Some shales are hard, tough, and strong enough to serve as temporary mine roofs. Hard shales are sometimes called “slate” but this name is technically incorrect. _True slate_ is a metamorphic rock, composed chiefly of the mineral mica in very fine flakes, and will resist the action of water (weathering) for a long time. Therefore, it is a good roofing material for buildings, whereas shale is composed chiefly of clay minerals, and despite the strength and compactness of the more “slaty” varieties soon disintegrates in water. Missouri “slaty” shale would not serve as satisfactory roofing material. The red “burned” shale found on burned-out coal mine dumps is called “shale” locally. It is, of course, shale which has been fired more or less to the condition of building brick by the hot burning waste coal. The same original shale could be crushed, molded into brick, “burned” in a kiln, and become a satisfactory building brick. The “burned shale” of the coal mine dumps is used in many places as a drive-way covering. “Soapstone” is a name applied by some persons to some soft, slippery to greasy shales, but this name is incorrect in a technical sense. True soapstone is a metamorphic rock (shale is sedimentary) which is composed chiefly of the mineral talc. Soapstone occurs abundantly in certain parts of the Appalachian Mountains but is exceedingly sparse in Missouri. The chief commercial uses of shale are in the manufacture of common brick, building brick, building tile, drain tile, sewer pipe, Portland cement, and other ceramic products. Many shale beds and occurrences are technically suitable for these uses but have no real commercial value because other necessary factors are lacking. In order to make brick, tile, or cement there must be sufficient fuel available at low cost, low-priced bulk transportation of the raw and finished products, available labor, capital for the erection of a plant, and above all a large near-by, dependable market for the manufactured product. The value of a shale deposit, therefore, depends as much upon outside conditions as upon the properties of the rock (shale) itself.