Iron Mask

Prospect in Alaska, United States with commodities Copper, Zinc

Geologic information

Identification information

Deposit ID 10000428
MRDS ID A010595
Record type Site
Current site name Iron Mask

Geographic coordinates

Geographic coordinates: -149.29142, 59.90646 (WGS84)
Relative position The prospect is on the east shore of Resurrection Bay, opposite Renard Island (Fox Island) in the NW1/4 of section 21, T. 3 S., R. 1 E., of the Seward Meridian. A small adit has been driven above the high tide level in a brecciated metamorphosed basalt. The breccia as exposed is 12 feet thick and has been traced 100 feet or more along the shore. This is prospect number 78 of Martin and others (1915, p. 235) and location 108 of Tysdal (1978). This location is accurate to within a quarter of a mile.
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Zinc Primary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrite Ore
Sphalerite Ore
Calcite Gangue
Quartz Gangue

Alteration

  • (Local) Silicification.

Mineral occurrence model information

Model code 90
USGS model code 24a
Deposit model name Massive sulfide, Cyprus
Mark3 model number 11

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite > Diabase
    Rock unit name Valdez Group
    Rock description Valdez Group;Valdez Group

Nearby scientific data

(1) -149.29142, 59.90646

Comments on the geologic information

  • Geologic Description = The host rock is a Lower Cretaceous diabase (Tysdal and Case, 1979) that has been brecciated and recemented by quartz and sulfide mineralization. The breccia is composed of fine-grained, diabase fragments which range in size from less than a fourth of an inch to several inches in size. The matrix material is a greenish cement. The original breccia is probably a flow breccia mixed with tuffaceous material that has been slightly broken and rehealed with quartz, and pyrite with a little calcite and chalcopyrite (Martin and others, 1915). The breccia is about 12 feet wide at this location and an sample across this zone showed 1.1% copper (Grant and Higgins, 1909, p. 104-105).
  • Age = Probably Upper Cretaceous; massive sulfide.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Seward

Comments on the reserve resource information

  • Reserves = None report.

Comments on the workings information

  • Workings / Exploration = A small adit above the high tide line assayed 1.1% copper (Grant and Higgins, 1909, p. 104-105).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A010595
USGS Alaska Resource Data File ARDF BS007

Bibliographic references

  • 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.

  • Deposit

    Cobb, E.H., 1972, Metalic mineral resources map of the Blying Sound quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Stuudies Map MF-440, 1 sheet, scale 1:150,000.

  • Deposit

    Tysdal, R.G., and Case, J.E., 1979, Geologic map of the Seward and Blying Sound quadrangles, Alaska: U.S. Geological Survey Miscellaneous Investigations Series Map I-1150, scale 1:250,000.

  • Deposit

    Cobb, E.H. and Tysdal, R.G., 1980, Summaries of data on and list of references to metallic and selected nonmetallic mineral deposits in the Blying Sound and Seward quadrangle, Alaska: U.S. Geological Survey Open-File Report 80-621, 276 p.

  • Deposit

    Cobb, E.H., 1972, Metalic mineral resources map of the Blying Sound quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-440, 1 sheet, scale 1:150,000.

  • Deposit

    Tysdal, R.G., 1978, Mines, prospects, and occurrences map of the Seward and Blying Sound quadrangles, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-880-A, 2 sheets, scale 1:250,000.

  • 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.

  • Deposit

    Grant, U.S., and Higgins, D.F., Jr., 1909, Notes on geology and mineral prospects in the vicinity of Seward, Kenai Peninsula: U.S. Geological Survey Bulletin 379-C, p. 98-107.

Comments on the references

  • Primary Reference = Grant and Higgins, 1909

General comments

Subject category Comment text
Deposit Model Name = Cyprus massive sulfide (Cox and Singer, 1986; model 24a).
Deposit Other Comments = On the 1:250,000-scale map the island is called Fox Island while on the 1:63,000-scale map is Renard Island.

Reporter information

Type Date Name Affiliation Comment
Reporter 25-JAN-1999 Jeff A. Huber U.S. Geological Survey