Blue Gem Coal is known for its hardness, as well as being low in ash and sulfur. It contains high carbon, low fusion, and low grind. Blue Gem Coal is the most sought after coal in the world but is only found on the Kentucky-Tennessee border along the Cumberland Mountains. The thickness is around 18 – 28 inches.  It is best suited for the production of silicon metals, which is another reason why it is so sought after. Blue Gem Coal is one of three grades of coal that helps with the production of silicon metals, and the other two grades are only found in West Virginia, Columbia, and South Africa. With the silicon market expanding yearly and the demand continuing to grow, the mineable reserves for Blue Gem Coal are becoming increasingly more valuable. The mine price is as much as 100% higher than high-quality steam coal and is typically the highest priced of any grade of coal produced in the U.S.