... , stannum, tungsten, tantalum, niobium, gold ore, colliery, monazite, rutile and zircon of the size between 0.3 and 0.02mm, metals ... , stannum, tungsten, tantalum, niobium, gold ore, colliery, monazite, rutile and zircon of the size between 0.3 and 0.02mm, metals ...