Fire is one of the oldest civilizing influences on earth. Since civilization began, fire has been near at hand, inspiring human beings to search for ways to create and use new substances. Fire helped humans survive the Ice Age. The chemical energy released by the combustion (burning) of wood warmed Stone Age people, cooked their food, and lit up the cold, dark caves in which they sought shelter.
When prehistoric people began to settle down and raise crops, the drawbacks of their stone tools soon became apparent. Metal is much more versatile. It can be shaped into tools that work more efficiently. Metal tools are thinner and lighter. They take a sharp cutting edge and can be easily resharpened. And since copper is virtually the only metal found in usable form in nature, it became the first metal used by our prehistoric ancestors.
Copper is softer than stone, so these ancient metalworkers found that copper cutting tools had to be constantly resharpened. Then, in the fires of a primitive furnace fueled by burning charcoal, the early metallurgists discovered they could release copper from several blue and green mineral compounds. Later, they found that combining the hot, molten copper with another metal—tin—created an alloy—a harder, more useful substance called bronze. And, about 1000 B.C., ancient chemists learned howto use fire to free iron from its mineral compounds, creating tools and weapons far superior to any others of that time.
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