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Of or pertaining to a volcano or volcanoes; as, volcanic heat.

A column of igneous rock formed by congelation of lava in the conduit of a volcano and later exposed by the removal of surrounding rocks.

A wind associated with a volcanic outburst and due to the eruption or to convection currents over hot lava.

Like a volcano.

Quality or state of being volcanic; volcanic power.

A mass of angular volcanic fragments united by heat; -- distinguished from conglomerate.

eous rocks (Geol.), those which are deposited from water and lie in strata, as opposed to volcanic rocks, which are of igneous origin; -- called also sedimentary rocks.

e expression of grief or repentance; -- from the method of mourning in Eastern lands. -- Volcanic ashes, or Volcanic ash, the loose, earthy matter, or small fragments of stone or lava, ejected by volcanoes.

Minute acicular or dendritic crystalline forms sometimes observed in glassy volcanic rocks.

el. -- Bomb lance, a lance or harpoon with an explosive head, used in whale fishing. -- Volcanic bomb, a mass of lava of a spherical or pear shape. "I noticed volcanic bombs." Darwin.

mposed of silica, magnesia, and iron, of a yellow to green color. It is common in certain volcanic rocks; -- called also olivine and peridot. Sometimes used as a gem. The name was also early used for yellow varieties of tourmaline and topaz.

Anything shaped more or less like a mathematical cone; as, a volcanic cone, a collection of scoriæ around the crater of a volcano, usually heaped up in a conical form. Now had Night measured with her shadowy cone Half way up hill this vast sublunar vault. Milton.

A minute mineral form like those common in glassy volcanic rocks and some slags, not having a definite crystalline outline and not referable to any mineral species, but marking the first step in the crystallization process. According to their form crystallites are called trichites, belonites, globulites, etc.…

out; pouring forth freely. "Washed with the effusive wave." Pope. Effusive rocks (Geol.), volcanic rocks, in distinction from so-called intrusive, or plutonic, rocks. -- Ef*fu"sive*ly, adv. -- Ef*fu"sive*ness, n.

Produced by eruption; as, eruptive rocks, such as the igneous or volcanic.

Pertaining to Etna, a volcanic mountain in Sicily.

A variety of opal occuring in the cavities of volcanic tufa, in smooth and shining globular and botryoidal masses, having a pearly luster; -- so called from Fiora, in Ischia.

to its flowing motion. Fluidal structure (Geol.), the structure characteristic of certain volcanic rocks in which the arrangement of the minute crystals shows the lines of flow of thew molten material before solidification; -- also called fluxion structure.

A hole or spot in a volcanic or other region, from which fumes issue.

A low, oven-shaped mound, common in volcanic regions, and emitting smoke and vapors from its sides and summit. Humboldt.