What Is The Percentage Of Plagioclase In A Typical Granite

If you start to get mainly plagioclase and less k feldspar the rock becomes more like a granodiorite or diorite.

What is the percentage of plagioclase in a typical granite. And the feldspar is both potassium feldspar and plagioclase. True granite which has a quartz content between 20 and 60 percent and a greater concentration of alkali feldspar than plagioclase feldspar is only one of several granitoids. It depends on the granite but that is a reasonable value. I would expect about 60 feldspar 30 quartz and 10 biotite in a generalized granite.

The accepted classification scheme for felsic coarse grained magmatic rocks such as granite by its mineral content is via the qapf diagram where q stands for quartz a for alkali feldspar p for plagioclase feldspar and f for feldspathoid fig. Learn more about the properties and uses of granite in this article. A granite containing both muscovite and biotite micas is called a binary or two mica granite. Two mica granites are typically high in potassium and low in plagioclase and are usually s type granites or a type granites.

Granite coarse or medium grained intrusive igneous rock that is rich in quartz and feldspar. It is the most common plutonic rock of the earth s crust forming by the cooling of magma silicate melt at depth. Applying this definition requires the mineral identification and quantification abilities of a competent geologist.