Bertrandite
Bertrandite | |
---|---|
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 |
Luster | 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 French 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.[4][5]
See also
References
- ^ a b c Handbook of Mineralogy
- ^ a b Bertrandite on Mindat.org
- ^ a b Bertrandite on Webmineral
- ^ Fact Sheet 2016–3081 (October 2016). "Beryllium—A Critical Mineral Commodity—Resources, Production, and Supply Chain" (Article). usgs.gov/. pubs.usgs.gov: USGS. p. 4. Retrieved 16 May 2017.
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: CS1 maint: numeric names: authors list (link) - ^ 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.