南薩型珪化岩鉱床に伴うスド : アイトとトスダイト

概要

論文の詳細を見る
Sudoite and tosudite were found in hydrothermal alteration aureole of Nansatsu-type silicified rock deposit in the Makurazaki area, Kagoshima Prefecture, Japan. The d(060) values of the sudoite and tosudite are 1.508 and 1.506A, respectively. The structural formula of the sudoite is (Al_<2.08> Mg_<2.56> Fe^<3+>_<0.40> Ti_<0.06> Li_<0.02> K_<0.04> Na_<0.02>)(OH)_<12> A1_<4.00>(Si_7.08> Al_<0.92>)O_<20>(OH)_4,and that of the tosudite is (Al_<1.26> Mg_<1.60> Fe^<3+>_<0.11> Ti_<0.01> Li_<0.01> Mn_<0.01> K_<0.17> Na_<0.03>)(OH)_6 A1_<4.00>(Si_<6.46> Al1.54)O_<20>(OH)_4. These specimens are characterized by relatively large amounts of Mg and very small amounts of Li. The basal spacing of tosudite is 29.77A under 50% relative humidity, and it changed to 31.37A after ethylene glycol solvation and to 23.74A after heating at 500℃ for 1 hr. The basal spacing of Mg-saturated tosudite sample expanded to 31.41 and 32.17A after ethylene glycol and glycerol solvation, respectively. However, K-saturated sample showed resistivity against the expansion by these treatments. Based on statistic analysis of chemical composition, a positive relationship was recognized between the number of tetrahedral Al and that of octahedral Mg. The result suggests that the small expansion ability of K-saturated present tosudite sample may be attributable to higher negative charge of the tetrahedral sheets.
日本粘土学会の論文
1991-05-20