Fused magnesia is produced by melting magnesite in an electric arc furnace, yielding a very high-density, high-purity product with large crystal size — ideal for demanding applications like steel ladle linings. Dead-burned (sintered) magnesia is fired at high but sub-melting temperatures, producing a less dense but still highly refractory material used in basic brick and monolithic refractories. The choice between them depends on the thermal and chemical severity of the end-use environment.

Commercial invoices and certificates of analysis should specify the production method (fused vs. sintered), MgO purity percentage, bulk density, and crystal size where applicable. These parameters not only support classification but are also required by refractory manufacturers to verify product suitability. A licensed customs broker can advise on whether additional documentation is needed for specific origins subject to trade-remedy measures.