porphyroid

porphyroid

[pawr-fuh-roid]
noun
1.
a rock resembling porphyry.
2.
a sedimentary rock that has been metamorphosed so as to leave some original crystals in a fine-textured, layered matrix.

Origin:
1790–1800; porphyr(y) + -oid

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World English Dictionary
porphyroid (ˈpɔːfɪˌrɔɪd)
 
adj
1.  (of metamorphic rocks) having a texture characterized by large crystals set in a finer groundmass
 
n
2.  a metamorphic rock having this texture

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