Pyrite, Marcasite 51 Conglomerate 54 Gneiss 54 Hematite 56 Limonite 57 Paint Ore, Ochre 58 Iron Band Diaspore 58 Manganese Ore 58 Galena 59 Sphalerite 60 Barite 61 Gypsum 63 Meteorites 64 Gold 65 Silver 65 Diamonds 65 Uranium Minerals 65 MISCELLANEOUS ROCK STRUCTURES 66 Concretions 66 Geodes 67 Fossils 69 Arrow Heads, Artifacts 71 THE ROCKS OF MISSOURI 71 MINERALS OF MISSOURI 74 GEOLOGICAL VALUES 74 INDEX 76 INTRODUCTION Missourians are interested in the rocks and minerals which they find on their farms, in excavations, and while on their vacation trips. Some of the specimens are unusual in shape or appearance, some are crystalline and beautiful, some may be ores of economic importance, but many simply arouse the curiosity of the finder. Many of these specimens are received each year at the University at Columbia, and each is usually accompanied by a request for information on the correct name for the specimen, its composition, its commercial value, and the manner of its formation. Frequently the requests include questions of a broader geological nature, or seek the recommendation of a general, easily-read book written on rocks and minerals which may be purchased at a book store or consulted at a library. Moreover, many persons ask how they may determine for themselves the geological specimens which they have collected.