Potassium feldspar

Potassium feldspar refers to a number of minerals in the feldspar group, and containing potassium:
 * 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