Calciborite

Calciborite, CaB2O4, is a rare calcium borate mineral.

Calciborite
White crystals of calciborite from the type locality in Russia (Novofrolovskoye Deposit)
General
CategoryInoborates
Formula
(repeating unit)
CaB2O4
IMA symbolCbo[1]
Strunz classification6.BC.10
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space groupPccn
Unit cella = 8.38 Å, b = 13.82 Å,
c = 5.00 Å; Z = 8
Identification
Formula mass125.70 g/mol
ColorWhite
Crystal habitPrismatic crystals and radial clusters
CleavageNone
FractureConchoidal to uneven
Mohs scale hardness3.5
LusterVitreous
StreakWhite
DiaphaneityTranslucent
Specific gravity2.878
Optical propertiesBiaxial (-)
Refractive indexnα = 1.595 nβ = 1.654 nγ = 1.670
Birefringenceδ = 0.075
2V angleMeasured: 54°
References[2][3][4][5]

It was first described in 1955 in the Novofrolovskoye copper–boron deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, Russia.[4] It occurs in a skarn deposit formed in limestone adjacent to a quartz diorite intrusive. It occurs associated with: sibirskite (another rare calcium borate mineral), calcite, dolomite, garnet, magnetite and pyroxene.[5] It has also been reported from the Fuka mine of Okayama Prefecture, Japan.[4]

References


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