Repository of the Academy's Library

Relationships between microstructure and composition in enargite and luzonite

Pósfai, Mihály and Buseck, Peter R. (1998) Relationships between microstructure and composition in enargite and luzonite. American Mineralogist, 83 (3-4). pp. 373-382. ISSN 0003-004X

[img] PDF
1039018.pdf
Restricted to Registered users only

Download (916Kb) | Request a copy

Abstract

Cu-3(As,Sb)S-4 minerals commonly contain structurally disordered crystals of intergrown enargite and the luzonite-famatinite series (Posfai and Sundberg 1998). Here we discuss the relationships between the fine-scale structural variations and the Sb/As ratios of these minerals. Although luzonite typically contains more Sb than enargite, individual layers of luzonite within Sb-bearing enargite are not associated with higher Sb/As ratios. Defect-free enargite can also contain Sb. We develop a ``structure-composition'' diagram in which both the structural enargite-luzonite and the compositional luzonite-famatinite solid solutions can be represented. Compositions plotted in this diagram reveal that Sb-bearing enargite and luzonite contain only a relatively small number of defects, whereas Sb-free crystals can be heavily disordered. Coexisting enargite and famatinite and zoning in luzonite-famatinite indicate fluctuations in the Sb-content of the fluid during ore deposition. On the other hand, assemblages of Sb-free enargite and luzonite probably reflect thermal oscillations; heavily disordered, intermediate structures may have formed near the transition temperature of low-temperature luzonite to high-temperature enargite. Our results suggest that characteristic microstructures in enargite, luzonite, and famatinite can be useful for constraining fluid composition and temperature during ore deposition.

Item Type: Article
Subjects: Q Science / természettudomány > QD Chemistry / kémia > QD06 Mineralogy / ásványtan
Q Science / természettudomány > QE Geology / földtudományok
Depositing User: Erika Bilicsi
Date Deposited: 22 Nov 2012 17:26
Last Modified: 22 Nov 2012 17:26
URI: http://real.mtak.hu/id/eprint/3428

Actions (login required)

View Item View Item