Diaspore clay occurs in old sink-hole, funnel-shaped pits which formed in the dolomite (limestone) underlying that region. A sandstone layer which lines the pit and commonly stands somewhat above the level of the clay because of the sandstones superior resistance to weathering is known as the “rim rock” of the pit. The diaspore clay may be thought of as an extra-refined type of fire clay from which silica has been leached during prolonged solution in swamps and ground water and the more stable alumina (Al₂O₃) left behind as the refined product. Pits in the diaspore region may contain from a few truck loads of clay to over 50,000 tons of it, but a pit which produces 10,000 tons of good clay is a valuable and not very common deposit. A small fortune falls to the landowner who finds a large diaspore deposit (pit) on his farm, for royalty rates at this time are not less than $1.00 per ton for first grade, 70% Al₂O₃ clay. Because of the high value of diaspore, a highly competitive prospecting, leasing, mining, and brokerage business has developed in the diaspore region. Practically all of the thrills, hopes, disappointments, and good fortunes that are associated with oil booms are found in this business and clay area; clay pits are only smaller in scale than wild oil gushers. Clay scouts work in secret, mining leases are contested in court, rumors fly fast in English, German, and German-Swiss over the country telephones, prospecting results may be hidden, personal pressure may be brought to influence a deal, and speedy salesmanship is employed when an exciting find is in the offing. When the legends, traditions, and facts of the diaspore region are collected and recorded, an interesting and essential part of Missouri history will have been written. Missouri has the only locality in the entire world where relatively pure diaspore clay is now mined in commercial quantities. Because of its extreme resistance to fusion under very high temperatures, diaspore has been called the “aristocrat of fire clays.” Diaspore contains a higher percentage of aluminum than does bauxite, the chief ore of aluminum, but because of diaspore’s extremely refractory nature it is less easily reduced to aluminum metal than is bauxite, and therefore finds a more specialized use in the manufacture of refractory and super-refractory brick and tile which may even be used in furnaces to calcine aluminum ore. Where resistance to very high temperature has been required, diaspore super fire brick has been remarkably useful. Burley Clay [Illustration: Burley clay. Note the oolitic structure, the “burls.” From a diaspore pit near Swiss.]