Pacific Mine (Pacific Coast Borax Company properties; Borate; Borate Colemanite Mines; Calico; Old Borate; Pacific Coast Borax Co. workings), Calico, Calico District (Daggett District; Calico-Daggett area), Calico Mts (Calico Hills), San Bernardino County, California, USA (original) (raw)

Latitude & Longitude (WGS84):

34° 57' North , 116° 49' West

Latitude & Longitude (decimal):

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Long-form identifier:

mindat:1:2:26609:8

e6417dcb-b957-4df5-977c-41b51eebe180

A former borate-gypsum-Sr occurrence/mine located in secs. 18, 19 & 20, T10N, R2E, and in secs. 23, 24 & 25, T10N, R1E, SBM, 4.3 km (2.7 miles) E of Calico in the Calico Hills. Discovered in 1882. First production was in 1884. Owned by the Pacific Coast Borax Company (1907- ). Production years were 1884 to 1907. MRDS database stated accuracy for this location is 500 meters.

Mineralization is hosted in the Fisset Brook Formation (lake sediments, shale, limestone). The ore body is 9.14 meters thick. Local rocks include Tertiary intrusive rocks (hypabyssal), unit 7 (Northern Mojave Desert) and/or Tertiary volcanic flow rocks, unit 16 (Northern Mojave Desert). This mine was the first underground mining of colemanite in the USA.

Borates occur as podiform and stratiform deposits. The pods occur below the bedded deposits. Five borate beds are exposed at the surface and range from 0.6 to 4.6 meters in thickness. The stratiform and podiform borates are separated by 15.2 meters of B-rich shale. Near the surface, colemanite has commonly been replaced by calcite. Local geologic structures include numerous faults. Sediments are severely folded.

Workings include underground openings. Many of the near-surface stopes have collapsed. The dumps are 18 to 21 meters high and several hundred meters wide. At one point, mining extended to a depth of 500 to 600 feet. The belt of borate workings extends 2.4 km.

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13 valid minerals.

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Localities in this Region

• California
  • San Bernardino County
    * Calico Mts (Calico Hills)
    * Calico District (Daggett District; Calico-Daggett area)
    * Calico
    * Pacific Mine (Pacific Coast Borax Company properties; Borate; Borate Colemanite Mines; Calico; Old Borate; Pacific Coast Borax Co. workings)
    * Borate (Borate Camp)
    * Borax Consolidated Company Mines
    * Unnamed Sr deposit [1]

Other Regions, Features and Areas containing this locality

• **Basin and Range Basins**Basin
• **Mojave Domain**Domain
• **Southern Basin and Range**Wide Rift

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References

**Palache, Charles, Berman, Harry, Frondel, Clifford (1951) The System of Mineralogy (7th ed.) Vol. 2 - Halides, Nitrates, Borates, Carbonates, Sulfates, Phosphates, Arsenates, Tungstates, Molybdates, Ect. John Wiley and Sons, New York.**p.418