LITHIUM, CESIUM, AND RUBIDIUM 



371 



has been found to contain 210 ppm lithium in addi- 

 tion to a wide variety of other potentially valuable 

 constituents (White, 1968, table 1). Observations 

 by Helen L. Cannon (written commun., 1972) indi- 

 cate concentrations of lithium in several closed 

 basins in Nevada and California, especially those 

 surrounded by volcanic rocks. 



Foreign localities have as yet received little at- 

 tention. Chong (1971, p. 26) has found that lithium 

 is concentrated in subsurface potassic brine in the 

 Salar de Atacama of northern Chile. Though analy- 

 ses are unpublished, the average grade is reported 

 to be 2,000 ppm lithium (Mining Jour., June 26, 

 1970, p. 597; Guillermo Chong, written commun., 

 Aug. 21, 1972). This seems too high to be accepted 

 without confirmation but is nonetheless an indica- 

 tion that lithium-rich brines exist in western South 

 America as in western North America. 



All these lithium-rich brines are associated with 

 continental sediments. Analyses of marine evapo- 

 rites are invariably discouraging. 



OTHER LITHIUM DEPOSITS 



Fragmentary evidence has been cited from time 

 to time to show that there may be other deposits of 

 potential commercial value (Norton and Schlegel, 

 1955, p. 332-333, 336-S37, and 341). Hectorite (a 

 magnesium-rich bentonite) at Hector, Calif, con- 

 tains about 1 percent LiaO (Ames and others, 1958, 

 table 3). Other clay deposits, which contain 0.2-0.5 

 percent LizO, have been recorded near Amboy, Calif. 

 (Foshag and Woodford, 1936, table 1, p. 241), Kirk- 

 land, Ariz. (Norton, 1965), and Spor Mountain, Utah 

 (Shawe and others, 1964). Kesler (1960, p. 524) 

 mentioned an average content of 0.5-1 percent LisO 

 in the shaly matrix of borate deposits at Boron, 

 Calif. During study of zeolitic tuffs in lake beds of 

 the southwestern States, R. A. Sheppard (written 

 commun., 1972) found that lithium not infrequently 

 attains levels of several hundred parts per million 

 in montmorillonoid clay minerals, especially in saline 

 environments; a nearly pure separate of saponite 

 from Pleistocene Lake Tecopa, Calif., has 0.34 per- 

 cent LiaO. Tardy, Krempp, and Trauth (1972) re- 

 corded the lithium contents of many additional clays. 



Whether any metamorphic rocks or hydrothermal 

 veins contain enough lithium to attract interest is 

 unknown. The mineral ephesite, a sodium-rich mar- 

 garite detected in emery deposits in Turkey and in 

 manganese deposits in South Africa, contains as 

 much as 3.85 percent LijO (Schaller and others, 

 1967, p. 1692), but so far as known, it is a rare 

 mineral. 



EXPLORATION AND MINING 



Though sporadic production was recorded from a 

 few localities in the 1880's and 1890's, the world's 

 first lithium mining of consequence began in 1898 

 at the Etta mine, Keystone, S. Dak. For the next 

 40 years, the chief sources were small mines in 

 which spodumene, amblygonite, and lepidolite were 

 recovered by hand sorting. During this period, pro- 

 duction of lithium minerals in the United States was 

 generally less than 2,000 tons annually; but in five 

 of these years it exceeded 4,000 tons, and in 1920, 

 a record year, the production was 11,696 tons, 

 valued at $173,002 (Schreck, 1961, table 10), which 

 probably contained about 250 tons of lithium. Dur- 

 ing these early years, the Etta mine was the largest 

 individual source of lithium, and the only other im- 

 portant sources were the Harding mine, Dixon, N. 

 Mex. ; the Stewart mine, Pala, Calif.; and the Tin 

 Mountain mine, west of Custer, S. Dak. Domestic 

 production during this period was far greater than 

 production from other countries. 



The first important change came in 1938, when 

 the American Potash and Chemical Corp. began 

 producing lithium at Searles Lake, Calif. This 

 marked the beginning of a period in which large, 

 fully mechanized operations took the place of small 

 mines that depended on hand sorting. 



Expanding use during World War H caused the 

 production of lithium minerals to reach a new peak 

 in 1944, when 13,319 tons was produced in the 

 United States and 17,169 tons was produced in the 

 entire world (Schreck, 1961, table 9). This large 

 production was made possible by the introduction 

 of mineral dressing techniques, especially by the 

 Solvay Process Co. at Kings Mountain, N. C. 



A sharp postwar slump, which lasted until 1950, 

 was followed by the tremendous increase in produc- 

 tion of the 1950's that soon far surpassed all pre- 

 vious records. The greatest incentive was the pur- 

 chase of lithium hydroxide by the U.S. Atomic 

 Energy Commission. By 1954, domestic output was 

 37,830 tons of lithium minerals, containing 1,142 

 tons of lithium; and world production was 102,763 

 tons (Schreck, 1961, tables 9 and 10). Domestic pro- 

 duction figures have not been published since 1954. 

 For other parts of the world, however, production in 

 the latter years of the 1950's was record setting, 

 reaching a maximum in 1957, when the total was 

 about 170,000 tons of lithium minerals and concen- 

 trates (Schreck, 1961, tables 9 and 11), which prob- 

 ably contained about 3,500 tons of lithium. If, as 

 seems likely, domestic production also increased 

 after 1954, the world's maximum output, in 1957 



