An understanding of the environment of deposition of sediment overlying a coal seam can be as important as a knowledge of underlying sediments in predicting a coal's properties. There are various physical properties of Coal like Hardness, Grain Size, Fracture, Streak, Porosity, Luster, Strength etc which defines it. They consist of undecayed organic matter that either accumulated in place or was transported from elsewhere to the depositional site. Many coal fines are in the range of 10–100 μm, and their grain size distribution is uniform, essentially a normal distribution . The smaller ones tend to be composed of a single mineral crystal, and the larger ones are typically composed of pieces of rock. Grain size. Anthracite coal, mined from the planet's oldest geological formations, has spent the longest time underground. Hard coal contains greater potential to produce heat energy than softer, geologically "newer" coal. Detrital rock is classified according to sediment grain size, which is graded from large to small on the Wentworth scale (see figure).Grain size is the average diameter of sediment fragments in sediment or rock. (metallurgy) Average size of grains in a metal expressed as average diameter, or grains per unit area or volume. grain size[′grān ‚sīz] (geology) Average size of mineral particles composing a rock or sediment. (graphic arts) Average size of silver halide grains in a photosensitive material. 6.1 Clastic Sedimentary Rocks A clast is a fragment of rock or mineral, ranging in size from less than a micron [1] (too small to see) to as big as an apartment block. Journal of Geology, 62, 344-359. The size of particles in sediment or sedimentary rock. Coal is formed when dead plant matter decays into peat and is converted into coal by the heat and pressure of deep burial over millions of years. and MIDGLEY, N.G. Grain sizes are used to classify different types of sedimentary rocks (e.g., siltstone, sandstone, etc.). In 1996, the Education Committee of the Kentucky Geological Survey, in conjunction with the Kentucky Society of Professional Geologists, established the Earth Science Education Network (ESEN). Sedimentary rock - Sedimentary rock - Coal: Coals are the most abundant organic-rich sedimentary rock. Physical properties of rocks are used to identify the type of rocks and to discover more about them. The journal aims to advance the exploration, exploitation and utilization of these resources, and to stimulate environmental awareness as well as advancement of engineering for effective resource management. HCl. Physical Properties of Coal. Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams.Coal is mostly carbon with variable amounts of other elements; chiefly hydrogen, sulfur, oxygen, and nitrogen. Originally, the network provided a group of geologists who served as resource persons for teachers. The distinction between grain size and mineral composition in sedimentary rock nomenclature. Integrated studies of clastic sedimentology, coal petrography and palaeontology are necessary for an understanding of the nature of ancient swamps. The most important organic component in coal is humus. Grain size classification of clastic rock types (data from Wentworth, 1922). Various types of clasts are shown in Figure 5.12 and in Exercise 5.3. There are three basic types of sedimentary rocks. Geological Educational Resources for K-16. Grain size is typically measured in millimeters, microns, and phi units. The coal has been subjected to the most pressure and heat, making it the most compressed and hardest coal available. Sedimentary rocks are formed by the accumulation of sediments. The grade or rank of coal is determined by the percentage of carbon present. 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