Mineral - Roselite
Roselite
Chemical Properties
Mineral Class
Arsenates
Toxicity
middle
Formula
Ca₂Co(AsO₄)₂ · 2H₂O
Unit Cell
a=5.80 b=12.90 c=5.62 β=107° Z=2
Physical Properties
Hardness
3.5
Streak
red
Density
Heavy (3,5-6)
Cleavage
Perfect after {010}
Fracture
Tenacity
Brittle
Optical Properties
Color
redpink
Birefringence
0.025
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Rosa-Rot
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
prismatic, Rhombohedron, rosette, Scalenohedron, tabular
Formation
Secondary formation in the oxidation zone of arsenic-bearing cobalt deposits through the reaction of cobalt-bearing solutions with arsenates in the presence of calcium under low-temperature hydrothermal conditions
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Roselite
Composition
Elements
Mass
As₂O₅
49.96
CoO
12.45
MgO
4.67
CaO
23.72
H₂O
9.69
Germany (Palache et al. 1952)
Groups and Members
Kröhnkite-Supergroup
Brandtite-Group