Also found in: Thesaurus, Encyclopedia, Wikipedia.
A usually black or banded, hard volcanic glass that displays shiny, curved surfaces when fractured and is formed by rapid cooling of lava.
[Latin obsidiānus, misreading of obsiānus (lapis), Obsian (stone), obsidian, after Obsius, a Roman who supposedly discovered it or a similar mineral.]
(Geological Science) a dark volcanic glass formed by very rapid solidification of lava. Also called: Iceland agate
[C17: from Latin obsidiānus, erroneous transcription of obsiānus (lapis) (stone of) Obsius, the name (in Pliny) of the discoverer of a stone resembling obsidian]
ob•sid•i•an(əbˈsɪd i ən)
a volcanic glass similar in composition to granite, usu. dark but transparent in thin pieces, and having a good conchoidal fracture.
[1790–1800; < Latin Obsidiānus, printer's error for Obsiānus pertaining to Obsius, the discoverer (according to Pliny) of a similar mineral in Ethiopia; compare Middle English obsianus < Latin; see -an1]
A shiny, usually black, volcanic glass. Obsidian forms from lava that cools so quickly that minerals do not have a chance to form within it.
A glassy volcanic rock.