BENITOITE

benitoite, a mineral discovered in 1907 near the headwaters of the san benito river, san benito co., california, and described by prof. g.d. louderback. it is a titano-silicate of barium (batisi3o9), crystallizing in the hexagonal system, with a hardness of 6.5, and specific gravity 3.65. it may be colourless or blue, the colour varying sometimes in different parts, and passing to a deep sapphire blue. the blue variety is cut as a gem stone, and often resembles blue spinel, though its softness distinguishes it from spinel and sapphire. it is a brilliant stone, with high refractive index, and is strongly dichroic, being pale when viewed parallel to the principal axis and dark when viewed transversely.