Dawsonite
Chemical Formula	NaAlCO3(OH)2
Species	Carbonates
Crystal System	Orthorhombic
Mohs Scale	3
Specific Gravity	2.436
Color	white
Streak	white
Luster	Vitreous, Silky
Refractive Index	n = 1.466 n = 1.542 n = 1.596
Diaphaneity	Transparent
Cleavage	PerfectOn
Fracture	uneven
Crystal Habit：encrustations or radial
Geological Setting：Nepheline syenites, authigenic in alkaline shales and coal bearing rocks, saline soils on nepheline tuffs.