*volcanic*

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 ]