The environmental legacies of metal mining are often dominated by large waste facilities, which can be sources of acid and metalliferous drainage, resulting in both local pollution and irreversible loss of some of the soluble minerals. Whether a material is treated as waste or ore depends on a wide variety of factors and circumstances. Three critical aspects - time, the extractive strategy and the economic context - are discussed in this paper. The authors argue that the fine line between waste and ore requires a mine waste management (MWM) hierarchy that properly considers waste as a potential future resource. This hierarchy exhibits four main levels: reduce, reprocess & stockpile, downcycle and dispose, which are illustrated by a review of both academic research and public data on industrial practices. The authors conclude that to generate the most successful outcomes the hierarchy must operate across all levels and is a core component of an overall mine sustainability framework. (C) 2016 Published by Elsevier Ltd.