Peridot
Always green, only green: the colour comes from iron in the mineral's own recipe, not from an impurity, so it cannot grow any other way.
Hardness — 6.5 to 7 Care — avoid acids and hard knocks Source — Arizona, Pakistan
Peridot
Gem olivine — one of the few stones that forms in the mantle rather than the crust, and it occasionally arrives in meteorites.