Abstract
Torai “Roseki” clay, in spite of the low refractoriness, is favoured for industrial uses, due to its special characteristics, and has been pretty much imported as one of the refractory raw materials for firebrick of iron furnaces. The dominant mines under working are Shokiri and Rinkiri in Tesuba-men, Torai-gun, Keisho-nan-do. The clay deposits are of hydrothermal origin and assume bedded form, which is roughly conformable to the sedimentary beds of tuffs, breccia-tuffs, sandstones and shales of Mesozoic age. The clay in principally composed of sericite flakes annexed by quartz grains, and contains little pyrophyllite. Occassionally, kaolin minerals, andalusite and dumortierite are accompanied. As the impurities, pyrite, tourmaline and chlorite are common, and their relative abundance in the clay specify its quality. The clays of the mentioned two mines are somewhat different from each other with many common charactcristics.
