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Relationships between microstructure and composition in enargite and luzonite |
Tartalom: | http://real.mtak.hu/3428/ |
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Archívum: | MTA Könyvtár |
Gyűjtemény: |
Status = Published
Type = Article |
Cím: |
Relationships between microstructure and composition in enargite and luzonite
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Létrehozó: |
Pósfai, Mihály
Buseck, Peter R.
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Kiadó: |
Mineralogical Society of America
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Dátum: |
1998-03
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Téma: |
QD06 Mineralogy / ásványtan
QE Geology / földtudományok
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Tartalmi leírás: |
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.
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Típus: |
Article
PeerReviewed
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Formátum: |
application/pdf
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Azonosító: |
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
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Kapcsolat: |