Commodities
PrimaryPlatinum, Palladium
SecondaryCopper, Nickel
TertiaryCobalt, Iridium, Gold, Arsenic, Antimony
Commodity typeM
Deposit
Deposit sizeN
Orebody formLENSES, PODS, PIPES, DISSEMINATED
Ore controlCrystallization Processes Within Anorthosite
Materials
Ore mineralsChalcopyrite, Pentlandite, Pyrite, Pyrrhotite, Sperrylite
GangueApatite, Calcite, Chlorite, Graphite, Magnetite, Plagioclase, Quartz, Talc
Geology
Host rockAnorthosite
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), Cross Faults Offset Sulfide Bearing Zone
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
AlterationPlagioclase Is Altered To Clinozoisite-Epidote, Pyroxene To Chlorite-Calcite-(Talc)- Magnetite-Quartz, Pyrrhotite To Pyrite
Economic & production
Development statusOccurrence
Discovery year1936
Identification
Deposit ID10048501
MRDS IDMP00090
RegionNA
Data scoreB
Coordinates45.44936, -110.05108
References
BOUDREAU, A.E., AND MCCALLUM, I.S., 1986, INVESTIGATIONS OF THE STILLWATER COMPLEX: III. THE PICKET PIN PT/PD DEPOSIT: ECONOMIC GEOLOGY, V. 81, P. 1953-1975.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.HOWLAND, A.L., PEOPLES, J.W., AND SAMPSON, EDWARD, 1936, THE STILLWATER IGNEOUS COMPLEX AND ASSOCIATED OCCURRENCES OF NICKEL AND PLATINUM GROUP METALS: MONTANA BUREAU OF MINES AND GEOLOGY MISCELLANEOUS CONTRIBUTION 7, 15 P.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.