Mineralogical studies of mine waste

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Metal-bearing sulfate minerals often have a significant impact on water quality near mining centers. They form through the oxidation and hydration of sulfur-containing ores. This process is accelerated dramatically when mining activity creates fine-grained sulfide-containing waste that can interact with oxygen and water. Mine waste from processing these sulfide ores creates very complex geochemical problems as the minerals interact with the atmosphere on the surface at a mine site and pollute the ground water. These problems can only be understood if there is detailed mineralogical information for the many sulfate minerals which come and go as the waste alters through the freeze/thaw cycle of the Canadian climate and over time as the waste matures. It is not enough to study well crystallized minerals from museum collections as these do not often have the same properties as materials that have formed under conditions found at active mine waste sites. To understand the mineralogical relationships a combination of field and laboratory studies are required. The field studies identify the particular mineralogical interactions which are important in mine waste settings. Laboratory experiments model these existing interactions in controlled settings so individual effects and processes can be isolated. These are not rare minerals from a restricted locality but are widespread in a variety of natural and disturbed environments. They are difficult to study because of their fine grain size and the intimate mixing of several species in one sample. The ability to design successful mine waste containment systems requires a thorough understanding of the minerals that are present. There is a tremendous opportunity for students to be trained in the various field and laboratory techniques during these studies.