Extrusive

Science / Geology / Extrusive: Igneous rocks that crystallize at Earth's surface.

Basalt

Science / Geology / Basalt: A dark-colored fine-grained extrusive igneous rock composed largely of plagioclase feldspar and pyroxene. Similar in composition to gabbro. Basalt is thought to be one of the main components of oceani MORE

Rhyolite

Science / Geology / Rhyolite: The fine-grained volcanic or extrusive rocks that are equivalent in composition to granite. Normally white, pink or gray in color. Picture of Rhyolite. MORE

Andesite

Science / Geology / Andesite: A fine-grained, extrusive igneous rock composed mainly of plagioclase with other minerals such as hornblende, pyroxene and biotite. Picture of Andesite. MORE

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