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Abstract
Shales* form a group of raw materials that are of vital interest to the structural-clay products manufacturers. These raw materials vary widely in composition and behavior, and therefore are blended together in such proportions as to bring out the most desirable characteristics. Rarely does one individual shale exhibit all the desirable firing properties necessary to form a product that is strong, durable, and pleasing to the eye. Frequently the producers mix the raw materials on a trial-and-error basis rather than using data from chemical, mineralogical, and thermal analyses. As a result, little is known generally about the property-mineral relation- ships of these materials. If they had been more thoroughly studied, better products undoubtedly could have been manufactured at lower costs.
