ABSTRACT
Coal is a typical conventional solid fuel that has long history of human exploitation. It has become a main source of energy generation ever since the Industrial Revolution. Despite the many environmental concerns and misgivings in recent years, the relative importance of coal as fuel has lost any ground. Electric power generation in the United States is heavily dependent on coal combustion, 57% in 1994. Petrography is an alternative classification of coal; instead of using ranks, it emphasizes the compositional description of coal as a rock material. Coal is a complex sedimentary rock derived from a variety of plant materials that have undergone various physical and chemical transformations and are mainly composed of macerals. Modern petrographic classification is concerned with the microscopic separation of coal macerals according to color and consistency. The maceral carbon content increases and the atomic H/C ratio decreases in the order of exinite, vitrinite, inertinite.
