EVAPORITES AND BRINES 



207 



Searles and Owens Lakes, Calif., contain amounts 

 of sodium carbonate smaller than those in Colorado. 

 The deposits are of Quaternary age and consist of 

 porous crystalline bodies saturated with brines 

 (Smith, G. I., 1966a). They are estimated by us to 

 contain about 700 million tons of sodium carbonate. 

 Some sodium carbonate occurs in numerous small 

 playa lakes in the Western United States; the re- 

 source potential of these deposits probably does not 

 exceed 200 million tons (Garrett and Phillips, 1960) . 



Production of sodium carbonate from natural 

 sources also comes from the trona deposits of Lake 

 Magadi, Kenya (Eugster, 1970) . The lake generates 

 new trona at about the same rate as present annual 

 production (150,000-200,000 tons). Other sodium 

 carbonate lakes in the rift valleys of eastern Africa 

 contain large but unknown amounts of additional 

 material. Deposits of unknown, but probably small, 

 size occur also in South America, eastern Europe, 

 the U.S.S.R., central Africa, China, and India. 



SODIUM SULFATE 



Sodium sulfate (NaaSOi, known also as "salt 

 cake"), is produced in the United States from na- 

 tural brines and as a byproduct of certain manufac- 

 turing processes. About 1.5 million tons is produced 

 annually of which 46 percent, valued at $12.5 mil- 

 lion, comes from natural sources in California, Utah, 

 Texas, and Wyoming (Lansche, 1971b; MacMillan, 

 1970d). The kraft paper industry consumes nearly 

 75 percent of U.S. production whereas the glass, 

 caramic glaze, detergent, and other industries con- 

 sume the balance (Goudge and Tompkins, 1960) . 



California sodium sulfate production from natural 

 sources comes from subsurface Pleistocene brines in 

 Searles Lake ; Utah production is from the brines in 

 Great Salt Lake; Texas pi-oduction is from subsur- 

 face brines; and Wyoming production is from sur- 

 face crusts on dry lakes. Canadian production, which 

 is about equal to U.S. production from natural 

 sources, comes from salt lakes in Saskatchewan. All 

 deposits are in arid to semiarid environments. The 

 presence of sodium sulfate in a closed basin is a 

 result of several geologic controls, especially the 

 chemical composition of rocks and soils within the 

 drainage area and the composition of mineral springs 

 that discharge into the basin. Extraction processes 

 can be relatively simple because of the marked in- 

 fluence of temperature on the solubility of sodium 

 sulfate at temperatures below 32°C (Rueffel, 1970) . 



Resources of sodium sulfate are large. Searles 

 Lake, Calif., is estimated by us to contain 400 mil- 

 lion tons, a 600-year supply at present rates of U.S. 



consumption from natural sources. Great Salt Lake 

 contains about 30 million tons, and both solid and 

 brine deposits are known in 10 other States in the 

 United States. Canadian deposits contain about 60 

 million tons. Production has come also from several 

 countries in Europe and South America, and a 

 single deposit in the U.S.S.R. contains an estimated 

 2 billion tons (Goudge and Tompkins, 1960). 



BORON MINERALS 



Boron minerals mined in the United States in 1970 

 supplied more than 60 percent of world needs. Pro- 

 duction totaled about 1 million short tons of ore 

 which contained about 560,000 tons of BoO, ; value of 

 the ore was approximately $85 million (Kistler, 

 1972). All domestic production came from Califor- 

 nia; small deposits in Nevada and Oregon are un- 

 mined (Smith, W. C, 1960, 1962). Foreign produc- 

 tion came mostly from Turkey with smaller amounts 

 coming from Italy, Argentina, and probably China 

 and the U.S.S.R. 



Boron mineral consumption by the United States 

 was about 35 percent of world production. Consump- 

 tion was largely by the manufacturers of glass, glass 

 fiber, enamel, chemical and agricultural products, 

 soaps and detergents, abrasives, gasoline additives, 

 flre-retardants, metal alloys, and other industries 

 (West, 1971). Annual growth in U.S. consumption 

 over the next quarter century is estimated to be 3.5- 

 4.6 percent, with greater growth possible (MacMil- 

 lan, 1970a). 



Boron minerals being mined today occur chiefly as 

 deposits in nonmarine Cenozoic rocks. Production at 

 Boron, Calif., comes from a thick, slightly deformed 

 lacustrine deposit of middle Tertiary age that con- 

 tains borax (Na,B,O-10H.O) and kernite (NasB^O- 

 •4H,0) (Barnard and Kistler, 1966). The near lack 

 of other evaporite components in the deposit indi- 

 cates that it was formed from lake waters unusually 

 rich in sodium borate, but the existence of compara- 

 ble deposits in Turkey and Argentina show that this 

 setting is not unique. Production near Death Valley, 

 Calif., consists mostly of calcium borates (such as 

 colemanite) from deformed upper Cenozoic mud- 

 stone and sandstone deposited in a depression an- 

 cestral to Death Valley (McAllister, 1970). Sodium 

 borate production from Searles Lake, Calif., comes 

 from brines pumped from the interstices of mineral- 

 ogically complex salt layers beneath the dry lake 

 surface; the salts are an upper Quaternary deposit 

 formed by desiccation of a succession of large Pleis- 

 tocene lakes (Smith, G. I., 1966c) . Less is known of 

 the geologic setting of major deposits in other parts 



