Andalusite, Kyanite & Sillimanite, Whether or Not Calcined

Andalusite, kyanite, and sillimanite are polymorphic aluminosilicate minerals that convert to mullite at high temperatures, making them essential raw materials for high-performance refractories, technical ceramics, and spark plug insulators. All three minerals — whether raw or calcined — are classified under a single US tariff line (2508500000), simplifying entry but requiring careful documentation of mineral identity. Peru is the leading supplier to the US market, with France and South Africa also among the top sources.