Mineral class: silicates
Crystal system: hexagonal
Mohs scale: 6 - 6.5
Density (g/cm3): 3.64 - 3.68
Refractive index: 1.757 - 1.804
Colors: colorless, orange, rose, purple, blue
Pleochroism: colorless - greenish-blue
Largest faceted Benitoite: 15.42 ct
Deposits: See my special page!
1st Description: 1907
Name: after the type locality in San Benito County / California / USA
Discovery of Benitoite in February 1907 by prospector James M. Couch. He staked claims in the name of Roderick W. Dallas in the area of the Diablo Mountains / San Benito County, searching for cinnabar or copper ores. At a hillside he spotted an interesting outcrop of rocks, detected a human-sized cave, and stepped into it. Before his feet lay thousands of blue crystals, and even more were weathered out of the white natrolite vains in the walls: Benitoite! Some crystals were sent to a San Francisco jeweler for cutting.
Finally G.D. Louderback, professor of geology at the University of California in Berkeley, was asked for identification of the unknown stones. He identified them as a new mineral, and described it in the same year, in 1909 more detailed.
Use of dynamite to ease the mining work. Only about 1% of the benitoites "survived" these "activities".
Establishment of the "Dallas Mining Company". Erection of a mine camp.
Closure of the mine in 1912 because Dallas thought that the mine had been "pinched out."
Briefly re-opening of the mine in 1933, then the mine was leased to various individuals.
Buzz Gray and Bill Forrest leased the mine in 1967.
In 1985 Benitoite became California’s State Gemstone.
Buzz Gray and Bill Forrest purchased the mine in 1987, expanded the property, tested it, and renamed it "Benitoite Gem Mine".
AZCO Mining, Inc. leased the mine in 1997 but were not very successful despite larger investments.
Collector's Edge Minerals, Inc. purchased the mine in 2000.
Collector's Edge sold the mine to Dave Schreiner of Coalinga in 2005. Dave is under a contractual agreement that prevents him from doing any heavy mining on the property until 2015.
He is allowing people, for a fee, to dig on the property however.
Origin: California / USA
Benitoite Brooch "Butterfly"
Benitoites: Body: 5,96 ct; wings: 28,71 ct; eyes: orange benitoite; antennas: colorless benitoites.
San Benito County / California / USA
Size: appr. 6.4 x 5.7 cm
Photo: © Robert Weldon; image by kind permission of the owners © Bernadine Johnston and Buzz Gray
Benitoite Mineral / UV Light
Size: 2.4 x 2.2 x 1.8 cm
Origin: Dallas Gem Mine / San Benito County / California / USA
Photo by kind permission of © www.lucianabarbosa.com