Vitrophyre, a porphyritic variety of volcanic glass. See OBSIDIAN, PITCHSTONE.
Vitrophyre
Chambers's Encyclopaedia, Volume 10: Swastika to Zyrianovsk and Index, p. 498
Source scan(s): p. 0525
Vitrophyre, a porphyritic variety of volcanic glass. See OBSIDIAN, PITCHSTONE.