Chemical composition -- Aluminum silicate.
Color -- Blue, green, pink, white, yellow.
Optics -- R.I. 1.71-1.75. Biaxial negative.
Durability -- Hardness 4-7.5, varying with crystal orientation. Perfect cleavage in one direction.
Crystal structure -- Triclinic.
Specific Gravity-- 3.53-3.70.
Sources -- Many locales, including the USA (North Carolina, Virginia, Vermont, Georgia), India, Mozambique, Kenya.
Kyanite is seldom faceted due to difficulties in cutting and remains an unusual collector's gem.