Formula: BaTiSi₃O₉
Mineral class: silicates
Crystal system: hexagonal
Mohs scale: 6 - 6.5
Density (g/cm³): 3.6
Cleavage: poor
Colors: blue, purple, rose, clear
Luster: vitreous
Fluorescence: blue
Pleochroism: colorless - greenish-blue
Largest faceted Benitoite: 15.42 ct
Deposits: See my special page!
1st Description: 1907
History:
• 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.
• B. Grey and B. Forrest leased the mine in 1967.
• In 1985 Benitoite became California’s State Gemstone.
• B. Grey and B. 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.
Sources:
www.collectorsedge.com
www.tucsonshowguide.com
www.attawaygems.com

Benitoite

Weight: 0.62 ct

Origin: California / USA

Photo by kind permission of © www.djraregems.com, Donna & John Rhoads.

Benitoite

Weight: 0.64 ct

Origin: California / USA

Photo by kind permission of © www.americanthai.com, Scott Davies.

Benitoite

Weight: 0.36 ct

Origin: California / USA

Photo by kind permission of © www.multicolour.com, David Weinberg.