Found 2 items, similar to Volcanic rocks.
English → English (WordNet) Definition: volcanic rock volcanic rock n : extrusive igneous rock solidified near or on the surface of the Earth
English → English (gcide) Definition: Volcanic rocks Volcanic \Vol*can"ic\, a. [Cf. F. volcanique, It. vulcanico.] 1. Of or pertaining to a volcano or volcanoes; as, volcanic heat. [1913 Webster] 2. Produced by a volcano, or, more generally, by igneous agencies; as, volcanic tufa. [1913 Webster] 3. Changed or affected by the heat of a volcano. [1913 Webster] Volcanic bomb, a mass ejected from a volcano, often of molten lava having a rounded form. Volcanic cone, a hill, conical in form, built up of cinders, tufa, or lava, during volcanic eruptions. Volcanic foci, the subterranean centers of volcanic action; the points beneath volcanoes where the causes producing volcanic phenomena are most active. Volcanic glass, the vitreous form of lava, produced by sudden cooling; obsidian. See Obsidian. Volcanic mud, fetid, sulphurous mud discharged by a volcano. Volcanic rocks, rocks which have been produced from the discharges of volcanic matter, as the various kinds of basalt, trachyte, scoria, obsidian, etc., whether compact, scoriaceous, or vitreous. [1913 Webster]