| 2506 | | Quartz (other than natural sands); quartzite, whether or not roughly trimmed or merely cut, by sawing or otherwise, into blocks or slabs of a rectangular (including square) shape: | | | | |
| 2506.10.00 | | Quartz | | Free | | Free |
| 2506.10.00 | 10 | Sands (other than natural) containing by weight 95 percent or more of silica and not more than 0.6 percent of oxide of iron | t | | | |
| 2506.20.00 | | Quartzite | | Free | | Free |
| 2506.20.00 | 10 | Crude or roughly trimmed | t | | | |
| 2508 | | Other clays (not including expanded clays of heading 6806), andalusite, kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earths: | | | | |
| 2508.40.01 | 10 | Common blue clay and other ball clays | t | | | |
| 2508.40.01 | 20 | Decolorizing earths and fuller's earth | t | | | |
| 2508.50.00 | 00 | Andalusite, kyanite and sillimanite | t | Free | | Free |
| 2508.60.00 | 00 | Mullite | t | Free | | 30% |
| 2509.00.10 | 00 | Crude | t | Free | | Free |
| 2510 | | Natural calcium phosphates, natural aluminum calcium phosphates and phosphatic chalk: | | | | |
| 2510.10.00 | 00 | Unground | t | Free | | Free |
| 2510.20.00 | 00 | Ground | t | Free | | Free |
| 2511 | | Natural barium sulfate (barytes); natural barium carbonate (witherite), whether or not calcined, other than barium oxide of heading 2816: | | | | |
| 2511.10 | | Natural barium sulfate (barytes): | | | | |
| 2511.10.10 | 00 | Ground | t | Free | | $7.38/t |
| 2511.20.00 | 00 | Natural barium carbonate (witherite) | kg | Free | | 30% |
| 2512.00.00 | 00 | Siliceous fossil meals (for example, kieselguhr, tripolite and diatomite) and similar siliceous earths, whether or not calcined, of an apparent specific gravity of 1 or less | t | Free | | Free |
| 2513 | | Pumice; emery; natural corundum, natural garnet and other natural abrasives, whether or not heat-treated: | | | | |
| 2513.10.00 | | Pumice stone | | Free | | Free |
| 2513.10.00 | 10 | Crude or in irregular pieces, including crushed pumice | kg | | | |
| 2513.20 | | Emery, natural corundum, natural garnet and other natural abrasives: | | | | |
| 2513.20.10 | 00 | Crude or in irregular pieces | kg | Free | | Free |
| 2514.00.00 | 00 | Slate, whether or not roughly trimmed or merely cut, by sawing or otherwise, into blocks or slabs of a rectangular (including square) shape | t | Free | | 25% |
Harmonized Tariff Schedule of the United States inquiry: 3203Ã
