The higher calcium leaching at lower pH cannot be demonstrated for mine waste. Only 38 % of the calcium content from the copper mine and 47 % from the iron mine can be leached from both tailings. This maximum is also independent of acidity, so it must be due to unavailable calcium. To make more calcium available, grinding the tailings may help. More magnesium can be dissolved from the tailings than from the talc. This can be explained by the chemical resistance of talc to acid. Both target products, Ca 2+ and Mg 2+ , behave the same in terms of leaching rate with the rates of the individual particles.