Commodities
PrimaryChromium
TertiaryPGE
Commodity typeM
Deposit
Model2: Bushveld Cr
Deposit sizeN
Orebody formMASSIVE LAYERS, DISSEMINATED
Ore controlCrystal Settling In Large Magma Chamber
Materials
Ore mineralsChromite
GangueOlivine
Geology
Host rockHarzburgite
StructureThe 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), Small Faults
Tectonic settingTectonic 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
Economic & production
Development statusOccurrence
Identification
Deposit ID10048026
MRDS IDM700434
RegionNA
Data scoreB
Coordinates45.45659, -110.1683
References
HOWLAND, A.L., GARRELS, E.M., AND JONES, W.R., 1949, CHROMITE DEPOSITS OF BOULDER RIVER AREA, SWEETGRASS COUNTY, MONTANA: U.S. GEOLOGICAL SURVEY BULLETIN 948-C, P. 74.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.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.