Trachsel

The Trachsel is a iron 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: Trachsel
Secondary: Snug Harbor

Commodity

Primary: Iron

Location

State: Alaska
District: Redoubt

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

Model Name: Skarn Fe

Orebody

Not available

Structure

Not available

Alterations

Alteration Type: L
Alteration Text: Hornfels and metasomatic alteration are present in this occurrence.

Rocks

Not available

Analytical Data

Not available

Materials

Ore: Magnetite
Gangue: Garnet
Gangue: Pyroxene

Comments

Comment (Deposit): Model Name = Fe skarn (Cox and Singer, 1986; model 18d)

Comment (Geology): Geologic Description = Magnetite Island consists of metamorphosed volcanic rocks of Early Jurassic Talkeetna Formation and an Upper Triassic marble that has been subjected to contact metamorphism by Jurassic quartz diorite associated with the Alaska-Aleution Range batholith (Grantz, 1956). There are two magnetite occurrences on the island. The western occurrence consists of a single lens of magnetite garnet skarn. The skarn appears to be about 35 feet wide and is exposed for about 55 feet along strike. A reconnaissance dip -needle traverse indicated the total strike length of the body is about 110 feet. This exposed skarn strikes N40E and dips 40SE. The hanging wall of the skarn is a white medium grain marble of Upper Triassic age which has been recrystallized by contact metamorphism. The foot wall of this occurrence is hornfelsed siltstone and volcanic rock of the Talkeetna Formation. The contact between the marble and the hornfels is unclear but it may be a fault (Grantz, 1956). ? the eastern occurrence consists of magnetite disseminated in hornfels, probably derived from volcanic rocks. The magnetite occurs in two parallel zones. The upper zone is about 30 feet thick and is separated from the lower zone by 20 feet of hornfelsed volcanics. The lower zone is at least 10 feet thick but its base is not exposed. The mineralized zones strike approximately N35 to 45E and dip 45SE. The magnetite in the eastern zone is disseminated in a matrix of garnet, diopside, chlorite, and plagioclase. No zoning of the skarn minerals are reported. An assay from the upper zone contained 25.8% iron and 0.01% sulfur. However, about one-fifth of the iron may occur in silicate minerals (Grantz, 1956).

Comment (Reference): Primary Reference = Grantz, 1956

Comment (Reserve-Resource): Reserves = Up to several thousand tons in zones with 20 to 75% magnetite (Grantz, 1956).

Comment (Workings): Workings / Exploration = Small excavation in sea cave at the western deposit contains 25% to 50% iron.

Comment (Exploration): Status = Inactive

Comment (Geology): Age = Jurassic; hornfels related to Intrusion of Jurassic quartz diorite.

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): Detterman, R.L., and Hartsock, J.L., 1966, Geology of the Iniskin-Tuxedni region, Alaska: U.S. Geological Survey Professional Paper 512, 78 p.

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): Cobb, E.H., 1979, Summary of references to mineral occurrences (other than minerals fuels and construction materials) in the Kenai and Tyonek Quadrangles, Alaska: U.S. Geological Survey Open-File Report 80-86, 36 p.

Reference (Deposit): Cobb, E.H., 1972, Metallic mineral resources map of the Kenai quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-377, 1 sheet, scale 1:150,000.

Reference (Deposit): Grantz, Arthur, 1956, Magnetite deposits at Tuxedni Bay, Alaska: U.S. Geological Survey Bulletin 1024-D, p. 95-106.

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

Reference (Deposit): Moffit, F.H., 1927, The Iniskin-Chinitna Peninsula and Snug Harbor district, Alaska: U.S. Geological Survey Bulletin 789, 71 p.

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