leucitite

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leucitite An extrusive, undersaturated (see SILICA SATURATION), mafic igneous rock consisting of essential leucite and augite, with accessory iron oxide and apatite. When olivine or nepheline are also present, the rock is termed an olivineleucitite or a nepheline-leucitite respectively. Leucitites are allied to phonolites, with which they are commonly associated in the field.