Abstract
The 3R-type modification of molybdenite was found as the first occurrence in Japan by means of X-ray powder diffraction method. Three examples are described here: (1) products of fumarolic activity on the Satsuma-Iwo-jima, southern Kyushu, (2) samples in high temperature hydrothermal wolframite-bearing quartz veins of the Yamate (Shitekurayama) mine, Okayama Prefecture, and (3) those in contact metasomatic molybdenum deposits of the Okawame mine, Iwate Prefecture. All the specimens examined are admixture of the 3R and 2H1 polytypes with varying ratios.
