| NiAs2-3This sample of nickel-skutterudite is displayed in the Smithsonian Museum of Natural History. Nickel-skutterudite is an arsenide of nickel  with the composition NiAs2-3.  The sample at left is about 6 cm across and is from Schneeberg, Sachsen, Germany.   Skutterudite is the corresponding cobalt mineral , CoAs3 |