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Any igneous rock of simple composition, such as granite composed only of alkali feldspar, muscovite mica, and quartz; in a more restricted sense, uniformly fine-grained (less than 0.08 in., or 2 mm), light-coloured igneous rocks that have a characteristic granular texture. Unlike pegmatite, which is similar but much coarser-grained, aplite occurs in small bodies that rarely contain zones of different minerals. The two rocks may occur together and are assumed to have formed at the same time from similar magmas.
Variants of APLITE
aplite or haplite
This entry comes from Encyclopædia Britannica Concise. For the full entry on aplite, visit Britannica.com.