porphyroid


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por·phy·roid

 (pôr′fə-roid′)
n.
Metamorphic rock having porphyritic texture.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

porphyroid

(ˈpɔːfɪˌrɔɪd)
adj
(Geological Science) (of metamorphic rocks) having a texture characterized by large crystals set in a finer groundmass
n
(Geological Science) a metamorphic rock having this texture
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
References in periodicals archive ?
The relict porphyroid texture of the rock is caused by the presence of olivine coarse grains (separated by a fine grained mass composed of serpentine grains and ore mineral) fully substituted by serpentine.
They locally contain intercalations of crystalline limestones and dolomites (marbles), amphibolites, amphibole schists, quartzite and quartzite schists, graphite quartzites and mica schists, porphyroids and leptynites.
Fine flakes of muscovite (sericite) and chlorite are typical constituents of shales, slates, phyllites, porphyroids, etc.