Megacryst
![](http://upload.wikimedia.org/wikipedia/commons/thumb/6/63/AmphiboleMegacrystsQuartenschiefer.jpg/220px-AmphiboleMegacrystsQuartenschiefer.jpg)
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
See also
- Xenolith, an inclusion of one rock type in another
References
Notes
- Significance of k-feldspar megacryst size and distribution in the tuolumne intrusive suite, California
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