Mineral - Arseniosiderite
Arseniosiderite
Chemical Properties
Mineral Class
Arsenates
Toxicity
middle
Formula
Ca₂Fe³⁺₃(AsO₄)₃O₂ · 3H₂O
Unit Cell
a=17.76 b=19.53 c=11.30 β=96° Z=12
Physical Properties
Hardness
4.5
Streak
yellow
Density
Normal (2-3,5)
Cleavage
Perfect after {001}
Fracture
fibrous
Tenacity
Brittle
Optical Properties
Color
brownredyellow
Birefringence
0.080
Luster
Metallic,
Silky
Transparency
translucent,
opaque
Pleochroism
X: Braun-Rot
Y: Dunkelbraun
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
C2/c (15)
Habit
fibrous, felted, spherical, acicular, kidney-shaped, radial, radial
Formation
Oxidation zone of arsenic deposits (e.g. from arsenopyrite)
Paragenesis
Twinning
Rarity
Rather rare
Synonyms
Arseniosiderite
Composition
Elements
Mass
As₂O₅
42.67
Fe₂O₃
32.71
FeO
0.12
PbO
0.28
MgO
0.61
CaO
14.44
H₂O
9.34
0.40
Mexiko (Palache et al. 1952)
Groups and Members
Mitridatite-Group
Name and first discovery : Named after two of its main components, arsenic and iron (ancient Greek: sideros). First described in 1842.
Chemistry :
Synonyms : Arseniansiderite, Arsenocrocite, Mazapilite
Varieties :
Abbreviation : Assd
literature
Palache, C., Berman, H., & Frondel, C. (1952). Dana's system of mineralogy. Geologiska Föreningen i Stockholm Förhandlingar , 74 (2), 218-219.