Bertrandite
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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... Wikipedia
Crystal class: Pyramidal (mm2); H-M symbol: (mm2)
Crystal habit: Thin tabular, prismatic to needle-like crystals commonly in radial clusters
Crystal system: Orthorhombic
Formula (repeating unit): Be4Si2O7(OH)2
Mohs scale hardness: 6–7
Optical properties: Biaxial (−)
Space group: Ccm21
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