Daniel Macheca, age 15, of St. Louis, Missiouri, for his question:
Why is Africa so diamond rich?
Diamonds were discovered first in India, ages ago. In the 1700s deposits were found in South America. The rich gem stones of South Africa were discovered in the 1870s and later, richer deposits were found in the Congo. These treasure troves were found more or less by accident and chances are, someday even richer diamond deposits will be found elsewhere.
So far Africa is where most of the earth's diamond supplies have been found. Nobody knows exactly where to look for them because geologists are not exactly sure how diamonds were formed, or when and where they were concealed in the earth's crust.
Hard, brilliant diamond is made entirely from atoms of ordinary carbon. Scientists have used intense heat and pressure to crystallize carbon to form diamonds. We know that crustal upheavals create many deep pockets of intense heat and pressure, where diamonds could be formed from trapped particles of carbon, perhaps similar to coal.
The rocks in diamonds are found to provide a few clues, but they do not explain the whole story. Most of the known deposits are embedded in ancient lava tyke minerals or among sands and gravels that have eroded from ancient lavas. The rich deposits of South Africa seem to have formed at great depths and welled up with lava toward the surface. The diamonds are found in so called pipes of bluish mineral called kimberlite. The pipes are deep plugs of this blue ground from 50 feet to half a mile wide. About 10,000 tons of this blue kimberlite must be processed to yield a pound of diamonds.
However, most diamonds are smallish stones, flawed and murky. They do not have the clear sparkling beauty to become gems. Nevertheless, since diamond is the hardest by far of all the natural substances, they are very useful in industry. They are used in cutting tools and drills, in abrasive and polishing materials. These workers are industrial diamonds and at least half the world supply is mined in the African Congo.
Other known diamond deposits are mined in the Urals and northern regions of Russia and in the mountains of Brazil. A few handsome stones have been found near Murfreesport, Arkansas. But without a doubt, the richest known deposits are on the continent of Africa. Most of the gem stones come from the mines in south and southwest Africa. The bulk of the world's industrial diamonds are from mines in the Congo and in the African countries of Ghana, Sierra Leone, Angola and Liberia.
Obviously Africa is rich in diamonds because of certain geological events that occurred there in the distant past. Most likely, similar diamond making conditions occurred on other continents.
Who knows, someday even richer diamond mines may be discovered in North America. There is one known deposit in Arkansas. And several fine diamonds have been found in eroded materials around the Great Lakes. Some geologists suspect these specimens may have been washed down by melting glaciers from rich diamond deposits, perhaps in the far north.