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Gish Chromium Mine

McLeod, Montana

45.4775°N 110.2028°W

Mine Overview

The Gish Chromium Mine is near McLeod, Montana. Historically the site has been associated with the Stillwater Mining District which is now part of the Gallatin National Forest. The site was first discovered in 1918. The Gish Chromium Mine is a underground mining operation. Mine operations consist of surface and underground workings. There is one known shaft. Subsurface length extends a maximum of 1,239 meters (4,065 feet). The ore mined is composed of chromite with waste material consisting primarily of olivine. The ore body is massive and disseminated in form reaching 914 meters (3,000 feet) long and 1 meters (4 feet) thick. The host rock in this area is harzburgite from the Lower Cretaceous epoch 145.00 to 100.50 million years ago. The Middle Rocky Mountains physiographic province of the Rocky Mountain System characterize the geomorphology of the surrounding area.

Site identification and general characteristics. Learn about USGS mines.

  • Chromium Primary Commodity
  • Copper, Nickel, and Palladium Secondary Commodity
  • Site Record Type?
  • Mine Development Status?
  • Underground Operation Type?
  • Open Stope Mining Method?
  • 1918 Year Discovered?
  • Ore Mineral In Place Discovery Method?
  • Significant Significance?
  • Metallic Site Commodity Type?
  • Small Mine Size?
Gish Chromium Mine Near McLeod, Montana

Gish Chromium Mine Near McLeod, Montana

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Mine Names

Notes

PART OF THE STILLWATER COMPLEX

  1. Name? Status?
  2. Gish Mine Current
  3. Boulder River Chromite Deposit Current
  4. Bonanza Claims Previous
  5. Bonanza Group Previous
  6. Boulder River Previous
  7. Dark Group Previous
  8. Lost Shaft Previous
  9. Blue Bird Fraction Previous
  10. M. & R. Group Previous
  11. Gish Prospect Previous

Owner Name and Address

Anaconda Company

Type
Operator

David Davis

Roundup, Montana
Type
Owner

Monte Vista Company

Montana
Type
Owner
Stake
Majority

Commodities

Additional textual information about a site or mine.

  1. Commodity Type Importance
  2. Chromium Metallic Primary
  3. Copper Metallic Tertiary
  4. Nickel Metallic Tertiary
  5. Palladium Metallic Tertiary
  6. Platinum Metallic Tertiary
  7. Rhodium Metallic Tertiary

Deposit

THICKNESS AVERAGES 4. 8 FEET 2 MASSIVE BANDS WITH SHARP FOOTWALLS AND DISSEMINATED ORE UP INTO HANGING WALL.

Location Info

  1. Continent Country State County
  2. North America The United States Montana Sweet Grass

Notes

IN GALLATIN NATIONAL FOREST. UNSURVEYED. LOCATED WITHIN CLAIM GROUP ON EAST SLOPE OVERLOOKING BOULDER RIVER.

Meridian / Township / Range Description

  1. Meridian? Township? Section? Aliquot?
  2. Montana Principle Meridian T.4S R.12E Sec. 23 NE
  3. Montana Principle Meridian T.4S R.12E Sec. 25 -

Land Status

Land status information.

  1. Land Status? Admin Area?
  2. National Forest -
  3. Private -

Mining Districts

Formal or informal mining district names.

  1. District
  2. Stillwater Mining District

Development

SOME ORE MINED BUT NONE WAS MILLED DURING WWI AND WWII.

Workings

Workings at the site.

Workings #1

  • Type: Surface and Underground
  • Surface Length: 240.49 Meters
  • Sub Surface Length: 1239.01 Meters

Workings

TWO ADITS, 61 TRENCHES, 770 FEET DIAMOND DRILL HOLES (ANACONDA ), 1, 924 FEET DIAMOND DRILL HOLES (USBM).

MINE ROAD DISTANCE IS TWO KILOMETERS. DISTANCE TO ADEQUATE WATER SUPPLY IS ONE KILOMETER. DISTANCE TO ADEQUATE ELECTRICAL SUPPLY IS 6 KM.

Concentration Process

Processes that concentrated or enriched the mineralization of the mine.

  1. Concentration Process
  2. Magmatic Segregation, Crystal Settling

Geology

AGE OF STILLWATER COMPLEX IS 2, 705 +/-4 MA BASED ON U-LEAD SYSTEMATICS ON ZIRCON-BADDELEYITE (PREMO AND OTHERS, 1990).

CR/FE RATIO IS 1. 2:1

Materials

Minerals or other materials present in the mine.

  1. Role? Material?
  2. Gangue/Waste Olivine
  3. Ore Chromite
  4. Unknown Bronzite
  5. Unknown Diopside
  6. Unknown Plagioclase
  7. Unknown Serpentine

Orebody

Characteristics of the ore body.

