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Benitoite on natrolite
Chemical formulaBaTiSi3O9
(barium titanium silicate)
ColorBlue; Colorless
Crystal habitTabular dipyramidal crystals, granular
Crystal systemHexagonal
Cleavage[1011] Poor
Mohs Scale hardness6 - 6.5
Refractive index1.757-1.759; 1.802-1.804
PleochroismDichroic (blue to white)
Specific gravity3.6
SolubilityInsoluble: HCl, H2SO4
Soluble: HF
DiaphaneityTransparent to translucent

Benitoite is a rare blue silicate mineral, found in hydrothermally altered serpentinite. Benitoite fluoresces under short wave ultraviolet light, appearing light blue in color. Dr. Louderback, who conducted the discovery examination of this mineral, named it Benitoite, “as it occurs near the head waters of the San Benito River in San Benito County,” California.[3][4]


Uses of benitoite

Benitoite's rarity makes it a minor ore for barium or titanium at best. Rather, benitoite's main uses are as collector's specimens, especially in specimens which show off this mineral's unique crystals, or specimens in which benitoite occurs with its commonly associated minerals. Benitoite's hardness also makes it suitable for use as a gemstone, though the general lack of usable material has limited this use.

Associated minerals and locations

Benitoite typically occurs with an unusual set of minerals, along with minerals that make up its host rock. Frequently associated minerals include:

natrolite Na2Al2Si3O10 · 2H2O
neptunite KNa2Li(Fe, Mn)2Ti2Si8O24
joaquinite NaBa2FeCe2(Ti, Nb)2(SiO3)8(OH, F) · 1H2O
serpentine (Mg, Fe)3Si2O5(OH)4
albite NaAlSi3O8

  Benitoite is a rare mineral, found in very few locations, most prominently in southern San Benito County, California, but also in Japan and Arkansas. In the San Benito occurrence it is found in natrolite veins within glaucophane schist within a serpentinite body. In Japan it occurs in a magnesio-riebeckite-quartz-phlogopite-albite dike cutting a serpentinite body.[5] Benitoite is typically found with some combination of natrolite, joaquinite, and neptunite on a greenish-grey serpentinite base. Finally, benitoite's fluorescence is used for identification purposes.


Benitoite is the official state gem of California.[6]

Benitoite is the official gem of E Clampus Vitus.


  1. ^ WebMineral Listing
  2. ^ MinDat Listing
  3. ^ Louderback, George Davis. Bentiote, A New California Gen Mineral. Bulletin of The Department of Geology, Vol. 5, No. 9. University of California Publications. July, 1907
  4. ^ Friends of Mineralogy review of benitoite
  5. ^ Handbook of Mineralogy
  6. ^ Mineral Resources California Geologic Survey. Accessed December 31, 2005
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Benitoite". A list of authors is available in Wikipedia.
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