[buh-sawlt, bas-awlt, bey-sawlt] 
| the dark, dense igneous rock of a lava flow or minor intrusion, composed essentially of labradorite and pyroxene and often displaying a columnar structure. |
tēs (líthos) touchstone, equiv. to básan(os) touchstone (ult. < Egyptian b
n(w) graywacke) + -ītēs -ite 1 
[buh-sawl-tin, -tahyn] , adjective | ba·salt (bə-sôlt', bā'sôlt') n.
[Latin basaltēs, alteration of basanītēs, touchstone, from Greek basanītēs (lithos), from basanos, of Egyptian origin.] ba·sal'tic (-sôl'tĭk) adj. |
A hard, dense igneous rock that makes up much of the material in tectonic plates. The part of the Earth's crust beneath the oceans consists mainly of basalt whereas continental crust consists mainly of less dense rocks, such as granite. (See plate tectonics.)
| basalt (bə-sôlt', bā'sôlt') Pronunciation Key
A dark, fine-grained, igneous rock consisting mostly of plagioclase feldspar and pyroxene, and sometimes olivine. Basalt makes up most of the ocean floor and is the most common type of lava. It sometimes cools into characteristic hexagonal columns, as in the Giant's Causeway in Anterim, Northern Island. It is the fine-grained equivalent of gabbro. |