Natural worked slate is quarried stone that has been cut, split, or shaped but retains its original mineral composition. Agglomerated slate is produced by bonding slate particles or powder with a binder under pressure, yielding a composite material. Both forms are classified under 680300, so the distinction does not affect heading-level classification, though it may matter for product specifications and end-use suitability.

Crude or roughly split slate — not yet worked into finished or semi-finished articles — is classified under the chapter covering natural stone in crude or roughly trimmed form, not under 6803. This heading requires that the slate have been worked: cut to shape, polished, or otherwise processed beyond rough splitting.