Mineral - Legrandite
Legrandite
Chemical Properties
Mineral Class
Arsenates
Toxicity
middle
Formula
Zn₂[OH|AsO₄]·H₂O
Unit Cell
a=12.81 b=7.93 c=10.22 β=104° Z=8
Physical Properties
Hardness
4.5
Streak
white
Density
Heavy (3,5-6)
Cleavage
Indistinct after {100}
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
orangeyellowcolorless
Birefringence
0.060
Luster
Vitreous
Transparency
translucent,
transparent
Pleochroism
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /c (14)
Habit
acicular, prismatic, radial, prismatic, radial
Formation
Oxidation zone of zinc and arsenic-bearing sulfide deposits, primarily due to the chemical weathering of arsenopyrite and sphalerite
Paragenesis
Twinning
Rarity
Very rare
Synonyms
Legrandite
Composition
Elements
Mass
As₂O₅
37.70
FeO
1.40
MnO
1.70
ZnO
50.10
H₂O
8.90
Mexico (Palache et al. 1952)