Why do Bolivian tin concentrates contain less tin than many alluvial concentrates?

Bolivian tin concentrates contain less tin than alluvial concentrates because of the nature of the ore deposits. While alluvial fields primarily contain cassiterite, which is relatively free of impurities, Bolivian deposits consist of complex sulfide ores.12

These underground lode deposits often contain other metals, such as silver, and minerals like stannite and cylindrite. Because of this complexity, the ore requires more intricate processing methods, such as froth flotation, to separate the tin from other materials. Even with these advanced techniques, the resulting concentrates typically average only 50 to 60 percent tin, compared to the 70 to 75 percent purity often found in alluvial concentrates.21