U.S. Borax Mine (Pacific West Coast Borax; Pacific Coast Borax Co.; Boron Mine; Boron open pit; U.S. Borax and Chemical Corporation Mine; Kramer Mine; Kramer pit; Baker Mine), Kramer Borate deposit, Boron, Kramer District (Kramer Borate District), Kern Co., California, USA
|Latitude & Longitude (WGS84):||35° 2' 40'' North , 117° 41' 40'' West|
|Latitude & Longitude (decimal):||35.04444,-117.69444|
|Köppen climate type:||BWk : Cold desert climate|
A B (borates)-As-Sb-clay occurrence/mine located in secs. 19, 23 & 24, T11N, R8W, MDM, approximately 7 miles NW of Kramer and 4 miles NW of Boron. Ownedr-Operated by the U.S. Borax (subsidiary Of Rtz Borax Ltd. Of Rtz Corporation PLC (London, UK), Home office = Los Angeles, California (until 1992).
The primary mineralization is borax, precipitated in a permanent shallow lake, fed from thermal (volcanic) springs rich in sodium & boron. Kernite was formed later upon deep (+1500 feet) burial and temperatures above 53 degrees C (Christ and Garrels, 1959). The sodium borates together with claystone are hosted as a core facies within the Middle Miocene (16 mybp) Kramer beds (Barnard & Kistler, 1967) and are completely enveloped by ulexite-bearing shales (Gale, 1946). Stratigraphic and structural studies indicate the Kramer borates were deposited in a small structural, nonmarine basin, elongated in an east-west direction and limited on the south by the Western Borax fault.
[Joe Siefke 2010]
Additional names which apply to this locality: Osborne shaft; Discovery shaft; West Baker Mine.
Workings at the site included underground workings that were subsequently subhumed by a large open pit operation. The workings have an overall depth of 182.88 meters, overall length of 2,000 meters and an overall width of 1,600 meters. The underground workings were employed from 1927 to 1957, when the open pit mining became more profitable. The above listed dimensions are for the open pit.
U.S. Borax operates the open pit, refinery and boric acid plant at the site. The waste to ore ratio is about 7:1 with almost 100% ore recovery. The waste to ore ratio is expected to increase as the pit expands to the SSW. On average, one train of 30 to 35 one hundred-ton cars aserves the mine. The mine operations are energy intensive.
Approximately 50% of the kernite is stacked in the pit, wetted with water, and left to hydrate to borax (usually takes a few weeks). Processing is described by O'Driscoll (1990).
In 1989, production averaged 3,000 to 3,500 short tons per day (O'Driscoll, 1990).
Reserve-Resource data are found in: Kistler, R.B., and Smith, W.C. (1975); Roskill Information Services Ltd. (1993).
Reserves and resources data: Type: in-situ (estimate year: 1975): total resources: 36,281,000 metric tons of ore at 25 weight percent B2O3. Estimate year: 1992: total resources: 127,000,000,000 metric tons at 27.7% weight percent B2O3. At 1990 mining rates, reserves were held to be adequate for 30 to 40 years (O'Driscoll, 1990).
Commodity ListThis is a list of exploitable or exploited mineral commodities recorded from this region.
Mineral ListMineral list contains entries from the region specified including sub-localities
34 valid minerals. 4 (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
|Quaternary - Miocene|
0 - 23.03 Ma
|Cenozoic sedimentary rocks|
Age: Cenozoic (0 - 23.03 Ma)
Lithology: Sedimentary rocks
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. 
|Holocene - Pliocene|
0 - 5.333 Ma
|Quaternary alluvium and marine deposits|
Age: Cenozoic (0 - 5.333 Ma)
Stratigraphic Name: Temescal Formation; Modesto Formation; Victor Formation; Alameda Formation; Aromas Red Sands; Bautista Beds; Brawley Formation; Borrego Formation; Burnt Canyon Breccia; Cabezon Fanglomerate; Campus Formation; Casitas Formation; Chemehuevi Formation; Corcoran Clay; Cushenbury Springs Formation; Dos Picachos Gravels; Dripping Springs Formation; Frazier Mountain Formation; Friant Formation; Harold Formation; Heights Fanglomerate; Hookton Formation; Huichica Formation; La Habra Formation; Manix Lake Beds; Mohawk Lake Beds; Montezuma Formation; Nadeau Gravel; Ocotillo Conglomerate; Orcutt Formation; Pacoima Formation; Pauba Formation; Peckham Formation; Pinto Formation; Resting Springs Formation; Riverbank Formation; Rohnerville Formation; San Dimas Formation; Shoemaker Gravel; Temecula Arkose; Battery Formation; Bay Point Formation; Colma Formation; Lindavista Formation; Lomita Marl; Merritt Sand; Millerton Formation; Palos Verdes Sand; San Pedro Formation; Sweitzer Formation; Timms Point Silt
Description: Alluvium, lake, playa, and terrace deposits; unconsolidated and semi-consolidated. Mostly nonmarine, but includes marine deposits near the coast.
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. 
Localities in this RegionShow map
- Kern Co.
- Kramer District (Kramer Borate District)
- Kern Co.