological Survey Open-File Report 75-587, 130 p. Cobb, E.H., and Sainsbury, C.L., 1972, Metallic mineral resources map of the Teller quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-426, 1 sheet, scale 1:250,000. Harrington, G.L., 1919, Graphite mining in Seward Peninsula: U.S. Geological Survey Bulletin 692-G, p. 363-367. Hudson, T.L., 1981, Preliminary notes on the Kigluaik graphite deposits, Seward Peninsula, Alaska: Anchorage, Alaska, Anaconda Minerals Company internal memorandum (Report held by Cook Inlet Region, Inc., Anchorage, Alaska). Hudson, T.L., and Plafker, George, 1978, Kigluaik and Bendeleben faults, Seward Peninsula, in Johnson, K. M., ed., The United States Geological Survey in Alaska--Accomplishments during 1977: U.S. Geological Survey Circular 772-B, p. B47-B50. Mertie, J.B., Jr., 1918, Lode mining and prospecting on Seward Peninsula: U.S. Geological Survey Bulletin 662-H, p. 425-449. Sainsbury, C.L., 1972, Geologic map of the Teller quadrangle, Seward Peninsula, Alaska: U.S. Geological Survey Map I-685, 4 p., 1 sheet, scale 1:250,000. Swainbank, R.C., Bundtzen, T.K., Clough, A.H., Henning, M.W., and Hansen E.W., 1995, Alaska's mineral industry 1994: Alaska Division of Geological and Geophysical Surveys Special Report 49, 77 p. Weiss, P.L., 1973, Graphite: U.S. Geological Survey Professional Paper 820, p. 277-283. Wolgemuth, L.G., 1982, Graphite flake samples from Kigluaik graphite deposits: Denver, Colorado, Anaconda Minerals Company internal memorandum.