Megacryst
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.[1] Megacrysts can be further classified based on the nature of their origin, either as:[2]
- 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
Megacrystic porphyroblasts in metasomatised Quartenschiefer (metapelitic unit in the Alps)
See also
- Xenolith, an inclusion of one rock type in another
References
- "Glossary of terms". Memphis Archaeological and Geological Society. 7 April 2006. Retrieved 29 December 2009.
- Chapman, Carleton A. (2014). Phenocryst. In AccessScience. McGraw-Hill Education. https://doi.org/10.1036/1097-8542.506500
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