Megacryst

thumb|Megacrystic porphyroblasts in metasomatised Quartenschiefer (metapelitic unit in the Alps) In geology, a '''megacryst''' is a crystal or grain that is considerably larger than the encircling matrix. They are found in igneous and metamorphic rocks.<ref>{{cite web|url=http://www.memphisgeology.org/glossary_ln.htm|title=Glossary of terms|accessdate=29 December 2009|publisher=Memphis Archaeological and Geological Society|date=7 April 2006}}</ref> Megacrysts can be further classified based on the nature of their origin, either as:<ref>Chapman, Carleton A. (2014). Phenocryst. In AccessScience. McGraw-Hill Education. https://doi.org/10.1036/1097-8542.506500</ref> *Phenocrysts, which crystallize in molten rock material (lava or magma) and are hence an earlier crystallization than the matrix in which they are embedded *Porphyroblasts, which develop in solid rock as the result of metamorphism or metasomatism

==See also== *Xenolith, an inclusion of one rock type in another

== References == {{reflist}}

== Notes == *[https://web.archive.org/web/20140808163939/https://gsa.confex.com/gsa/2006CD/finalprogram/abstract_104575.htm Significance of k-feldspar megacryst size and distribution in the tuolumne intrusive suite, California]

Category:Petrology {{Petrology-stub}}