  • Length:
  • Thickness: 1.52 meters (4.99 feet)
  • Strike: north 60 - 80 west
  • Dip: 40 - 65 northeast

  • Area: 100.00 hectares (247.11 acres)
  • Length:
  • Width: 159.00 meters (521.65 feet)
  • Thickness: 1.50 meters (4.92 feet)
  • Strike: north 65 west
  • Dip: 75 north
  • Ore Control: igneous
  • Ore Record Modified: 1983-03-16

Rocks

Geological materials at the site.

  1. Class? 1st Order Name? 2nd Order Name? 3rd Order Name? 4th Order Name? Most Specific Name? Begin Time End Time Description?
  2. Host Rock Plutonic Rock Ultramafic Intrusive Rock Peridotite - Harzburgite Lower Cretaceous Lower Cretaceous -
  3. Mineralization - - - - - Neoarchean Neoarchean -

Structure

Geologic structural features affecting or characterizing the site or mine.

  1. Scale Description
  2. Local Graham Creek Fault And Other Faults With Small Offsets
  3. Regional The Stillwater Complex Is Exposed Along The Northern Margin Of The Beartooth Uplift, One Of Several Laramide Basement-Cored Ranges That Make Up The Rocky Mountain Foreland Of South-Central Montana (foose And Others, 1961: Kulik And Schmidt, 1988)

Tectonic

Tectonic setting in which the site or deposit is situated.

  1. Setting?
  2. Tectonic Setting At Time Of Emplacement Of The Stillwater Complex Is Unknown- The Complex Was Emplaced Shortly After A Major Regional, Subduction-Related Magmatic Event That Culminated In Emplacement Of The 2-73-2-79 Ga Granitoid Suite In The Batholith Exposed In The Beartooth Uplift (wooden And Others, 1991)- However, There Is No Evidence That The Magmatism That Formed The Stillwater Complex Is Related To Convergent Margin Tectonics And Magmatism

Physiography

Physiographic area where the resource is found.

  1. Division Province? Section
  2. Rocky Mountain System Middle Rocky Mountains -

Analytical Data

Results of chemical or mineralogical analysis on materials at or near the site

  1. Line? Analysis Data?
  2. 1 AVERAGE OF CHROMITITE: 187.5 PPB PT, 139.5 PPB PD, 149 PPB RH (MAX. 290 PPB PT, 400 PPB PD, 260 PPB RH). TRENCH SAMPLES RANGED FROM 0.5-5.2 FT LONG AND 0.78-42.91% CR203 (AVERAGE 5.37 FT AT 15.1% CR2O3). DIAMOND DRILL HOLES (5) INTERSECTED 1.4-6.7 FT CHROMITE AT 12.3-21.7% CR2O3. MASSIVE ORE AVERAGES 36.33% CR2O3, DISSEMINATED 13.21%

Holdings

Mineral rights ownership information.

  1. Type?
  2. Patented

Model

Mineral deposit model of the site.

  1. Name? USGS Model Code? BC Model Code? Mark 3 model code?
  2. BUSHVELD CHROMIUM 2A - -

Ore Control

Controls on emplacement of ore such as faults or other structural features.

  1. Text?
  2. Crystal Settling In Large Magma Chamber

Nearby Deposits

Other deposits in the same region.

  1. Iron Dike Iron Prospect

    • Iron commodity Site type Prospect status
    • Sweet Grass, Montana
    • Surface
    • 0.13 miles
    Read More

  2. Dark Horse Chromium Prospect

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • 0.23 miles
    Read More

  3. Lost Shaft

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • Vein
    • 0.23 miles
    Read More

  4. Bonanza Lode

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • Vein
    • 0.23 miles
    Read More

  5. Blue Bird Fraction Chromium Prospect

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • Vein
    • 0.23 miles
    Read More

  6. Bonanza Lode

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • Vein
    • 0.23 miles
    Read More

  7. M. And R. Chromium Prospect

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • 0.23 miles
    Read More

  8. M. And R. Chromium Prospect

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • Vein
    • 0.23 miles
    Read More

  9. Bonanza Lode

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • Vein
    • 0.23 miles
    Read More

  10. M. And R. Chromium Prospect

    • Chromium commodity Site type Prospect status
    • Sweet Grass, Montana
    • Vein
    • 0.23 miles
    Read More

Nearby Places

Nearby Mining Districts

Nearby Lands

Footnotes

* Mine bounds on map indicate the general area that a mine occupies. For an detailed map, refer to the overseeing BLM field office.

** The mine central point is based on an average of the mine's bounding box(es) and does not necessarily fall on the claim itself.

1 World-class significance is determined by total endowment of the contained commodity. This includes all past production and remaining reserves. Each commodity is considered separately and commodities cannot be combined to arrive at a significant size. The tonnage thresholds are from the mine model grade-tonnage studies. As of June 2008, many entries were classified as significant under less strict rules.

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