Chemical composition -- A complex silicate.
Color -- Lavender, purple, reddish violet.
Optics -- R.I. 1.60-1.61, unaxial negative.
Durability -- Hardness 6-6.5.
Crystal structure -- Hexagonal.
Specific Gravity -- 2.74.
Sources -- South Africa is the primary source. Fine, deep purple material is used for cabochons, inlays, and ornamental objects. A few small translucent pieces have been faceted.