Plagioclase Feldspar Granite

Plagioclase is a series of tectosilicate framework silicate minerals within the feldspar group.

Plagioclase feldspar granite.

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. 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. 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.

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. Cloud granite morton gneiss and wausau. When a granitoid is devoid or nearly. The plagioclase feldspar subgroup consists of a continuous mineral series that is arbitrarily subdivided into six mineral categories whose composition varies from being relatively pure sodium aluminum silicate albite to a relatively pure calcium aluminum silicate anorthite.

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. Hornblende and biotite are the commonest mafic minerals however muscovite is also frequently encountered.