Garnierite (Si4O13[Ni, Mg]2•2 H2O) is a general name for a green nickel mineral found in deposits and veins within weathered and serpentinized ultramafic rocks. It forms from the erosion of ultramafic lateritic rocks and occurs in many of the world's lateritic nickel deposits. It is an important nickel mineral, containing a high percentage of NiO by weight.