Picket Pin Platinum Occurrence
Limestone, Montana
45.4493°N 110.0510°W
Mine Overview
The Picket Pin Platinum Occurrence is near Limestone, 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 before 1936. Ore mineralization has been found at this location and the size of the deposit is estimated to be medium, however the precise grade, tonnage, and extent of the mineralization are not known. There has been no production and little to no activity other than routine claim maintenance since the mineral discovery. The ore mined is composed of sperrylite, pyrite and pyrrhotite with waste material consisting primarily of graphite, calcite and apatite. The ore body has a lenticular or lens shaped form 22,000 meters (72,178 feet) long and 150 meters (492 feet) thick. The host rock in this area is anorthosite 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.
Owner Name and Address
Anaconda Company
- Type
- Operator
Commodities
Additional textual information about a site or mine.
- Commodity Type Importance
- Palladium Metallic Primary
- Platinum Metallic Primary
- Copper Metallic Secondary
- Nickel Metallic Secondary
- Antimony Metallic Tertiary
- Arsenic Metallic Tertiary
- Cobalt Metallic Tertiary
- Gold Metallic Tertiary
- Iridium Metallic Tertiary
Location Info
- Sweet Grass , Montana County / State
- Continent Country State County
- North America The United States Montana Sweet Grass
Notes
UNSURVEYED. IN CUSTER AND GALLATIN NATIONAL FORESTS. LOCATION GIVEN IS SUMMIT OF PICKET PIN MOUNTAIN; HOWEVER, DEPOSIT IS TRACEABLE ALONG STRIKE FOR 22 KM.
Development
PRESENCE OF MINERALIZATION WAS KNOWN FROM NEAR HEAD OF NORTH FORK PICKET PIN CREEK IN 1930'S. SOIL GEOCHEMICAL SAMPLING PROGRAM IN 1968 DEFINED AREA OF MINERALIZATION AROUND PICKET PIN.
Workings
SAMPLING ONLY
Concentration Process
Processes that concentrated or enriched the mineralization of the mine.
- Concentration Process
- Late Stage Concentration Of Sulfide
Geology
MINERALIZING FLUIDS WERE SILICA AND ALKALI RICH WITH HCL AND HF. A LACK OF IRON AND TI OXIDES INDICATES THE SULFIDES FORMED AT HIGHER SULFUR FUGACITIES. AGE OF STILLWATER COMPLEX IS 2, 705 +/-4 MA BASED ON U-LEAD SYSTEMATICS ON ZIRCON-BADDELEYITE (PREMO AND OTHERS, 1990).
Materials
Minerals or other materials present in the mine.
Orebody
Characteristics of the ore body.
- Length:
- Thickness: 150.00 meters (492.13 feet)
- Strike: northwest
- Dip: moderately to steeply north
Rocks
Geological materials at the site.
Structure
Geologic structural features affecting or characterizing the site or mine.
- Scale Description
- Local Cross Faults Offset Sulfide Bearing Zone
- 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.
- Setting?
- 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.
- Division Province? Section
- Rocky Mountain System Middle Rocky Mountains -
Alteration
Mineralogical and chemical alteration at or near the site, which may help to indicate the geographic extent of the geological processes producing the mine.
- Type? Alterations
- Local Plagioclase Is Altered To Clinozoisite-Epidote, Pyroxene To Chlorite-Calcite-Talc-Magnetite-Quartz, Pyrrhotite To Pyrite
Analytical Data
Results of chemical or mineralogical analysis on materials at or near the site
Ore Control
Controls on emplacement of ore such as faults or other structural features.
- Text?
- Crystallization Processes Within Anorthosite
Nearby Deposits
Other deposits in the same region.
-
Picket Pin Platinum Prospect
- Platinum Group Elements (PGE) commodity Site type Prospect status
- Sweet Grass, Montana
- Surface
- 0.04 miles
-
Alaskite Chromium Occurrence
- Chromium commodity Site type Occurrence status
- Sweet Grass, Montana
- 0.77 miles
-
Stillwater Anorthosite
- Aluminum commodity Site type Prospect status
- Sweet Grass, Montana
- Surface
- 1.34 miles
-
Monkey West Platinum Occurrence
- Palladium commodity Site type Occurrence status
- Sweet Grass, Montana
- 1.74 miles
-
Monkey East Camp Zone Palladium Occurrence
- Palladium commodity Site type Occurrence status
- Sweet Grass, Montana
- 2.15 miles
-
Janet Copper Occurrence
- Arsenic commodity Site type Occurrence status
- Sweet Grass, Montana
- 2.20 miles
-
Coors Palladium Occurrence
- Palladium commodity Site type Occurrence status
- Sweet Grass, Montana
- 2.24 miles
-
Frog Pond East Rhodium Occurrence
- Palladium commodity Site type Occurrence status
- Sweet Grass, Montana
- 2.79 miles
-
Iron Mountain Chrome Chromium Occurrence
- Chromium commodity Site type Occurrence status
- Sweet Grass, Montana
- 2.87 miles
-
Iron Mountain Nickel-Copper Iron Creek Nickel Occurrence
- Copper commodity Site type Occurrence status
- Sweet Grass, Montana
- 2.92 miles
Nearby Places
- Limestone (7.46 miles away)
- Nye (11.77 miles away)
- McLeod (15.07 miles away)
- Springdale (21.70 miles away)
Nearby Mining Districts
- Stillwater Mining District (0 miles away)
Nearby Lands
- Custer National Forest (0 miles away)
- Gallatin National Forest (0.00 miles away)
- Absaroka-Beartooth Wilderness (3.42 miles away)
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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Deposit
SULFIDE ZONE IS STRATIFIED WITHIN UPPER 150 M OF ANORTHOSITE SUBZONE II AND CAN EXTEND UP TO TROCTOLITE BUT GENERALLY ENDS ABOUT 10 M FROM TOP OF ANORTHOSITE WHERE THERE IS A DISTINCT TEXTURAL CHANGE. MINERALIZING SOLUTIONS PERCOLATED UPWARD DURING SOLIDIFICATION OF ANORTHOSITE. HOWLAND AND OTHERS NOTED THAT THE SULFIDES ARE INTERSTITIAL TO SILICATES AND PARTLY REPLACE THEM. DEPOSIT HAS HIGHER COPPER AND LOWER NICKEL THAN J-M REEF; UNPUBLISHED MODEL NAME: PICKET PIN MINERALIZATION.