The Volcanic Fine Grained Compositional Equivalent Of Granite

Intermediate in silica content it is usually gray in color and may be fine grained or porphyritic.

The volcanic fine grained compositional equivalent of granite.

Its principal minerals are feldspars quartz and mica. Rhyolite refers to the volcanic and felsic igneous rocks and granite refer to intrusive and felsic igneous rocks. Material consisting of rock glass ash and scoria ejected during violent volcanic eruptions. It contains more than 68 weight of silica in composition and is granular and coarse grained in texture.

It consists of the plagioclase feldspar minerals andesine and oligoclase together with one or more dark ferromagnesian minerals such as pyroxene and biotite. Andesite is the volcanic equivalent of diorite. This chart illustrates the generalized mineral composition of igneous rocks. The fine grained volcanic equivalent of granite is basalt.

Andesite and diorite likewise refer to extrusive and intrusive intermediate rocks with dacite and granodiorite applying to those rocks with composition between felsic and intermediate. One example of an aphanitic rock with felsic composition. Granites and rhyolites compositionally equivalent to granite but of a fine grain size are composed mainly of orthoclase feldspar quartz plagioclase feldspar mica and amphibole. An ultralight felsic vesicular rock.