Of the three types of fossil fuels, coal is the only one still in a solid state. It appears as chunks of midnight black rock, which are harvested from the Earth by workers in mining operations. Coal is composed of five different elements: carbon, nitrogen, oxygen, hydrogen, and sulfur, with the distributions of those five elements varying depending on the piece of coal. In fact, because of these differing elemental make-ups, there are actually three different types of coal, each with different energy properties. The highest in energy content is anthracite coal, which is harder and has a higher distribution of carbon than the other varieties. The other two types of coal – lignite and bituminous – aren’t quite as energy-rich, but still have their uses. Lignite is high in oxygen and hydrogen instead of carbon, while bituminous occupies a sort of happy medium between the two extremes. Coal is a dynamic fossil fuel in terms of how it is used. Depending on the breakdown of coal uses that you look at, you might see the top uses listed as a generic “electricity generation” or “electrical utilities,” or you might see things broken down a bit into smaller categories. In any case, coal today is used for everything from producing steel and cement to keeping the lights on in homes and businesses.