Mineral Information and Data:

Bariandite
Al0.6(V5+,V4+)8O20 • 9H2O [CNMNC approved formula]

Named for Pierre Bariand (1933-), French mineralogist.

IMA status : Approved Species 1971 (IMA1970-043)
CLASSIFICATION 
Dana
(8th edition) :
47.03.02.04  
  (47) Vanadium Oxysalts
  (47.03) (Hydrated)
  (47.03.02) Straczekite Group
  
Nickel-Strunz
(10th edition) :
04.HE.20
  (04) Oxides and Hydroxides
  (04.H) V[5+,6+] Vanadates
  (04.HE) Phyllovanadates
  
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Unit cell: a = 11.7Å, b = 3.63Å; c = 20.06Å β = 101.5°
Crystal Habit: Crystals elongated || [010], forming fibers, platy on {001}, to 3 mm; in sheeted aggregates of parallel fibers, such layers sometimes stacked.
  
Color: Black to dark green; in reflected light shows green internal reflections.
Diaphaneity: Nearly opaque
Measured Density: ~2.7 g/cm3
Cleavage: {001}, perfect
  
Geologic Setting: In the oxidation zone of a uranium mineral deposit (Mounana mine, Gabon); in the oxidation zone of a vanadium deposit (Minasragra, Peru).
Mineral Association: Duttonite, lenoblite (Mounana mine, Gabon); roscoelite, gypsum (Minasragra, Peru)
  

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