blister copper

English Thesaurus

1. an impure form of copper having a black blistered surface (noun.substance)

hypernym	:	atomic number 29, copper, cu,
definition	:	a ductile malleable reddish-brown corrosion-resistant diamagnetic metallic element; occurs in various minerals but is the only metal that occurs abundantly in large masses; used as an electrical and thermal conductor (noun.substance)