Megacryst Explained

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

Notes

• Significance of k-feldspar megacryst size and distribution in the tuolumne intrusive suite, California

Notes and References

1. Web site: Glossary of terms. 29 December 2009. Memphis Archaeological and Geological Society. 7 April 2006.
2. Chapman, Carleton A. (2014). Phenocryst. In AccessScience. McGraw-Hill Education. https://doi.org/10.1036/1097-8542.506500