Bismutotantalite Value, Price, and Jewelry Information
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.
By Joel E. Arem, Ph.D., FGA, updated on
STREAK: Yellow-brown to black
OPTICS: α = 2.388; β = 2.403; γ = 2.428
Biaxial (+), 2V = 80°
OCCURRENCE: Pegmatites.
Gamba Hill, Uganda; Acari, Brazil.
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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