藍晶石, 紅柱石および珪線石の劈開面における平均荷電量と等電点に対する結晶化学的考察

アルミニウム珪酸塩鉱物の結晶構造が界面現象に及ぼす影響 (第2報)

抄録

To study the correlation between the characteristics of fracture surface and the electrochemical properties of aluminum-silicate minerals, cleavage planes of kyanite, andalusite and sillimanite have been predicted from crystal structures of these minerals, and then the arrangement of atoms exposed to the surfaces along these ckavage planes have been assumed.
The electrochemical phenomena of these minerals in the solid-solution interface are discussed with respect to the weighted average charge per metallic atom on the assumed cleavage planes. The weighted average charge has been calculated as a function of oxidation number of the metals and number of oxygen atoms coordinated to these metallic atoms.
It is found that the pH of the isoelectric point of kyanite, andalusite and sillimanite decreases as the weighted average charge increases. Together with the above three minerals, corundum and quartz are found to be in good linear relation between the pH of the isoelectric point and the weighted average charge, indicating that the arrangement of metallic atoms on the fracture surface of minerals plays an important role upon their surface properties.
The effect of surface oxygen atoms on the pH of the isoelectric point of minerals is also discussed briefly.