Heading 2518

Dolomite, whether or not calcined or sintered, including dolomite roughly trimmed or merely cut, by sawing or otherwise, into blocks or slabs of a rectangular (including square) shape

251810 Dolomite, not calcined or sintered; including dolomite roughly trimmed, or merely cut by sawing or otherwise into blocks or slabs of rectangular (including square) shape 251820 Dolomite, calcined or sintered; including dolomite roughly trimmed, or merely cut by sawing or otherwise into blocks or slabs of rectangular (including square) shape