1989 Volume 39 Issue 217 Pages 305-309
Silician magnetite, recently found in chalcopyrite-pyrrhotite-cubanite ore from the Tengumori ore deposit of the Kamaishi mine, northeastern Japan (SHIGA, 1988), was further studied. Microprobe analyses of the mineral give 4.72 to 6.19 weight percent SiO2 and a probable ideal formula Fe2+(Fe3+/1.6 Si0.2Fe2+/0.2)O4. The mineral is frequently in direct contact with normal magnetite having SiO2 content less than 0.1 weight percent, suggesting a com-positional gap between them. The mineral was formed under reducing condition at a temperature approximate to 300°C, simultaneously with the associated normal magnetite and sulfides.
