Heading 2525 covers mica in its natural and waste forms, including powder produced by grinding. Once mica is further processed into manufactured articles — such as built-up mica sheets, plates, or electrical insulation boards — it moves to the chapter covering articles of mica, which addresses fabricated mica products rather than the raw mineral.

The three subheadings — crude/splittings, powder, and waste — each carry their own tariff line and potentially different duty rates. Mica waste is a byproduct of mica processing and is often used as a filler or in lower-grade applications. Importers should verify the applicable rate for each form rather than assuming uniform treatment across the heading.