Clays; (not including expanded clays of heading no. 6806), andalusite kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earth

250810 Clays (excluding expanded clays of heading no. 6806); bentonite, whether or not calcined 250830 Clays (excluding expanded clays of heading no. 6806); fireclay, whether or not calcined 250840 Clays (excluding expanded clays of heading no. 6806); n.e.c. in heading no. 2508, whether or not calcined 250850 Clays (excluding expanded clays of heading no. 6806); andalusite, kyanite and sillimanite, whether or not calcined 250860 Clays (excluding expanded clays of heading no. 6806); mullite 250870 Clays (excluding expanded clays of heading no. 6806); chamotte or dinas earths