Geology of Coal

Coal geology is concerned with the origin, formation, distribution, resources, as well as the chemical and physical characteristics, of coal and coal-bearing strata, with the purpose of determining mining techniques, beneficiation processes, and utilization options. Formed by peatification and coalification processes, over millions of years, coal contains macromolecular organic compounds, mineral matter, elements, moisture, gases, and hydrocarbons. Coal type is dependent on conditions in the peat mire, including plant type, climate, and water conditions. Coal grade refers to the inorganic (mineral and elemental) inclusions in the coal. Coal rank, indicative of the degree of maturity the organic matter reached during coalification, is a progression, influenced by temperature, burial pressure and time. Globally, coal is widely distributed, and the Permo-Carboniferous represents the most important coal-forming period, although slightly older and substantial younger deposits do occur. In order for vegetation to form a workable coal seam, a variety of factors is required, and peat-forming swamps, bogs, and marshes developed in a wide array of sedimentary environments. Facies models have clustered coal-bearing sequences into fluvatile, lacustrine, deltaic, coastal, and back-barrier sedimentary processes, or combinations thereof. Coal production continues to grow globally due to the demand for low cost energy and iron and steel, as well as cement. An understanding of the shape, morphology, and quality of coal seams is vitally important when determining resources and reserves.