What is Feldspar? Industrial Minerals Association ...
Feldspar minerals are essential components in igneous, metamorphic and sedimentary rocks, to such an extent that the classification of a number of rocks is based upon feldspar content. The mineralogical composition of most feldspars can be expressed in terms of the ternary system Orthoclase (KAlSi3O8), Albite (NaAlSi3O8) and Anorthite (CaAl2Si2O8).