Answer: niobium

AnswerCrossword Clue
NIOBIUMElement in stainless steel
NIOBIUMElement used in alloy steels
NIOBIUMIts principal ore is columbite
NIOBIUMElement named for a mythical queen
niobiumsteel-gray metallic element resembling tantalum in its chemical properties; becomes a superconductor below 9 K; used chiefly in alloy steels. Symbol: Nb; at. no.: 41; at. wt.: 92.906; sp. gr.: 8.4 at 20┬░C