What is a leucitite in geology ?
Leucitite : definition
A leucitite is a volcanic rock undersaturated with silica formed by automorphic crystals of leucite (of the order of 30% of the rock), in a dark paste with dominant augite (20% on average), melilite, nepheline, rare bytownite, sometimes olivine, and containing varying amounts of accessory minerals. It is an extremely rare feldspathoidite associated with tephrites and leucite basanite. Its plutonic equivalent is missourite.