Natrolite
Chemical Formula	Na2Al2Si3O10·2H2O
Species	Silicates
Crystal System	Orthorhombic
Mohs Scale	5
Specific Gravity	2.25
Color	White, colorless
Streak	White
Luster	Vitreous, Pearly
Refractive Index	n = 1.473 - 1.483 n = 1.476 - 1.486 n = 1.485 - 1.496
Diaphaneity	Transparent, Translucent
Cleavage	Perfecton
Fracture	Irregular/Uneven
Crystal Habit：Acicular
Geological Setting：Cavities in amygdaloidal basalts