Specific Gravity
2.60-2.90
2.56-2.60
Fracture
Uneven, Conchoidal, Irregular
Uneven, ConchoidalWalter Schumann
Cleavage
Imperfect on {0001}
2,1 basal ; 2,1 prismatic ; 3,1 pinacoidal
Mohs Hardness
7.5-8
6-6.5
Chemical Composition
Be3Al2Si6O18
Plagioclase Feldspar s: (Na,Ca)Al1-2Si3-2O8 Orthoclase Feldspar : KAlSi3O8