Niobium
. Niobium or Columbium, symbol Nb, steel-gray, lustrous, ductile, and malleable metallic element. The atomic number of niobium is 41. Niobium is one of the transition elements of the periodic table . This metal was discovered in 1801 by the British chemist Charles Hatchett. Niobium burns when heated in air and combines with nitrogen, hydrogen, and the halogens. It resists the actions of most acids. Its principal use is as an alloying element in stainless steel, to which it lends additional corrosion resistance, particularly at high temperatures. Niobium ranks about 32nd in natural abundance among the elements in crustal rock. It occurs, associated with the similar element tantalum , in various minerals, the most important of which is called columbite or tantalite, depending on which of the two elements predominates. Pure niobium has excellent characteristics as a construction material in nuclear power plants. Niobium melts at about 2468° C (about 4474° F), boils at about 5127° C (abo