Conclusions
Mineral composition of post-tin mining provides strategic roles in providing the potential amount and type of native nutrient sources and heavy metals which are basic information required to determine soil nutrient management in supporting rehabilitation measures.
Post-tin mining areas have many severe constraints for crop development and ecological reclamation. The characteristics of tailings are a dominant sand fraction (up to 96% sand), limited clay fraction (< 14%), dominant quartz minerals, low water holding capacity, extremely low organic matter and all nutrients (especially N, P, K, Ca, Mg, S), slightly acid, and the limited number of weatherable minerals (potential native nutrient sources). Total elemental oxide composition was dominated by SiO2 (92-96%) deriving from quartz minerals.
Heavy metals were occluded in structures of hot-minerals meaning that they were less availability and low health risk. Heavy metals consisted of mainly Cr and small amounts of Sn, Pb and Hg. Sn availability was minimum in all cases since it was preserved in host-mineral structure (cassiterite) which was resistant to chemical weathering.
Without technology intervention, the reclamation of post-tin mining areas was unlikely and was uneconomically feasible in the short-term. Strategic reclamation includes building up soil organic matter content, establishing pot planting point technique, thoroughly incorporated initial topsoil if it is available, complete fertilizer application and selection of adaptive crops with an ability to fix nutrient from the atmosphere.