Niobium is a chemical element. It is sometimes named columbium. It has the chemical symbol Nb. It has the atomic number 41. It is a rare metal. Niobium is soft and grey. It is ductile. In chemistry it is placed in a group of metal elements named the transition metals. Niobium was discovered in a variety of a mineral called columbite (now called niobite). Niobite is an ore of niobium. 