The split is based on the dominant refractory material: siliceous fossil meal or siliceous earth compositions fall under a separate heading, while alumina, magnesia, chrome, dolomite, and other non-siliceous mineral-based shapes fall under this category. The precise HTS subheading depends on the percentage of specific oxides (e.g., alumina content thresholds), so a chemical composition certificate from the manufacturer is typically required for correct classification.

Yes. Certain non-siliceous refractory products, particularly magnesia-carbon and alumina-based bricks from specific origins, have historically been subject to antidumping or countervailing duty orders in the US. Importers should check the current scope of active orders with CBP and the International Trade Administration before sourcing, as scope rulings can be narrow and product-specific.