Niobium or columbium is a metallic element that has the symbol Nb and atomic number 41. Niobium is the official name used by chemical authorities but it is still called columbium by most in the metallurgical field. A rare, soft, gray, ductile transition metal, it does not tarnish or or oxidize at room temperature. Niobium is found in pyrochlore and columbite mainly in Canada and Brazil. It is used in special steel alloys as well as in welding, nuclear industries, electronics, optics, and jewelry.