516 



UNITED STATES MINERAL RESOURCES 



About 70 percent of the domestic consumption of 

 phosphate rock is in fertilizers, and the major use 

 will continue to be in fertilizers because there is no 

 substitute for phosphorus as a plant food element. 

 Other uses are many ; they include animal feed sup- 

 plement, detergent, electroplating and polishing of 

 metals, insecticides, medicines, and incendiary 

 bombs. 



Phosphate fertilizers are used extensively in the 

 developed countries, but are used sparingly or not at 

 all in some of the less developed countries. Produc- 

 tion of agricultural materials is limited by deficiency 

 in plant nutrients, and chemical fertilizers, including 

 phosphorus, are vital to the production of adequate 

 food in the world. 



Phosphorus is found in minable concentrations in 

 three principal environments — guano or deposits de- 

 rived from guano, igneous apatites, and marine phos- 

 phate deposits. Other types of concentrations such 

 as phosphatized rock, residual phosphate, and river 

 pebble deposits are secondarily derived. 



All types of deposits are found in the United States 

 and are widely distributed areally and geologically. 

 Occurrences of phosphate rock are known from al- 

 most all geologic eras from Precambrian to Cenozoic, 

 and in almost all of the States, but in 1971, phosphate 

 rock was produced only from Ordovician rocks in 

 Tennessee and Alabama; from Permian rocks in 

 Idaho, Montana, Utah, and Wyoming; and from 

 Miocene and Pliocene rocks in Florida and North 

 Carolina. Some production from the Miocene of Cali- 

 fornia is included in the totals for the Western 

 States. Production in 1971 was about 38 million 

 short tons, of which 83 percent was from Florida 

 and North Carolina, 11 percent from the Western 

 States, and 6 percent from Tennessee. About 27 mil- 

 lion tons was used domestically; the rest was 

 exported. 



Reserves of phosphate rock in Florida, North 

 Carolina, and the Western States are measured in 

 billions of tons in each area ; Tennessee reserves are 

 in millions of tons. These reserves can supply domes- 

 tic demands for scores or hundreds of years, but 

 political, economic, and ecological demands may 

 radically alter the traditional supply patterns in the 

 United States, and at some time in the future the 

 supply of phosphate rock to the eastern seaboard 

 may possibly come from foreign sources. 



World production of phosphate rock in 1970 was 

 about 94 million tons. About 75 percent of the pro- 

 duction came from marine phosphorite, 17 percent 

 from igneous apatite, and the rest from guano- 

 derived deposits. The United States produced about 



40 percent, the U.S.S.R. about 20 percent, and North 

 Africa about 20 percent. 



Reserves of phosphate rock in the world are meas- 

 ured in scores of billions of tons and resources are 

 equally vast. Most of the reserves and resources are 

 in the marine phosphorites ; reserves in igneous apa- 

 tite are large but account for only a small percentage 

 of the total and those in guano or guano-derived 

 deposits are limited. 



EXPLOITATION 



The first record of phosphate rock mining was in 

 1847 when a few tons of nodules ("coprolites") were 

 produced from Pliocene beds near Suffolk in Eng- 

 land; mining of igneous apatite began in 1851 in 

 Norway. Mining of rock phosphate began after the 

 discovery of Leibig and Lawes that bones and phos- 

 phate rock treated with sulfuric acid increased crop 

 response. 



The first mining of rock phosphate in North Amer- 

 ica was of pegmatite apatite in Canada that started 

 in about 1863 ; mining in the United States began in 

 1867, when a few tons of South Carolina phosphate 

 rock was produced. By 1870, production in the United 

 States had reached 65,000 tons (table 104) . Produc- 

 tion of phosphate from Florida began in 1888, in 

 Tennessee in 1894, and in the Western States in 1906. 

 The maximum production of phosphate from South 

 Carolina coincided with the start of production from 

 Florida (table 104) . The coincidence was due to the 

 lower costs of producing from the much more exten- 

 sive Florida deposits, and the increased Florida pro- 

 duction eventually brought about the closing of the 

 mines in South Carolina. 



Tennessee production is mostly from residual 

 "brown rock" deposits and has steadily increased 

 from 1894 to about 1965, except for a slight decline 

 in the depression years of the 1930's. For the past 

 several years, the rate of increase of production from 

 Tennessee has lessened and production in 1970 was 

 slightly less than production in 1969. 



The first production of phosphate rock in Florida 

 was a few thousand tons in 1888. Rate of production 

 increased rapidly and by 1920 was 3 million tons per 

 year. The rate of production decreased during the 

 depression and war years of the 1930's and 1940's, 

 and then increased rapidly; as a result by 1970 the 

 production was 31 million tons. Production has 

 leveled off in the last few years; 1969 and 1970 

 showed slight decreases from the maximum year 

 1968, but 1971 showed a slight increase. 



Production of phosphate from the Western United 

 States began in 1906 and has increased steadily to 



