Ketchem Dome

The Ketchem Dome is a tin 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: Ketchem Dome

Commodity

Primary: Tin

Location

State: Alaska
District: Circle

Land Status

Not available

Holdings

Not available

Workings

Not available

Ownership

Not available

Production

Not available

Deposit

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

Physiography

Not available

Mineral Deposit Model

Model Name: Sn greisen

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Chloritic, quartz-white mica, topaz, fluorite.

Rocks

Role: Host
Age Type: Host Rock
Age in Years: 60.500000+-1.800000
Dating Method: K-Ar
Age Young: Middle Paleocene

Analytical Data

Not available

Materials

Ore: Cassiterite
Gangue: Feldspar
Gangue: Muscovite
Gangue: Quartz
Gangue: Tourmaline

Comments

Comment (Geology): Age = Chron age is for the biotite granite pluton into which the tin-bearing greisen vein cuts.

Comment (Deposit): Model Name = Sn greisen deposit (Cox and Singer, 1986; model 15c)

Comment (Geology): Age = The tin-bearing greisen vein mineralization near Ketchem Dome cuts a biotite granite pluton near its contact with hornfelsed sedimentary rocks. The pluton has been K-Ar dated at 60.5 +/- 1.8 m.a. (Wilson and Shew, 1981).

Comment (Workings): Workings / Exploration = Five pits in area, excavated by Resource Associates of Alaska in 1983.

Comment (Geology): Geologic Description = The following information is taken from a Bureau of Mines report by Dahlin and others (1987). The tin mineralization on Ketchem Dome consists of cassiterite which occurs as grains disseminated in a greisen matrix. A bulk sample from the largest and best-developed greisen vein exposed at Ketchem Dome contained 0.51 percent Sn. Concentration of the cassiterite by gravity table methods resulted in a product that contained 56 percent cassiterite at a grade of 41.4 percent Sn. The tin-bearing greisen vein mineralization near Ketchem Dome cuts a leucocratic, seriate phase of the Circle Hot Springs biotite granite pluton near its contact with hornfelsed sedimentary rocks. The pluton has been K-Ar dated at 60.5 +/- 1.8 m.a. (Wilson and Shew, 1981). Four hand-excavated trenches expose the greisen near Ketchem Dome. The greisen is mineralogically zoned, with a selvage of muscovite-altered granite that grades into a core of dense, black, chlorite- and sericite-altered granite with traces of limonite after pyrite and veinlets of quartz. Purple fluorite occurs on fractures, and topaz is locally associated with more pervasive alteration. The mineralization exposed at Ketchem Dome is typical of greisen found elsewhere in the area. One sample assayed greater than 1,000 ppm Sn (Dave Menzie, USGS, field notes, 1984).

Comment (Exploration): Status = Inactive

Comment (Reference): Primary Reference = Dahlin and others, 1987.

References

Reference (Deposit): Dahlin, D.C., Brown, L.L., and Warner J.D., 1987, Characterization of Ketchem Dome tin prospect, east-central Alaska: U.S. Bureau of Mines Report of Investigation 9145, 11 p.

Reference (Deposit): 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.

Reference (Deposit): Wilkinson, K., 1987, Geology of a subarctic, tin-bearing batholith, Circle Hot Springs, Alaska: Fairbanks, Alaska, University of Alaska, Mineral Industry Research Laboratory Report 74, 70 p.

Reference (Deposit): Wilson, F.H., and Shew, N., 1981, Map and tables showing preliminary results of potassium-argon age studies in the Circle Quadrangle, Alaska, with a compilation of earlier dating work: U.S. Geological Survey Open-File Report 81-889, 1 sheet, scale 1:250,000.

Reference (Deposit): Foster, H.L., Laird J., Keith T.E.C., Cushing, G.W., and Menzie, W.D., 1983, Preliminary geologic map of the Circle quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-170-A, 1 sheet, scale 1:250,000.

Reference (Deposit): Menzie, W.D., Foster, H.L., Tripp, R.B., and Yeend, W.E., 1983, Mineral resource assessment of the Circle quadrangle, Alaska: U.S. Geological Survey Open-File Report 83-170-B, 61 p., 1 sheet, 1:250,000.

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