Lazurite
Chemical Formula	(Na,Ca)8[(S,Cl,SO4,OH)2|(Al6Si6O24)]
Species	Silicates
Crystal System	Isometric
Mohs Scale	5
Specific Gravity	2.38-2.45
Color	Deep blue, azure, Purple-blue, greenish blue
Streak	Bright blue
Luster	Vitreous
Refractive Index	n = 1.502 - 1.522
Diaphaneity	Transparent, Opaque
Cleavage	Imperfect/FairImperfect on
Fracture	Irregular/Uneven
Crystal Habit：Crystals occur as dodecahedra, or rarely cubes; granular, disseminated, or massive
Geological Setting：Contact metamorphic mineral in limestones.