Hypertext Webster Gateway: "porphyry"
From Webster's Revised Unabridged Dictionary (1913) (web1913)
Porphyry \Por"phy*ry\, n.; pl. {Porphyries}. [F. porphyre, L.
porphyrites, fr. Gr. ? like purple, fr. ? purple. See
{Purple}.] (Geol.)
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.
{Porphyry shell} (Zo["o]l.), a handsome marine gastropod
shell ({Oliva porphyria}), having a dark red or brown
polished surface, marked with light spots, like porphyry.
From WordNet (r) 1.7 (wn)
porphyry
n : any igneous rock with crystals embedded in a finer
groundmass of minerals [syn: {porphyritic rock}]
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