extrusive(redirected from Extrusive rocks)
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Derived from magma poured out or ejected at the earth's surface. Used of igneous rocks.
1. tending to extrude
2. (Geological Science) (of igneous rocks) formed from magma issuing from volcanoes or cracks in the earth's crust; volcanic. Compare intrusive2
ex•tru•sive(ɪkˈstru sɪv, -zɪv)
1. pertaining to extrusion.
2. of or pertaining to a class of igneous rocks that have been forced out in a molten or plastic condition upon the surface of the earth.