Be -Nb- is a chemical element with atomic number 41. A rare, soft, grey, ductile transition metal, niobium is found in the minerals pyrochlore, the main commercial source for niobium and columbite. Niobium has physical and chemical properties similar to those of the element tantalum, and the two are therefore difficult to distinguish. Brazil is the leading producer of niobium and ferroniobium, an alloy of niobium and iron. Niobium is used mostly in alloys, such as the specialized steel alloy used in gas pipelines.