Gaskets made of other mineral substances are provided for in subheading 6815.99.
The Section XVII Note 2(a) exclusion for joints, washers or the like precludes gaskets of any material from classification in any of the provisions of that Section. Chapter 84 Note 1-a states that the Chapter does not cover articles of Chapter 68. Therefore, gaskets of other mineral substances for use in the goods of Section XVII (i.e. Motor vehicles, transportation vehicles etc.) or in the goods of Chapter 84 would be classifiable in subheading 6815.99 rather than elsewhere in the tariff.
There is no exclusionary language in Chapter 85 or Chapter 90 for either gaskets or articles of Chapter 68. Therefore, an gaskets of other mineral substances used as a part of an article described in Chapter 85 or Chapter 90 is classifiable in the appropriate parts provision in those Chapters.