General Information:
Chemical Formula:(Al,Fe+++)1.3(V++++,Fe)8O20·4.7(H2O)
Composition:(Molecular Weight = 858.38 gm)Aluminum 3.14 %
AlVanadium 44.51 %
V Iron 5.20 %
FeHydrogen 1.10 %
H Oxygen 46.04 %
O Empirical Formula: AlFe3+0.3V4+7.5Fe3+0.5O204.7(H2O)
IMA Status:Approved IMA 1963
Locality:Kurumsak area, Kazakhstan.
Name Origin:Named for Ivan I. Bok, (1898-), Kazakh mineralogist.
Physical Properties: Cleavage:[???] Perfect
Color:black.
Density:2.97 - 3.1, Average = 3.03
Diaphaniety:Opaque
Habits:Reniform - "Kidney like" in shape (e.g.. hematite)., Encrustations - Forms crust-like aggregates on matrix., Radial - Crystals radiate from a center without producing stellar forms (e .g. stibnite)
Hardness:3 - Calcite
Luster:Metallic - Dull
Streak:brownish black
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