Mineral - Aluminite
Aluminite
Chemical Properties
Mineral Class
Sulphates
Toxicity
none
Formula
Al₂[(OH)₄|SO₄]·7H₂O
Unit Cell
a=7.44 b=15.58 c=11.70 β=110° Z=4
Physical Properties
Hardness
1 - 2
Streak
white
Density
Light (<2)
Cleavage
Fracture
earthy
Tenacity
Brittle
Optical Properties
Color
white
Birefringence
0.011
Luster
Earthy
Transparency
opaque
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
earthy, bulbous, kidney-shaped, grape-shaped
Formation
Reaction of sulphate-containing solutions (from the decomposition of marcasite or pyrite) at moderate temperatures with Al-containing silicates
Paragenesis
Twinning
Rarity
Common
Synonyms
Aluminite
Composition
Elements
Mass
SO₃
23.37
Al₂O₃
29.87
H₂O
46.76
England (Palache et al. 1952)
Groups and Members
Aluminite-Group
Name and first discovery : Named for its chemical composition, in which aluminum is the main cation. First described in 1805 by Karl Konstantin Haberle (1764-1832) from its type locality in Germany.
Chemistry :
Synonyms : Hallite
Varieties :
literature
Palache, C., Berman, H., & Frondel, C. (1952). Dana's system of mineralogy. Geologiska Föreningen i Stockholm Förhandlingar , 74 (2), 218-219.