Mineral - Beraunite
Beraunite
Chemical Properties
Mineral Class
Phosphates
Toxicity
none
Formula
Fe³⁺₆(PO₄)₄O(OH)₄ · 6H₂O
Unit Cell
a=20.95 b=5.17 c=19.27 β=93° Z=4
Physical Properties
Hardness
3 - 4
Streak
browngrayyellowgreenyellow browngreen grey
Density
Normal (2-3,5)
Cleavage
Distinct after {100}
Fracture
splintery,
uneven
Tenacity
Brittle
Optical Properties
Color
brownredred brown
Birefringence
0.040
Luster
Greasy,
Pearly
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
C2/c (15)
Habit
coarse, sheaf-shaped, crusty, spherical, acicular, prismatic, radial, prismatic, radial, tabular
Formation
Secondary through the alteration of primary phosphates, such as triphylite in the oxidation zone of iron deposits
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Beraunite
Composition
Elements
Mass
P₂O₅
30.17
Al₂O₃
0.02
Fe₂O₃
54.41
FeO
1.92
H₂O
13.45
New Jersey (Palache et al. 1952)
Groups and Members
Beraunite-Group