Carbon: Prevalence


Diamond

Diamond is the only precious stone composed of a single element. Though diamonds have been discovered on all the major continents, over 90% of the world's natural diamond production comes from Africa. Other significant producers are Russia (mainly Siberia), China, Brazil and Angola. In the United States, diamonds can be found in the states of Arkansas, Virginia, Wisconsin and California. India, that was the only producer before the XVIII century, has a very small production nowadays. Diamond crystals can also be found in meteorites.

In spite of the first attempt of the Scottish chemist J. Balentine Hannay, in 1880, to produce artificial diamond it was not until 1955 that the General Electric Company first announced the successful development of a reproducible process. The work of Francis Bundy, Tracy Hall, Herbert M. Strong and Robert H. Wentorf complemented the research by Percy W. Bridgman from the University of Harvard. This diamonds have industrial quality being nowadays produced by an identical method, in large scale. Precious-stone quality crystals were obtained in 1970 by Strong and Wentorf in a process involving extremely high pressures and temperatures.

In spite of the popular interest on diamonds based on its value as gems, it is on the industrial domain that diamonds play a major role. They can be used in cutting or in turnery and to pierce alumina, quartz, glass and ceramics. Diamond powder is used to polish steel and alloys.