Manganese Ore Several manganese minerals make up the manganese ore which occurs to a limited extent in southeast Missouri, principally in Shannon, Reynolds, Carter, Iron, and Madison counties. Although the Missouri manganese minerals are usually heavy, black or nearly so, and have a black or brownish-black mark or streak, the identification of the individual minerals is difficult and should be left to a technically trained mineralogist. Manganese minerals are used in the chemical industry and in the production of certain kinds of iron. A special report on the manganese deposits of Missouri is available at the Missouri Geological Survey, Rolla, Missouri. Galena Galena (“lead”) is a heavy, soft, somewhat brittle ore of lead. It has a brilliant metallic luster, and silvery gray color on a freshly broken surface. Where weathered it appears dull gray. It can be scratched with a knife, and breaks with surfaces at 90°, forming cubes. The unbroken, original crystal form of galena which has grown unobstructed in a vein opening is commonly cubical in habit or a modification thereof. It leaves a dark, lead-gray to black mark or streak when rubbed across unglazed porcelain or chert. [Illustration: A “cube” of galena.] [Illustration: Cluster of galena crystals from Joplin region.] Galena is lead sulphide, PbS, and when pure contains 86.6 per cent lead and 13.4 per cent sulphur. Small amounts of silver may also be present. Galena commonly occurs in Missouri as a cavity filling in crushed limestone or chert, or as a replacement in limestone or dolomite, or in shale, so that a large quantity of practically worthless enclosing rock (gangue) must be taken out in order to obtain the desired galena. If a person desires to estimate the value of his galena (lead) prospect by having an analysis or assay made of his ore, he must include in his sample the gangue rock that would of necessity have to be taken out when mining his ore. Too often persons carefully select for analysis a choice galena specimen which may run over 80% lead, only to find that as a practical mine product it would be reduced to less than 5% lead in all the rock which also would have to be taken out.