How Diamonds Are Mined

In mining Kimberlite, shafts are sunk some distance from the blue-ground pipe. Tunnels are then driven from the mine shaft to the pipe. Elevators take the Kimberlite above ground, where it is processed. The shaft of the Kimberly mine is more than 3500 feet (1,000 meters) deep. Pipe mines are found in South Africa and Tanzania. Arkansas diamonds are also taken from a pipe.

In other parts of Africa and in the rest of the world, diamonds are found in alluvial soils, or soils of sediment that have been deposited by running water. In 1962, however, diamonds were for the first time taken from the ocean floor, near Namibia. In this process a rubber hose 12 inches in diameter is extended from a barge to the bottom of the sea. Like a huge vacuum cleaner, it sucks up the gravel, the diamonds are removed and the gravel is dumped. On the average a ton of gravel contains one diamond, whereas it requires some 20 tons of kimberlite to yield a diamond.