Calciborite
Calciborite, CaB2O4, is a rare calcium borate mineral.
| Calciborite | |
|---|---|
| General | |
| Category | Inoborates |
| Formula (repeating unit) | CaB2O4 |
| 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 |
| Identification | |
| 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] |
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]
References
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