Abstract
Chlorites formed in metabasites have been studied using XRD, EPMA, and HRTEM. There is a correlation between the number of Si cation and Ca+Na+K content and/or the octahedral vacancy and the Ca+Na+K content, indicating that the chlorites can be regarded as chlorite/smectite mixed-layer minerals. In most chlorites, the Ca+Na+K content is less than 0.10 (O = 28). When the EPMA analyses and HRTEM observations of the chlorites are quantitatively compared, the theoretically estimated smectite component ratio and actual smectite component ratio in the chlorites are mutually in agreement. In some chlorites, the Ca+Na+K content ranges from 0.10 to 0.63. It is impossible to interpret the origin of Ca, Na, and K cations only from smectite layers stacked in chlorite. In some chlorites, it is concluded that Ca, Na, and K cations are ascribed to not only smectite layers stacked in the chlorites but also the fine-grained smectite and corrensite.
