402 



UNITED STATES MINERAL RESOURCES 



million in 1971. When this report was prepared in 

 mid-1972, all major mercury mines in the United 

 States had drastically curtailed or ceased produc- 

 tion because of the low price of mercury brought 

 about by concern over mercury pollution. 



USES 



In addition to being fluid at normal temperatures, 

 mercury possesses a unique combination of proper- 

 ties, such as high surface tension, linear thermal 

 expansion, good electrical conductivity, high density, 

 ability to alloy readily, and tendency to form very 

 toxic compounds. These properties make mercury 

 useful in a great variety of processes and products. 

 Some uses, such as in thermometers or mercury 

 switches, require minute amounts in each apparatus, 

 but others, such as in chlorine-caustic soda plants, 

 require several tons. Amounts and trends by cate- 

 gories are shovim in table 78. Note that the two 

 largest uses, electrical apparatus (mostly batteries) 

 and catalysts (chlorine manufacture) , together have 

 accounted for about half the U.S. consumption in 

 recent years, and uses dependent on the toxicity of 

 mercury compounds have amounted to another quar- 

 ter of the consumption. For a detailed review of 

 uses and projected trends for the United States, 

 see reports by the National Research Council (1969) 

 and by Greenspoon (1970). 



Metallic mercury of 99.9-percent purity is gen- 

 erally recovered by a distillation process at the 

 mine site, and it is bottled and marketed directly in 

 standard steel flasks containing 76 pounds (about 

 2.5 liters or 2.7 quarts) of the liquid metal. For 

 some uses, it is redistilled to achieve greater purity 

 and redistributed in glass, plastic, or earthenware 

 bottles containing from 4 ounces to 10 pounds. 

 Mercurial compounds are nowhere made at the mine 

 but are manufactured from refined mercury metal. 



Table 78. — Uses and consumption of mercury in the United 

 States 



[Thousands of flasks] 



1942 1951 1970 1971 



Agriculture (germicides, fungicides, 



algaecides) 1.5 7.7 1.8 "1.5 



Amalgamation (major use before 1900) .2 .2 .2 



Catalysts : 



Chlorine-caustic soda (started 1937) .5 1.5 15.0 12.3 



Plastics, resins, acetic acid, other chemicals- 3.3 2.6 2.2 1.1 



Dental preparations 2.1 1.6 2.3 2.4 



Electrical apparatus (mostly batteries) 5.5 13.2 16.0 16.9 



Felt manufacture (none since 1943) .2000 



Instruments, industrial, control 6.6 10.4 4.8 4 



Laboratory, general .3 .5 1.8 .18 



Munitions, blasting caps (none since 1956) 7.8 .5 



Paint, antifouling (mostly ship bottoms) 1.2 2.6 .2 .4 



Paint, mildew proofing 10.1 8.2 



Paper and pulp manufacture (slimicide) .2 .002 



Pharmaceuticals 8.1 2,8 .7 .7 



Vermilion (none since 1944) .2000 



Other, concealed, unknown ^12.2 13.3 -6.3 2.3 



Total 49.7 56.8 61.6 52.5 



" Includes fungicides and bactericides for industrial use. 



* Includes installation and expansion of chlorine-caustic soda. 



Substitutes for mercury have been found in many 

 formerly important mercury uses, and very little 

 mercury is now used for amalgamation (largest use 

 in 1870's), antisyphilitics (largest use in 1917), 

 munitions, detonators (fulminate), felt manufac- 

 ture, pattern making, paper manufacture, vermilion, 

 fireworks, and cosmetics. In some other major uses, 

 substitutes could be used but would result in sacri- 

 ficing quality of the product or economy of manu- 

 facture, or both. For example, in the manufacture 

 of chlorine-caustic soda, a diaphragm cell can be 

 used instead of the mercury electrolytic cell, but it 

 yields a product of lower purity at a higher cost, 

 which ultimately affects the price of nylon, rayon, 

 petroleum products, aluminum, detergents, and 

 many other consumer items. However, for many 

 uses, such as batteries, mercury lamps, wall 

 switches, thermostats, barometers, manometers, 

 thermometers, pressure gages, and laboratory uses, 

 substitution is impractical and undesirable. For 

 agricultural uses and paint, substitution may in the 

 future be practical as nonmercurial germicides and 

 fungicides having selective toxicity are discovered. 



SIZE AND IMPORTANCE OF THE INDUSTRY 



World production of mercury reached an all-time 

 high in 1969 of 290,000 flasks, valued at about $159 

 million. U.S. mercury production in the same year 

 was 29,640 flasks, valued at about $15 million, or 

 0.02 percent of the $7.2 billion of national income 

 generated by mining. The importance of the mercury 

 industry, however, outweighs its relative size. About 

 300 U.S. companies use primary mercury, and an- 

 other 400 that use redistilled mercury account for 

 about 20 percent of the total U.S. consumption. Al- 

 most everyone safely uses a little mercury every 

 day, and without it we would be forced to use in- 

 ferior products made at increased cost. It is classi- 

 fied by the U.S. Government as a strategic commod- 

 ity, essential to the economy. Financial assistance in 

 exploration for new mercury deposits is provided 

 by the Government through the U.S. Geological Sur- 

 vey, Office of Minerals Exploration. Of the 36 eligi- 

 ble commodities, mercury is one of nine eligible for 

 assistance of 75 percent of the allowable costs of 

 exploration, as compared with 50 percent for the 

 others. 



EXPLOITATION 



MINING 



By most mining standards, mercury mines are 

 all small. The largest probably is the New Almaden 

 mine in California, where about 30 miles of hori- 

 aontal underground workings were driven for ex- 



