An introduction to minerals and rocks under ... - OpenLearn
A QAPF diagram is a double ternary diagram which is used to classify igneous rocks based on mineralogic composition. The acronym, QAPF, stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)".
feldspar rock classification - greenmountainpta.org
Granite: The specimen above is a typical granite. It is about two inches across. The grain size is coarse enough to allow recognition of the major minerals. The pink grains are orthoclase feldspar, and the clear to smoky grains are quartz or muscovite.
Alkali feldspar granite, some varieties of which are called 'red granite', is a felsic igneous rock and a type of granite rich in the mineral potassium feldspar (K-spar). It is a dense rock with a phaneritic texture.
Plagioclase: the white or chalky looking grain is the common feldspar, plagioclase. Plagioclase is the most common mineral in igneous rocks. The illustration to the left shows a large chalky white grain of plagioclase.
Granite: Igneous Rock - Pictures, Definition & More
Classification. Granite is a coarse-grained quartzo-feldspathic igneous rock which contains 20-60% quartz of total quartz + feldspar (other minerals are neglected) and 35-90% of the feldspar is alkali feldspar (orthoclase or microcline).
Igneous Rocks Amethyst Galleries Mineral Gallery. Igneous rocks are one of the three major rock types and are further classification of igneous rocks is a sodium and calcium and form quartz and feldspar