Penobscot Mine

The Penobscot Mine is a silver and gold mine located in Lewis and Clark county, Montana at an elevation of 6,880 feet.

About the MRDS Data:

All mine locations were obtained from the USGS Mineral Resources Data System. The locations and other information in this database have not been verified for accuracy. It should be assumed that all mines are on private property.

Mine Info

Name: Penobscot Mine  

State:  Montana

County:  Lewis and Clark

Elevation: 6,880 Feet (2,097 Meters)

Primary Mineral: Silver, Gold

Lat, Long: 46.73056, -112.35611

Map: View on Google Maps

Satelite View


Satelite image of the Penobscot Mine

Penobscot Mine MRDS details

Site Name

Primary: Penobscot Mine


Commodity

Primary: Silver
Primary: Gold


Location

State: Montana
County: Lewis and Clark
District: Marysville District


Land Status

Not available


Holdings

Not available


Workings

Type: Underground


Ownership

Owner Name: Longmaid, H. E.
Home Office: Helena, Montana


Production

Year: 1941
Time Period: 1890 - 1941
Material type: AU
Description: Cp_Grade: ^1 - 500 Oz/St
Year: 1945
Time Period: 1890-1945
Mined: 48000.000 mt
Material type: ore


Deposit

Record Type: Site
Operation Category: Past Producer
Deposit Type: Polymetallic veins
Operation Type: Unknown
Year First Production: 1878
Discovery Year: 1872
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: Y
Deposit Size: S


Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Northern Rocky Mountains


Mineral Deposit Model

Model Name: Polymetallic veins


Orebody

Form: PINCH AND SWELL


Structure

Type: R
Description: Boulder Batholith, Prickly Pear Dome

Type: L
Description: Marysville Stock, Post-Mineral Downthrown Fault Blocks


Alterations

Not available


Rocks

Name: Diorite
Role: Associated
Description: PORPHYRITIC DIORITE
Age Type: Associated Rock
Age Young: Pliocene

Name: Diorite
Role: Associated
Description: PORPHYRITIC DIORITE
Age Type: Host Rock
Age Young: Neoproterozoic

Name: Diorite
Role: Associated
Description: PORPHYRITIC DIORITE
Age Type: Host Rock Unit
Age Young: Neoproterozoic


Analytical Data

Not available


Materials

Ore: Gold
Ore: Quartz


Comments

Comment (Workings): 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.

Comment (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.

Comment (Location): ALONG CONTINENTAL DIVIDE.

Comment (Production): PRODUCTION HAD REPORTED VALUE OF $1,250,000. PRODUCED ABOUT $50,000 1936-1941 . PRODUCTION YEARS ABOUT 1890 - 1900 , 1936 - 1941.


References

Reference (Deposit): USGS BULL 527, P. 74-5.

Reference (Deposit): USGS BULL 842, P. 63, PL. 5.

Reference (Deposit): AM INST MINING METALL ENGINEERS BULL 92, P. 2113-16.

Reference (Production): MCDERMOTT, 1914, A. I. M. M. E. BULL. 92.; MBMG MEM. 31, 1950