11. Leucite lavas from which feldspar is absent are divided into the leucitites and leucite basalts.12. Leucite lavas from which feldspar is absent are divided into the leucitites and leucite basalts. 13. At Vesuvius it occurs as alterations from gypsum within leucite tephrite and as fumarole deposits. 14. This pseudo-cubic character of leucite is very similar to that of the mineral boracite. 15. They are of trachytic appearance, containing phenocysts of sanidine, leucite , augite and biotite. 16. Other minerals occurring in the rock include sanidine, andradite, fassaite, leucite and hauyne. 17. It is associated with other minerals typical of undersaturated environments, namely leucite , cancrinite and natrolite. 18. Those leucite rocks which contain abundant essential plagioclase feldspar are known as leucite tephrites and leucite basanites. 19. Those leucite rocks which contain abundant essential plagioclase feldspar are known as leucite tephrites and leucite basanites. 20. Those leucite rocks which contain abundant essential plagioclase feldspar are known as leucite tephrites and leucite basanites.
