Kenneth Neeley, age 11, of Salt Lake City, Utah, for his question:

Who discovered copper?

If you go rock hunting in the right places, sooner or later you will find a gob of natural copper on the ground. You may not recognize it because native copper usually is mixed with rocky minerals and tinged with tones ranging from black to greenish blue. Nuggets of native copper were found by our remote ancestors and perhaps the cavemen treasured it for its shiny metallic qualities. Later, mankind learned to melt and mold copper vessels. However, the native metal is too soft to be used to make tools and weapons. But prehistoric man't experiments with it led him to his first major step toward the use of metals.

Sooner or later, most early cultures learned how to smelt metal and use heat to beat it into useful shapes. And sooner or later, they discovered that a smelted mixture of copper and tin produced a very sturdy metal called bronze. This opened the Bronze Age of human history that began more than 6,000 years ago. The discovery of copper nuggets is lost in antiquity. And there are no records of the geniuses who discovered how to use copper and tin to make tools and weapons of sturdy bronze.