Alkali feldspar granite they provide 'crystallized' telltale clues of their environment of formation. Alkali feldspar granite is used as construction material in the form of dimension stones, and polished slabs or tiles for building facades, pavements, and kitchen countertops. Alkali feldspar granite 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. The abundance of K-spar gives the rock a predominant pink to reddish hue; peppered with minor amounts of black minerals. As shown in the
Rapakivi granite Rapakivi granite Rapakivi granite is a hornblende-biotite granite containing large round crystals of orthoclase each with a rim of oligoclase (a variety of plagioclase). The name has come to be used most frequently as a textural term where it implies plagioclase rims around orthoclase in plutonic rocks. Rapakivi is Finnish for "crumbly rock", because the different heat expansion coefficients of the component minerals make exposed rapakivi crumbly. Rapakivi was first described by Finnish petrologist Jakob Sederholm in 1891. Since then, southern Finland's rapakivi granite intrusions have been the type locality of this variety of granite. Rapakivi is a fairly uncommon