Heading 2506

Quartz; (other than natural sands), quartzite, whether or not roughly trimmed or merely cut, by sawing or otherwise, into blocks or slabs of a rectangular (including square) shape

250610 Quartz; other than natural sands 250620 Quartzite; whether or not roughly trimmed or merely cut, by sawing or otherwise, into blocks or slabs of a rectangular (including square) shape