Talnakhite Associated with Andradite Skarn at Fuka, Okayama Prefecture, Japan
| Accession number;03A0780449 |
| Title;Talnakhite Associated with Andradite Skarn at Fuka, Okayama Prefecture, Japan |
| Author;TAKECHI Y(Kurashiki Museum Of Natural History, Kurashiki, Jpn) KUSACHI I(Okayama Univ., Okayama, Jpn) NAKAMUTA Y(Kyushu Univ., Fukuoka, Jpn) KASE K(Okayama Univ., Okayama, Jpn) |
Journal Title;Resour Geol
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Journal Code:G0131A
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ISSN:1344-1698
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VOL.53;NO.3;PAGE.227-232(2003)
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| Figure&Table&Reference;FIG.5, TBL.2, REF.12 |
| Pub. Country;Japan |
| Language;English |
| Abstract;Talnakhite occurs in an andradite skarn forming adjacent to a leucocratic quartz monzonite dike intruded into limestone at Fuka. The mineral densely contains exsolution lamellae of chalcopyrite, and the talnakhite-chalcopyrite intergrowth is intimately associated with bornite that contains chalcopyrite as a lattice-form exsolution. The chemical composition of the talnakhite acquired on an electron probe microanalyzer corresponds to Cu9.00Fe8.08S15.92, very close to the ideal chemical formula Cu9Fe8S16. Nickel is not detected. The X-ray powder diffraction lines are well indexed on a body-centered cubic cell with a=10.589.ANGS.. The characteristic (110) reflection of talnakhite is clearly observed at 7.49.ANGS.. The present talnakhite retains the chalcopyrite-like colored polished surface without tarnish in air more than a month. Talnakhite at Fuka is likely to be derived from breakdown of Cu-rich intermediate solid solution (iss), which was in equilibrium with Fe-rich bornite at elevated temperatures. Talnakhite thus formed has survived the subsequent cooling processes, probably because the fZ:Z=S2 was maintained in suitable levels preventing its decomposition into bornite and chalcopyite. (author abst.) |
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