Chemistry:Berborite
| Berborite | |
|---|---|
 Berborite on natrolite | |
| General | |
| Category | Borate minerals |
| Formula (repeating unit) | Be2(BO3)(OH,F)•H2O |
| Strunz classification | 6.AB.10 |
| Dana classification | 26.1.1.1 |
| Crystal system | 1T polytype: Trigonal 2H polytype: Hexagonal 2T polytype: Trigonal |
| Crystal class | 1T polytype: Pyramidal (3) 2H polytype: Pyramidal (6) 2T polytype: Ditrigonal pyramidal (3m) |
| Space group | 1T polytype: P3 (no. 143) 2H polytype: P63 (no. 173) 2T polytype: P3c1 (no. 158) |
| Unit cell | a = 4.43 Å, c = 5.34 Å; Z = 2; V = 90.76 Å3 (2H polytype) |
| Identification | |
| Color | Colorless |
| Twinning | Complex |
| Cleavage | {0001} Perfect |
| Fracture | Uneven - Flat surfaces (not cleavage) fractured in an uneven pattern. |
| Mohs scale hardness | 3 |
| |re|er}} | Vitreous (Glassy) |
| Streak | white |
| Diaphaneity | Transparent |
| Density | 2.2 |
| Optical properties | Uniaxial (-) |
| Refractive index | nω = 1.580 nε = 1.485 |
| Birefringence | δ = 0.095 |
| Ultraviolet fluorescence | none |
| References | [1][2][3][4] |
Berborite is a beryllium borate mineral with the chemical formula Be2(BO3)(OH,F)·(H2O). It is colorless and leaves a white streak. Its crystals are hexagonal to pyramidal. It is transparent and has vitreous luster. It is not radioactive. Berborite is rated 3 on the Mohs Scale.[2]
Berborite occurs in 1T, 2T, 2H polytypes.[3]
It was first described in 1967 for an occurrence in the Lupikko Mine, Ladoga Region Karelia Republic, Russia . It has also been reported from Tvedalen, Larvik, Vestfold, and Siktesøya Island, Langesundsfjord, Porsgrunn, Telemark, Norway .[1][3] It occurs in serpentine altered dolomite in association with skarn enriched in tungsten, strontium, beryllium and boron in the Karelia occurrence and in vugs with natrolite and thomsonite in Norway.[2][3]
References
- ↑ 1.0 1.1 Mindat.org http://www.mindat.org/min-629.html
- ↑ 2.0 2.1 2.2 Webmineral.com http://www.webmineral.com/data/Berborite.shtml
- ↑ 3.0 3.1 3.2 3.3 Handbook of Mineralogy
- ↑ Mineralienatlas
- ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine 85 (3): 291–320. doi:10.1180/mgm.2021.43. Bibcode: 2021MinM...85..291W.
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