Hambergite
| Hambergite | |
|---|---|
2.3 x 1.1 x 1 cm crystal of hambergite on albite from Paprok, Nuristan Province, Afghanistan
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| General | |
| Category | Borate mineral |
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Formula (repeating unit) |
Be2BO3OH |
| Strunz classification | 6.AB.05 |
| Crystal system | Orthorhombic |
| Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
| Space group | Pbca |
| Unit cell | a = 9.71, b = 12.2 c = 4.42 [Å]; Z = 8 |
| Identification | |
| Color | Colorless, pale gray, pale yellow |
| Crystal habit | Prismatic crystals |
| Twinning | On {110} |
| Cleavage | Perfect on {010}, good on {100} |
| Tenacity | Brittle |
| Mohs scale hardness | 7.5 |
| Luster | Vitreous |
| Streak | White |
| Diaphaneity | Transparent to translucent |
| Specific gravity | 2.347–2.372 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.554 - 1.560 nβ = 1.587 - 1.591 nγ = 1.628 - 1.631 |
| Birefringence | δ = 0.074 |
| 2V angle | 87° |
| References | |
Hambergite (Be2BO3OH) is a beryllium borate mineral named after Swedish explorer and mineralogist Axel Hamberg (1863–1933). The mineral occurs as white or colorless orthorhombic crystals.
Hambergite occurs in beryllium bearing granite pegmatites as a rare accessory phase. It occurs associated with beryl, danburite, apatite, spodumene, zircon, fluorite, feldspar and quartz.
It was first described by mineralogist and geographer W. C. Brøgger in 1890. The type locality is Salbutangen, Helgeroa, Langesundsfjorden, Larvik, Vestfold, Norway where it was found in a pegmatite dike of nepheline syenite composition.
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