Benitoite | Gemopedia

Benitoite is a single-source gemstone, meaning that so far, it has been found in only one place on Earth: San Benito County, California. Benitoite grows in relatively small crystals, only a portion of which are gem quality--further increasing the rarity and value of this unique gemstone. Gem-quality benitoite over one carat is incredibly difficult to come by. California's state gemstone, benitoite is especially prized by collectors for its strong dispersion, which rivals that of diamond in lighter material.
Colors
Blue, Violetish Blue, Colorless, Zoned With Light Blue, White, Very Rarely Pink

Benitoite Classification

Common Name

Benitoite

Species

Benitoite

Variety

Colors

Blue, Violetish Blue, Colorless, Zoned With Light Blue, White, Very Rarely Pink

Alternate Names

Gemstone Groups

Key Separations

refractive index, birefringence, optic character, pleochroism and possibly fluorescence

Comments

Benitoite Optical Properties

Transparency

Transparent

Refractive Index

Over the Limit 1.757-1.804

Birefringence

0.047-0.047

Optic Character

Uniaxial

Optic Sign

Positive

Polariscope Reaction

Doubly Refractive (DR)

Fluorescence

SWUV: Inert to strong bluish white
LWUV: Inert to weak red

CCF Reaction

Pleochroism

Dichroic, strong blue and colorless

Dispersion

Strength: moderate fire Value: 0.044

Comments

Benitoite Chemistry & Crystallography

Chemical Name

barium titanium silicate

Chemical Formula

BaTiSi3O9

Synthesis

Crystal System

Hexagonal

Classification

Silicate

Nature

Natural

Crystallinity

Crystalline

Comments

Benitoite Characteristic Physical Properties

Hardness

6-6.5

Streak

White

Specific Gravity

3.61-3.69 Range:0.01/-0.07 Typical:3.68

Toughness

Fair

Inclusions

Benitoite may be color zoned with strong pleochroism.

Luster

Vitreous

Stability

Fracture

Conchoidal, Uneven

Cleavage

Poor, in one direction

Comments

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