Benitoite is an extremely rare mineral that is best known for being the official state gemstone of California. It is a barium titanium silicate mineral, usually blue in color, that is found in rocks that have been altered by hydrothermal metamorphism. Its chemical composition is BaTi(Si3O9).
Benitoite’s identification and original description was based upon specimens found in the headwaters of the San Benito River, in San Benito County, California, from which it received its name. Small amounts of benitoite have also been found at other locations in California, Arkansas, Montana, Australia, Czech Republic, Japan, and Romania. [1] The only location where gem-quality material has been found is in San Benito County, California.
Because of its rarity, gemstones and mineral specimens of benitoite are extremely expensive. It is a mineral rarely seen in jewelry or gem and mineral collections.