phenocryst

[ fee-nuh-krist, fen-uh- ]

noun

, Petrology.

1. any of the conspicuous crystals in a porphyritic rock.

phenocryst

/ ˈfɛn-; ˈfiːnəˌkrɪst /

noun

1. any of several large crystals that are embedded in a mass of smaller crystals in igneous rocks such as porphyry

phenocryst

/ fē′nə-krĭst′ /

1. A large crystal that is surrounded by a finer-grained matrix in an igneous rock. Phenocrysts are usually the first crystals to form from a cooling magma, and therefore have sufficient room to grow to a large size. They are analogous to porphyroblasts in metamorphic rock.

Word History and Origins

Origin of phenocryst¹

First recorded in 1890–95; pheno- + cryst(al)

Word History and Origins

Origin of phenocryst¹

C19: from pheno- (shining) + crystal