Benitoite
| From The Gemology Project | In affiliation with GemologyOnline.com |
From The Gemology Project
You can contribute to this topic through the submission page.| Benitoite | |
|---|---|
| Chemical composition | BaTiSi3O9 |
| Crystal system | Trigonal |
| Habit | Bipyramids |
| Cleavage | None |
| Fracture | Conchoidal |
| Hardness | 6.5 |
| Optic nature | Uniaxial + |
| Refractive index | 1.75-1.80 |
| Birefringence | 0.047 |
| Dispersion | High, 0.046 |
| Specific gravity | 3.65 |
| Lustre | Bright vitreous |
| Pleochroism | Strong |
Beniotite is a very rare mineral that was discovered in 1907 in San Benito County in California. It has never been found elsewhere. It was originally mistaken for sapphire. Benitoite is very highly dispersive (the ability to take white light and disperse it into various components of the spectrum). Benitoite is associated with other rare minerals such as black-red neptunite, snow white natrolite and brown-yellow joaquinite. Since the only source of this rare combination occurs at San Benito County, California, it has been designated the California state gemstone. Crystals, and cut stones, tend to be small and quite expensive!
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