The Dawn of Metallurgy
Summary: 5,000 years ago, humans transitioned from the Stone Age to the Bronze Age thanks to the development of metallurgy, the process of separating metal from impurities.
Around 5,000 years ago, humans began transitioning from the Stone Age to the Bronze Age, largely due to the advent of metallurgy. This process involved heating copper ores in stone or ceramic pots to separate the metal from impurities.
While there are no records of how metallurgy came about, it's theorized that ancient peoples accidentally discovered that blowing air through hollow rods increased the temperature of furnaces, aiding in the release of molten metal. These early metalworkers didn't realize that carbon in charcoal was reacting with oxygen in the ore, converting it to CO2 and releasing the copper that was bound to it.
The Bronze Age
Summary: The development of bronze alloys, specifically copper and tin, was a landmark achievement in human history. These alloys were harder than pure copper, making them ideal for creating tools and weapons.
Copper proved a suitable metal for crafting tools and weapons, which were vastly superior to their predecessors made of stone. Copper could be hardened by hammering and could be melted and poured into molds to create standardized items.
Moreover, copper could be greatly enhanced by combining it with tin, creating a new alloy. This alloy was not only harder than pure copper when hammered but also melted at a much lower temperature, making it easier to cast.
The widespread adoption of this alloy around 3000 BCE marked the beginning of the Bronze Age, a period where various alloys were developed as people experimented with adding zinc and other metals to copper. Indeed, this experimentation has never truly stopped, with new alloys continuing to be discovered with myriad useful applications.
The Iron Age
Summary: The technological advancements of the Bronze Age gave rise to some of the most powerful civilizations in the ancient world. However, this era eventually ended when humans discovered how to smelt iron from ore, creating a material of even greater utility, ushering in the Iron Age.
Initially, ancient furnaces could not reach high enough temperatures to truly melt iron, so these early smiths had to work with wrought iron, which was obtained by reducing the iron from the slag produced by the smelting process. Around 300 BCE, Chinese metalworkers invented bellows that could generate a flame hot enough to melt iron.
Ironically, iron is not as hard as bronze alloys, so iron objects were often of inferior quality to their earlier alloy counterparts. However, iron was much cheaper to produce than bronze, primarily because it was far more abundant than tin. Iron would eventually be used to create steel, one of the most essential materials in the modern world.