phenocryst

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phenocryst

[′fēn·ə‚krist]
(petrology)
A large, conspicuous crystal in a porphyritic rock. Also known as phanerocryst.
References in periodicals archive ?
Phenocrystic plagioclase cores range between [An.sub.43] and [An.sub.10], rarely [An.sub.50].
Groundmass plagioclases show generally higher proportion of Ab component than the phenocrystic ones, indicating a fractionation trend.