Black Pine Mine (Combination Mine; Black Pine tailings; Black Pine dump), Black Pine Ridge, John Long Mts, Philipsburg District (Flint Creek District), Granite Co., Montana, USA
|Latitude & Longitude (WGS84):||46° 26' 52'' North , 113° 21' 56'' West|
|Latitude & Longitude (decimal):||46.44778,-113.36556|
|Köppen climate type:||Dfb : Warm-summer humid continental climate|
A former Ag-Au-Cu-Pb-Zn-Sb mine located in secs. 7, 8, 9, 16, 17 & 18, T8N, R14W, MPM. 6.2 km (3.9 miles) E of Black Pine Ridge (coordinates of record), along the South Fork Lower Willow Creek (approximately 14.5 km NW of Philipsburg), on patented mining claims within National Forest land. Owned & operated by the Inspiration Resources Corp. (100.00%), New York (1983) (Inspiration Consolidated Copper Co. is 50% controlled by Hudson Bay Mining and Smelting Co., Ltd., Toronto, Canada). Owned & operated by ASARCO (American Smelting and Refining Co.) (100.00%), New York (1990). MRDS database stated accuracy for this location is 100 meters.
The mine complex is approximately 14 km NW of Philipsburg. The property is accessible year round. The property is made up of 57 patented mining claims and 12 patented millsites containing approximately 1,027 acres and approximately 127 unpatented claims (updated May, 1997).
Mine chronology of significant events: 1882 - discovered; 1885 - few tons of ore put through the Hope Mill in Philipsburg; 1887 - combination mining and milling company purchased holdings of the Black Pine Mining Company; 1888 - combination mill built; 1888-1897 - operated continuously until low Ag prices and mined out oxides closed the mine; 1937 - shut down; 1974 - mine reopened; 1985 - (January) mine shut down; 1986 - (March) mine shut down; 1987 - (May) Inspiration reopens the mine; 1988 - mine closed because of low Ag prices.
ASARCO LLC purchased mine in 1990 and operated intermittently until 2000. Asarco mined high grade silica ore with various oxide minerals from the Tim Smith Vein for use as flux at the Asarco East Helena Smelter. Asarco deeded property to the Montana Custodial Trust in 2009.
Mineralization is a polymetallic deposit (Mineral occurrence model information: Model code 85; USGS model code 22c; Deposit model name ; Polymetallic veins; Mark3 model number 46), hosted in Neoproterozoic rocks of the Missoula Group (quartzite), and rocks of the Precambrian Spokane Formation (red shale). The ore body is fissure vein, tabular, strikes N30W and dips 25S at a thickness of 1.2 meters, a width of 1,070 meters, and a length of 1,070 meters, over an area of 162 HA. The primary mode of origin was hydrothermal. Primary ore control was bedding. Degree of wallrock alteration is unknown. The deposit is comprised of 4 fissure veins in quartzite. The Combination vein was the main producer. It is 0.5 to 4 feet wide, explored 1,900 feet along strike and 2,200 feet downdip. Its strike length may be GT 5,500 feet. The vein is cut and offset by a system of normal strike faults. The vein follows the bedding plane of the quartzite nearly everywhere. Little work was done on the Upper, Tim Smith, and Onyx veins. All 4 veins are similar. Controls for ore emplacement included northerly-striking sedimentary horizons. Local alteration included oxidation. Local rocks include rocks of the Missoula group.
Local geologic structures include 2 systems of faulting on the surface. Oner set strikes ESE and dips N; and the second set strikes ESE and dips S. Granodiorite outcrops 1 mile N of the mine.
workings include surface and underground openings and operations. There are 8 vertical shafts, 3 tunnels, drifts, inclines, and crosscuts (1906). All surface openings are closed except the Lewis shaft and Combination adit. 10,732 feet of bulldozing. The Combination vein was developed 2,400 feet down dip and 3,300 feet along strike (Alder, 1974). Flotation Mill.
Production statistics: Year: 1897; Period: 1885-1897: 62,199,999 grams of Ag.
[1888-1897 - Production was 2,135,000 ounces of Ag, and 1,411 ounces of Au (Anon, 1963) ($1,496,862.00 - period values).
Year: 1989; Period: 1885-1989: Ore mined: 1,339,000 metric tons.
Production history details: Ag: 174,863,770 grams; Au: 93,310 grams; Cu: 4,843,459 metric tons; Pb: 117,934 metric tons; Zn: 12,247 metric tons.
Resource/reserves data: Type: In-situ; Estimate year: 1997: Total resources: 1,180,000 metric tons ore (USGS OFR 2004-1038). Silver: 192.000000 grams/metric ton (1997).
Note: "The boleite attributed to the Black Pine mine actually came from the bricks of the Bi-Metallic Mill (Red Mill) in Philipsburg, Montana and are a reaction of the lime from the mortar in the bricks with the copper and silver left from the milling, smelter process. These specimens were found in the 50's or 60's and made their way into collections as boleite with the location as Black Pine, Montana." (Brent Thorne information)
76 valid minerals. 3 (TL) - type locality of valid minerals.
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
1000 - 1600 Ma
|Upper Missoula Group: McNamara, Bonner, and Mount Shields Formations; locally includes lower Libby Formation in northwestern Montana|
Age: Mesoproterozoic (1000 - 1600 Ma)
Stratigraphic Name: McNamara Formation; Bonner Quartzite; Mount Shields Formation; Libby Formation
Description: McNamara Formation: Dense green and red siltite and argillite in mudcracked couplets containing diagnostic chert beds and rip-up clasts. Thickness as much as 1,650 m (5,413 ft). Bonner Formation: Pink, cross-bedded, feldspathic, medium- to coarse grained quartzite. Thickness as much as 580 m (1,903 ft). Mount Shields Formation: Upper part: red quartzite, siltite, and argillite in mud-cracked couples and couplets with abundant salt casts. Lower part: light gray, flat-laminated, feldspathic, fine-grained quartzite. Thickness as much as 2,000 m (6,562 ft). In northwestern Montana - Libby Formation:Light to dark gray and greenish gray siltite and argillite with subordinate quartzite in mud-cracked couplets. Thickness as much as 2,300 m (7,546 ft).
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. 
1000 - 1600 Ma
|Mount Shields Formation|
Age: Mesoproterozoic (1000 - 1600 Ma)
Reference: Zientek, M.L., P.D. Derkey, R.J. Miller, J.D. Causet et al. Spatial Databases for the Geology of the Northern Rocky Mountains - Idaho, Montana, and Washington. U.S. Geological Survey Open-File Report 2005-1235 Version 1.0.