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Mineralpedia Details for Bertrandite

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Bertrandite

Bertrandite

Named for French mineralogist Emile Bertrand. An uncommon mineral that is found in fissures in granite and associated pegmatites, as well as in crystal lined cavities in greisens, and is often found as an common alteration product of beryl, but rarely as a primary mineral. Numerous localities, however pure specimens and large crystals come from localities in France, the Czech Republic, Italy, the United States, Mexico, Brazil, Namibia, South Korea, and Kazakhstan. Minerals associated with Bertrandite include beryl, phenakite, herderite, tourmaline, muscovite, fluorite, and quartz. Bertrandite is pyroelectric and will generate a charge in response to temperature changes.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/bertrandite.pdf

Formula
Be4Si2O7(OH)2 
Crystal System
Orthorhombic 
Crystal Habit
Crystalline - Fine, Tabular, Prismatic 
Cleavage
Perfect, Distinct, Distinct 
Luster
Vitreous (Glassy) 
Color
colorless, pale yellow 
Streak
white 
Class
Orthorhombic - Pyramidal 
Fracture
Brittle 
Hardness
6-7 
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Bertrandite from Hayes mine, Greenwood, Oxford Co., United States

Bertrandite
            from Hayes mine, Greenwood, Oxford Co., United States
Special Info
Phillips Collection

Good eastern US pegmatite representative mineral from this important pegmatite province,

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Bertrandite from Kara-Oba W deposit, Betpakdala Desert, Karagandy, Kazakhstan

Bertrandite
            from Kara-Oba W deposit, Betpakdala Desert, Karagandy, Kazakhstan

White prismatic Bertrandite crystals to 3mm covering pink Rhodochrosite on Quartz with dark Sphalerite crystals.

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Bertrandite from Golconda pegmatite, Governador Valadares, Doce valley, Minas Gerais, Brazil

Bertrandite
            from Golconda pegmatite, Governador Valadares, Doce valley, Minas Gerais, Brazil

Colorless, sharp and well-defined orthorhombic crystals to maybe 0.75mm composing of the entire mass of this specimen.

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Bertrandite from Devil's Den, Boise Co., Idaho, United States

Bertrandite
            from Devil's Den, Boise Co., Idaho, United States

Colorless tiny and fabulous micro crystals lining the many crevices and vugs of this specimen.

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