Orthoclase (endmember formula KAlSi3O8), 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 (K,Na)(Si,Al)4O8 Adularia, a more ordered low-temperature variety of orthoclase or partially disordered microcline Amazonite (sometimes called "Amazon stone"), a green variety of microcline