Rev. Rul. 56-405

The M company produces chemical grade limestone, crushed rock for road ballast, and agricultural limestone. In crushing rock for chemical grade limestone and crushed rock products, a certain amount of pulverized material suitable for agricultural limestone is produced as a by-product. In another operation, limestone is pulverized to make agricultural limestone. Held, in crushing rock for chemical grade limestone and crushed rock products, the production of pulverized limestone as a by-product from the primary and secondary crushing will not exclude such processes from treatment as `ordinary treatment processes,' within the meaning of section 613 of the Internal Revenue Code of 1954, but the pulverization of limestone for the purpose of making agricultural limestone is excluded from such `ordinary treatment processes' under section 39.23(m)-1(f)(2) of Regulations 118, made applicable herein by Treasury Decision 6091, C.B. 1954-2, 47.