Subheading 251720 covers macadam made from slag, dross, or similar industrial waste without a bituminous binder, while 251730 applies specifically to macadam that has been coated or mixed with tar. The presence or absence of a tar binder is the operative distinction between the two subheadings.

They serve different markets. Marble granules, chippings, and powder (251741) are used as decorative aggregates, fillers, and surface coatings, while marble blocks and slabs under 2515 are primary inputs for construction and stone fabrication. The form of the material — bulk granular versus dimensioned block — determines which heading applies.