What is Cast iron?
[[Image:Cast-iron_pan_with_a_blue_handle_-_20060905.jpg|thumb|A cast iron [[pan]]]] '''Cast iron''' is an [[alloy]] of [[iron]]. The term is usually used for '''grey cast iron'''. There are two main types of cast iron: ''grey cast iron'' and ''white cast iron''. The differences between the two are mainly based on the amount of [[silicon]] in the alloy. All cast iron has about 95% iron in it. Grey cast iron has 3% silicon and 2% [[carbon]]. White cast iron has less silicon. The silicon in grey cast iron causes the carbon to change into [[graphite]]. This causes it to have a dark grey or almost black [[color]]. With less silicon, the carbon in white cast iron changes to [[cementite]] or ''iron carbide'' (Fe<sub>3</sub>C). This causes white [[Fracture (mineralogy)|fractures]] to form on the surface and give white cast iron the name. Grey cast iron is very good at [[conduction|conducting]] heat. Because of this, it is often used to make [[cook]]ware. [[Category:Alloys]] [[Category:Iron]]