GEOLOGY & PLANETARY SCIENCE A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z                    HOME ABOUT CATEGORIES SITE MAP COPYRIGHT ADVERTISE CONTACT entire Web this site orthoclase A common mineral in igneous rocks, consisting of potassium aluminum silicate (KAlSi2O8); it occurs in the form of vitreous crystals of various colors. Orthoclase is one of the end-members (pure compounds) of the feldspar group. See also microcline. Related category    • GEOLOGY AND PLANETARY SCIENCE Also on this site: Encyclopedia of Alternative Energy & Sustainable Living Encyclopedia of History Transport Concepts & Designs (partner site) BACK TO TOP