Skip to Main Content
Skip Nav Destination

Relationships between microstructure and composition in enargite and luzonite

Mihaly Posfai and Peter R. Buseck
Relationships between microstructure and composition in enargite and luzonite
American Mineralogist (April 1998) 83 (3-4): 373-382


Cu (sub 3) (As,Sb)S (sub 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.

ISSN: 0003-004X
EISSN: 1945-3027
Serial Title: American Mineralogist
Serial Volume: 83
Serial Issue: 3-4
Title: Relationships between microstructure and composition in enargite and luzonite
Affiliation: Arizona State University, Department of Geology and Chemistry, Tempe, AZ, United States
Pages: 373-382
Published: 199804
Text Language: English
Publisher: Mineralogical Society of America, Washington, DC, United States
References: 22
Accession Number: 1998-031625
Categories: Mineralogy of non-silicates
Document Type: Serial
Bibliographic Level: Analytic
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2018, American Geosciences Institute.
Update Code: 199812
Close Modal

or Create an Account

Close Modal
Close Modal