Explanatory notes
… earths such as kieselguhr, tripolite or diatomite (mostly falling in heading 25.12), or of silica obtained by … products (e.g., rice boll ash). These materials are usually mixed with binders (such as clay or magnesia) and … 69.02 or 69.03 as refractory goods, articles must not only be capable of resisting high temperatures, they must …