Alexandria Baker, age 10, of Louisville, Ky., for her question:

WHERE DO WE FIND COPPER?

Copper is one of the world's most useful metals, and it has been in use for more than 5,000 years. It is the best low cost conductor of electricity.

Almost 7 million tons of copper are mined each year throughout the world. Every continent has copper deposits. Much of the world's supply, however, comes from the ranges of mountains that extend from Alaska to the tip of South America.\

Copper ore is found in mines far below the earth's surface, and it is also obtained from great open pits at the surface. Open pit copper mining is especially common in the United States. A fourth of the world's copper comes from the United States, with half of that supply coming from Arizona. Ontario and Quebec in Canada provide about 10 percent of the world's copper.