bertrandite

noun

ber·​trand·​ite

ˈbər-trən-ˌdīt

plural -s

: 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)

Word History

Etymology

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

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