Wesley, G, Mackenzie, S & Campbell, G 2019, 'Mine waste characterisation: the benefits of applying practical geological knowledge', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 275-286, https://doi.org/10.36487/ACG_rep/1915_22_Wesley (https://papers.acg.uwa.edu.au/p/1915_22_Wesley/) Abstract: Mine waste characterisation involves the determination of the physical and geochemical character of waste rock (including fresh, transitional and oxide material). In many studies however, geological interpretation is rarely given sufficient consideration during both the sample selection and results interpretation stages, resulting in incomplete characterisation and potentially requiring additional sampling and testwork at a later date. During the sample selection process, it is imperative that the most representative samples from all major rock types in a deposit are selected. To do so accurately, an understanding of the deposit morphology, genesis, alteration and structure is required. If these aspects are not well understood by the practitioner conducting sample selection, then important geological zones may not be represented in the set of selected samples, resulting in an invalid assessment. Conversely, site geologists may select appropriate and representative samples; however, the practitioner conducting the characterisation assessment may not fully appreciate the geological context of the materials being tested and miss potentially important intricacies in alteration and mineralogy, resulting again in an invalid or incomplete assessment. Knowing how the major rock types from a deposit will typically behave from a physical perspective is important in providing management recommendations that complement the geochemical results. This applies especially to rock types within the fresh zone in terms of their competency and stability as candidate materials for sheeting and cladding of the outer slopes of waste landforms. Geological knowledge can aid in the selection of appropriate samples for various physical tests assessing the suitability of fresh zone rock units for erosion control over the longer term. This paper explores the ways in which geological knowledge is intrinsically linked to technically sound mine waste characterisation; the starting point for pragmatic decision-making on waste rock management, waste rock dump design and closure. Keywords: materials characterisation, geological assessment, waste rock, sample selection