Feldspar properties feldspar mineral group Feldspar is a silicate mineral of K, NA, Ca composed of siliconoxygen Tetrahedra. Its main components are SiO2, Al2O3, K2O, Na2o, CaO, and MgO, which are important raw materials for manufacturing, and widely used in chemical, abrasive, glass fiber, electrode, Enamel and filler industries. The prevalence of top quality glass .