48 



UNITED STATES MINERAL RESOURCES 



ciated with Mesozoic or Tertiary igneous rocks are 

 about equally divided between dikes and lava flows 

 and coarse-grained intrusive rocks, commonly grano- 

 diorite or quartz monzonite. The often-held view 

 that antimony deposits are of Tertiary age and vol- 

 canic association is an oversimplification. 



Most antimony produced in the United States 

 comes from the complex deposits, as a byproduct 

 of the treatment of silver, lead, copper, and zinc 

 ores. The deposits in the Coeur d'Alene district, 

 Idaho, are outstanding examples of complex depos- 

 its. In the Yellow Pine district, Valley County, 

 Idaho, another example of an area of complex ores, 

 gold and tungsten were the principal metals, but 

 with a high enough price antimony outvalues the 

 other metals. For detailed information about spe- 

 cific U.S. deposits, see White (1951; 1962). 



Most antimony deposits presumably formed from 

 hydrothermal solutions at relatively low tempera- 

 ture and shallow depth, which gave rise to filled 

 fissures, joints, and irregular replacement masses. 

 In places, antimony is disseminated through the 

 wallrock alteration zone. 



RESOURCES 



IDENTIFIED AND HYPOTHETICAL RESOURCES 



Estimated identified and hypothetical resources 

 are summarized in table 8; these estimates are 

 based on sparse data in files of the U.S. Geological 

 Survey and a few published sources of information 

 on the occurrence of antimony as a relatively minor 

 constituent in ore deposits of major metals. Approxi- 

 mately 25 percent of the known U.S. antimony re- 

 sources is in scattered simple-type deposits, which 

 are not of economic importance unless the price for 



Table 8. — Estimated world resources of antimony, in short 

 tons of metal 



[Figures are modified from data compiled by U.S. Bureau of Mines ex- 

 cept where otherwise noted] 



Identified Hypothetical 

 Country resources ^ resources ^ 



United States 100,000 =100,000 



Mexico 200,000 



Bolivia 420,000 



Yugoslavia 100,000 



Turkey 120,000 



Republic of South Africa 300,000 



U.S.S.R. 300,000 



China 3,800,000 1,500,000 



Thailand 110,000 



Australia 150,000 



World total 5,600,000 



^Identified resources: Specific, identified mineral deposits that may 

 or may not be evaluated as to extent and grade and whose contained 

 minerals may or may not be profitably recoverable with existing tech- 

 nology and economic conditions 



- Hypothetical resources; Undiscovered mineral deposits, whether of 

 recoverable or subeconomic grade, that are geologically predictable as 

 existing in known districts. 



2 Based on unpublished data in files of U.S. Geological Survey. 



ore or concentrates would triple or quadruple and 

 stabilize at that level. Although 25 percent of the 

 U.S. antimony resources is contained in the Yellow 

 Pine district, little antimony has been produced since 

 the Yellow Pine mine was closed in 1952. Ranchers 

 Exploration and Development Corporation leased 

 the Yellow Pine mine and carried out a diamond- 

 drilling program in 1970, but there is no indication 

 that any ore was produced (B. F. Leonard, oral 

 commun., 1972) . At least 50 percent of the U.S. anti- 

 mony resources is contained in known complex 

 lead-silver-copper and gold ores. 



During the last 40 years, about four-fifths of U.S. 

 mine production of antimony has come from Idaho. 

 Reserves of ore in the Coeur d'Alene district are 

 considered adquate for continuous operations for 

 many years. 



The Fairbanks district, Alaska, has produced 

 about 2,500 tons of stibnite ore, and since 1936, 

 when it began operations, the Stampede mine in the 

 Kantishna district, Alaska, has produced about 2,700 

 tons of stibnite ore. About 75 percent of Alaska's 

 antimony was produced before World War II. From 

 1960 to 1971, about 100 tons of antimony was pro- 

 duced from Alaskan deposits, mainly the Stampede 

 mine. Known Alaskan resources are estimated as 

 nearly 10,000 tons of low-grade material (Berg 

 and others, 1964). 



On the basis of scattered analyses, it is estimated 

 that lead ores in southeastern Missouri, the Tri- 

 State district, and the Upper Mississippi Valley may 

 contain as much as 50,000 tons of antimony, here 

 considered as a hypothetical resource. So far as is 

 known, no antimony is now being recovered from 

 these ores. 



SPECULATIVE RESOURCES 



Potential resources of antimony that may be 

 mined in the future are tied directly to lead-silver- 

 copper-zinc deposits like those from which most 

 domestic antimony is recovered as a byproduct or 

 coproduct. 



Antimony is present in some galenas from Mis- 

 sissippi Valley-type lead deposits (Allen Heyl, oral 

 commun., 1972), and antimony is a constituent of 

 some base-metal deposits in the Eastern United 

 States. Apparently, fringe areas of some mineralized 

 zones, such as in Nevada, show anomalous amounts 

 of antimony; potential resources possibly exist 

 there. When the United States can no longer import 

 antimony in quantities to meet the needs, some addi- 

 tional domestic production may be obtainable from 

 these base-metal deposits and from areas of known 

 base-metal, tungsten, silver, and gold mineralization. 



