Use
olivine: An important group ofrock-forming silicate minerals crystallizingin the orthorhombic system.Olivine conforms to the general formula(Mg,Fe)2SiO4 and comprises acomplete series from pure magnesiumsilicate (forsterite, Mg2SiO4) topure iron silicate (fayalite, Fe2SiO4). Itis green, brown-green, or yellowgreenin colour. A gem variety ofolivine is peridot.