Mineral - Bariandite
Bariandite
Chemical Properties
Mineral Class
Vanadates
Toxicity
radioactive
Formula
Al₀,6(V⁵⁺,V⁴⁺)₈O₂₀ · 9H₂O
Unit Cell
a=11.70 b=3.63 c=20.06 β=101° Z=2
Physical Properties
Hardness
3
Streak
blackbrown
Density
Normal (2-3,5)
Cleavage
Perfect after {001}
Fracture
Tenacity
Optical Properties
Color
blackbrowngreenbrown blackgreen black
Birefringence
0.000
Luster
Greasy,
Metallic
Transparency
opaque
Pleochroism
X: Schwarz
Y: Grün-Schwarz
Geomineralogical Properties
Crystal System
monoclinic
Point Group
monoclinic-prismatic - 2/m
Space Group
C2/c (15)
Habit
acicular, radial, prismatic, radial
Formation
In the oxidation zone of supergene, vanadium-containing uranium deposits
Paragenesis
Twinning
Rarity
Rare
Synonyms
Bariandite
Composition
Elements
Mass
V₂O₅
63.26
V₂O₄
14.19
Al₂O₃
3.75
Fe₂O₃
0.17
H₂O
18.11
Gabon (Cesbron & Vachey 1971)
Groups and Members
Straczekite-Group
Name and first discovery: Named after the French mineralogist Dr Pierre Bariand (1933-2021). First described in 1970.
Chemism:
Synonyms:
Varieties:
Abbreviation: Brd
Literature
Cesbron, F., & Vachey, H. (1971). La bariandite, nouvel oxyde hydraté de vanadium (IV) et (V). Bulletinde Minéralogie, 94(1), 49-54.