BISMUTH 



97 



I 



Bismuth, therefore, becomes concentrated in the 

 hydrolyzates. Although the biological role is un- 

 known, bismuth is known to occur in some marine 

 organisms (Rankama and Bahama, 1950). 

 BISMUTH ORES 

 Most bismuth produced in the United States is 

 a byproduct of lead refineries which treat crude 

 bullion, flue dust, and other metallurgical products. 

 The bismuth content of ores and concentrates is 

 generally so low that it is not reported in assays, 

 even from mines known to be relatively rich in 

 bismuth; thus the primary sources of bismuth are 

 known only in a general way (Cooper, 1962). 



MAJOR SOURCES 



Hypogene deposits in the Western United States 

 account for most of the domestic bismuth produc- 

 tion. These deposits generally formed at high to 

 medium temperatures, commonly within or near 

 intrusive igneous rocks. A few small pockets of 

 bismuth ore have been mined from pegmatite dikes, 

 quartz veins, and contact-metamorphic deposits, but 

 most of the bismuth occurs as a minor constituent 

 of ores of silver, lead, zinc, copper, gold, tungsten, 

 and molybdenum. Lead and lead-zinc ores that are 

 high in bismuth also tend to be high in silver, gold, 

 and commonly copper. A distinct association of bis- 

 muth with silver is apparent in some mines. 



Lead-zinc-silver replacement deposits in limestone 

 have probably been the most important sources of 

 bismuth in the United States. Deposits of this type 

 occur at Leadville and Oilman, Colo. ; Tintic and 

 Little Cottonwood, Utah ; Darwin, Calif. ; and Pata- 

 gonia, Ariz. In these deposits the bismuth occurs 

 in the oxidized as well as in the sulfide ores. Pri- 

 mary bismuth minerals, where known, include bis- 

 muth sulfosalts of lead, silver, and copper, bismuth- 

 inite, and native bismuth. 



Complex lead-copper-silver-bismuth ores have 

 been mined in the Red Mountain, Poughkeepsie 

 Gulch, Upper Uncompahgre, Mineral Point, Engi- 

 neer Mountain, and Lake City districts in the San 

 Juan Mountains, Colo., and also in the Montezuma 

 district in the Front Range, Colo. The ore bodies 

 are small, but some are very rich in bismuth and 

 precious metals. 



In the Coeur d'Alene district, Idaho, bismuth in 

 recoverable amounts has been reported from the 

 Sunshine mine and certain other mines in the 

 "Silver Belt." Gold-bismuth ores are reported from 

 gold deposits in Riverside County, Calif., and Grant 

 County, N. Mex. Relatively abundant bismuth min- 

 erals are reported in complex gold ores of the Boise 

 Basin district, Idaho ; the Goldfield and Yellow Pine 



districts, Nevada; and the Argenta and Elkhorn 

 districts, Montana. Lead and zinc ores and concen- 

 trates from deposits of the Mississippi Valley type 

 contain no detectable bismuth. 



MINOR OCCURRENCES 



Bismuth minerals, generally in very minor quan- 

 tities, have been reported in many gold-quartz veins 

 in the southern Piedmont gold belt, which extends 

 from northern Virginia southwestward to Alabama 

 in the southeastern part of the United States. These 

 deposits are of general interest only. 



Lead deposits from North Carolina to Maine con- 

 tain 0.05 ppm to as much as 1 percent bismuth. The 

 eastern lead deposits occur in the Appalachian 

 Mountains and on the west side of the Adirondack 

 Mountains in New York. All the deposits are in 

 rocks that have been folded and faulted to a con- 

 siderable extent. The host rocks include Precam- 

 brian dolomite on the west side of the Adirondacks, 

 Precambrian or Cambrian schists in the districts 

 east of the Blue Ridge in North Carolina and Vir- 

 ginia, lower Paleozoic dolomites west of the Blue 

 Ridge in Tennessee and Virginia, Silurian conglom- 

 erates in southeastern New York, and both Precam- 

 brian granitic rocks and Triassic red beds and dia- 

 base in southeastern Pennsylvania. The Piedmont 

 province is composed of Precambrian and highly 

 metamorphosed Paleozoic rocks, relatively high in 

 bismuth, whereas Triassic rocks are low in bismuth 

 and high in antimony. Pegmatites in southeastern 

 Pennsylvania and in western Maine commonly carry 

 native bismuth and bismuthinite in small amounts. 



The spatial proximity of igneous intrusive rocks 

 to which the deposits can be related genetically 

 varies from district to district. Deposits in the west- 

 ern Adirondack Mountains are associated with 

 Precambrian granite intrusives, and those east of 

 the Blue Ridge occur near batholithic masses of 

 granite to which a Devonian or late Paleozoic age 

 has been ascribed. 



Native bismuth and other bismuth minerals are 

 reported in placer gold deposits at many localities 

 in Alaska and some localities in the southwestern 

 and Rocky Mountain States. Bismuth minerals are 

 said to be very abundant in the black sands in the 

 Boise Basin district, Idaho, and some other locali- 

 ties, but bismuth is not known to have been recov- 

 ered from these sources. 



Bismuth is reported to occur in uranium veins in 

 the Ralston Buttes district, Jefferson County, Colo., 

 and native bismuth and emplectite (CuBiS2) have 

 been found in some deposits. A fairly clean hand- 

 picked sample of pitchblende from the Schwartz- 



