Chapter 26 - NOTES 1. This Chapter does not cover: (a) Slag or similar industrial waste prepared as macadam (heading No. 25.17); (b) Natural magnesium carbonate (magnesite), whether or not calcined (heading No. 25.l9); (c) Basic slag of Chapter 3l; (d) Slag wool, rock wool or similar mineral wools (heading No. 68.06); (e) Waste or scrap, of precious metal or of metal clad with precious metal (heading No. 71.l2); or (f) Copper, nickel or cobalt mattes produced by any process of smelting (Section XV). 2. For the purposes of headings Nos. 26.01 to 26.17, the term "ores" means minerals of mineralogical species actually used in the metallurgical industry for the extraction of mercury, of the metals of heading No. 28.44 or of the metals of Section XIV or XV, even if they are intended for non-metallurgical purposes. Headings Nos. 26.01 to 26.17 do not, however, include minerals which have been submitted to processes not normal to the metallurgical industry. 3. Heading No. 26.20 applies only to ash and residues of a kind used in industry either for the extraction of metals or as a basis for the manufacture of chemical compounds of metals.