Mine detail: Iron Mountain-Chrome Group W

Previously called 'Chrome Group'

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Location: Sweet Grass County, Montana, United States, North America
Lat / long: 45.4077, -110.05136
dep_id: 10048025
mrds_id: M700433
Commodity type: metallic
Major mineral: Chromium
Minor mineral: PGE
Operation type: Unknown
Production size: No production occurred
Development status: Occurrence
ore: Chromite
gangue: Olivine, Serpentine
orebody_fm: MASSIVE BAND, DISSEMINATED
model: 2: Bushveld Cr
conc_proc: Magmatic Segregation, Crystal Settling
ore_ctrl: Crystal Settling In Large Magma Chamber
Reporter: Dohrenwend, John C., Doyle, Brien (Wells, John), Peterson, Jocelyn A.
hrock_type: Harzburgite
Structure: 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), Cross-Faulting
tectonic: 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
disc_yr: 1940
References:
  • Deposit:: WIMMLER, N.L., 1948, INVESTIGATION OF CHROMITE DEPOSITS OF THE STILLWATER COMPLEX, STILLWATER AND SWEETGRASS COUNTIES, MONT.: U.S. BUREAU OF MINES REPORT OF INVESTIGATIONS 4368, P. 38-39.
  • Deposit:: HOWLAND, A.L., 1955, CHROMITE DEPOSITS IN THE CENTRAL PART OF THE STILLWATER COMPLEX, SWEET GRASS COUNTY, MONTANA: U.S. GEOLOGICAL SURVEY BULLETIN 1015-D, P. 113-114.
  • Deposit:: PAGE, N.J, RILEY, L.B., AND HAFFTY, JOSEPH, 1972, VERTICAL AND LATERAL VARIATION OF PLATINUM, PALLADIUM, AND RHODIUM IN THE STILLWATER COMPLEX, MONTANA: ECONOMIC GEOLOGY V. 67, P. 915.
  • Deposit:: PAGE, N.J, RILEY, L.B., AND HAFFTY, JOSEPH, 1969, PLATINUM, PALLADIUM, AND RHODIUM ANALYSES OF ULTRAMAFIC AND MAFIC ROCKS FROM THE STILLWATER COMPLEX, MONTANA: U.S. GEOLOGICAL SURVEY CIRCULAR 624, P. 10.
  • Deposit:: SCHAFER, P.A., 1937, CHROMITE DEPOSITS OF MONTANA: MONTANA BUREAU OF MINES AND GEOLOGY MEMOIR 18, P. 14-16.
  • Deposit:: ZIENTEK, M.L., 1993, MINERAL RESOURCE APPRAISAL FOR LOCATABLE MINERALS: THE STILLWATER COMPLEX, IN HAMMARSTROM, J.M., ZIENTEK, M.L., AND ELLIOTT, J.E., EDS., MINERAL RESOURCE ASSESSMENT OF THE ABSAROKA-BEARTOOTH STUDY AREA, CUSTER AND GALLATIN NATIONAL FORESTS, MONTANA: U.S. GEOLOGICAL SURVEY OPEN-FILE REPORT 93-207, P. F1-F83.
  • Deposit:: PREMO, W.R., HELZ, R.T., ZIENTEK, M.L., AND LANGSTON, R.B., 1990, U-PB AND SM-ND AGES FOR THE STILLWATER COMPLEX AND ITS ASSOCIATED SILLS AND DIKES, BEARTOOTH MOUNTAINS, MONTANA: IDENTIFICATION OF A PARENT MAGMA?: GEOLOGY, V. 18, P. 1065-1068.
  • Deposit:: 1955 GEOLMAP HOWLAND, BULL. 1015-D, P. 11
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