Cast iron

[Sarah]

Highly carbonized iron, the direct product of the blastfurnace; -- used for making castings, and for conversion into wroughtiron and steel. It can not be welded or forged, is brittle, andsometimes very hard. Besides carbon, it contains sulphur, phosphorus,silica, etc.

[Mark Zuckerberg]

a type of hard iron that will not bend easily and is made into shapes by being poured into a mould when melted