Benitoite Natrolite. Five fine, sharp benitoite crystals, nicely balanced on the matrix. — Photo: Rob Lavinsky · CC Attribution-Share Alike 3.0 Unported
Benitoite
A rare sapphire-blue barium-titanium ring silicate from California's serpentinites — it fluoresces bright blue under UV and is the state gem of California.
Intro adapted from Wikipedia (CC BY-SA).
Benitoite is an IMA-recognized mineral species in the silicate class, with the chemical formula BaTiSi₃O₉.
It crystallizes in the hexagonal crystal system (space group P-6c2). It is a member of the Benitoite structural group.
Key properties: Mohs hardness 6–6.5; specific gravity 3.65; typically blue or colorless; white streak; Vitreous luster; refractive index 1.78; optically uniaxial.
IMA symbol Bni, grandfathered status — known before the IMA’s founding, named in 1907.
Found in natrolite veins cutting glaucophane schist in a serpentine body (San Benito Co., California, USA); in a magnesio-riebeckite-quartz-phlogopite-albite dike cutting serpentinite (Ohmi, Japan).
It is found associated with Neptunite, joaquinite, natrolite (San Benito Co., California, USA); ohmilite, bario-orthojoaquinite, leucosphenite (Ohmi, Japan).
The name refers to the occurrence in San Benito Co., California, USA.
Collections: Gemstones, Collector Favorites, Rare & Remarkable.