Other clays — HTS 2508
Other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths
Chapter 25 › Heading 2508
2026 HTS Rev 19 Synced Rules verified Operational
Written to help non-specialists understand this page. Rates, dates, and legal facts come from the official records above and on the linked source.
HTS heading 2508 is a broad product category for certain natural mineral materials used as clays or refractory raw materials. It covers “other clays” not covered as expanded clay in heading 6806, plus andalusite, kyanite, sillimanite, mullite, chamotte, and dinas earths. The heading can include these materials whether or not they have been calcined, meaning heat-treated, unless another tariff provision applies.
To reach the correct 8-digit HTSUS code, first identify the material or mineral type, then check the more specific subheading and statistical breakout under heading 2508. Classification may depend on the product’s composition, whether it is a named mineral or clay, whether it has been calcined, and whether it is presented as a raw material, powder, granule, or other preparation. The product’s commercial name alone is not enough; review its technical specifications and the current HTSUS text and notes.
What to check
- Confirm the product’s actual mineral or clay identity using the supplier’s specification sheet, safety data sheet, certificate of analysis, or laboratory information.
- Check whether the material is expanded clay, because expanded clay is directed to a different heading rather than heading 2508.
- Determine whether the product is andalusite, kyanite, sillimanite, mullite, chamotte, dinas earth, or another type of clay covered by the heading.
- Verify whether calcining or other processing changes the applicable subheading, and review any relevant section, chapter, or heading notes.
- Compare the full product description and technical facts with the current 8-digit HTSUS options; request a customs-broker review or binding ruling when the classification is uncertain.
HTS heading 2508 summary
Other clays is a 4-digit product category containing 6 published product-code lines in this snapshot. A heading does not carry one universal duty rate; classification must be narrowed to the line matching the product facts.
How to find your code in this category
A heading is a product category. To get the exact duty, narrow from this 4-digit heading to a sub-category (usually by material), then open the 8-digit code that matches your product.
Open any code in the tables below to see its exact duty rate, a duty calculator (enter your shipment value → estimated duty and landed cost), the rate-change history chart, and the country-by-country breakdown (including Section 301/232 add-on duties).
Why you have to click in: a single category can contain products with very different duties. The rate depends on the specific product — its material and construction — and on the country of origin, and those only get pinned down at the 8-digit code level. That is why this page points you to codes instead of showing one rate for the whole category.
Product codes & duty rates
👇 Each row is a specific product code — click a blue code to open its full page with exact duty rates by country, the rate-history chart, and a duty calculator. 👉
| Code | Description | General (MFN) | Special | Column 2 |
|---|---|---|---|---|
| 2508.10.00.00 👉 | Bentonite | Free | — | $3.20/t |
| 2508.30.00.00 👉 | Fire-clay | Free | — | $1.97/t |
| 2508.40.01 👉 | Other clays | Free | — | $1.97/t |
| 2508.50.00.00 👉 | Andalusite, kyanite and sillimanite | Free | — | Free |
| 2508.60.00.00 👉 | Mullite | Free | — | 30% |
| 2508.70.00.00 👉 | Chamotte or dinas earth | Free | — | Free |
"Special" shows the free-trade-agreement rate; open a code to see exactly which countries qualify.
Common questions
What products fall under HTS heading 2508?
Other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths. To classify a specific item you must pick the matching sub-category and 8-digit code above; the right choice usually depends on the material and construction of the product.
How do I choose the right code within this category?
Start from the sub-categories (typically divided by material—for example cotton versus man-made fibers), then open the active 8- or 10-digit code that matches the product. When unsure, a licensed customs broker or a CBP binding ruling can confirm the classification.
Reference information only, not customs, legal, or classification advice. Confirm the current code and rate against the official HTS before you import.