Extremely rare as a cut gem, even in very complete collections. Many of the minerals in the tantalite group have been faceted; bismutotantalite is perhaps the rarest of them all. The color is attractive, but low hardness and good cleavage make use in jewelry unadvisable.
COMMENTS: Extremely rare as a cut gem, even in very complete collections. Many of the minerals in the tantalite group have been faceted; bismutotantalite is perhaps the rarest of them all. The color is attractive, but low hardness and good cleavage make use in jewelry unadvisable.
NAME: On account of the composition.
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