Sally Hanson, age 12, of Overland Park Kansas, for her question:

WHEN WAS COPPER FIRST USED?

Copper was first used about 8000 B.C. by the peple living along the Tigris and Euphrates Rivers in what is now Iraq. Then by about 6,000 B.C. the ancient Egyptians learned to hammer native copper into sheets to make tools and ornaments.

Copper was later used by people in China and Peru and by the North American Indians.

About 3,500 B.C., men had discovered how to melt and alloy copper with tin to make bronze. About the same time they learned to smelt copper from ore.

From about 3,000 B.C. until about 1,100 B.C. bronze became important. Much later, the Romans used bronze swords.

The process of combining zinc with copper to make brass was probably discovered sometime between 1,000 B.C. and 600 B.C.