Iron is one of the most useful materials, but it starts out inside rock. Releasing it requires heat and chemical reactions.
The first people to discover how to do this started the Iron Age. As their fire burned, the iron-rich lumps of rock containing the fire must have got hot enough for the rock to soften and for the iron to flow out. Stomping on it with another stone changed its shape. Today we do all this in an iron and steel works.
