01 n. A term used somewhat loosely to designate a rock consisting of a fine-grained base (usually feldspathic) through which crystals, as of feld…
pl.
Porphyries ((#))
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1.
A term used somewhat loosely to designate a rock consisting of a fine-grained base (usually feldspathic) through which crystals, as of feldspar or quartz, are disseminated. There are red, purple, and green varieties, which are highly esteemed as marbles.(Geol.)
Phrases & compounds
Porphyry shell —
a handsome marine gastropod shell (Oliva porphyria), having a dark red or brown polished surface, marked with light spots, like porphyry.