Plagioclase Feldspar Granite

Cloud granite morton gneiss and wausau.

Plagioclase feldspar granite. Plagioclase feldspar group minerals are the most common rock forming minerals. Rather than referring to a particular mineral with a specific chemical composition plagioclase is a continuous solid solution series more properly known as the plagioclase feldspar series. They are importantly dominant minerals in most igneous rock. True granite according to modern petrologic convention contains both plagioclase and alkali feldspars.

The names of the minerals in the series are arbitrarily given based upon their relative abundance of albite and anorthite. Granite is classified according to the qapf diagram for coarse grained plutonic rocks and is named according to the percentage of quartz alkali feldspar orthoclase sanidine or microcline and plagioclase feldspar on the a q p half of the diagram. This was first shown by the german mineralogist johann friedrich christian hessel 1796 1872 in 1826. Plagioclase is the name of a group of feldspar minerals that form a solid solution series ranging from pure albite na alsi 3 o 8 to pure anorthite ca al 2 si 2 o 8 minerals in this series are a homogenous mixture of albite and anorthite.

When a granitoid is devoid or nearly. They are major constituents in a wide range of intrusive and extrusive igneous rocks including granite diorite gabbro rhyolite andesite and basalt. Alkali feldspar granite granite is a medium tocoarse grained acid igneous rock with essential quartz 20 and feldspar where alkali feldspar constitutes between 100 and 35 of the feldspars and minor mafic minerals.