Color:
Colorless, blue and very rarely pink
Clarity: Type
II
Optic Character: DR
Uniaxial Positive
Cause
of Color: Charge
transfer involving Fe and Ti
Fluorescence: Inert
LW; Strong chalky blue SW
Fracture
: Concoidal to
uneven
Luster
: Vitreous
Cleavage : One
direction; indistinct
Durability: Fair
Characteristics
for Identification:
High
dispersion, color zoning, strong pleochroism, high birefringence
Localities:
San Benito County, California, USA
(only known source)
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Benitoite
BaTiSi3O9
(barium titanium silicate)
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 occurres at San
Benito, California, it has been designated the California
state gemstone. Crystals, and cut stones, tend to be small
and quite expensive!
Associated
Minerals:
Neptunite
Natrolite
Joaquinite
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Benitoite is highly fluorescent.
The Gemology Project: Benitoite
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