Bertrandite

Bertrandite
Bertrandite
	Bertrandite from the Golconda pegmatite, Minas Gerais, Brazil
General
Category	Sorosilicate
Formula; (repeating unit)	Be4Si2O7(OH)2
IMA symbol	Btd
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

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.^[2]

It, with beryl, are ores of beryllium.

It was discovered near Nantes, France in 1883 and named after French mineralogist, Emile Bertrand (1844–1909).^[2]^[3]^[4]

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]

References[]

^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
^ ^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.
^ 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.

[1] Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.

[HBM-2] Handbook of Mineralogy

[Mindat-3] Bertrandite on Mindat.org

[Webmin-4] Bertrandite on Webmineral

[USGS1-5] 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.

[Full1968-6] 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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[2]

[3]

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[5]

[6]

Bertrandite

See also[]

References[]