What is the chemical composition of potassium feldspar?
Potassium feldspars are common members of the alkali feldspar
group and form a complete solid solution series from KAaSi3O8
through (K, Na)AlSi3O8 to NaAlSi3O8. You really need more
information for a precise chemical composition as K-Feldspars can
have a wide range of chemical compositions.