Studies op Roseki from Ugu mine, Yamaguchi-prefecture

Especially on its Mineral Composition and the Applicability for Ceramic Raw Material

Abstract

In the present paper, the results of petrographical and mineralogical observations on Roseki from Ugu mine, Nago-machi, Yamaguchi-prefecture, are described, together with some considerations on its applicability for refractory materials. The characteristic features of this mine may be summed up as follows:
1) Main clay mineral composing the Roseki is sericite, but not pyrophyllite. This fact seems to be responsible for its higher sintering power than that of normal pyrophyllitic Roseki.
2) Andalusite is so widely distributed throughout this mine that the existence was confirmed in more than half of the collected specimens. In some case, it occupies as much as 40% of the bulk. This causes its high refractoriness, in spite of its containing a considerable amount of sericite.
3) The specimens are fairly rich in non-hydrous minerals, such as andalusite, corundum, quartz, etc.. This suggests that the formation of the mine was taken place under a comparatively dry condition or at the comparatively high temperature.
4) The granularity of the sepcimens of this Roseki is, in many cases, markedly higher than those of the normal Rosekis in other districts. Especially, the diameter of the clay minerals sometimes attain up to 5mm or more.