Schaeffer

Prospect in Alaska, United States with commodities Mercury, Antimony

Geologic information

Identification information

Deposit ID 10002512
MRDS ID A013452
Record type Site
Current site name Schaeffer
Related records 10112696

Geographic coordinates

Geographic coordinates: -158.85279, 60.78934 (WGS84)
Relative position The Schaeffer prospect is located on the ridge north of Cinnabar Creek (TA002). The map site is at an elevation of about 1,550 feet, in the NE1/4 of section 13, T 8 N, R 55 W, of the Seward Meridian. It is 0.8 mile southeast of Cinnabar Gulch (TA001). This is locality 2 of Cobb 1972 [MF 384]; 1976 [OF 76-606]).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Mercury Primary
Antimony Secondary

Materials information

Materials Type of material
Cinnabar Ore
Marcasite Ore
Pyrite Ore
Stibnite Ore
Limonite Gangue
Quartz Gangue

Alteration

  • (Local) Silicification and limonite-staining.

Mineral occurrence model information

Model code 177
USGS model code 27a
Deposit model name Hot-spring Hg

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock unit name Gemuk Group;Gemuk Group;Gemuk Group
    Rock description Gemuk Group;Gemuk Group;Gemuk Group

Nearby scientific data

(1) -158.85279, 60.78934

Comments on the geologic information

  • Geologic Description = This prospect was discovered by Russell Schaeffer in 1958 and subsequently explored by a few shallow, hand-dug (?) trenches (Sainsbury and MacKevett, 1965, p. 40). The deposit is cinnabar- and stibnite-bearing, quartz-cemented breccia of Triassic chert and siltstone. The breccia is irregular in thickness and trends N 20 W, parallel to bedding in the host rocks. Cinnabar and stibnite are irregularly disseminated in the breccia and locally replace quartz and breccia fragments; the owner reported to Sainsbury that fossils replaced by cinnabar had been found at this prospect. The richest ore contains 1 to 2 percent cinnabar. The breccia is limonite-stained, but pyrite and/or marcasite has only been observed in the altered siltstone.
  • Age = Cretaceous or Tertiary. Inferred to be similar in age to other mercury deposits of southwest Alaska that postdate deposition of mid-Cretaceous clastic sedimentary rocks and intrusion of Upper Cretaceous or Tertiary igneous rocks.

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Mining district

District name Aniak

Comments on the workings information

  • Workings / Exploration = A few shallow trenches were dug on this prospect.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013452
USGS Alaska Resource Data File ARDF TA003

Bibliographic references

  • Deposit

    Sainsbury, C.L. and MacKevett, E.M., Jr., 1965, Quicksilver deposits of southwestern Alaska: U.S. Geological Survey Bulletin 1187, 89 p.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the Taylor Mountains quadrangle: U.S. Geological Survey Miscellaneous Field Studies Map MF-384, scale 1:250,000.

  • Deposit

    Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Dillingham, Sleetmute, and Taylor Mountain quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-606, 92 p.

  • Deposit

    Cobb, E.H., 1976, Summary of references to mineral occurrences (other than mineral fuels and construction materials) in the Dillingham, Sleetmute, and Taylor Mountains quadrangles, Alaska: U.S. Geological Survey Open-File Report 76-606, 92 p.

Comments on the references

  • Primary Reference = Sainsbury and MacKevett, 1965

General comments

Subject category Comment text
Deposit Model Name = Cinnabar and stibnite disseminated in quartz-cemented breccia (Hot-spring Hg ?; Cox and Singer, 1986; model 27a)

Reporter information

Type Date Name Affiliation Comment
Reporter 30-DEC-2000 Travis L. Hudson Applied Geology