Publisher © Czech Geological Survey, ISSN: 2336-5757 (online), 0514-8057 (print)
Analcimized leucites and Ti-phlogopite from Doupovské hory Mts.
Abstract
Basaltoids, formerly named as leucitites, have commonly their original leucite altered to analcime. The analcimization is confirmed by a large number of microprobe analyses. The original leucite had lost potassium that was replaced by sodium and water. Any other way of leucite decomposition (pseudoleucites, epileucites) was not observed. In some rocks containing analcimized leucite, the phlogopite crystallized as a late magmatic phase; this is indicated by relations to older minerals (clinopyroxene, nepheline) and by crystallization in cavities. The chemical composition of these phlogopites is unusual. The phlogopite is rich in Ti (over 13 wt per cent) so that Ti enters the tetrahedral position.
