Iron oxides are chemical compounds composed of iron and oxygen. Cast iron, wrought iron, and steel were all used. Its major industries were iron and steel production. There are large iron and steel, chemical, and textile industries. Kosovo has large reserves of lead, zinc, silver, nickel, cobalt, copper, iron and bauxite. Varying amounts of potassium, sodium, phosphorus, calcium, magnesium, iron, and zinc were present. Then men learnt to use tough iron and copper. The Ozarks contain ore deposits of lead, zinc, iron and barite. Higher tensile wrought iron is brittle. Demand for tar declined with the advent of iron and steel ships. Their light shows evidence of elements such as carbon, magnesium, iron and oxygen. It is a compound of iron and titanium. Soldiers would often buy cast iron or brass knuckles. Their method was something similar to the method of carburization of wrought iron. The keel consisted of wooden beams bound together with iron hoops.