Colour: Found in an array of shades from olive green to lime green in colour.
Hardness: 6Ĺ (on Mohís hardness scale).
Specific Gravity: 3.34. 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: 1.64 to 1.69. This is a measure of the amount light is bent from its original path when passing through a stone.
Chemical composition: Magnesium iron silicate.
Principal sources: St Johnís Island (Egypt), China, Brazil and Hawaii.