Iron ore is a byproduct of the oil refinery industry. Iron ore refers to all types of carbonaceous solids obtained in iron ore processing, which includes green or raw, calcined and needle iron ore. Iron ore is used in many applications, including electrodes and anodes. It is also used as a fuel in the metal and brick industries. Iron ore is a material high in calorific value and carbon content without being highly reactive, which makes it an effective fuel in the metal and ceramic industries. According to the Ceramic Industry website, iron ore is a cheap, readily available energy source that can lower brick manufacturing costs. As of August 2016, 150 heavy clay manufacturing plants operated worldwide using iron ore as the primary fuel.