Colour: Found in shades of purple, lilac or mauve.
Hardness: 7 (on Moh’s hardness scale.)
Specific Gravity: 2.65. This is an indication of the stone's density, calculated by comparing the stone's weight with the weight of an equal volume of water.
Refractive Index: 1.54 to 1.55. This is a measure of the amount light is bent from its original path when passing through a stone.
Chemical composition: Silicon dioxide. Part of the Quartz family of minerals.
Principal sources: Brazil, Russia, Canada, Sri Lanka and India.