Chemistry:Bertrandite
| Bertrandite | |
|---|---|
 Bertrandite from the Golconda pegmatite, Minas Gerais, Brazil | |
| General | |
| Category | Sorosilicate |
| Formula (repeating unit) | Be4Si2O7(OH)2 |
| Strunz classification | 9.BD.05 |
| Crystal system | Orthorhombic |
| Crystal class | Pyramidal (mm2) H-M symbol: (mm2) |
| Space group | Ccm21 |
| Unit cell | a = 8.7135(4) Å, b = 15.268(1) Å, c = 4.5683(3) Å; Z = 4 |
| Identification | |
| Color | Colorless to pale yellow |
| Crystal habit | Thin tabular, prismatic to needle-like crystals commonly in radial clusters |
| Twinning | Common on {011} or {021} forming heart- or V-shaped twins |
| Cleavage | Perfect on {001}; distinct on {100}, {010} and {110} |
| Mohs scale hardness | 6–7 |
| |re|er}} | Vitreous, pearly on cleavage surfaces |
| Diaphaneity | Transparent |
| Specific gravity | 2.59–2.60 |
| Optical properties | Biaxial (−) |
| Refractive index | nα = 1.591 nβ = 1.605 nγ = 1.614 |
| Birefringence | δ = 0.023 |
| 2V angle | Measured: 73° to 81° |
| References | [1][2][3] |
Bertrandite is a beryllium sorosilicate hydroxide mineral with composition: Be4Si2O7(OH)2. Bertrandite is a colorless to pale yellow orthorhombic mineral with a hardness of 6–7.
It is commonly found in beryllium rich pegmatites and is in part an alteration of beryl. Bertrandite often occurs as a pseudomorphic replacement of beryl. Associated minerals include beryl, phenakite, herderite, tourmaline, muscovite, fluorite and quartz.[1]
It, with beryl, are ores of beryllium.
It was discovered near Nantes, France in 1883 and named after France mineralogist, Emile Bertrand (1844–1909).[1][2][3]
One of the world's largest deposits of bertrandite is Spor Mountain, Thomas Range, Utah which is currently the source of most of the world's beryllium production.[5][6]
See also
References
- ↑ 1.0 1.1 1.2 Handbook of Mineralogy
- ↑ 2.0 2.1 Bertrandite on Mindat.org
- ↑ 3.0 3.1 Bertrandite on Webmineral
- ↑ 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.
- ↑ Fact Sheet 2016–3081 (October 2016). "Beryllium—A Critical Mineral Commodity—Resources, Production, and Supply Chain" (in English) (Article). pubs.usgs.gov: USGS. pp. 4. https://pubs.usgs.gov/fs/2016/3081/fs20163081.pdf. Retrieved 16 May 2017.
- ↑ Shawe, Daniel (1968). Ridge, John. ed. Geology of the Spor mountain Beryllium District, Utah, in Ore deposits of the United States, 1933–1967. New York: The American Institute of Mining, Metallurgical, and Petroleum engineers, Inc.. pp. 1148–1161.
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