Interstratified Mineral of Illite and Montmorillonite

Abstract

A YELLOWISH-GREY tuff, about 1 m thick, is distributed over a considerable area of the Sorachi coal field, Hokkaido, Japan1, as a member of the Noborikawa coal-bearing formation. The tuff contains a small amount of quartz and plant fragments, but is generally homogeneous. Having dispersed some of the material in water, the minus-two-micron fractions of the tuff were separated by the sedimentation method; Fig. 1 shows its electron micrograph. The X-ray powder patterns and data on the well-oriented specimens are shown in Fig. 2 and Table 1. The specimens were dried in air, heated at 150° C, 300° C, 450° C, 600° C, 750° C, for 1 h, and treated with ethylene glycol, glycerol and ammonium nitrate. The chemical compositions and differential thermal analysis curves of both natural and piperidine-treated specimens are shown in Table 2 and Fig. 3.