Coal MiningCoal, a mineral I talked about previously, is necessary for our daily lives. Coal is an incredible source of energy; it heats our homes and buildings, and also powers our stoves. We often wonder where this extremely useful mineral comes from. Coal doesn't just appear; it must be extracted through a process that allows us to use it. Coal mining is relatively inexpensive, occurs on a large scale, and can be mined in underground or surface mines. Surface mining is the process of extracting coal, which accounts for approximately 60% of the United States' coal. It tends to be very efficient, with a single worker recovering up to 30 to 40 tons of coal per day. To begin surface mining of coal, a drill must first survey the area to be mined to determine the depth of the coal as well as the overburden that lies above the coal. Bulldozers are then used to remove the topsoil, which is then piled up and later replaced with the stripped areas of soil. Then large, even enormous, pieces of equipment called draglines are used to remove more and more overburden as the stripping gets deeper and deeper. After this process, machines called crawler dozers fracture the coal, allowing cranes or bulldozers to collect the coal and transport it to the crushers. Today, the topsoil that was initially set aside is being replaced. This process is called recovery. Mined areas can then be used for various things: from parks to f...