HS Code 25.08 – Clays; (not including expanded clays of heading no. 6806), andalusite kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earth

HS code 2508 is a 4-digit heading in the Harmonized System that covers: Clays; (not including expanded clays of heading no. 6806), andalusite kyanite and sillimanite, whether or not calcined; mullite; chamotte or dinas earth. Heading 2508 covers a broad spectrum of clays, excluding expanded clays of heading 6806, along with specific aluminosilicate minerals: andalusite, kyanite, sillimanite (whether or not calcined), mullite, and chamotte or dinas earth. This classification is vital for industries requiring specialized natural earths and refractory minerals. Its scope is extensive, encompassing various non-kaolinitic clays like bentonite, ball clay, fire clay, and fuller's earth, each with distinct properties and applications. The inclusion of andalusite, kyanite, and sillimanite highlights their importance as raw materials for high-temperature refractories due to their ability to form mullite upon heating. Mullite itself, a calcined aluminosilicate, is also covered. Chamotte (calcined fireclay) and dinas earth (siliceous refractory material) are included for their use in refractory products. For trade compliance, understanding the specific type of clay or mineral and its degree of processing is paramount to avoid misclassification. This heading serves as a catch-all for industrial clays not specifically covered elsewhere, making precise identification crucial. Historically, these clays and minerals have been fundamental to ceramics, metallurgy, and construction. As part of Chapter 25, these materials represent naturally occurring earths and stones, typically traded in bulk for industrial processing, reinforcing their role as essential raw materials.

Bentonite clay (sodium), bentonite clay (calcium), fuller's earth, attapulgite clay, sepiolite clay, fire clay (raw), calcined fire clay, ball clay, common clay, stoneware clay, brick clay, pipe clay, andalusite (raw), calcined andalusite, kyanite (raw), calcined kyanite, sillimanite (raw), calcined sillimanite, mullite (sintered), fused mullite, chamotte (grog), dinas earth, foundry clay, drilling mud clay, cat litter clay, ceramic clay.

Misclassification often occurs when traders confuse specific clays covered here with kaolin (2507), which is specifically for kaolinitic clays. Another common mistake is classifying expanded clays, explicitly excluded from 2508, under this heading; they correctly belong to 6806. Furthermore, highly processed or chemically modified clays, or mixtures designed for specific chemical reactions, might fall under heading 3824 (prepared binders for foundry moulds or cores) or other chemical chapters, rather than 2508, which is for natural or simply calcined forms.

In 2025, the top exporters of HS code 2508 in UN Comtrade data were the United States ($409M, 19% of world exports), China ($245M) and the Netherlands ($161M). World exports came to about $2.1B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Germany reports $147M of its chapter 25 exports without product detail (confidential), so it may also belong among the top exporters.

In 2025, the top importers of HS code 2508 in UN Comtrade data were Italy ($255M, 9.7% of world imports), Germany ($223M) and the Netherlands ($177M). World imports came to about $2.6B, adding countries' reported figures and partner-based estimates for those that did not report (UN Comtrade data). Countries that did not report 2025 data are estimated from partner records, which can understate them.

HS code 2508 is a 4-digit heading under Chapter 25 of the Harmonized System. The first 2 digits (25) identify the chapter, and digits 3-4 (08) specify the heading. This code contains multiple 6-digit subheadings for precise product classification.