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Category Inoborates
(repeating unit)
Strunz classification 6.BC.10
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)
Space group Pccn
Unit cell a = 8.38 Å, b = 13.82 Å,
c = 5.00 Å; Z = 8
Formula mass 125.70 g/mol
Color White
Crystal habit Prismatic crystals and radial clusters
Cleavage None
Fracture Conchoidal to uneven
Mohs scale hardness 3.5
Luster Vitreous
Streak White
Diaphaneity Translucent
Specific gravity 2.878
Optical properties Biaxial (-)
Refractive index nα = 1.595 nβ = 1.654 nγ = 1.670
Birefringence δ = 0.075
2V angle Measured: 54°
References [1][2][3][4]

Calciborite, CaB2O4, is a rare calcium borate mineral.

It was first described in 1955 in the Novofrolovskoye copper–boron deposit, near Krasnoturinsk, Turinsk district, Northern Ural Mountains, Russia.[3] 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.[4] It has also been reported from the Fuka mine of Okayama Prefecture, Japan.[3]