Reef

The Reef is a chromium mine located in Alaska.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

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Site Name

Primary: Reef
Secondary: Anderson
Secondary: Bluff
Secondary: Claim Point

Commodity

Primary: Chromium

Location

State: Alaska
District: Homer

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Years of Production:
Organization:
Significant:

Physiography

Not available

Mineral Deposit Model

Model Name: Podiform chromite (minor)

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Serpentization.

Rocks

Name: Dunite
Role: Associated
Age Type: Host Rock
Age Young: Late Cretaceous

Name: Dunite
Role: Associated
Age Type: Associated Rock
Age Young: Pliocene

Analytical Data

Not available

Materials

Ore: Chromite

Comments

Comment (Geology): Age = Mesozoic; based on the age of the ultramafic body that hosts the deposit.

Comment (Reference): Primary Reference = Gill, 1922

Comment (Exploration): Status = Inactive

Comment (Production): Production Notes = There is a little information regarding the mining of this deposit.

Comment (Workings): Workings / Exploration = Production totaled 2,000 metric tons from the Reef and Bluff mines from 1916 to 1918; development included a wharf and camp (Gill, 1922). Some drilling occured during WW II by the U.S. Bureau of Mines. Anaconda Minerals flew regional airborne geophysics over the area in the early 1980's which showed a major magnetic high underlying the outer part of Port Chatham (William Ellis, 1999 personal communcation).

Comment (Geology): Geologic Description = The chromite at Claim Point is hosted in dunite that is part of the informally named Border Ranges ultramafic and mafic complex of Burns (1985). The Border Ranges complex is Mesozoic 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 S76W with a nearly vertical dip, although some of the chrome layers show much local variation in dip and strike. The chromite layer is about 135 feet long and the width ranges from three to 35 feet. The chromic oxide content of the ore as shipped, ranged from 42 to 49 percent. ? Foley and Barker (1985) estimates there is 82,000 metric tons of ore with grades ranging from 5 to 30% chromic oxide.

Comment (Deposit): Model Name = Podiform chromite (Cox and Singer, 1986; model 8a)

Comment (Deposit): Other Comments = the airborne geophysics suggests the dunite may extend under all of the Claim Point peninsula and under Port Chatham.

Comment (Reserve-Resource): Reserves = 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 with 17.8% chromic oxide, while MacKevett and others (1978, p. 17) estimate a resource of 260,000 tons with17.8% chromic oxide.

References

Reference (Deposit): 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.

Reference (Deposit): 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.

Reference (Deposit): Mertie, J.B., Jr., 1919, Chromite deposits in Alaska: U.S. Geological Survey Bulletin 692-D, p. 265-267.

Reference (Deposit): 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.

Reference (Deposit): Bird, M.L., 1977, Electron-microprobe analyses of chromite and olivine from alpine ultramafic complexes: U.S. Geological Survey Open-File Report 77-236, 69 p.

Reference (Deposit): Gill, A.C., 1920, Preliminary report on the chromite of Kenai Peninsula: U.S. Geological Survey Bulletin 712, p. 99-129.

Reference (Deposit): Cobb, E.H., 1972, Metallic minerals resources map of the Seldovia quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-397, 1 sheet, scale 1:250,000.

Reference (Deposit): Berg, H.C., and Cobb, E.H., 1967, Metalliferous Lode Deposits of Alaska. U.S. Geological Survey Bulletin 1246, 254 p.

Reference (Deposit): Twenhofel, W.S., 1953, Potential Alaskan mineral resources for proposed electrochemical and electrometallurgical industries in the upper Lynn Canal area, Alaska: U.S. Geological Survey Circular 252, 14 p.

Reference (Deposit): Brooks, A.H., 1918, Mineral resources of Alaska, 1916: U.S. Geological Survey Bulletin 662, 469 p.

Reference (Deposit): Martin, G.C., 1920, The Alaska mining industry in 1918: U.S. Geological Survey Bulletin 712-A, p. 1-52.

Reference (Deposit): 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, p. 5-57.

Reference (Deposit): Gill, A.C., 1922, Chromite of Kenai Peninsula, Alaska: U.S. Geological Survey Bulletin 742, 52 p.

Reference (Deposit): Guild, P.W., 1942, Chromite deposits of Kenai Peninsula, Alaska: U.S. Geological Survey Bulletin 931-G, p. 139-175.

Reference (Deposit): 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.

Reference (Deposit): Burns, L.E., 1985, The Border Range ultramafic and mafic complex, southcentral Alaska: Cumlative fractionates of island-arc volcanics: Canadian Journal of Earth Science, v. 22, p.1020-1038.

Reference (Deposit): 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, 58 p.

Reference (Deposit): 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.

Reference (Deposit): 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 65 p.

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