Black Granite Minerals

The small black specks in the granite above are likely small amphibole grains.

Black granite minerals. Granites can be predominantly white pink or gray in color depending on their mineralogy the word granite comes from the latin granum a grain in reference to the coarse grained structure of such a completely crystalline rock. The black grains can be biotite or hornblende. Granite ˈ ɡ r æ n ɪ t is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Magnetite or lodestone is a common accessory mineral in coarse grained igneous rocks and metamorphic rocks.

The pink grains are orthoclase feldspar and the clear to smoky grains are quartz or muscovite. The specimen above is a typical granite. Numerous other minerals can be present in granite. The grain size is coarse enough to allow recognition of the major minerals.

Its three main minerals are feldspar quartz and mica which occur as silvery muscovite or dark biotite or both. White granite is a granite that is composed primarily of quartz milky white and feldspar opaque white minerals. The crystals in granite provide a variety of mixed colors feldspar pink or red mica dark brown or black quartz clear pink white or black and amphibole black. Look for a black streak and a strong attraction to a magnet.

Granite is the most common intrusive rock in earth s continental crust it is familiar as a mottled pink white gray and black ornamental stone it is coarse to medium grained. Color variation is a response to the percent of each mineral found in the sample. It may be gray black or have a rusty coating. It is about two inches across.