Increasing environmental legislation has resulted in a need to test and characterise waste materials, particularly those from mining operations. The waste characterisation laboratory tests materials for their ‘leachability’ using short-term ‘static’ methods and longer-term dynamic methods (e.g. humidity cells). These tests allow an assessment of the likelihood that waste materials will release high levels of potentially hazardous substances when exposed to the atmosphere. In addition, it is possible to determine the ability of such materials either to generate acid during weathering (e.g from pyrite) or neutralise any such acid produced (e.g. by carbonates).