Mine detail: Forge Ni-Cu

Previously called 'Placer BasinBoulder Forge'

Location:	Sweet Grass County, Montana, United States, North America
Lat / long:	45.42325, -110.10497
dep_id:	10048504
mrds_id:	MP00094
Commodity type:	metallic
Major mineral:	Nickel, Copper
Minor mineral:	Cobalt, Platinum, Palladium, Rhodium
Trace mineral:	Silver, Gold, PGE
Operation type:	Unknown
Production size:	No production occurred
Development status:	Occurrence
ore:	Chalcopyrite, Pentlandite, Pyrrhotite
gangue:	Magnetite, Plagioclase
orebody_fm:	STRATIFORM, PODS, LENSES, DISSEMINATED
model:	1: Stillwater Ni-Cu
alteration:	None Related To Ore-Forming Process
conc_proc:	Magmatic Segregation, Liquid Immiscibility
ore_ctrl:	Immiscible Sulfide Liquid Enriched In Ni And Cu Exsolved From Mafic Silicate Magma And Accumulated Near Lower Contact Of The Stillwater Complex. Assimilation Of Sulfur From Rocks Adjacent To The Stillwater Complex May Have Led To The Exsolution Of The Sulfide Liquid (Zientek And Ripley, 1990)
Reporter:	Peterson, Jocelyn A.
hrock_type:	Peridotite,Hornfels
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)
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
dy_ba:	<
disc_yr:	1932
References:	Deposit:: PAGE, N.J, ROWE, J.J., AND HAFFTY, JOSEPH, 1976, PLATINUM METALS IN THE STILLWATER COMPLEX, MONTANA: ECONOMIC GEOLOGY, V. 71, P. 1352-1363. Deposit:: PAGE, N.J, AND NOKLEBERG, W.J., 1974, GEOLOGIC MAP OF THE STILLWATER COMPLEX, MONTANA: U.S. GEOLOGICAL SURVEY MISCELLANEOUS GEOLOGIC INVESTIGATIONS MAP I-797, SCALE 1:12,000. 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:: ZIENTEK, M.L., AND RIPLEY, E.M., 1990, SULFUR ISOTOPIC STUDIES OF THE STILLWATER COMPLEX AND ASSOCIATED ROCKS, MONTANA: ECONOMIC GEOLOGY, V. 85, P. 376-391. Deposit:: PAGE, N.J, 1979, STILLWATER COMPLEX, MONTANA - STRUCTURE, MINERALOGY, AND PETROLOGY OF THE BASAL ZONE WITH EMPHASIS ON THE OCCURRENCE OF SULFIDES: U.S. GEOLOGICAL SURVEY PROFESSIONAL PAPER 1038, 69 P.