Cape Darby

The Cape Darby is a tungsten, uranium, and ree 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: Cape Darby

Commodity

Primary: Tungsten
Primary: Uranium
Primary: REE

Location

State: Alaska
District: Council

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

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

Physiography

Not available

Mineral Deposit Model

Not available

Orebody

Not available

Structure

Not available

Alterations

Not available

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Allanite
Ore: Monazite
Ore: Scheelite
Gangue: Magnetite
Gangue: Ilmenite
Gangue: Hematite
Gangue: Fluorite
Gangue: Epidote
Gangue: Biotite
Gangue: Zircon

Comments

Comment (Geology): Age = Mid-Cretaceous; K/Ar ages for the Darby pluton are 88.3 +/- 1.5 and 92.8 +/- 2.6 Ma (Berry and others, 1976). A K/Ar age for the Kachauik pluton is 99.9 +/- 3 Ma (Miller and others, 1972; Miller and Bunker, 1976).

Comment (Deposit): Model Name = Disseminated; the heavy mineral concentrate is from a sample of detrital materials.

Comment (Geology): Geologic Description = West (1953) collected slope wash or detrital material from a small drainage at this locality. A heavy mineral concentrate obtained from the sample material (concentration ratio approximately 1,200:1) contained 0.049 percent equivalent uranium. The minerals identified in this concentrate included allanite, scheelite, monazite, fluorite, hematite, ilmentite, magnetite, epidote, biotite, and zircon. The bedrock here is an amphibolite facies, metasedimentary assemblage that forms a regional selvage between the Darby pluton to the east the the Kachauik pluton to the west (Miller and others, 1972; Till and others, 1986). The Darby pluton, is a large mid-Cretaceous granodiorite and granite body that has elevated background levels of uranium and thorium (Miller an Bunker, 1976; Johnson and others, 1979; Till and others, 1986). The Kachauik pluton is a composite syenite to granodiorite body, locally cut by nepheline syenite dikes, that is slightly older than the Darby pluton ( 99.9 +/- 3 Ma; Miller and others, 1972; Miller, 1972; Miller and Bunker, 1976). Parts of the Kachauik pluton contain U, Th, and REE mineralization near nepheline syenite dikes (Miller and others, 1976). Many of the minerals identified in the heavy mineral concentrate from this location are known accessory minerals in the Darby pluton.

Comment (Workings): Workings / Exploration = The reconnaissance sampling by West (1953) is the only work known in the area.

Comment (Reference): Primary Reference = West, 1953

Comment (Exploration): Status = Inactive

References

Reference (Deposit): Till, A.B., Dumoulin, J.A., Gamble, B. ., Kaufman, D.S., and Carroll, P.I., 1986, Preliminary geologic map and fossil data, Soloman, Bendeleben, and southern Kotzebue quadrangles, Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 86-276, 10 p., 3 plates, scale 1:250,000.

Reference (Deposit): Johnson, B.R., Miller, T.P., and Karl, S., 1979, Uranium-thorium investigations of the Darby pluton, Seward Peninsula, Alaska: U.S. Geological Survey Circular 804-B, p. 68-70.

Reference (Deposit): Cobb, E.H., 1978, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Solomon quadrangle, Alaska: U.S. Geological Survey Open-File Report 78-181, 185 p.

Reference (Deposit): Miller, T.P., Elliott, R.L., Finch, W.I., and Brooks, R.A., 1976, Preliminary report on uranium-, thorium-, and rare-earth-bearing rocks near Golovin, Alaska: U.S. Geological Survey Open-File Report 76-710, 12 p.

Reference (Deposit): Miller, T.P., Grybeck, D.J., Elliott, R.L., and Hudson, T.L., 1972, Preliminary geologic map of the eastern Solomon and southeastern Bendeleben quadrangles, eastern Seward Peninsula, Alaska: U.S. Geological Survey Open-File Report 72-256, 11 p.

Reference (Deposit): West, W.S., 1953, Reconnaissance for radioactive deposits in the Darby Mountains, Seward Peninsula, Alaska, 1948: U.S. Geological Survey Circular 300, 7 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic resources map of the Solomon quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-445, scale 1:250,000.

Reference (Deposit): Miller, T.P., and Bunker, C.M., 1976, A reconnaissance study of the uranium and thorium contents of plutonic rocks of the southeastern Seward Peninsula, Alaska: U.S. Geological Survey Journal of Research, v. 4, p. 367-377.

Reference (Deposit): Berry, A.L., Dalrymple, G.B., Lamphere, M.A., and Von Essen, J.C., 1976, Summary of miscellaneous potassium-argon age determinations, U. S. Geological Survey, Menlo Park, California, for the years 1972-1974: U.S. Geological Survey Circular 727, 13 p.

Reference (Deposit): Miller, T.P., 1972, Potassium-rich alkaline intrusive rocks of western Alaska: Geological Society of America Bulletin, v. 83, p. 2111-2128.

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