Bertrandite Explained

Bertrandite
Category:Sorosilicate
Formula:Be4Si2O7(OH)2
Imasymbol:Btd[1]
Strunz:9.BD.05
System:Orthorhombic
Class:Pyramidal (mm2)
H-M symbol: (mm2)
Symmetry:Ccm21
Unit Cell:a = 8.7135(4) Å,
b = 15.268(1) Å,
c = 4.5683(3) Å; Z = 4
Color:Colorless to pale yellow
Habit:Thin tabular, prismatic to needle-like crystals commonly in radial clusters
Twinning:Common on or forming heart- or V-shaped twins
Cleavage:Perfect on ; distinct on, and
Mohs:6–7
Luster:Vitreous, pearly on cleavage surfaces
Diaphaneity:Transparent
Gravity:2.59–2.60
Opticalprop:Biaxial (−)
Refractive:nα = 1.591 nβ = 1.605 nγ = 1.614
Birefringence:δ = 0.023
2V:Measured: 73° to 81°
References:[2] [3] [4]

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]

See also

Notes and References

  1. Warr. L.N.. 2021. IMA–CNMNC approved mineral symbols. Mineralogical Magazine. 85. 3. 291–320. 10.1180/mgm.2021.43. 2021MinM...85..291W. 235729616. free.
  2. http://rruff.geo.arizona.edu/doclib/hom/bertrandite.pdf Handbook of Mineralogy
  3. http://www.mindat.org/min-642.html Bertrandite on Mindat.org
  4. http://webmineral.com/data/Bertrandite.shtml Bertrandite on Webmineral
  5. Web site: Fact Sheet 2016–3081. Beryllium—A Critical Mineral Commodity—Resources, Production, and Supply Chain. usgs.gov/. USGS. 16 May 2017. pubs.usgs.gov. 4. English. Article. October 2016.
  6. Book: Shawe . Daniel . Ridge . John . Geology of the Spor mountain Beryllium District, Utah, in Ore deposits of the United States, 1933–1967 . 1968 . The American Institute of Mining, Metallurgical, and Petroleum engineers, Inc. . New York . 1148–1161.