Etch Figure Patterns of Magnetite from Skarn Deposits in Japan

Magnetites from skarn type deposits in Japan were cut, polished and etched, and etched surfaces were examined for textural types of etch figures. Various types of etched figures occur, and distinct patterns are associated with magnetites from distinct deposits. The figures are roughly classified into etch pits and zonings. The etch pits almost always appear on the polished surfaces of magnetites from several deposits. Etch pits are attributed to lattice defects or the presence of minor elements. The zoning patterns are observed in magnetites from several other deposits. The zoning patterns reflect multistage mineralization during skarn formation. For the Akaiwa deposit, zoning in magnetites are related to a shift from metasomatic to hydrothermal mineralization. These etch figures can be sensitive indicators of fluctuations of ore forming environments. Keywords; magnetite, etch figure, skarn deposit