… Siliceous fossil meals (for example, kieselguhr, tripolite and diatomite) and similar siliceous earths, whether or not calcined, of an apparent specific gravity of 1 or less. …
Explanatory notes
… 25.12 ‑ S iliceous fossil meals (for example, kieselguhr, tripolite and diatomite) and … are kieselguhr, tripolite, diatomite and moler earth. Although certain earths classified here are sometimes … impurities or washed for that purpose in acid, without altering the structure of the product, remains in this …