Color: colorless, white, gray, yellow, reddish, greenish

Streak: White

Luster: vitreous to pearly

Habit: Ccrystals short prismatic, blocky, may have orthorhombic or tetragonal aspect, massive, cleavable to granular, twinned

Hardness: 6 to 6.5

Specific gravity: 2.55 to 2.63

Cleavage: 2, perfect on {001} {010} 4 partings on {100}, {110} {-110} and {-201}

Tenacity: brittle, conchoidal to uneven

Twinning: common by Carlsbad, Baveno or Manebach law

Crystal system: Monoclinic

Crystal class: 2/m

Unit cell: a = 8.56 Å, b = 12.98 Å, c = 7.21 Å, b = 116.0°

Synonyms/varieties: adularia (wedge-shaped variety), K-feldspar, potassium feldspar, potash feldspar, moonstone (adularescent gem variety)