Olivine is a group of minerals characterised by their green colour, the typical olivine has the formulae (Mg,Fe)2SiO4 and a relative hardness of 7. It's name is derived from the characteristic olive green colour. A common rock forming mineral. A clear green variety is called peridot and has some uses as a gem.
Olivine minerals are hard and resistant to heat, and are used as abrasives and refractory sands. Research Olivine