Imagine living in a world in which everything was made from wood and rocks and clay. Farm tools like digging sticks and axes were functional but fragile and not very sharp. Weapons were deadly but fairly easy to shield against.
Then one morning there's a glint of metallic light in the ashes of an especially big campfire from the night before. Some rocks used to make a fire ring have partly melted and a weird liquid substance has flowed out to pool up and later harden into a shiny object in the ashes.
Something like this must have happened over and over thousands of years ago with the discovery of copper, which is the most common metal whose melting point of about 1085 °C (about 1980 °F) is lower than the temperature of a big campfire.
Copper and the "Chalcolithic Age"
By 7000 BCE, people were mining and extracting copper metal to make tools and weapons and decorative art in Southwest Asia and North America. Copper metallurgy was independently developed in Africa, South America, Europe, and China over subsequent millennia. Copper was widely used in ancient societies around the world. It is soft and malleable, which makes it easy to work into useful objects, but which also means that tools and weapons made of copper wear out and break.
 |
| Dancing Girl, Mahenjo-Daro, ~2500 BCE |
The period during which the use of copper along with wood and stone tools characterized many cultures around the world is called the chalcolithic age, which literally means "the Copper and Stone Age." It follows the Neolithic ("New Stone Age") when agriculture was developed in at least five widely separated regions.
Bronze Age
By 3000 BCE, ancient metallurgists in Egypt, the Middle East, Eastern Europe, and China had learned to make a much harder metal called bronze. Bronze is an alloy of copper and another metal, usually tin. Other types of bronze use arsenic, nickel, or other trace metals. These trace metals melt at even lower temperatures than copper and so could be blended with molten copper to make the more durable bronze.
Bronze metallurgy was often limited by the availability of tin, which is pretty rare. The island of Cyprus in the eastern Mediterranean was a famous source of copper int he ancient world. Its name literally means "copper" (Kupros) in Ancient Greek and was later translated to Cuprus in Latin. Cyprus was the main source of copper for the Roman Empire. But tin was hard to come by and the locations of the mines were a well-guarded state secret. Romans mined tin as far away as the British Isles and Afghanistan.
The earliest Chinese bronze objects are dates to about 3100 BCE. Chinese Shang and Zhou Dynasties made huge amounts of bronze artifacts from the 16th to the 3rd Centuries BCE. The Indus Valley civilization in what is now Pakistan was using bronze by 3300 BCE. Bronze artifacts recovered in Thailand are dated to 2100 BCE.
Iron Age
Nearly pure metallic iron derived from meteorites was a rare and precious commodity in antiquity and probably led to heroic tales of people with super-strong weapons and tools.
Only when people were able to build furnaces capable of sustaining temperatures in excess of 1250 °C (2280 °F) could they smelt iron from ore. This can't be achieved in open fires and instead requires contained combustion with specially designed airflow that blows oxygen across the fire to make it hotter.
Iron smelting was developed independently in Anatolia (modern Türkiye), India, and Cameroon in West Africa by 2000 BCE, and had spread across much of the ancient world by about 1200 BCE. Iron is much harder and stronger than bronze.
Iron ore is also much more abundant than copper and tin, so once people learned how to build iron smelters bronze quickly became obsolete. Arguably, the development of relatively cheap iron weapons played an important role in the "Late Bronze Age Collapse" across the eastern Mediterranean around 1200 BCE.
The development of iron metallurgy in West Africa is thought to have been an important factor in the very rapid spread of Bantu farming culture across all of tropical Africa starting about 2000 BCE.
Steel is an allow of iron that is much stronger yet. making steel involves the use of carbon in the form of coke that helps reduce the ore (in the chemical sense of removing oxygen). Although steel was known in antiquity, carbon steel didn't come into wide use until the modern period.
Posts
