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Penobscot Mine

Past Producer in Lewis and Clark county in Montana, United States with commodities Gold, Silver
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Mineral occurrence model information
  9. Host and associated rocks
  10. Nearby scientific data
  11. Geologic structures
  12. Ore body information
  13. Controls for ore emplacement
  14. Economic information about the deposit and operations
  15. Mining district
  16. Ownership information
  17. Production statistics
  18. Workings at the site
  19. Links to other databases
  20. Bibliographic references
  21. General comments
  22. Reporter information

Geologic information

Identification information

Deposit ID 10071383
MRDS ID W014728
Record type Site
Current site name Penobscot Mine

Geographic coordinates

Geographic coordinates: -112.357, 46.73046 (WGS84)
Elevation 2097
Relative position 2 MI SW OF MARYSVILLE.

Site location context

Political divisions (FIPS codes)

Lewis and Clark(county)

Montana(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Greenhorn Mountain(quadrangle 1:24,000 scale)

Elliston(quadrangle 1:100,000 scale)

Butte(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Missouri(hydrologic unit)

Upper Missouri(hydrologic accounting unit)

Missouri-Marias(hydrologic subregion)

Missouri(hydrologic region)

Geographic areas

Country State County
United States Montana Lewis and Clark

Public Land Survey System information

Meridian Township Range Section Fraction State
Montana Principal 011N 006W 04,09 Montana

Comments on the location information

  • ALONG CONTINENTAL DIVIDE.

Commodities

Commodity Importance
Gold Primary
Silver Primary

Materials information

Materials Type of material
Gold Ore
Quartz Ore

Mineral occurrence model information

Model code 85
USGS model code 22c
Deposit model name Polymetallic veins
Mark3 model number 46

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock unit name Helena Formation
    Rock description Helena Formation
  • Host or associated Associated
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Rock type qualifier PORPHYRITIC DIORITE
    Rock unit name Belmont Porphyry
    Rock description Belmont Porphyry;Marysville Stock
    Stratigraphic age (youngest) Pliocene
    Stratigraphic age (youngest) Neoproterozoic
    Stratigraphic age (youngest) Neoproterozoic
  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid > Granodiorite
    Rock unit name Marysville Stock

Nearby scientific data

(1) -112.357, 46.73046
ListMap

Economic information

Geologic structures

Type of structure Regional
Structure description Boulder Batholith, Prickly Pear Dome
Type of structure Local
Structure description Marysville Stock, Post-Mineral Downthrown Fault Blocks

Ore body information

  • General form PINCH AND SWELL
    Dip 65-80 NW
    Thickness 1.22M
    Depth to top 0M

Controls for ore emplacement

  • Ore Mineralization Associated With Fissure Filling And Along Intrusive Contact

Economic information about the deposit and operations

Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant Yes
Discovery year 1872
Discoverer Nate Vestal
Year of first production 1878

Mining district

District name Marysville District

Ownership information

  • Type Owner
    Owner Longmaid, H. E.
    Home office Helena, Montana

Production statistics

  • Year 1941
    Period 1890 - 1941
    Material AU
    Accuracy Estimate
    Description Cp_Grade: ^1 - 500 Oz/St
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Minor Gold Gold 7059g/mt
  • Year 1945
    Period 1890-1945
    Material ore
    Ore mined 48000mt
    Accuracy Accurate
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Major AG Silver Silver 1.8mt
    Major AU Gold Gold 1.6mt

Comments on the production information

  • PRODUCTION HAD REPORTED VALUE OF $1,250,000. PRODUCED ABOUT $50,000 1936-1941 . PRODUCTION YEARS ABOUT 1890 - 1900 , 1936 - 1941.

Workings at the site

  • Type of workings Underground
    Length 304.8M
    Overall depth 152.4M

Comments on the workings information

  • INCLINE ON EAGLE VEIN; MAIN MINE EXTRACTED ORE FROM THE PENOBSCOT VEIN 1000 FT ALONG STRIKE; TUNNEL 300 FT LONG AND 90 FT DEEP; TUNNEL THAT WAS TO THE VEIN ON THE 300 FT LEVEL.

Reference information

Bibliographic references

  • Deposit

    USGS BULL 527, P. 74-5.

  • Deposit

    USGS BULL 842, P. 63, PL. 5.

  • Deposit

    AM INST MINING METALL ENGINEERS BULL 92, P. 2113-16.

  • Production

    MCDERMOTT, 1914, A. I. M. M. E. BULL. 92.; MBMG MEM. 31, 1950

General comments

Subject category Comment text
Deposit 2 PARALLEL VEINS, EAGLE AND LENARD, LIE IN FOOTWALL OF PENOBSCOT VEIN AT 250 FT AND 600 FT RESPECTIVELY. ORE PRINCIPALLY FROM ABOVE 200 FT LEVEL.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-APR-1976 Mlynarczyk, Meg S. U.S. Geological Survey
Updater 01-DEC-1981 Wise, Kristine K. (Elliott, James E.) U.S. Geological Survey

Beyond USGS

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

External references

Maps centered on this site