Alkali Feldspar Granite Composition

Scituate igneous suite alkali feldspar granite gray to pink medium to coarse grained porphyritic to subporphyritic alkali feldspar granite phenocrysts of perthite.

Alkali feldspar granite composition.

The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. As shown in the qapf diagram alkali feldspar granite contains between 20 60 quartz. In addition to granite intrusive rocks with over 20 vol of quartz are commonly referred to as. Less quartz content would lead to quartz alkali feldspar syenite.

Less than that amount would designate the rock as a granite. All the rock forming feldspars are aluminosilicate minerals with the general formula at4o8 in which a potassium sodium or calcium ca. More than 90 of the total feldspar content is in the form of alkali feldspar. Less than that amount would designate the rock as a granite.

Alkali fledspar granite is an intrusive igneous rock which is very hard crystalline and is visibly homogeneous in texture and forms by melting of continental rocks. And t silicon si and aluminum al with a si al ratio ranging from 3 1 to 1 1. The perthitic textures in the alkali feldspars of many granites can be seen with the naked eye. The streak of alkali feldspar granite is white.

Both plagioclase feldspar and alkali feldspar are usually abundant in it and their relative abundance has provided the basis for granite classifications. Contains perthite quartz and accessory biotite hornblende and lesser riebeckite aegerine zircon allanite sphene fluorite and opaque minerals. Search photos of peralkaline alkali feldspar granite edit add synonym add sub type rock clear cache a term that may be used for a variety of alkali feldspar granite that contains alkali pyroxene and or amphibole. Alkali feldspar granite also known as red granite is a felsic igneous rock and a type of granite rich in the mineral potassium feldspar.

Alkali feldspar granite contains between 20 60 quartz. Along with alkali feldspar granite formation also learn about alkali feldspar granite composition and transformation in the next section. Feldspar feldspar chemical composition. Formation of alkali feldspar granite is explained below.

Perthite is a typical texture in alkali feldspar due to exsolution of contrasting alkali feldspar compositions during cooling of an intermediate composition. Granite s s is a plutonic rock with a simple felsic mineralogy of quartz alkali feldspar plagioclase with more than 20 quartz and plagioclase representing 10 to 65 vol of total feldspar. Alkali feldspar granite is available in black grey orange pink white colors. Less quartz content would lead to quartz alkali feldspar syenite.