A metalloid. A not quite metallic enough metal. They sure *look* like metal.... except when you drop it and it shatters like glass! Antimony would be one good example of this (though it's not quite as fragile as glass). The element however crumbles easily and is a skin irritant. All the more reason to appreciate its intricate crystalline structure in this handy container containing little pieces of 99.9999% pure Sb.