Mafic Minerals In Granite

Granite is a felsic composed of light coloured feldspars and silica minerals intrusive rock.

Mafic minerals in granite.

The rock texture thus determines the basic name of a felsic rock. Mafic is a term used to describe both minerals that are rich in iron and magnesium and rocks that are rich in those minerals. The most common felsic rock is granite which represents the purified end product of the earth s internal differentiation process. Common rock forming mafic minerals include olivine pyroxene amphibole biotite and other micas augite and the calcium rich plagioclase feldspars.

Common examples of mafic minerals include olivine biotite hornblende. These minerals are high in magnesium and ferric oxides and their presence gives mafic rock its characteristic dark colour. In terms of chemistry mafic rocks are on the other side of the rock spectrum from the so called felsic rocks. Felsic minerals are usually light in color and have specific gravities less than 3 0.

Often the species of mafic minerals is included in the name for instance hornblende bearing granite pyroxene tonalite or augite megacrystic monzonite because the term granite already assumes content with feldspar and quartz. It is formed by the slow cooling and crystallisation of magma below the earths surface in a pluton. In addition such a study of mafic silicates and opaque minerals can indicate rela tive oxidation states within granitic plutons e g cza. Common felsic minerals include quartz muscovite mica and the orthoclase feldspars.

Common mafic rocks include basalt and gabbro.