Does mining release toxic chemicals?

In addition, like most traditional forms of mining, underground mining can release toxic compounds into air and water. As water acquires harmful concentrations of minerals and heavy metals, it becomes a pollutant. Surface and groundwater associated with mines are often affected by acidification. Acid mine drainage (AMD) is recognized as one of the most important environmental side effects of mining.

Coal mines may have the most serious acidification problems, as some coal seams contain pyrite, which has high sulfur concentrations. Runoff from sulfuric acid mines can occur when pyrite is exposed to water and oxygen, meaning this can have serious detrimental effects on water quality and on Mahinga Kai.