The 99.8% threshold separates high-purity magnesium (810411), used in specialty chemical and pharmaceutical applications, from commercial-grade unwrought magnesium (810419), which is the dominant form used in aluminum alloying and structural die-casting. The distinction affects both the applicable duty rate and, where antidumping orders exist, whether a specific order covers the shipment.

Yes. Raspings, turnings, granules, and powders are specifically classified under 810430 regardless of purity, while solid unwrought forms (ingots, billets, slabs) are split between 810411 and 810419 based on the 99.8% purity threshold.