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phenocryst

American  
[fee-nuh-krist, fen-uh-] / ˈfi nə krɪst, ˈfɛn ə- /

noun

Petrology.

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

phenocryst British  
/ ˈfiːnəˌkrɪst, ˈfɛn- /

noun

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

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
phenocryst Scientific  
/ 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.

Etymology

Origin of phenocryst

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

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.