Mineral - Ardennite-(As)
Ardennite-(As)
Chemical Properties
Mineral Class
Silicates
Toxicity
low
Formula
Mn²⁺₄Al₄(Al,Mg)(AsO₄)(SiO₄)₂(Si₃O₁₀)(OH)₆
Unit Cell
a=8.71 b=18.51 c=5.81 Z=2
Physical Properties
Hardness
6 - 7
Streak
white
Density
Heavy (3,5-6)
Cleavage
Perfect after {010}, indistinc after {110}
Fracture
conchoidal,
uneven
Tenacity
Brittle
Optical Properties
Color
brownorangeyellow
Birefringence
0.015
Luster
Vitreous,
Greasy
Transparency
translucent,
opaque
Pleochroism
X: Braun
Y: Orange
Z: Gelb
Geomineralogical Properties
Crystal System
orthorhombic
Point Group
orthorhombic-dipyramidal - 2/m 2/m 2/m
Space Group
Pmmm (47)
Habit
coarse, fibrous, massive, acicular, tabular
Formation
In quartz veins of metamorphic overprinted Mn-rich metasediments
Paragenesis
Twinning
Rarity
Rarely
Synonyms
Ardennite-(As), Ardennite
Composition
Elements
Mass
SiO₂
27.85
Al₂O₃
23.55
Fe₂O₃
0.86
As₂O₅
13.25
V₂O₅
0.89
MnO
25.70
CuO
0.26
MgO
2.30
CaO
1.17
H₂O
5.12
Belgium (Dana 1892)
Groups and Members
Ardennite-Group