volcanic glass

Webster's Dictionary (GCIDE)

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]