دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: finely crystalline, generally lightcoloured extrusive igneous rock com- posed largely of plagioclase feldspar with smaller amounts of dark-coloured minerals. Compare diorite.

n: an extrusive igneous rock that is dense, fine grained, and often dark gray to black. Compare gabbro.

the most common volcanic rock. Usually fine grained.

a description of rock resulting from a magma breach to surface and exposed to atmospheric conditions during cooling.

n: an extrusive igneous rock that cooled so rapidly that no crystals formed at all, i.e., volcanic glass.

dark, volcanic glass.