Ferrous metallurgy is the metallurgy of iron and its alloys. The earliest surviving prehistoric iron artifacts, from the 4th millennium BC in Egypt, were made from meteoritic iron-nickel. It is not known when or where the smelting of iron from ores began, but by the end of the 2nd millennium BC, iron was being produced from iron ores in the region from Greece to India, The use of wrought iron (worked iron) was known by the 1st millennium BC, and its spread defined the Iron Age. During the medieval period, smiths in Europe found a way of producing wrought iron from cast iron, in this context known as pig iron, using finery forges. All these processes required charcoal as fuel. By the 4th century BC southern India had started exporting wootz steel, with a carbon content between pig iron and wrought iron, to ancient China, Africa, the Middle East, and Europe. Archaeological evidence of cast iron appears in 5th-century BC China. New methods of producing it by carburizing bars of iron in the cementation process were devised in the 17th century. During the Industrial Revolution, new methods of producing bar iron emerged, by substituting charcoal in favor of coke, and these were later applied to produce steel, ushering in a new era of greatly increased use of iron and steel that some contemporaries described as a new "Iron Age". In the late 1850s Henry Bessemer invented a new steelmaking process which involved blowing air through molten pig-iron to burn off carbon, and so producing mild steel. This and other 19th-century and later steel-making processes have displaced wrought iron. Today, wrought iron is no longer produced on a commercial scale, having been displaced by the functionally equivalent mild or low-carbon steel.
Meteoric iron
Iron was extracted from iron–nickel alloys, which comprise about 6% of all meteorites that fall on the Earth. That source can often be identified with certainty because of the unique crystalline features (Widmanstätten patterns) of that material, which are preserved when the metal is worked cold or at low temperature. Those artifacts include, for example, spear tips and ornaments from ancient Egypt and Sumer around 4000 BC. These early uses appear to have been largely ceremonial or decorative. Meteoric iron is very rare, and the metal was probably very expensive, perhaps more expensive than gold. The early Hittites are known to have bartered iron (meteoric or smelted) for silver, at a rate of 40 times the iron's weight, with Assyria in the first centuries of the second millennium BC. Meteoric iron was also fashioned into tools in the Arctic when the Thule people of Greenland began making harpoons, knives, ulus and other edged tools from pieces of the Cape York meteorite. Typically pea-size bits of metal were cold-hammered into disks and fitted to a bone handle. These artifacts were also used as trade goods with other Arctic peoples: tools made from the Cape York meteorite have been found in archaeological sites more than 1,000 miles (1,600 km) distant. When the American polar explorer Robert Peary shipped the largest piece of the meteorite to the American Museum of Natural History in New York City in 1897, it still weighed over 33 tons. Another example of a late use of meteoric iron is an adze from around 1000 AD found in Sweden.
Native iron
Native iron in the metallic state occurs rarely as small inclusions in certain basalt rocks. Besides meteoritic iron, Thule people of Greenland have used native iron from the Disko region.
Iron smelting and the Iron Age
Iron smelting—the extraction of usable metal from oxidized iron ores—is more difficult than tin and copper smelting. While these metals and their alloys can be cold-worked or melted in relatively simple furnaces (such as the kilns used for pottery) and cast into molds, smelted iron requires hot-working and can be melted only in specially designed furnaces. Iron is a common impurity in copper ores and iron ore was sometimes used as a flux, thus it is not surprising that humans mastered the technology of smelted iron only after several millennia of bronze metallurgy. The place and time for the discovery of iron smelting is not known, partly because of the difficulty of distinguishing metal extracted from nickel-containing ores from hot-worked meteoritic iron. The archaeological evidence seems to point to the Middle East area, during the Bronze Age in the 3rd millennium BC. However, wrought iron artifacts remained a rarity until the 12th century BC. The Iron Age is conventionally defined by the widespread replacement of bronze weapons and tools with those of iron and steel. This transition happened at different times in different places, as the technology spread. Mesopotamia was fully into the Iron Age by 900 BC. Although Egypt produced iron artifacts, bronze remained dominant until its conquest by Assyria in 663 BC. The Iron Age began in India about 1200 BC, in Central Europe about 800 BC, and in China about 300 BC. Around 500 BC, the Nubians, who had learned from the Assyrians the use of iron and were expelled from Egypt, became major manufacturers and exporters of iron. The development of bloomery versus cast iron across regions may be due to influence by the applications demanded of iron within the respective socio-political environments In pre-Roman Britain, iron smelting was certainly firmly established during the Middle Iron Age in Yorkshire and may be linked to the Arras culture. The large-scale, communal nature of the smelting at Thornton suggests it supported the significant demand for iron tools and funerary goods required by these communities.
Ancient Near East
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