Mineral Information and Data:

Na2V5+6O16 • 3H2O [CNMNC approved formula]

Named for William H. Barnes (1903- ), National Research Council of Canada, Ottawa, Canada, authori.

IMA status : Approved Species 1963 ()
(8th edition) :  
  (47) Vanadium Oxysalts
  (47.03) (Hydrated)
  (47.03.01) Hewettite Group
(10th edition) :
  (04) Oxides and Hydroxides
  (04.H) V[5+,6+] Vanadates
  (04.HG) Unclassified V oxides
Crystal system: Monoclinic System
Point group (H-M): 2/m — prismatic
Space group: P2/m
Unit cell: a = 12.17Å, b = 3.602Å, c = 7.78Å; β = 95.03°
Crystal Habit: As small clusters of subparallel to radiating bladed to fibrous crystals, elongated along [010], to 0.5 mm; in spherical aggregates, and as botryoidal to velvety coatings.
Color: Brilliant dark red; brownish red on exposure
Diaphaneity: Semitransparent
Luster: Adamantine, less brilliant after exposure
Hardness (Mohs): 3
Measured Density: 3.09 – 3.15 g/cm3
Cleavage: {001}, perfect; {100}, {010}, fair
Tenacity: Fragile, prone to smearing.
Geologic Setting: In small cavities and fractures and as interstitial filling in sandstone in the oxidized zone of a vanadiferous uranium deposit, possibly formed as an oxidation product of hewettite (Cactus Rat mines, Utah, USA); in weathered black schist (Kazakhstan).
Mineral Association: Metahewettite, thenardite (Cactus Rat mines, Utah, USA); bokite (The Fish, Nevada, USA); hewettite, metahewettite, jarosite, alunite, gypsum, barite (Kazakhstan).