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>> Group(s) : silicates
See the pictures :

It was discovered in the early twentieth century by the San Benito river in San Benito County, California.
Its color is very close to that of sapphire but its strong dichroism can easily distinguish it from sapphire, and even other blue stones.

Exploited sites

Single deposit: San Benito County, California, USA for gemstones, but it is present in Japan.

See pictures of the mines / other pictures

Use in jewelry

It is a stone for collectors, the crystals are small and only allow to be cut faceted some stones that rarely exceed a carat.

Looking alike stones

iolite , kyanite , sapphire , tanzanite , zircon

Imitations and treatments

no known imitations.

Chemical characteristics

barium titanium cyclosilicate mineral

Physical characteristics

Main color : blue

Other colors : colourless, pink, purple

Color of streak : white

Luster : vitreous

Hardness : 6.0 to 6.5

Density : 3.62 to 3.68

Cleavage : indistinct

Fracture : conchoidal, uneven

Optical properties

Transparency : transparent, translucent

only the very small crystals are transparent

Refractive Index : 1.755 - 1.805

Double refraction : 0.047

Strong, positive uniaxial

visible double refraction : yes

Dispersion : 0,045 (0.025)

Pleochroism : strong

Number of colors : 2

Colorless to blue

Fluorescence : strong



Small, flat and in double pyramid


Crystal system : hexagonal

Other informations
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