THE ORIGINS OF METALLURGY
8,000 years ago
|Replicas of early metallurgy. From left: The “Ice Man’s” copper axe, an early bronze dagger, a bronze axe, and a bronze spear point.
Credit: Photo by Kathy Schick, courtesy of the Stone Age Institute. All rights reserved.
Metallurgy probably accidentally emerged from the high-temperature technologies required to fire pottery. If rocks containing copper were heated to a high enough temperature, the copper would melt and could be cast into various shapes such as axes or knives and daggers, or even jewelry. The earliest evidence for this goes back to between 8,000 and 6,000 years ago in Thailand and the Near East. Then craftsmen found that if you alloy copper with tin, you produce an even harder material called bronze. The search for copper and tin ores became an important part of the economies for these early metallurgists. The Bronze Age revolutionized human societies, making more durable tools and weapons that were superior to stone for keeping their edge. And, unlike stone, these metals could easily be recycled by melting them down and recasting them.
The melting point of copper is 1084 degrees Centigrade or 1984 degrees Fahrenheit. This is several hundred degrees higher than a typical campfire, so it is likely that pottery kilns were adapted as smelting furnaces to generate higher temperatures by introducing more oxygen through blow pipes or bellows. Early metallurgists must have viewed the smelting process as an almost magical event, turning rocks into glowing blobs of metal that could be cast into desired shapes.
HOW DO WE KNOW?
We find the direct evidence of copper and bronze artifacts, as well as stone and ceramic molds which were used to cast the molten metals. Early evidence of developing Bronze Age cultures in the Old World appear in various places in the Old World, first in the Near East (including Mesopotamia, the Levant, and Ancient Egypt), and then in Europe, central Asia and eastern and southern Asia.
WHY SHOULD I CARE?
With the rise of metallurgy, human populations were much less dependent on stone as a raw material. Casting copper and bronze enabled people to make new and innovative tools and weapons that would have been impossible to make in stone, and these metal artifacts could keep their edge better, were easily resharpened by grinding and polishing, and could be recycled by melting into some other artifact form. The age of metals, first forged over 5,000 years ago, essentially laid the foundation for the materials worked and the technological innovations during the Industrial Revolution, setting the stage for the world we live in today.
This is a good history of metallurgy.
This is a discussion of Chinese Bronze and Iron ages.
This YouTube video is about the smelting process of making a bronze sword.