AlkaliFeldspäten
Alkali feldspäten is a group of tectosilicate minerals that together form a solid solution series. This series is primarily composed of potassium feldspat (KAlSi3O8) and sodium feldspat (NaAlSi3O8). The end-member potassium feldspat is known as orthoclase or microcline, while the end-member sodium feldspat is albite. Within this solid solution, various intermediate compositions exist, such as sanidine and anorthoclase. These minerals are characterized by their framework structure of silicon-oxygen and aluminum-oxygen tetrahedra, with alkali metal cations (potassium and sodium) occupying interstitial sites.
Alkali feldspäten are extremely common in igneous rocks, particularly in granites, syenites, and rhyolites, where they