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25.25 Mica, including splittings; mica waste.
Mica (muscovite, phlogopite, biotite, etc.) constitutes a group of natural complex aluminium silicates characterised by the fact that they are readily split into glistening, transparent, flexible sheets of varied colour.
The heading includes :(A) Crude mica, which consists of mica crystals, of irregular shape, size and thickness, covered with earth ("books"). (B) Mica sheets, obtained by rifting cobbed and trimmed books. The sheets take the shape of irregular polygons, like the crystals from which they were obtained, and their edges are roughly trimmed and bevelled. Their thickness usually varies from 200 to 750 micrometres (microns). (C) Mica splittings, obtained by rifting sheet mica. Like the sheets from which they have been rifted, they have the shape of irregular polygons. Their edges are roughly trimmed.
They are marketed as : (1) Condenser film, usually of a thickness between 25 and 200 micrometres (microns), or (2) Splittings, usually of a thickness between 12 and 30 micrometres (microns), used solely for the manufacture of built up mica (e.g., micanite).
The heading also includes mica waste and powder.
The heading excludes products obtained by cutting out or die stamping from mica sheets or splittings (heading 68.14 or Chapter 85), and products made from bonded (built up) splittings (e.g., micanite, micafolium) or from pulped (reconstituted) mica (heading 68.14).
Vermiculite, a mineral allied to mica, falls in heading 25.30, as do perlite and the chlorites (minerals chemically related to vermiculite).
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