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Title: Cadmium in zinc deposits: Economic geology of a polluting element

Abstract

The chief host of cadmium in zinc deposits is sphalerite, the cadmium content of which depends on the type of deposit. Sphalerite from Mississippi Valley-type (MVT) deposits has high cadmium concentrations whereas sphalerite from exhalative deposits has low cadmium concentrations. The Cd content of sphalerite depends on the Cd/Zn ratio, ligand activities, and temperature of the ore-forming fluids. The combined effect of variation of temperature, pH, total activity of reduced sulfur, and activity of Cl{sup {minus}} cannot by itself account for either Cd depletion (exhalative deposits) or Cd enrichment (MVT deposits). Variations in the Cd/Zn ratio of the fluid have a significant effect in determining that of sphalerite. Basinal brines, which can be considered to be the recent equivalents of MVT fluids, have high Cd/Zn ratios, and active exhalative systems are characterized by low Cd/Zn ratios. Probably the differences in sphalerite composition between the different deposit types are less a function of temperature and ligand activities than Cd/Zn ratio of the ore-forming fluids. In the hydrothermal environment, the Cd/Zn ratio is generally not high enough to allow crystallization of cadmium sulfides (greenockite or hawleyite). The abundance of greenockite in the supergene alteration zone of hydrothermal zinc deposits can be explainedmore » on the basis of Zn scavenging by crystallizing smithsonite.« less

Authors:
Publication Date:
Research Org.:
Bundesanstalt fuer Geowissenschaften und Rohstoffe, Hannover (DE)
OSTI Identifier:
20076058
Resource Type:
Journal Article
Journal Name:
International Geology Review
Additional Journal Information:
Journal Volume: 42; Journal Issue: 5; Other Information: PBD: May 2000; Journal ID: ISSN 0020-6814
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; 54 ENVIRONMENTAL SCIENCES; 58 GEOSCIENCES; ZINC ORES; CADMIUM; ECOLOGICAL CONCENTRATION; SULFIDE MINERALS; GEOLOGIC HISTORY; MINERAL INDUSTRY; ECONOMICS; WASTE MANAGEMENT

Citation Formats

Schwartz, M.O. Cadmium in zinc deposits: Economic geology of a polluting element. United States: N. p., 2000. Web. doi:10.1080/00206810009465091.
Schwartz, M.O. Cadmium in zinc deposits: Economic geology of a polluting element. United States. doi:10.1080/00206810009465091.
Schwartz, M.O. Mon . "Cadmium in zinc deposits: Economic geology of a polluting element". United States. doi:10.1080/00206810009465091.
@article{osti_20076058,
title = {Cadmium in zinc deposits: Economic geology of a polluting element},
author = {Schwartz, M.O.},
abstractNote = {The chief host of cadmium in zinc deposits is sphalerite, the cadmium content of which depends on the type of deposit. Sphalerite from Mississippi Valley-type (MVT) deposits has high cadmium concentrations whereas sphalerite from exhalative deposits has low cadmium concentrations. The Cd content of sphalerite depends on the Cd/Zn ratio, ligand activities, and temperature of the ore-forming fluids. The combined effect of variation of temperature, pH, total activity of reduced sulfur, and activity of Cl{sup {minus}} cannot by itself account for either Cd depletion (exhalative deposits) or Cd enrichment (MVT deposits). Variations in the Cd/Zn ratio of the fluid have a significant effect in determining that of sphalerite. Basinal brines, which can be considered to be the recent equivalents of MVT fluids, have high Cd/Zn ratios, and active exhalative systems are characterized by low Cd/Zn ratios. Probably the differences in sphalerite composition between the different deposit types are less a function of temperature and ligand activities than Cd/Zn ratio of the ore-forming fluids. In the hydrothermal environment, the Cd/Zn ratio is generally not high enough to allow crystallization of cadmium sulfides (greenockite or hawleyite). The abundance of greenockite in the supergene alteration zone of hydrothermal zinc deposits can be explained on the basis of Zn scavenging by crystallizing smithsonite.},
doi = {10.1080/00206810009465091},
journal = {International Geology Review},
issn = {0020-6814},
number = 5,
volume = 42,
place = {United States},
year = {2000},
month = {5}
}