Thermoplastics, in basic terms, are melt-processable plastics (materials that are processed with heat). When enough heat is added to bring the temperature of the plastic above its melt point, the plastic liquefies (softens enough to be processed).
In the U.S., diamonds have been found in Arkansas, Colorado, Wyoming, and Montana. In 2004, the discovery of a microscopic diamond in the U.S. led to the January 2008 bulk-sampling of kimberlite pipes in a remote part of Montana.
To date the Uncle Sam, discovered in 1924, is the largest diamond ever found in the U.S. It was found in the worldâs only diamond mine open to the public. The Crater of Diamonds State Park in Arkansas is a dig-for-fee operation for tourists and rock hounds.