"Compositional zoning and ""chalcopyrite disease"" in sphalerite contained in the Pb-Zn-quartzcalcite ore from the Mozumi deposit of the Kamioka mine, Gifu Prefecture"

Abstract

Sphalerite contained in the Pb-Zn-quartz-calcite ore ("Shiroji-ore") from the Mozumi deposit of the Kamioka mine exhibits complex compositional zoning and includes both chalcopyrite dots and "chalcopyrite disease". The results of microscopic observation and EPMA analysis suggest that the compositional zoning and chalcopyrite dots and "disease" in sphalerite are replacement products by later hydrothermal solution after the crystallization of primary Fe-poor sphalerite. The inferred processes are as follows: (1) Fe enrichment to the margins and along the cracks of the Fe-poor sphalerite by Fe-rich solution. (2) Formation of chalcopyrite dots in the Fe-enriched sphalerite formed at the stage (1) and Fe reduction of sphalerite near the chalcopyrite dots by Cu-bearing solution. (3) Formation of "chalcopyrite disease" penetrating the compositional zoning of sphalerite.