Gold.

Cost: $ 56 per gram. addition to the traditional use in the jewelry industry, gold can be used as an electrical conductor, and to prevent corrosion. Gold - a very heavy metal: the density of pure gold is 19 621 kg / m? (a ball of pure gold with a diameter of 46 mm has a mass of 1 kg). Among the metal density in sixth place: after osmium, iridium, rhenium, platinum and plutonium. The high density of gold makes it easier to catch. The most simple technological processes such as, for example, flushing the gateway can provide a very high degree of recovery of gold from the rock to be washed.