Orthoclase

Chemical Formula : KAlSi₃O₈
Hardness : 6
Cleavage : Two, good
Luster : Sub-vitreous to pearly
Color : White, cream, pink
Streak : White
Density : 2.56
Diagnostic Features and Trivia : Orthoclase is the definitio of hardness 6 on Moh's scale. Its steroetypical color of salmon pink, and its cleavages at 90 degrees help to identify it.
Crystal System and Habit : Monoclinic; uncommon crystals are short prismsatic, somewhat flattened parallel to {010}.
Twinning :
Polymorphs : Microcline
Index of Refraction : alpha=1.518-1.520; beta=1.522-1.524; gamma=1.522-1.524