Intermediate Granite Rocks

Compilations of many rock analyses show that rhyolite and granite are felsic with an average silica content of about 72 percent.

Intermediate granite rocks.

Granite is a light colored igneous rock with grains large enough to be visible with the unaided eye. For igneous rock the composition is divided into four groups. Felsic and mafic rocks. Granodiorite is a plutonic igneous rock formed by intrusion of silica rich magma which cools in batholiths or stocks below the earth s surface.

Felsic intermediate mafic and ultramafic. Those with between 45 and 55 percent silica are mafic. It is usually only exposed at the surface after uplift and erosion have occurred. These groups refer to differing amounts of silica iron and magnesium found in the minerals that make up the rocks.

Typical intermediate rocks include andesite dacite and trachyandesite among volcanic rocks and diorite and granodiorite among plutonic rocks. Intermediate rocks are roughly even mixtures of felsic minerals mainly plagioclase and mafic minerals mainly hornblende pyroxene. Other articles where intermediate rock is discussed. Syenite diorite and monzonite.

It forms from the slow crystallization of magma below earth s surface. The name comes from two related rocks to which granodiorite is an intermediate. Ultramafic rocks are dominated by olivine and or pyroxene. And 65 percent silica are intermediate.

And those with less than 45 percent are ultramafic. In igneous petrology an intermediate composition refers to the chemical composition of a rock that has 52 63 wt sio 2 being an intermediate between felsic and mafic compositions. Igneous rocks are classified according to their mineral content.