Page:Brinkley - Japan - Volume 8.djvu/85



The Tsuji-tsuchi is a dull, white, coarse-grained, and coherent mass, not unlike chalk, but harder and much tougher. It is slightly adhesive; is composed of small granules which have a distinct but dull lustre, and, though apparently homogeneous, is not really so. In its pulverized form it fuses easily, but in the mass resists a very high temperature.

The Shiro-tsuchi is finer, tougher, and harder than the Tsuji-tsuchi, which in other respects it closely resembles. It contains some small, dark-coloured spots which under the microscope are found to be remnants of pyrite crystals. It appears dull to the naked eye, but under the lens the granulæ composing it are found to have a distinct lustre, almost equal to that seen on the surface of a porcelain fracture. It is much more fusible than the Tsuji-tsuchi.

The Sakaime-tsuchi is scarcely distinguishable from the Shiro-tsuchi, except that it is somewhat softer and coarser.

The Uwa-gusuri-tsuchi (which, as its name indicates, is used for glazing purposes) resembles the preceding varieties, but is much softer, more adhesive, and has many dark spots caused by the presence of pyrites.

The Indo-tsuchi is coarse-grained, and of uneven colour; some parts being white, while others are darkened by the presence of limonite. It is composed of soft and hard particles, the latter resembling undecomposed felspar. When heated its granulæ change to black and then to white, while the vapour given off shows acid reaction, probably due to the presence of sulphuric acid.