Natural Fractures in Coal

Coal, "the black rock that burns," is the subject of song, story, and legend. The earliest literature citation of coal (combustible bodies, some of which by inference must be coal) is credited to Aristotle in his treatise "Meteorology," which may date near the middle of the fourth century B.C. Theophrastus, a student of Aristotle, at what is probably a slightly later date provides descriptions of different forms of coal based on their behavior in combustion, identifies areas of occurrence, and states that it was used by smiths (footnote by Hoover to Agricola, 1556).Though the Greek philosophers are responsible for the earliest known literature citations, China and perhaps other parts of eastern Asia are usually believed to have preceded the Mediterranean area in recognition of coal as a peculiar material with usable properties. Inouye (1913) states that although there is no authentic record of the history of the Fu-shun coal field in southern Manchuria, "it is said that the coal was used as fuel … for copper smelting in times as remote as 2,000 or even 3,000 years ago."Fires through most of man's history have been fed by "traditional fuels"—wood, straw, dung, and other plant materials. That coal could be of complementary usage is recorded in the remains of funeral pyres in Wales, dated about 3,000 years ago (Lindbergh and Proverse, 1977). However, the versatility of coal was not widely appreciated, and the discovery and use of charcoal satisfied most needs of primitive metal-working.By the end of the