“凤凰石”的成分特征及其形成的蚀变作用

Composition Characteristics and Alteration of “Fenghuangite”

通过扫描电镜研究和电子探针分析 ,证明赛马碱性岩体中的“凤凰石”为Ca RE Th的硅酸盐固溶体 ,其化学通式为A1 0 (BO4) 6 X2 ,A位的主要成分为稀土元素 (RE) ,属富钍铈硅磷灰石。样品为点式带状和连续带状蚀变结构 ,意味着矿物经历了不同程度的原生蚀变作用 ,同时Si和Th含量增加。由于变晶化作用和风化作用 。

Fenghuangite” from the Saima alkali complex, Liaoning Province, China, was studied by scanning electron microscopy and electron microprobe analyses. It indicates that “Fenghuangite” is a silicate solid solution of Ca RE Th. Rare earths as the main component occupy the A site, and the mineral can be identified as Th rich britholite (Ce). The spotted zoning texture and the continuous zoning texture imply that the mineral undergo various degrees of the early primary alteration with increasing of Si and Th. The later metamictization and weathering processes lead to increasing of hydration and decreasing of the A site cations.