Metal-bearing sands — those valued primarily for their metallic mineral content, such as titanium-bearing ilmenite sands or tin-bearing cassiterite sands — are classified in the chapter covering ores, slag, and ash, not here. Heading 2505 covers sands whose commercial value lies in the silica or other non-metallic mineral matrix itself. If a sand is processed or concentrated to recover a metal, it almost certainly belongs in the ores chapter.

Silica content (often expressed as SiO₂ percentage), grain size distribution, roundness or angularity, and iron oxide impurity levels are the key commercial specifications. These determine whether a sand qualifies for high-value uses such as frac sand, glass batch, or semiconductor-grade applications. Classification within 250510 does not change based on grade, but customs value and end-use documentation may reflect these distinctions.