Vol*can"ic (?), a. [Cf.
F. volcanique, It.
vulcanico.]
1. Of or pertaining to a
volcano or volcanoes; as, volcanic heat.
2. Produced by a volcano,
or, more generally, by igneous agencies; as, volcanic tufa.
3. Changed or affected by the heat of a volcano.
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.
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