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A deep blue, sapphire-like gemstone with fiery yellow flashes. Benitoite is composed of a barium-titanium silicate. These rare and valuable crystals were first found close to the San Benito River in California, but have since been found in Montana, Arkansas, Australia, and Japan. Benitoite stones were formerly cut and sold as sapphires.

IR spectrum of benitoite from RRUFF
Raman spectrum of benitoite from RRUFF

Physical and Chemical Properties

  • Hexagonal crystal system with tabular dipyramidal crystals
  • Fracture = conchoidal to uneven
  • Luster = vitreous
  • Transparent to translucent
  • Streak = white
  • Fluorescence = blue stones fluoresce bright to chalky blue in SW; colorless stones fluoresce red under LW
  • Pleochroism = strong, usually blue and colorless
Composition BaTi(SiO3)3
Mohs Hardness 6.0 - 6.5
Density 3.65 - 3.68 g/ml
Refractive Index 1.756-1.757, 1.802-1.804
Birefringence 0.046

Resources and Citations

  • Gem Identification Lab Manual, Gemological Institute of America, 2016.
  • Thomas Gregory, The Condensed Chemical Dictionary, Reinhold Publishing, New York, 3rd ed., 1942
  • R.F.Symmes, T.T.Harding, Paul Taylor, Rocks, Fossils and Gems, DK Publishing, Inc., New York City, 1997
  • Wikipedia: Benitoite Accessed Dec 2022
  • Encyclopedia Britannica,,m/topic/Britannica-Online Comment: "Mineral." Accessed 12 May 2004 .

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