Alstonite
Chemical Formula	BaCa(CO3)2
Species	Carbonates
Crystal System	Triclinic
Mohs Scale	4
Specific Gravity	3.70
Color	Colourless to snow white, yellow-gray; pale gray, pale cream, pink to pale rose-red
Streak	White
Luster	Vitreous
Refractive Index	n = 1.526 n = 1.671 n = 1.672
Diaphaneity	Transparent, Translucent
Cleavage	Imperfect/FairOn pseudo-orthorhombic , imperfect
Fracture	Irregular/Uneven
Crystal Habit：Steep pseudohexagonal dipyramids
Geological Setting：Typically in low-temperature hydrothermal Pb–Zn deposits; rare in carbonatites.