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Benitoite (barium
titano-silicate)
Color: Ranges from deep blue to colorless.
Pink is very rare.
Moh’s hardness: 6-6..5
Refractive index: 1.757-1.804
Critical angle: 34.5°
Specific gravity: 3.65-3.68
Cleavage: None
Fracture: Conchoidal, brittle.
Dispersion: Strong to very strong (.039
& .046).
Heat sensitivity: None
Pleochroism: Dichroic - Very strong
(colorless to blue or green).
Birefringence (double refraction): Strong
(.047)
Crystal structure: Trigonal, bipyramidal.
Treatments: Heating
Polishing: Polishing may be problematic. Use
alumina or cerium oxide on standard polishing laps.
Comments: With one exception, benitoite is
only found in San Benito County in California. There is only one other
occurrence, which is a small deposit in Santa Cruz County, California.
OPAL Server
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