HTS heading 2508 · Chapter 25
HTS 2508: Other clays, andalusite, kyanite and sillimanite,…
HTS heading 2508 covers other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths. It has 8 tariff lines with a duty rate; the general (MFN) rates are Free (8 lines).
Imports may also owe Chapter 99 tariffs (Section 232, 301 or 201) depending on origin and date, plus the Merchandise Processing Fee and, by sea, the Harbor Maintenance Fee.
Rates from the 2026 HTS Revision 22, effective October 30, 2026. Source: U.S. International Trade Commission.
Tariff lines and duty rates
| HTS code | Description | General | Special | Column 2 | Estimate |
|---|---|---|---|---|---|
| 2508.10.00.00 | Bentonite[t] | Free | $3.20/t | Estimate → | |
| 2508.30.00.00 | Fire-clay[t] | Free | $1.97/t | Estimate → | |
| 2508.40.01 | Other clays | Free | $1.97/t | ||
| 2508.40.01.10 | Common blue clay and other ball clays[t] | Estimate → | |||
| 2508.40.01.20 | Decolorizing earths and fuller's earth[t] | Estimate → | |||
| 2508.40.01.50 | Other[t] | Estimate → | |||
| 2508.50.00.00 | Andalusite, kyanite and sillimanite[t] | Free | Free | Estimate → | |
| 2508.60.00.00 | Mullite[t] | Free | 30% | Estimate → | |
| 2508.70.00.00 | Chamotte or dinas earth[t] | Free | Free | Estimate → | |
| 2509.00 | Chalk: | ||||
| 2509.00.10.00 | Crude[t] | Free | Free | Estimate → | |
| 2509.00.20.00 | Other[t] | Free | 13% | Estimate → |
11 lines shown. Statistical suffixes (the last two digits) inherit the rate of the 8-digit subheading above them.
Example: base duty and fees on $10000
For HTS 2508.10.00.00 at the general rate of Free, shipped by ocean, before any Chapter 99 tariffs:
| Base duty (Free) | $0.00 |
| Merchandise Processing Fee (0.3464%, min $34.58) | $34.64 |
| Harbor Maintenance Fee (0.125%) | $12.50 |
| Duty and fees | $47.14 |
Origin-specific tariffs can multiply this. Run this example from China or from Mexico to see every line.