Solubility of gold in the SiO2-NaCl-H2O system at 300°C and50 MPa |
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| Authors: | Yishan Zeng Fengzhen Wang Ruiying Ai |
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| Institution: | (1) Department of Geology, Peking University, 100871 Beijing, China |
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| Abstract: | The solubility of gold and quartz in 0.01, 0.10 and 1. 00 mol/kg NaCl solutions with various pH was determined in the presence
of the NNO oxygen buffer at 300°C and 50 MPa using a flexible gold cell hydrothermal apparatus. The Au speciation in the SiO2-NaCI-H2O system was inferred and the equilibrium constants for the following dissolution reactions were obtained: Au+H2O = AuOH0+1/2H2, logK(AuOH0) = -7.92 ± 0.25; Au+Cl-+H2O = AuOHCl-+1/2H2, logK(AuOHCl-) = - 7. 56 ± 0.65. The present study suggests that Au as AUOH0 and AuOHCl- is basically transported in ore-forming solutions under geologically realistic conditions of acidity, chloride molality and
oxygen fugacity. The reason for the common association of Au with SiO2 in hydrothermal gold deposits is discussed.
Project supported hy the National Natural Science Foundation of China. |
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| Keywords: | gold quartz NaCl hydrothermal solution solubility speciation |
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