22 Kalliope
Its spectrum is M-type, but Kalliope does not appear to be metallic. It is similar to other M-types such as 21 Lutetia. Firstly, its density is far too low to be metal. Second, spectroscopic studies have shown evidence of hydrated minerals  and silicates, so the surface is probably stony. Kalliope also has a low radar albedo, unlike most metallic surfaces.