… Quartz (other than natural sands); quartzite, whether or not roughly … into blocks or slabs of a rectangular (including square) shape. …
Explanatory notes
… two conditions : (a) It must be in the crude state or have not undergone any process beyond that allowed in Note 1 … of parts of tools. Quartzite is the name of very hard compact rock composed of grains of quartz agglomerated … falls in this heading when in the crude state or when it has not undergone any process beyond that allowed by Note 1 …