English: Tungsten is a very hard, brittle, silvery heavy metal with a very high melting point. Its most famous application therefore is as filament in light bulbs, which is declining because of their bad energy efficiency. More often used than pure tungsten is tungsten carbide, WC, which is a very hard and mechanically enduring ceramic material. This is used for drills, milling machines and even for jewellery. Tungsten carbide is much cheaper than the related carbides of hafnium and tantalum. Some bacteria use tungsten in enzymes, which makes it the element with the highest number that has a biological role.