"In 2016, about 728 billion short tons of coal were produced in 25 U.S. states. Surface mines were the source of 65% of total U.S. coal production and accounted for 62% of the total number of mines. About 0.9 million tons, or about 0.1% of total coal production, was refuse recovery coal.
The United States is a net exporter of coal. However, some coal is still imported, mostly for power plants on the eastern and southern coasts of the country, where it is cheaper to ship in coal by sea from South America than transport it from mines in the northern and western United States.1
Frac sand is a type of sand with small, uniform particles. It is injected into the rock formation along with the water used to fracture the rock in the process known as hydraulic fracturing ("fracking"). The sand is used to prop open the fractures that are created. Because the particles are uniform, fluids like water, oil, and gas are able to flow through the spaces between the particles.