ber·​trand·​ite | \ ˈbər-trən-ˌdīt\
plural -s

Definition of bertrandite

: a mineral Be4Si2O7(OH)2 consisting of a beryllium silicate occurring in hard colorless or pale-yellow prismatic crystals (hardness 6–7, specific gravity 2.59–2.60)

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History and Etymology for bertrandite

French, from E. Bertrand, 19th century Frenchman who first described it + French -ite

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