Studies of the geochemistry of the semimetal elements: Arsenic, antimony, and bismuth
Abstract
Three studies concerning the geochemistry of the semimetal elements: arsenic, antimony, and bismuth, were done to better understand ore-forming processes. The scope of these studies varied from regional distributions of the elements to small scale changes in mineral compositions. Regional distribution of the semimetal elements, measured by presence as discrete mineral phases, in the southwestern United States reveals areas of concentration of one semimetal element over another. In regions underlain by Precambrian contintental crust, bismuth minerals are fairly common. In regions of accreted terranes and absence of contintental crust, antimony is the dominant semimetal element while bismuth minerals are absent. Arsenic is distributed uniformly except where it is the exclusive semimetal element in deposits formed in high crustal, low heat flow regions. The differential distribution of these elements appears to be a function of lithochemical reservoirs and fluxes of the elements. The bismuthinite-stibnite solid solution was found to be complete, contrary to previous studies, in samples from the Julcani district, Peru. The compositions of the solid solution also vary along with metal ratios. Bismuthinite compositions become more antimony-rich down the hydrothermal flow path. Gaps in the natural solid solution, noted by other workers, can be explained by: (1) an intervening or peritectic reaction occurring as other cation activities of the solutions increase, or (2) the bismuthinite-stibnite solid solution has variable solubility along the composition range (i.e. intermediate compositions are more soluble) and behave as a type 2 Roozeboom solid solution. The coupled substitution of silver and bismuth or antimony into galena was observed in the Organ district. However, the systematics of the substitution could not be fully determined. Variation of the Ag-Bi and Ag-Sb substitutions appears as a weak function of temperature. However, some other parameter, untested, appears to be responsible for the linear variation of concentrations of Bi/Sb in galena observed during the study. Metal zoning in the Organ district was also reinterpreted with respect to a newly discovered type of mineralization: a hot spring quartz-tellurium system.
Subject Area
Geochemistry
Recommended Citation
Lueth, Virgil Walter, "Studies of the geochemistry of the semimetal elements: Arsenic, antimony, and bismuth" (1988). ETD Collection for University of Texas, El Paso. AAI8911142.
https://scholarworks.utep.edu/dissertations/AAI8911142