Where Are Diamonds Found?

Diamonds were probably formed millions of years ago in molten lava. As the lava flowed to the Earth's surface through vents known as pipes, it cooled and solidified into kimberlite, a blue rock. Kimberlite contains the diamonds and is known to diamond miners as blue ground.

Diamonds have been found on all continents. India was once a chief source. About 600 AD diamonds were found in Borneo and are still mined there. The rich fields of Brazil was discovered in the 1700s. In the 19th century even richer diamond fields were found in South Africa. Most of the world's diamonds are mined in African countries. Zaire produces mostly industrial diamonds. South Africa is the major source of gem-quality diamonds. Congo, Ghana, Namibia (South West Africa) and Angola are other major suppliers. Russia has diamond-mining operations in northeastern Siberia and since the late 1970s many diamond finds have been made in Australia.

About 20 percent of the world's output is used for industrial purposes, with the United States importing some 60 percent of the industrial diamonds mined. A few diamonds are found in Pike County, Ark., near Murfreesboro, and diamonds have also been found in the Upper Peninsula of Michigan.