58 



UNITED STATES MINERAL RESOURCES 



to as much as 2 percent and is estimated to average 

 not more than 0.2 percent. 



Examples of arsenical tin deposits include the 

 Aberfoyle mine, Australia (Connolly, 1953), the 

 Stavoren Fides tin mines, Republic of South Africa 

 (Union of South Africa Department of Mines, 

 Geology Survey, 1959), the Lost River mine, Alaska 

 (Sainsbury, 1964, p. 25), and the mines of the 

 Uncia area, BoHvia (Ahlfeld, 1931, p. 248). 



Tin and arsenical tin deposits are generally be- 

 lieved to be products of high-temperature solutions 

 charged with fluorine and boron which acted as 

 strong solvents for metals such as tin and tungsten. 

 The solutions originally constituted a part of the 

 magma, but as the magma cooled, they separated, 

 and subsequently, where fissures developed in the 

 chilled periphery of the magma body, they escaped. 

 The escaping solutions reacted with the fissure walls 

 in the chilled envelope and country rock to form 

 deposits containing fluorine and boron minerals and 

 cassiterite (Ferguson and Bateman, 1912). 



OTHER DEPOSITS 



Other types of arsenical deposits are known but 

 are not promising as signiflcant sources of arsenic. 

 The types are arsenical quartz, silver, and lead-zinc 

 deposits. 



Arsenical quartz deposits are commonly in veins 

 composed of quartz with arsenopyrite and pyrite 

 and, rarely, minor amounts of other sulfide minerals 

 and gold. The arsenical quartz veins represent an 

 early stage of a complex base- and precious-metal 

 mineralization but commonly were emplaced sepa- 

 rately from the main-stage ore. They are known in 

 orogenic belts and Precambrian terranes. They are 

 estimated to contain less than 1 percent arsenic. 



The arsenical silver deposits described in the lit- 

 erature occur in Precambrian schist in vein systems 

 as much as 1 mile long and more than 1,000 feet 

 wide. The ore includes silver sulfide and sulfosalts, 

 pyrite, arsenopyrite, and very minor amounts of 

 chalcopyrite and gold. The deposits occur in the 

 Randsburg district of Kern and San Bernardino 

 Counties, Calif. (Stewart, 1957, p. 529-530). De- 

 posits of this type may average as much as a few 

 tenths of 1 percent arsenic. 



Arsenical lead-zinc deposits are sparse and as a 

 type are best characterized by the Sullivan mine in 

 the Kootenay district of British Columbia (Scho- 

 field, 1915, p. 107-108, 131-133; Little and others, 

 1968, p. 504-505). This deposit formed by replace- 

 ment of argillitic beds in Precambrian quartzite. 

 The ore minerals are galena, sphalerite, pyrite, pyr- 

 rhotite, magnetite, cassiterite, arsenopyrite, jame- 



sonite, and boulangerite. The core of the deposit 

 is composed of pyrite and pyrrhotite. Around the 

 core is a zone relatively rich in lead, silver, tin, and 

 arsenic, and outward from it is a zone rich in zinc 

 and antimony. Deposits of this type, although large 

 producers of base metals, are not sufficiently numer- 

 ous or rich enough in arsenic to be considered a 

 significant arsenic source; they probably average 

 less than one-half percent arsenic. 



RESOURCES 



IDENTIFIED AND HYPOTHETICAL RESOURCES 



Arsenic resource estimates are based on a limited 

 amount of data. Arsenic has been or is almost en- 

 tirely obtained as a byproduct of gold, silver-nickel- 

 cobalt, copper, or copper-zinc-lead deposits. The 

 content of arsenic in such deposits is, with few ex- 

 ceptions, only generally known. The arsenic is re- 

 claimed from mill and smelter wastes, and produc- 

 tion data are available from only a few deposits. 

 Further, because arsenic is a byproduct, the esti- 

 mate of arsenic resources is in part dependent on 

 estimates of the resources of the primary commodi- 

 ties and, more importantly, on an understanding of 

 the relation of arsenic to them. 



The data base, weak for arsenic resources within 

 the United States, is even weaker for areas outside 

 the United States and is almost nonexistent for 

 countries of the Communist bloc. The resource data 

 are shown in table 9. Resources are considered more 



Table 9. — World identified and hypothetical resources of 

 arsenic, in short tons 



Identified Hypothetical 



resources ^ resources ^ 



United States 1,300.000 660,000 



North America exclusive of 



United States 600,000 300,000 



South America 3,000,000 2,700,000 



Eurasia (including insular 



areas of southeastern Asia) 10,100,000 8,460,000 



Africa 2,300,000 1,860,000 



Australia 400,000 360,000 



World total 17,600,000 14,300,000 



'Identified resources: Specific, identified mineral deposits that may or 

 may not be evaluated as to extent and grade and whose contained min- 

 erals may or may not be profitably recoverable with existing technology 

 and economic conditions. 



-Hypothetical resources: Undiscovered mineral deposits, whether of re- 

 coverable or subeconomic grade, that are geologically predictable as exist- 

 ing in known districts. 



than ample to fill the expected demands until the 

 year 2000. 



The assumptions that serve as a basis of treat- 

 ment are as follows : of the gold resources, 5 percent 

 are considered to be arsenical and to have an average 

 ratio of arsenic to gold of 2,000 : 1 ; of the resources 

 of copper and copper-zinc-lead, 15 percent are con- 

 sidered to be arsenical with a ratio of arsenic to 



