Mary Margaret

Prospect in Alaska, United States with commodities Mercury, Antimony

Geologic information

Identification information

Deposit ID 10002602
MRDS ID A015039
Record type Site
Current site name Mary Margaret
Alternate or previous names Coxcomb

Geographic coordinates

Geographic coordinates: -154.8759, 62.16334 (WGS84)
Relative position The Mary Margaret prospect is located along a steep, southeast bank of Cheeneetnuk River, about 1.5 miles (2.4 km) southwest of the airstrip at White Mountain Mercury mine at an elevation of 1,450 feet (442 m) in the SE1/4 sec. 13, T. 24 N., R. 30 W., of the Seward Meridian. Some of the mineralized zone crops out on a ridge about 150 meters south of a conspicuous cold water spring entering the Cheeneetnuk River. The prospect is location 16, of Cobb (1972); the reporter visited the site in 1989 (Alaska Division of Geological and Geophysical Surveys station # 89BT118).
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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
Stibiconite Ore
Stibnite Ore
Calcite Gangue
Quartz Gangue

Alteration

  • (Local) Oxidation of stibnite mineralization to stibiconite.

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
    Stratigraphic age (youngest) Late Ordovician

Nearby scientific data

(1) -154.8759, 62.16334

Comments on the geologic information

  • Geologic Description = The Mary Margaret prospect consists of cinnabar, quartz, carbonate and minor stibnite in brecciated limestone of the Early Devonian Cheeneetnuk limestone (Blodgett and Gilbert, 1983). The unit overlies the Dillinger subterrane, a lower Paleozoic continental margin assemblage (Bundtzen and others, 1997). ? On the bluff south of the Cheeneetnuk River, two mineralized fracture orientations were measured: (1) a strike of N50E, with a dip of 70SE; and (2) a strike of N65E with a dip of 30SE. The fracture system can be traced for a strike length of about 20 meters before disappearing under vegetation. The cinnabar veinlets average about 5 cm thick and exhibit an exceptional bright red color similar to cinnabar at the Mountain Top Mine described by Miller and others (1989) in the Sleetmute quadrangle.? At the creek level, a cold water sulfur spring that flows from fractured limestone in the area is depositing black, foul-smelling mud that contains Hg. Selected samples of ore contain from 2 to 13 percent mercury and up to 0.5 percent antimony, but with no precious metal values. The cinnabar to stibnite ratio averages about 10 to 1 (T.K. Bundtzen, written communication, 1989).

Economic information

Economic information about the deposit and operations

Development status Prospect
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name McGrath

Comments on the workings information

  • Workings / Exploration = Only surface sampling has been conducted at the prospect. Selected samples contain from 2 to 13 percent mercury and up to 0.5 percent antimony, but no precious metals.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A015039
USGS Alaska Resource Data File ARDF MG027

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

    Maloney, R.P., 1967, Investigations of the White Mountain mercury deposit, Kuskokwim River basin, Alaska: U.S. Bureau of Mines Report of Investigations 6892, 94 pages.

  • Deposit

    Gilbert, W.G., 1981, Preliminary geologic map of the Cheeneetnuk River area, Alaska: Alaska Division of Geological and Geophysical Surveys Open-File Report 153, 19 pages, 2 sheets, 1:63,360 scale.

  • Deposit

    Blodgett, R.B., and Gilbert, W.G., 1983, The Cheeneetnuk Limestone, a new Early(?) to Middle Devonian formation in the McGrath A-4 and A-5 quadrangles, west-central Alaska: Alaska Division of Geological and Geophysical Surveys Professional Report 85, 6 pages, one sheet, 1:63,360 scale.

  • Deposit

    Bundtzen, T.K., Harris, E.E., and Gilbert, W.G., 1997, Geologic Map of the eastern McGrath quadrangle, Alaska: Alaska Division of Geological and Geophysical Surveys Report of Investigations 97-14, 34 pages, one sheet, scale 1:125,000.

  • Deposit

    Cobb, E.H., 1972, Metallic mineral resources map of the McGrath quadrangle, Alaska: U.S. Geological Survey Miscellaneous Field Studies Map MF-379, 1 sheet, 1:250,000 scale.

Comments on the references

  • Primary Reference = Sainsbury and MacKevett, 1965

General comments

Subject category Comment text
Deposit Model Name = Hot Springs mercury (?) (Cox and Singer, 1986; model 27a).
Deposit Other Comments = the Mary Margaret prospect formed near or in an unnamed strand of the Farewell-Denali fault system (Gilbert, 1981).

Reporter information

Type Date Name Affiliation Comment
Reporter 30-OCT-1998 T.K. Bundtzen Pacific Rim Geological Consulting