Aplite is a medium- to fine-grained rock (average grain size usually 1.0 mm or less) with a characteristic equigranular, sugary (saccharoidal) texture. The origin of the term is uncertain, but the name may have been used as early as 1800. In 1823 it was used by von Leonhard for medium-grained granitic rocks that lack mica and are composed essentially of quartz and feldspar. The name, derived from the Greek απλóoσ, simple, alludes to this. Most early petrographers followed von Leonhardŉs usage though H. Rosenbuch widened the term to include most leucocratic dyke rocks. There are aplites corresponding in composition to many of the principal rock groups, for example, granite aplite, diorite aplite and so on. When the name is used without a prefix it is generally taken to refer to granite aplite.
The principal constituents of granite aplite are quartz and alkali feldspar (usually orthoclase, microcline, perthite, or sodic plagioclase) with minor proportions of muscovite, biotite, or...
- San Miguel, A., 1969, The aplite-pegmatite association and its petrogenetic interpretation, Lithos 2, 25–37.Google Scholar
- von Leonhard, K. C., 1823, Charakteristik der Felsarten, Vol. 1. Heidelberg: Joseph Engelmann.Google Scholar
- Wells, A. K. and A. C. Bishop, 1954, The origin of aplites, Proc. Geol. Assoc. 65, 95–114.Google Scholar