Intermediate Granite Rocks

Igneous rocks are classified according to their mineral content.

Intermediate granite rocks.

Composition refers to a rock s chemical and mineral make up. It forms from the slow crystallization of magma below earth s surface. Granite is composed mainly of quartz and feldspar with minor amounts of mica amphiboles and other minerals this mineral composition usually gives granite a red pink gray or white color with dark mineral. Those with between 45 and 55 percent silica are mafic.

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. Other articles where intermediate rock is discussed. Felsic and mafic rocks. Typical intermediate rocks include andesite dacite and trachyandesite among volcanic rocks and diorite and granodiorite among plutonic rocks.

Mafic rocks are dominated by plagioclase and pyroxene even if you can t see them with the naked eye and smaller amounts of olivine. Intermediate rocks are roughly even mixtures of felsic minerals mainly plagioclase and mafic minerals mainly hornblende pyroxene. And those with less than 45 percent are ultramafic. The name comes from two related rocks to which granodiorite is an intermediate.

It is usually only exposed at the surface after uplift and erosion have occurred. Granite is a light colored igneous rock with grains large enough to be visible with the unaided eye. Felsic intermediate mafic and ultramafic. These groups refer to differing amounts of silica iron and magnesium found in the minerals that make up the rocks.

Ultramafic rocks are dominated by olivine and or pyroxene. For igneous rock the composition is divided into four groups. Syenite diorite and monzonite.