The Iron Age

Historians and archeologists use the term The Iron Age to refer to a period in human civilization when the apex technology was based on tools made from Iron.

About three thousand years ago Iron Age technology largely replaced the technology based on the metal Copper, and its alloys, from The Bronze Age.

Copper, Tin and Zinc ores can be processed into Bronze and Brass fairly simply, by heating their ores to the melting point of those metals, pouring off the slag, and pouring the molten alloy into molds. Iron ore is more common than the ores for Copper, Tin and Zinc, but Iron is more complicated to prepare.

Iron's most useful alloy, Steel, is an alloy of Iron and Carbon. Just a little bit of Carbon is required for the most useful steels, about one percent. However, since wood, coal or charcoal was used to heat iron ore to Iron's melting point, it was not possible to control the amount of Carbon the melted iron absorbed, while being heated. So, cast iron contains small inclusions of pure Carbon, making it too brittle for most tools. Cast iron is used for cooking pots.

Metalworkers who work with Iron and Steel are called blacksmiths. Instead of heating iron ore to iron's boiling point they heated iron ore to lower temperatures, where the Iron portion of the ore was still solid, but the rocky components melted. They then went through the labor intensive process of beating the hot billet with hammers. This would squeeze out the molten rocky components, called slag. With enough beating relatively pure metal would be left.

During the purification process some unburned Carbon, from the fire in their forge, would be absorbed through the metal's surface. Blacksmiths would be careful to manage how much Carbon they allowed in.

Billets with relatively low amounts of carbon were called "wrought iron". Steel with carbon at around one percent is sometimes called "high carbon steel". It can take a sharp edge.