porphyroid


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por·phy·roid

 (pôr′fə-roid′)
n.
Metamorphic rock having porphyritic texture.

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
References in periodicals archive ?
Accordingly, the highest silver-copper-antimony grades are in those parts of the vein which are hosted by relatively ductile quartz-sericite phyllites on Levels 8 and 9 whilst lower grade mineralisation developed in parts of the vein hosted by competent porphyroids (mostly on Level 13).