Mineral - Erythrite
Erythrite
Chemical Properties
Mineral Class
Arsenates
Toxicity
middle
Formula
Co₃[AsO₄]₂·8H₂O
Unit Cell
a=10.25 b=13.45 c=4.76 β=105° Z=2
Physical Properties
Hardness
2 - 2.5
Streak
pink
Density
Normal (2-3,5)
Cleavage
Perfect after {010}
Fracture
uneven
Tenacity
Elastic-flexible
Optical Properties
Color
red
Birefringence
0.073
Luster
Vitreous,
Pearly
Transparency
translucent,
transparent
Pleochroism
X: Rosa
Y: Violett
Z: Rot
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
C2/m (12)
Habit
tufty, acicular, prismatic, tabular
Formation
Oxidation zone of cobalt deposits
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Erythrite
Composition
Elements
Mass
As₂O₅
38.30
FeO
4.01
CoO
33.42
H₂O
24.08
Germany (Palache et al. 1952)
Groups and Members
Vivianite-Group