WCO Explanatory Notes reproduced for reference. © World Customs Organization. Verify against official WCO publication.
25.08 - Other clays (not including e anded cla s of heading 68.09, andalusite, kyanite and sillimanite, whether or not ca cined; m ~ t echamotte ; or dmas earths (+). 'P dm 2508.10 - Bentonite 2508.40 - Other clays - Andalusite, kyanite and sillimanite - Mullite - Chamotte or dinas earths 2508.50 2508.60 2508.70 This heading covers all natural cla ey substances (other than kaolin and other kaolinic clays of heading 25.0'7) consisting of ear& or rocks of sedimentary origin with a basis of aluminium silicates. The characteristic properties of these products are plasticity, the faculty of hardening when fired and resistance to heat. Because of these properties cla s are used as raw materials in the ceramic industry (bricks, building tiles, porcelam, china, eadenware, refractory bricks and other refiactory goods, etc.); common clay is also used for soil improvement. These products remain in this heading even if they have been heated to remove some or most of the associated water (to produce absorbent clay) or when fully calcined. In addition to common clays, the following special products also fall in the heading : (1) Bentonite, a clay derived from volcanic ash; Iar ely used as an ingredient of moulding sand, as a filtering and decolouring agent in oil re ining and for degreasing of textiles. B (2) Fuller's earth, a natural earthy material with high absorptive ower, composed chiefly of attapulgite. It is used for decolomising oils, for degreasing texti es, etc. P (3) Andalusite, kyanite (or disthene) and sillimanite, natural anhydtous aluminium silicates used as refractories. (4) Mullite, obtained by heat treatment of sillirnanite, kyanite or andalusite or by fusing a mixture of silica or clay .and aluminium oxide in an electric furnace; used in the preparation of refractory products with great resistance to heat. (5) Chamotte earth, also called " fire-clay grog ", obtained either by crushing fire-clay bricks or by crushing a calcined mixture of clay with other refractory materials. (6) Dinas earth, a refract0 material which consists of quartzose earth containing clay or may be obtained by mixing c ay with ground quartz or quartz sand. This heading does not include : (a) Clays which are earth colours within the meaning of heading 25.30. (b) Activated clay (heading 38.02). (c) Special preparations for the manufacture of certain ceramic goods (heading 38.24). (d) Ex anded clays (used in li htweight concrete aggregates or for heat insulation) even if obtained so ely by calcming natural c ays (heading 68.06). P f
1.- Except where their context or Note 4 to this Chapter otherwise requires, the headings of this Chapter cover only products which are in the crude state or which have been washed (even with chemical substances eliminating the impurities without changing the structure of the product), crushed, ground, powdered, levigated, sifted, screened, concentrated by flotation, magnetic separation or other mechanical or physical processes (except crystallisation), but not products which have been roasted, calcined, obtained by mixing or subjected to processing beyond that mentioned in each heading. The products of this Chapter may contain an added anti-dusting agent, provided that such addition does not render the product particularly suitable for specific use rather than for general use. 2.- This Chapter does not cover : (a) Sublimed sulphur, precipitated sulphur or colloidal sulphur (heading 28.02); (b) Earth colours containing 70 % or more by weight of combined iron evaluated as Fe O 2 3 (heading 28.21); (c) Medicaments or other products of Chapter 30; (d) Perfumery, cosmetic or toilet preparations (Chapter 33); (e) Dolomite ramming mix (heading 38.16); (f) Setts, curbstones or flagstones (heading 68.01); mosaic cubes or the like (heading 68.02); roofing, facing or damp course slates (heading 68.03); (g) Precious or semi-precious stones (heading 71.02 or 71.03); (h) Cultured crystals (other than optical elements) weighing not less than 2.5 g each, of sodium chloride or of magnesium oxide, of heading 38.24; optical elements of sodium chloride or of magnesium oxide (heading 90.01); (ij) Billiard chalks (heading 95.04); or (k) Writing or drawing chalks or tailors' chalks (heading 96.09). 3.- Any products classifiable in heading 25.17 and any other heading of the Chapter are to be classified in heading 25.17. 4.- Heading 25.30 applies, inter alia, to : vermiculite, perlite and chlorites, unexpanded; earth colours, whether or not calcined or mixed together; natural micaceous iron oxides; meerschaum (whether or not in polished pieces); amber; agglomerated meerschaum and agglomerated amber, in plates, rods, sticks or similar forms, not worked after moulding; jet; strontianite (whether or not calcined), other than strontium oxide; broken pieces of pottery, brick or concrete.