əbˈsidēən, äb- noun
( -s )
Etymology: New Latin obsidianus, from Latin Obsidianus lapis (MS variant of Obsianus lapis), literally, stone of Obsidian, from Obsidius (MS variant of Obsius ), Roman traveler named by Pliny as its discoverer + -ianus -ian
: volcanic glass that is generally black, banded, or spherulitic and has a marked conchoidal fracture, a bright luster, and a composition similar to rhyolite but usually with more water