Mineral - Andyrobertsite
Andyrobertsite
Chemical Properties
Mineral Class
Arsenates
Toxicity
low
Formula
KCdCu₅(AsO₄)₄(H₂AsO₄) · 2H₂O
Unit Cell
a=9.81 b=10.04 c=9.98 β=102° Z=2
Physical Properties
Hardness
3
Streak
blue
Density
Heavy (3,5-6)
Cleavage
Good after {100}
Fracture
conchoidal
Tenacity
Brittle
Optical Properties
Color
blue
Birefringence
0.037
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /m (11)
Habit
platelet-shaped, rosette, tabular
Formation
Oxidation zone of polymetallic metal deposits
Paragenesis
Twinning
Rarity
Rare
Synonyms
Andyrobertsite
Composition
Elements
Mass
K₂O
4.00
CaO
1.36
MnO
0.64
CdO
6.48
ZnO
0.19
CuO
31.72
As₂O₅
47.58
H₂O
4.44
Namibia (Cooper et al. 1999)
Name and first discovery : Named after the Canadian mineralogist Andrew C. Roberts (1950), first discovered in Tsumeb in 1996
Chemistry :
Synonyms :
Varieties :
Abbreviation : Arb
literature
Cooper, MA, Hawthorne, FC, Pinch, WW, & Grice, JD (1999). Andyrobertsite and calcioandyrobertsite: two new minerals from the Tsumeb mine, Tsumeb, Namibia. Mineralogical Record , 30 (3), 181.