Mineral - Arsentsumebite
Arsentsumebite
Chemical Properties
Mineral Class
Arsenates
Toxicity
middle
Formula
Pb₂Cu(AsO₄)(SO₄)(OH)
Unit Cell
a=8.85 b=5.92 c=7.84 β=113° Z=2
Physical Properties
Hardness
4 - 5
Streak
green
Density
Very Heavy (>6)
Cleavage
Fracture
uneven
Tenacity
Brittle
Optical Properties
Color
green
Birefringence
0.041
Luster
Vitreous,
Adamantine
Transparency
translucent,
transparent
Pleochroism
X: Hellgrün
Y: Dunkelgrün
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
P2 1 /m (11)
Habit
earthy, crusty, massive
Formation
In the oxidation zone of supergene, polymetallic deposits
Paragenesis
Twinning
Rarity
Rarely
Synonyms
Arsentsumebite
Composition
Elements
Mass
SO₃
9.36
P₂O₅
0.55
As₂O₅
13.45
CuO
10.61
PbO
61.91
H₂O
1.58
Namibia (Bideaux et al. 1966)
Groups and Members
Brackebuschite-Supergroup
Name and first record : Named after the type locality, the Tsumeb Mine in Namibia, and its arsenic-containing chemistry. First described in 1935.
Chemistry :
Synonyms : As-Tsumebit
Varieties :
Abbreviation : Atsu
literature
Bideaux, R. A. (1966). The arsenate analogue of tsumebite, a new mineral. American Mineralogist , 51 , 258-259.