Tantalum (Ta)
Only tiny amounts of tantalum are taken by plants: the amount in vegetation rarely exceeds 5 ppb. The chief tantalum ores are tantalite, which also contains iron, manganese and niobium, and samarskite, which contains seven metals. Another ore which contains tantalum and niobium is pyrochlore. The main mining areas are Thailandia, Australia, Congo, Brazil, Portigal and Canada. The demand of ...