ANTIMONY 



47 



States rose from 938 short tons of contained anti- 

 mony in 1969 to 1,130 short tons in 1970 and then 

 dipped to 992 short tons in 1971. In 1969, U.S. 

 smelter production was 13,203 short tons of con- 

 tained antimony as compared to 13,381 short tons 

 in 1970 and 13,157 short tons in 1971. These statis- 

 tics indicate that the amount of antimony mined in 

 the United States and that produced by U.S. 

 smelters are not greatly affected by price fluctua- 

 tions. Mines reopened primarily for antimony could 

 not reach a production stage soon enough to take 

 advantage of the higher prices. Price levels during 

 the first quarter of 1972 approximated those of the 

 third quarter of 1969. 



Although antimony is toxic when taken internally, 

 its production alone probably would not constitute 

 a hazard to the environment. Lead smelters, where 

 antimonial lead is recovered, may be detrimental to 

 the environment, and many smelters cannot meet 

 present-day emission standards. 



GEOLOGIC ENVIRONMENT 



GEOCHEMISTRY 



The abundance of antimony in the earth's crust 

 ranges from 0.2 to 0.5 ppm (parts per million). In 

 igneous rocks the abundance is 0.1-1 ppm. Accord- 

 ing to Vinogradov (1962), basalts contain the high- 

 est percentage of antimony, and Turekian and 

 Wedepohl (1961) found that deep-sea clays contain 

 1 ppm antimony. 



The chemical and physical properties of antimony 

 are similar to those of arsenic and bismuth. Anti- 

 mony is chalcophile in distribution and combines 

 readily with sulfur and the preferred heavy metals 

 lead, copper, and silver. Metallic minerals found in 

 association with primary antimony minerals are 

 pyrite, galena, sphalerite, chalcopyrite, arseno- 

 pyrite, pyrrhotite, gold, and silver; the common 

 gangue minerals are quartz (predominantly), cal- 

 cite, and barite. 



The amount of antimony found distributed 

 through sedimentary rocks is very small, and the 

 changes that anitmony undergoes in the weathering 

 process are obscure. Antimony, like arsenic, tends 

 to be concentrated in hydrolyzates, chiefly by adsorp- 

 tion on ferric hydroxide. Although the antimony 

 content of sea water is beyond limits of detection 

 by most analytical methods, small amounts have 

 been reported in some marine animals and in ashes 

 of seaweeds. Although data are lacking, it seems 

 likely that during metamorphism much antimony in 

 stibnite is quickly remobilized and moved through 

 and into fissures, fractures, and brecciated zones, 



again forming low-temperature hydrothermal de- 

 posits. 



MINERALOGY 



Stibnite, Sb2S3, is the predominant ore of anti- 

 mony ; next in importance are valentinite, SbaO, ; 

 senarmontite, SbsO^; stibiconite, SboOi-HoO; bind- 

 heimite, PbaSboOr-nHaO ; and kermesite, 2Sb2S3 

 •SbaOa. Tetrahedrite, CugSbaSr, has become an im- 

 portant antimony ore, and jamesonite, PbsSbaSs, has 

 been mined from deposits at Zimapan, Hidalgo, 

 Mexico ; Candelaria, Nev. ; and the Arabia district, 

 Nevada. 



TYPES OF DEPOSITS 



Antimony occurs in a variety of deposits — epi- 

 thermal veins, pegmatites, and replacement and hot- 

 spring deposits. Deposits of antimony range in age 

 from Precambrian to Quaternary. Wang (1952, p. 

 6-10) showed a rather complex classification of 

 worldwide antimony deposits; White (1951; 1962) 

 classified world deposits into two types, with grada- 

 tions between these types; one of these is miner- 

 alogically and structurally simple and the other 

 complex. 



Simple antimony deposits consist principally of 

 stibnite, or rarely, native antimony in a siliceous 

 gangue, commonly with some pyrite and in places 

 a little gold and small amounts of other metal sul- 

 fides, principally silver and mercury. The "manto" 

 deposits of Mexico are of the simple type and con- 

 sist of selective replacements of favorable limestone 

 beds, generally overlain by shale. Most stibnite of 

 the hypogene deposits is oxidized to one or more 

 of the antimony oxides. Most deposits of Mexico, 

 Bolivia, Peru, China, Republic of South Africa, 

 Yugoslavia, Algeria, Hungary, Czechoslovakia, 

 Italy, and Japan are of the simple type. 



Complex antimony deposits consist of stibnite 

 associated with pyrite, arsenopyrite, cinnabar, or 

 scheelite or of antimony sulfosalts with varying 

 amounts of copper, lead, and silver as well as the 

 common sulfides of these metals and zinc. Ores of 

 the complex deposits generally are mined primarily 

 for lead, gold, silver, zinc, or tungsten. Most of the 

 antimony produced in the United States, Australia, 

 and Canada is from complex deposits. 



Neither the simple antimony deposits nor the 

 complex ones can be said to have affinity for a spe- 

 cific rock type, U.S. deposits range in age from Pre- 

 cambrian to Tertiary (White, 1962). Although many 

 U.S. deposits are of Tertiary age, equally as many 

 are of Mesozoic age, and about one-fifth of the de- 

 posits are of Paleozoic age. Deposits closely asso- 



