Johnston - Moffet Copper

The Johnston - Moffet Copper is a copper mine located in Madison county, Montana at an elevation of 7,116 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

Satelite View

MRDS mine locations are often very general, and in some cases are incorrect. Some mine remains have been covered or removed by modern industrial activity or by development of things like housing. The satellite view offers a quick glimpse as to whether the MRDS location corresponds to visible mine remains.

Site Name

Primary: Johnston - Moffet Copper
Secondary: Mountain View

Commodity

Primary: Copper
Secondary: Silver
Secondary: Gold

Location

State: Montana
County: Madison
District: Tidal Wave District

Land Status

Land ownership: National Forest
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.

Holdings

Not available

Workings

Type: Surface/Underground

Ownership

Owner Name: W. S. Moore Co. And Iso Copper

Production

Year: 1944
Time Period: 1944
Material type: CU
Description: Cp_Grade: ^ 0.39 Oz Ag/Ton
Year: 1916
Time Period: 1916
Material type: CU
Description: Cp_Grade: ^2.32 % Cu

Deposit

Record Type: Site
Operation Category: Past Producer
Deposit Type: Contact Metasomatic
Operation Type: Unknown
Year First Production: 1916
Discovery Year: 1900
Discovery Method: Ore-Mineral In Place
Years of Production:
Organization:
Significant: N
Deposit Size: S

Physiography

General Physiographic Area: Rocky Mountain System
Physiographic Province: Northern Rocky Mountains
Physiographic Detail: Tobacco Root Mountains

Mineral Deposit Model

Not available

Orebody

Form: IRREGULAR

Structure

Type: R
Description: North - Striking And Northeast - Striking Faults

Type: L
Description: North - Striking Fault May Have Exerted Structural Control On Emplacement Of Qtz Monzonite Stock.

Alterations

Alteration Type: L
Alteration Text: Tactite Minerals And Pyritization

Rocks

Name: Quartz Monzonite
Role: Associated
Age Type: Associated Rock
Age Young: Late Cretaceous

Name: Quartz Monzonite
Role: Associated
Age Type: Host Rock
Age Young: Mississippian

Name: Quartz Monzonite
Role: Associated
Age Type: Associated Rock Unit
Age Young: Late Cretaceous

Name: Quartz Monzonite
Role: Associated
Age Type: Host Rock Unit
Age Young: Mississippian

Analytical Data

Not available

Materials

Ore: Malachite
Ore: Chrysocolla
Ore: Chalcocite
Ore: Cuprite
Ore: Chalcopyrite
Gangue: Diopside
Gangue: Pyrite
Gangue: Garnet
Gangue: Magnetite

Comments

Comment (Production): NO PRODUCTION SINCE 1944

Comment (Workings): ORE HAS BEEN MINED FROM SURFACE CUTS. SOME SURFACE TRENCHING (430 FT) AND 10 DRILL HOLES TOTALING 1101 FT WERE DRILLED IN THE EARLY 1970'S ISO COPPER & W. S. MOORE DRILLED A NUMBER OF 200 FT PERCUSSION DRILL HOLES & OUTLINED ORE DEPOSIT

Comment (Geology): ORE DEPOSITS ARE ASSOCIATED WITH TACTITE ZONES AT STOCK CONTACTS & WITHIN STOCK PROPER

Comment (Reserve-Resource): THIS IS BASED ON PREVIOUSLY DESCRIBED DRILLING

Comment (Deposit): MAXIMUM LENGTH OF ORE BODIES ARE FROM 100 TO 300 FT, BUT TACTITE ZONE IS 500 FT LONG ON SURFACE OUTCROP

Comment (Location): 1 1/2 MILES UP BEAR GULCH

Comment (Deposit): ISO COPPER PERCUSSION DRILLING, SAMPLING AND ANALYSIS INDICATE MINERALIZATION WITHIN A ZONE APPROX. 1000 FT LONG AND 50 FT WIDE AVERAGING ABOUT 1.3 PERCENT COPPER

References

Reference (Deposit): MBMG BULL 24, P. 26-27.

Reference (Deposit): ROBY, R. N., 1946 , EXPLORATION OF THE MOFFET - JOHNSTON COPPER PROPERTY, MADISON COUNTY, MONTANA: U S BUREAU OF MINES REPORT OF INVESTIGATIONS 3939 , 12 P.

Reference (Deposit): 1943 DIREXPL ROBY, USBM PUBLISHED REPORT

Reference (Deposit): 1957 COMPILE JOHNS W. M. PUBLISHED REPORT

Reference (Production): ROBY, 1946 , MOFFET - JOHNSTON COPPER PROPERTY, P. 2 , 3

Reference (Reserve-Resource): W. S. MOORE CO. AND ISO COPPER

Principal Gold Districts of Montana

In Montana, 54 mining districts have each have produced more than 10,000 ounces of gold. The largest producers are Butte, Helena, Marysville, and Virginia City, each having produced more than one million ounces. Twenty seven other districts are each credited with between 100,000 and one million ounces of gold production. Read more: Principal Gold Districts of Montana.