Fluor-uvite
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Fluor-uvite is a tourmaline mineral with the chemical formula CaMg₃(BO₃)₃(OH)₃F. It is a rare mineral that is found in calcium rich contact metamorphic rocks with increased amounts of boron. Wikipedia
Crystal class: Ditrigonal pyramidal (3m); H-M symbol: (3m)
Crystal system: Trigonal
Formula (repeating unit): CaMg3(Al5Mg)(Si6O18)(BO3)3(OH)3F