Diamonds No diamond has ever been found in native Missouri rock. It is possible for diamonds to have been carried into the state with the glacial deposits in the northern part, but the probability of finding one, if it did come in, is extremely remote. Diamonds do occur in one part of Arkansas, but those rocks are strikingly different from all Missouri rocks except in a few localities, having small areas about the size of one’s house, in the southeastern part of the state. The writer has received quartz and calcite crystals for testing from persons who hoped they might be diamonds. It is almost a foregone conclusion that diamonds do not occur in Missouri. A diamond may be recognized by its extreme hardness. It is the hardest substance known, natural or artificial, and will scratch any known substance; but it, in turn, is scratched only by another diamond. Acids do not affect diamonds in the least. Uranium Minerals Three uranium-containing minerals, tyuyamunite (pronounced tyew-yuh-moon-ite), possibly carnotite, and metatorbernite, have been found in Missouri but none has been mined commercially. Tyuyamunite and carnotite are canary yellow powdery minerals so similar in appearance they can be differentiated only by chemical and x-ray properties. Both minerals contain uranium, vanadium, oxygen, water, and one other element, which, if it is calcium, the mineral is tyuyamunite, but if it is potassium the mineral is carnotite. The canary yellow color referred to is distinctly different from the brownish or reddish yellow color of iron oxide minerals. These yellow uranium minerals have been found near Ste. Genevieve along cracks in limestone and in the black shale above the limestone, and in dark, sandy shales near Shelbina, and elsewhere north of the Missouri River. Black shales (high in organic matter) of marine origin are the most highly radioactive, whereas black shales deposited on land (as with coal), and all shales of other colors are usually lower in radioactivity. Metatorbernite is a soft, pale apple-green scaly mineral that has been found in paper-thin cracks in flint fire clay deposits. It contains uranium, copper, phosphorus, oxygen, and water. All of these uranium minerals activate a Geiger counter. MISCELLANEOUS ROCK STRUCTURES Concretions