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Mary Margaret

Prospect in Alaska, United States with commodities Mercury, Antimony
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Commodities
  6. Materials information
  7. Alteration
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Economic information about the deposit and operations
  12. Mining district
  13. Links to other databases
  14. Bibliographic references
  15. General comments
  16. Reporter information

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).

Site location context

Political divisions (FIPS codes)

Yukon-Koyukuk(Census area)

Alaska(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

McGrath A-4(quadrangle 1:63,360 scale)

McGrath SW(quadrangle 1:100,000 scale)

McGrath C(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Stony River(hydrologic unit)

Upper Kuskokwim River(hydrologic accounting unit)

Southwest(hydrologic subregion)

Alaska(hydrologic region)

Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Mercury Primary
Antimony Critical 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
ListMap

Economic information

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 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

Bibliographic references

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

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Alaska resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.