- 1. This chapter does not cover: (a) slag or similar industrial waste prepared as macadam (heading (/headings/2517)); (b) natural magnesium carbonate (magnesite), whether or not calcined (heading (/headings/2519)); (c) sludges from the storage tanks of petroleum oils, consisting mainly of such oils (heading (/headings/2710)); (d) basic slag of Chapter (/chapters/31); (e) slag wool, rock wool or similar mineral wools (heading (/headings/6806)); (f) waste or scrap of precious metal or of metal clad with precious metal; other waste or scrap containing precious metal or precious metal compounds, of a kind used principally for the recovery of precious metal (heading (/headings/7112)); or (g) copper, nickel or cobalt mattes produced by any process of smelting (Section XV). 2. For the purposes of heading (/headings/2601) to (/headings/2617), the term 'ores' means minerals of mineralogical species actually used in the metallurgical industry for the extraction of mercury, of the metals of heading (/headings/2844) or of the metals of Section XIV or XV, even if they are intended for non-metallurgical purposes. Headings (/headings/2601) to (/headings/2617) do not, however, include minerals which have been submitted to processes not normal to the metallurgical industry. 3. Heading (/headings/2620) applies only to: (a) slag, 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, excluding ash and residues from the incineration of municipal waste (heading (/headings/2621)); and (b) slag, ash and residues containing arsenic, whether or not containing metals, of a kind used either for the extraction of arsenic or metals or for the manufacture of their chemical compounds. ### Subheading notes 1. For the purposes of subheading [2620 21](/subheadings/2620210000-80), 'leaded gasoline sludges and leaded anti-knock compound sludges' mean sludges obtained from storage tanks of leaded gasoline and leaded anti-knock compounds (for example, tetraethyl lead), and consisting essentially of lead, lead compounds and iron oxide. 2. Slag, ash and residues containing arsenic, mercury, thallium or their mixtures, of a kind used for the extraction of arsenic or those metals or for the manufacture of their chemical compounds, are to be classified in subheading [2620 60](/subheadings/2620600000-80).