Porphyry Dike Mine

The Porphyry Dike Mine is a gold mine located in Lewis and Clark county, Montana at an elevation of 7,480 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: Porphyry Dike Mine

Commodity

Primary: Gold
Tertiary: Arsenic

Location

State: Montana
County: Lewis and Clark
District: Rimini 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

Not available

Production

Not available

Deposit

Record Type: Site
Operation Category: Past Producer
Operation Type: Unknown
Year First Production: 1892
Discovery Year: 1890
Discovery Method: Ore-Mineral Not In Place
Years of Production:
Organization:
Significant: N
Deposit Size: S

Physiography

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

Mineral Deposit Model

Not available

Orebody

Form: IRREGULAR

Structure

Type: R
Description: Large Scale Volcanic And Igneous Intrusive Activities Boulder Batholith

Type: L
Description: Jointing, Overlapping Of Pyroclastics And Flow Units Thin Dikes And Faults

Alterations

Alteration Type: L
Alteration Text: Sericitization, Kaolinization

Rocks

Name: Rhyolite
Role: Host
Age Type: Associated Rock
Age Young: Pliocene

Name: Rhyolite
Role: Host
Age Type: Host Rock
Age Young: Pliocene

Analytical Data

Not available

Materials

Ore: Gold
Gangue: Limonite
Gangue: Pyrite

Comments

Comment (Development): REFERENCE MATERIAL INDICATES THAT THE ANACONDA CO. HAS THOROUGHLY SAMPLED THIS DEPOSIT BY DRILLING

Comment (Commodity): LIMONITE STAINED FRACTURES SAID TO BE PARTICULARLY FAVORABLE PLACES FOR GOLD OCCURRENCE

Comment (Location): NEAR HEAD OF MONITOR CREEK. ; INFO FROM LAND.ST :(1954)

Comment (Production): USGS BULL 1151, P. 115.

Comment (Workings): TWO 1200 FT ADITS UNDER THE PIT, BOTH WITH NUMEROUS CROSSCUTS AND CONNETING VERTICAL WORKINGS. OPEN PIT IS 150 FT WIDE, 300 FT LONG AND 150 FT DEEP.

Comment (Deposit): THE RICHEST ORE MINED AT THE PORPHYRY DIKE MINE WAS REMOVED FROM A VERTICALLY SHEETED ZONE OF THOROUGH AND DEEP OXIDATION ALONG WHICH CONCENTRATION OF GOLD IN OPEN JOINTS COULD EASILY OCCUR

Comment (Deposit): 4 INTERLAYERED AND OVERLAPPING PYROCLASTIC AND FLOW UNITS IN THE RHYOLITE. THESE UNITS ARE CUT BY THIN DIKES AND BY FAULTS. PRIMARY GOLD WAS DISSEMINATED IN THE CLOSELY HOINTED, LAMINATED FLOW ROCKS. PART OF FREE GOLD HAS BEEN WASHED INTO OPEN JOINTS AND DESCENDED THROUGH THE RHYOLITE AND CONCENTRATED. RICHEST ORE WAS FROM A VERTICAL SHEETED ZONE.

References

Reference (Deposit): USGS BULL 842, P. 259-60.

Reference (Deposit): USGS BULL 1151, P. 114-16, PL. 1.

Reference (Deposit): USGS BULL 527, P. 84-85.

Reference (Production): RUPPEL, E. T., 1963 , GEOL. OF THE BASIN QUAD., JEFF., LEWIS & CLARK, POWELL CO., MONT USGS BULL NO 1151

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.