US Department of Energy
U.s. Department of Energy: Coal: Our Most Abundant Fuel
The U.S. has enough coal to last for the next 200-300 years. So why are we not using more of it? This article describes the different types or "ranks" of coal, the history, and the problems with burning coal for energy.
Other
Black Hills Bentonite: Wyoming Lignite
A description of lignite coal as well as an explanation of some of its uses.