Bulk, sheet, or roll-form slag wool and rock wool fall under 680610, while articles that have been shaped or fabricated specifically for heat-insulating, sound-insulating, or sound-absorbing end uses are classified under 680690. The key test is whether the material has been further processed into a defined article beyond a simple roll or sheet.

Exfoliated (expanded) vermiculite and expanded clays in loose or granular form fall under 680620 within this heading. However, if vermiculite is incorporated into a finished article alongside a binder, the classification may shift to 680690 or another heading depending on the article's composition and primary function.