(ËlÉk tÉrn) n. 1. a reading desk in a church from which the Bible lessons are read during the service. 2. a stand with a slanted top, used to hold a book, speech, etc., at the proper height for a standing reader or speaker.
How a Diamond is Formed. In order for diamond to form there must be an available source of carbon and relatively narrow ranges of temperates and pressures must align. This happens around 100 miles below the crust. Once crystalized the diamonds must be rapidly transported to the surface without undergoing substantial change.
Diamond is not formed from metamorphosed coal, and most diamonds discovered on the surface in mining operations are at least one billion years old; some may be two or three times that age. Diamond can also be formed from the pressures of high speed impacts of meteors with the Earth, but these are more of scientific interest, having no economic usefulness due to their small size and dispersion.