Doug Bentley, age 13, of Glendale, Ariz., for his question:
WHEN WAS GOLD FIRST DISCOVERED?
We aren't sure exactly when gold was first discovered, but we know that ancient men made gold cups and jewelry as early as 2500 B.C. Examples of early gold items were discovered at Ur in Mesopotamia, which is now Iraq.
The ancient Egyptians were making jewelry about this same time. The fine craftsmanship of the items found in ancient tombs suggested that the craft of working in gold had been developed many hundreds of years before they were made.
Gold was also used extensively by craftsmen during the Middle Ages.
During the 1500s, the Spanish explorers searched for gold in the lands of the Aztecs in Mexico and of the Incas in Peru. These were the days when pirates and roving privateers looted the galleons which were carrying Spanish plunder from the Americas to Spain.
During the days of exploration, a legend grew up about a land rich in gold called El Dorado, meaning "the gilded." Here, gold was supposed to be as common as sand. Through the centuries, many set out to find E1 Dorado and they often thought they had found it.
Many thought they had found E1 Dorado when gold was discovered in California in 1849. People rushed from all parts of the world in this famous adventure.
California's gold rush in '49 wasn't the country's first. An earlier gold rush occured in Georgia in 1829.
The largest discovery of gold in United States history came in the early 1960s with a strike made near Carlin, Nevada. An open pit mine began operating there in 1965. The Carlin mine added about 10 percent to the annual gold production of the U.S.
Leading North American gold mining states, provinces and territories (listed in order of importance) are Ontario, Quebec, Nevada, South Dakota, Utah, Northwest Territory, British Columbia, Arizona, Colorado and Washington.
South Africa is the world's leading gold mining area followed by Russia in second place, Canada in third and the U.S. in fourth place.
Other leading areas, listed in order of their importance, include Australia, Ghana, Philippines, Rhodesia, New Guinea and Japan.
Egyptians in ancient times knew how to hammer gold into leaves so thin that it took 367,000 leaves to make a pile 1 inch high.
When gold is to be made into hard objects, such as jewelry, it must be combined with some other metal. Such substances are called "alloys." Gold and alloys are measured by carats. A carat is equal to one twenty fourth part. Thus, 24 carat gold is pure gold. Eighteen carat gold is 18 parts pure gold to six parts of alloy. Pure gold melts at 1,063 degrees Centigrade and boils at 2,966 degrees.
All seawater contains gold in solution. Seawater yields about one grain of gold per ton. Scientists are looking for ways to mine this gold in a profitable way.