The Economic Development of Searles Lake
The evaporite beds of Searles Lake were formed by desiccation of runoff from the eastern Sierra Nevada range. The resulting series of brine-bearing salt beds supply feed for the chemical plants on its shore. Minerals have been extracted since 1873, beginning with borax and raw trona scraped from the surface. Brine processing began in 1914 with potassium chloride and borax recovery. Expansions have added sodium sulfate and soda ash to the product mix. Current production methods include evaporation and crystallization for potash and borax, carbonation for soda ash, refrigeration for borax and sodium sulfate, solvent extraction for boric acid, and dredging for trona ore.
Figures & Tables
The Diversity of Mineral and Energy Resources of Southern California
The Kramer borate deposit is located in the northwestern Mojave Desert, about 90 air miles northeast of Los Angeles and 3 miles north of the town of Boron (figure 1). The deposit derives its name from the mining district in which it lies. The Kramer deposit, presently being mined from the Boron open pit, has been a world-class source of sodium borates since mine startup in 1926 and continues to be the largest source of borates in the world.
The Kramer ore body is a roughly lenticular sedimentary sequence of borax (Na2B4O7 • 10H2O) and kernite (Na2B4O7 • 4H2O) containing interbedded claystone. This central crystalline facies is successively enveloped by facies consisting of ulexite (Na,CaB5O9 • 8H2O) -bearing claystone, colemanite (Ca2B6O11 • 5H2O) -bearing claystone, and barren claystone. Studies indicate the Kramer borates were deposited in a small structural, nonmarine basin, associated with thermal (volcanic) spring activity during Miocene time.
The Kramer deposit does not crop out. It was discovered accidentally in 1213 by Dr. John Suckow, a homesteader, who struck colemanite while drilling a water well (figure 2). Exploratory drilling and shaft sinking after World War I by Pacific Coast Borax Company, the predecessor of U.S. Borax, led to the discovery of borax and kernite in 1925. In 1926 PCB went into large-scale, underground sodium borate mining in the Baker mine, located nearly 2 miles east of Suckow's discovery well. The company soon closed all its calcium borate operations near Ryan in Death Valley in favor of the more easily processed sodium borates at Boron.
U.S. Borax ships mostly bulk, refined sodium borate products and boric acid to both domestic and world markets from Boron. Principal uses for these products are in the manufacturing of glass and fiberglass, herbicides, ceramics, soaps and detergents, fluxes, fertilizers, and fire retardants.