Potassium feldspar refers to a number of minerals in the feldspar group, and containing potassium: Orthoclase, an important tectosilicate mineral that forms igneous rock Microcline, chemically the same as orthoclase, but with a different crystalline structure Sanidine, the high-temperature form of potassium feldspar 4O8 Adularia, a more ordered low-temperature variety of orthoclase or partially disordered microcline Amazonite, a green variety of microcline Wikipedia