A New Compound of the (K,Na)3Ca8Si6[Si4O12]3 Charoite Substrate

Resumo

As a result of experimental studies on the interaction between a charoite substrate and host lamprophyres of microcline-arfvedsonitic composition, a new (K,Na)₃Ca₈Si₆[Si₄O₁₂]₃ compound has been obtained with a new type of radical Si₂[Si₄O₁₂] found in its crystalline structure а = 15.2613 (3) Ǻ, I2/₁3, Z = 4. The chain-shaped Ca-octahedra connected through common faces encircle a radical and close in a K-octagon. In contrast to charoite with banded-tube radicals, an isometrically-island silicon radical is identified.