Analysis
HTS 2508.50.00 covers andalusite, kyanite and sillimanite under heading 2508 (other clays (not including expanded clays of heading 6806), andalusite, kyanite and…).
The normal trade relations rate here is zero, shared by about 91% of the 78 tariff lines in chapter 25, a useful check when a neighbouring dutiable line is a candidate. Free here means free of the base duty only: origin-specific Chapter 99 duties such as Section 301 can still be owed.
Census statistics map these goods to NAICS 21232 (Sand, Gravel, Clay, and Ceramic and Refractory Minerals Mining and Quarrying), an industry of 2,617 US establishments employing 36,740 people. That concordance is how imports of this line are compared with US output.
All 5 neighbouring lines carry the same duty-free rate, so a borderline choice between them changes the statistics reported, not the duty paid.
Every edition we compared, from Jan 2023 to Oct 2026 (Rev. 22), shows the same general rate of Free.
Neighbouring lines
| Line | Description | General rate |
|---|---|---|
| 2508.10.00 | Other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths: bentonite | Free |
| 2508.30.00 | Other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths: fire-clay | Free |
| 2508.40.01 | Other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths: other clays | Free |
| 2508.60.00 | Other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths: mullite | Free |
| 2508.70.00 | Chamotte or dinas earth | Free |