Formula: KAlSi3O8
Origin of name: From Greek for little and slanted
Crystal system: Triclinic
Crystal class: -1
Twinning: Common by Carlsbad, Baveno, or Manebach law; also by albite or pericline law
Unit cell: a = 8.56 Å, b = 12.97 Å, c = 7.21 Å, α = 90.3°, β = 116.1°, γ = 89.0°
Colour: White, gray, yellowish, reddish, green
Diaphaneity:
Luster: Vitreous, often pearly on cleavage
Habit: Crystals short prismatic, blocky; or tabular; massive, cleavable to granular; twinning on Carlsbad, Manebach , Baveno laws
Hardness: 6 to 6.5
Specific gravity: 2.55 to 2.63
Cleavage: 6; {001} and {010} perfect, {100}, {110, {-110} and {-201} parting
Tenacity: Uneven; brittle
Streak:
Synonyms/varieties: Amazonite (blue-green var.), barbierite, K-feldspar, Potassium feldspar, Potash feldspar
Comments: Trimorphous with orthoclase and sanidine
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