As to the geology of Hirose Mine and its environs, Nichinan Town, Tottori Pref., some notes by the writer have been described in the Journal of Mineralogists, Petrologists, and Economic geologists, in the Science Report of Shimane University, etc.. In the ultrabasic rock in that district, there are frequent occurrences of gabbro- and dioritedykes, the parent magma of which is supposed to be different from that of the former, which is a derivative from the peridotite magma, generated from the peridotite mantle, whereas the latter is the derivatives from the magma from the eclogite mantle.
Hirose Mine is well known, together with Wakamatsu Mine in the same prefecture and Takase Mine in Okayama Pref., for the rich production of chromite ore contained in the ultrabasic rock (serpentinite), and from these mines are also produced, occasionally, some minerals of special interest. Here a description will be made on the prehnite and tourmaline (dravite) from Hirose Mine.