Cannel coal in Missouri has been found chiefly in old sinkhole deposits through part of central Missouri. It is characterized by fracturing conchoidally and having a more massive structure (instead of the layered structure common to bituminous coal). Cannel coal burns to a very hot, rather quick fire because of high volatile content, and is thought to have developed from accumulations very rich in plant spores. Coal mining is an important industry in Missouri, and a special bulletin on coal has been published by the State Geological Survey at Rolla, Missouri. Pyrite and Marcasite Pyrite and Marcasite (Fool’s gold, “sulphur”) are brassy yellow, metallic, heavy minerals which will scratch glass but which cannot themselves be scratched by a knife, and which will leave a dark-greenish to black mark or streak when rubbed across unglazed porcelain or chert rock. Both are composed of iron sulphide, FeS₂—iron 46.6 per cent, and sulphur 53.4 per cent. Although they have the same chemical composition, they differ in internal atomic and crystalline structure, which is of interest to scientific mineralogists. Pyrite may crystallize in cubes, or in forms called pyritohedrons, named from pyrite, whereas marcasite crystallizes in characteristic arrow-shaped or cockscomb forms. Marcasite weathers a little more readily than does pyrite, but otherwise they are much the same to the casual observer. Pyrite and marcasite have been called “fool’s gold” because so many persons have been fooled, sometimes with serious financial consequences, by their slight resemblance to true gold. True gold is soft, usually slightly orange-yellow in color, malleable, and unaffected by ordinary acids; and it leaves a gold-colored streak when rubbed on unglazed porcelain or a hard white rock. Pyrite, in contrast, is quite hard (harder than steel), is brassy yellow with perhaps a slight greenish tinge except where tarnished, is brittle, is corroded by acids or oxidizing ground waters, and leaves a greenish black to black streak on a white rock. One readily notices the difference in color between pyrite and gold (such as is in a piece of good quality jewelry), when the two are viewed close together. Yellowish, partially weathered mica has also been mistaken for gold. [Illustration: Brassy, granular pyrite in hand specimen.] [Illustration: Pyrite in crystal cubes, and replacement of fossils.]