A phanerite[1] is an igneous rock whose microstructure is made up of crystals large enough to be distinguished with the unaided human eye. In contrast, the crystals in an aphanitic rock are too fine-grained to be identifiable. Phaneritic texture forms when magma deep underground in the plutonic environment cools slowly, giving the crystals time to grow.

Close-up of granite, a phanerite rock, from Yosemite National Park in California, U.S.
Phaneritic diorite from Massachusetts

Phanerites are often described as coarse-grained or macroscopically crystalline.

References Edit

  1. ^ Monroe, James Stewart; Wicander, Reed; Hazlett, Richard W. (2007). "4". In Dodson, Keith (ed.). Physical Geology: Exploring the Earth. Earth Sciences (6 ed.). USA: Thompson Brooks/Cole. p. 115. ISBN 0495011487.