Hostname: page-component-78c5997874-s2hrs Total loading time: 0 Render date: 2024-11-08T05:23:18.835Z Has data issue: false hasContentIssue false
  • English
  • Français

Arsenic-silver incompatibility in fahlore

Published online by Cambridge University Press:  05 July 2018

Denton S. Ebel  and
Richard O. Sack
Denton S. Ebel
Affiliation:
Department of Earth and Atmospheric Science, Purdue University, West Lafayette, Indiana, U.S.A. 47907
Richard O. Sack
Affiliation:
Department of Earth and Atmospheric Science, Purdue University, West Lafayette, Indiana, U.S.A. 47907
Get access Rights & Permissions [Opens in a new window]

Abstract

Silver-bearing zinc-iron tetrahedrite-tennantite and freibergit fahlores approximating the simplified formula (Ag,Cu)10(Fe,Zn)2(As,Sb)4S13 have been equilibrated with excess electrum (AuxAg1−x) and chalcopyrite + pyrite + iron-bearing sphalerite (CuFeS2 + FeS2 + Fe0.05Zn0.95S) in evacuated silica tubes at 300 °C, in reversed silver-copper exchange experiments with less than 0.1 mg NH4Cl added as a transport medium. A thermodynamic formulation and parameters describing As-Ag incompatibility at 400 °C (Ebel and Sack, 1989), which incorporate large temperature dependencies of standard-state properties and composition-ordering systematics, are shown to apply equally well to these 300 °C results. A generalised graphical model for this mineral assemblage is presented, describing fahlore composition as a function of temperature and the compositions of coexisting electrum and (Fe,Zn)S, which define the Ag(Cu)−1 and Fe(Zn)−1 exchange properties controlling fahlore compositions.

Keywords

tetrahedritethermodynamicsfahloresilversulphosaltgeothermometerelectrum
Type
Mineralogy
Information
Mineralogical Magazine , Volume 55 , Issue 381 , December 1991 , pp. 521 - 528
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1991

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Barton, M. D. (1980) Econ. Geol., 75, 303–16.CrossRefGoogle Scholar
Barton, P. B. Jr. and Skinner, B. J. (1979) In Geochemistry of Hydrothermal Ore Deposits, 2nd ed. (H. L. Barnes, ed.), J. Wiley and Sons, 404-60.Google Scholar
Ebel, D. S. and Sack, R. O. (1989) Geochim. Cosmochim. Acta, 53, 2301-9.CrossRefGoogle Scholar
Hall, H. T. (1967) Am. Mineral., 52, 1311-21.Google Scholar
Hultgren, R., Orr, R. L., Anderson, P. D., and Kelley, K. K. (1963) Selected Values of Thermodynamic Properties of Metals and Alloys, J. Wiley and Sons.Google Scholar
Ghiorso, M. S. (1990) Am. Mineral., 75, 539-43.Google Scholar
Makovicky, E. and Skinner, B. J. (1979) Can. Mineral., 17, 619-34.Google Scholar
O'Leary, M. J. and Sack, R. O. (1987) Contrib. Mineral. Petrol., 96, 415-25.CrossRefGoogle Scholar
Paar, Von W. H., Chert, T. T., and Gunther, W. (1978) Carinthia II, 168, 35–42.Google Scholar
Raabe, K. C. and Sack, R. O. (1984) Can. Mineral., 22, 577-82.Google Scholar
Ramdohr, P. (1969) The Ore Minerals and their Intergrowths, Pergamon, New York.Google Scholar
Sack, R. O. (1982) Contrib. Mineral. Petrol., 79, 169-82.CrossRefGoogle Scholar
Sack, R. O. (1991) In Stability of Minerals (N. L. Ross and G. D. Price, eds), Harper-Collins Academic (in press).Google Scholar
Sack, R. O. and Loucks, R. R. (1985) Am. Mineral., 70, 1270-89.Google Scholar
Sack, R. O. and Ebel, D. S., and O'Leary, M. J. (1987) In Chemical Transport in Metasomatic Processes (H. C. Helgeson, ed.), D. Reidel, 701-31.CrossRefGoogle Scholar
Spiridonov, E. M. (1984) Dokl. Akad. Nauk SSSR, 279, 166-72.Google Scholar
Yui, S. (1971) Society of Mining Geologists of Japan Special Issue, vol. 2, Proceedings of IMA-IAGOD Meeting (1970), Joint Symposium Volume, 22-9.Google Scholar