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.
1 Diamonds are formed deep within the Earth: between 100 km and 200 km below the surface. 2  The temperatures are about 900 - 1300 C in the part of the Earth's mantle where diamonds form. 3  The pressure is between 45 - 60 kilobars.