Aluminum is a silver-white metal, the third most abundant in the earth's crust after oxygen and silicon. The density of aluminum is relatively small, only 34.61% of iron and 30.33% of copper, so it is also called a light metal. Aluminum is the world's largest non-ferrous metal after steel in production and consumption. The density of aluminum is only 2.7103g/cm³, which is about 1/3 of the density of steel, copper or brass. Due to its light material, aluminum is often used in the manufacture of land, sea and air vehicles such as automobiles, trains, subways, ships, airplanes, rockets, and spaceships to reduce its own weight and increase its loading capacity.