抄録
Hunyu clay from Hunyu, Tochigi Prefecture was investigated mineralogically. X-rayanalysis shows the clay to be a regularly interstratified micasmectite mineral. It gives the basal reflection at 25Å, and its higher orders. After treated with ethylene glycol, glycerol and water, the 25Å basal spacing changes to 26.6, 27.4 and 28.4Å respectively. Chemical composition is analysed as SiO2 46.62%, TiO2 0.20%, Al2O3 33.32%, Fe2O3 0.76%, CaO 1.81%, MgO 0.27%, K2O 2.22%, Na2O 1.92%, H2O (-) 7.30% and H2O (+) 6.37%. The composition is close to that of rectorite. IR spectrum in the OH region shows two absorption bands at 3640 and 3400 cm-1. The band at 3400 cm-1 almost disappears at 500°C. The 3640 cm-1 band weakens at 600°C and weak shoulders appear at 3680 and 3630 cm-1. The specimen heated at 800°C shows two weak absorp-tion bands at 3650 and 3470 cm-1 and they change to 3640 and 3440 cm-1 keeping in air for a week.
