General Information:
Chemical Formula:
Al2(SO4)3·17(H2O)
Composition:
(Molecular Weight = 639.45 gm)
Aluminum 4.22 % Al
Hydrogen 5.67 % H
Sulfur 15.04 % S
Oxygen 75.06 % O
Empirical Formula:
Al(SO4)3·18(H2O)
Name Origin:
From the Latin alumen ="alum" and the Greek genos ="origin."
Physical Properties:
Cleavage:
[010] Perfect
Color:
white, yellowish white, reddish white, or yellowish white.
Density:
1.65 - 1.78, Average = 1.71
Diaphaniety:
Transparent
Habits:
Acicular - Occurs as needle-like crystals., Fibrous - Crystals made up of fibers., Encrustations - Forms crust-like aggregates on matrix.
Hardness:
1.5-2 - Talc-Gypsum
Luminescence:
None.
Luster:
Vitreous - Pearly
Streak:
white
More details...