Mineral - Apjohnite
Apjohnite
Chemical Properties
Mineral Class
Sulphates
Toxicity
none
Formula
Mn²⁺Al₂(SO₄)₄ · 22H₂O
Unit Cell
a=6.20 b=24.35 c=21.27 β=100° Z=4
Physical Properties
Hardness
1.5 - 2
Streak
white
Density
Light (<2)
Cleavage
Fracture
nd
Tenacity
Brittle
Optical Properties
Color
whitecolorless
Birefringence
0.004
Luster
Silky
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
coarse, fibrous, crusty, massive, acicular, radial
Formation
Secondary, through the oxidation of primary sulphides
In evaporites
Paragenesis
Twinning
Rarity
Very rare
Synonyms
Apjohnite
Composition
Elements
Mass
SO₃
33.51
Al₂O₃
10.56
MnO
6.60
MgO
0.36
H₂O
48.15
Mozambique (Palache et al. 1952)
Groups and Members
Halotrichite-Group
Name and first discovery : Named after the Irish chemist and mineralogist James Apjohn (1796-1886). First described in 1847.
Chemistry :
Synonyms :
Varieties :
Abbreviation : Apj
literature
Palache, C., Berman, H., & Frondel, C. (1952). Dana's system of mineralogy. Geologiska Föreningen i Stockholm Förhandlingar , 74 (2), 218-219.