Mining is much more harmful than quarrying:

Key differences between these industries make mining far more dangerous than quarrying.

Here are some adverse effects of mining - whether mine processing takes place onsite or elsewhere:

• Mining causes serious water pollution – acid mine drainage : Mining for precious metals involves extracting and crushing heavy metal bearing rock. The gold and silver mineralisation in the Coromandel is usually associated with copper, lead, zinc cadmium and arsenic. Sulphides in the rock, on contact with the air and water, form sulphates that leach the toxic elements out . Acid mine drainage is the term used for such toxic water pollution that results from water passing over the exposed rock in mine workings or tailings. This pollution is a very serious and long-lasting, a problem that remains long after a mine is abandoned. On the west coast of the Coromandel acid mine drainage impacts particularly on the shallow sedimented waters of the Firth of Thames.
  For example in Te Aroha, poisoned water from the waste dumps and exposed rocks of the abandoned Tui mine high up the mountain has been a problem for decades since this mine closed. There is no final solution but a Ministry for the Environment funded $9.88million project has commenced to remediate the site, . At the Monowai hearing too, acid mine drainage was a major concern with no solution evident – it was concluded that the only safe solution was to fill the mine with concrete after mining so that water cannot contact exposed rock surface. This however is prohibitively expensive.
  Quarries by comparison takes place on granite or other hard rock deposits that are not so poisonous in contact with water. They also result in less rock surface area exposed to water as they crush less finely and do not leave underground workings. As the rock is less toxic, the smaller amounts of quarry leachate are far less hazardous.
  
  
• Mining results in hazardous waste : Mining uses only a tiny proportion of the material extracted, and safe storage of the mine waste that is not used poses a serious problem – waste that is not processed as well as the highly toxic processing waste. Rock extracted from a mine has a first crushing on site then the material for processing is separated out, i.e. the likely gold- and silver-bearing material is removed. The crushed rock that will not be processed constitutes very hazardous waste, in addition to the processed tailings. Putting it back into the mine (“back fill”) is expensive, difficult and adds to pollution from acid mine drainage as water can flow over more exposed surface rock this way. Also the waste rock takes up more space once extracted so it will not all fit in the mine. The toxic nature of the rock results in serious storage problems for this hazardous waste.
  For example in Te Aroha at the Tui mine, stored waste posed a huge threat during the 1985 and more recent flood events, threatening to descend on the town. At the Monowaimine hearing the company proposed to use waste mine crushings for roads but this was disallowed because of its toxic nature, and no solution was found to the storage problem.
  Quarries by comparison use most of the rock extracted, so there is far less waste and what there is less dangerous because of the different mineralisation.

• Mining earthworks are damaging : Mining takes place in areas that are inherently unstable because of the nature of gold bearing rock (unlike quarries for hard, stable rock). Thus mines are likely to be in particularly sensitive areas of the Coromandel. Thus earthworks for mining access ways and other industrial developments required will be proportionately more harmful, especially in steep, eroding, valleys and water catchments. The Monowai was to require many km of roading into the sensitive entrance of the Coromandel forest park .
  
• Mining causes ground subsidence : Underground mine tunnels leave a serious risk of ground movement and subsidence as the residents of Waihi know only too well. Modern underground mining now also uses methods of "block caving", blasting out the inside of hills and allowing them to collapse into “glory holes”. Subsidence on a major scale is to be expected from mining methods.
  
• Flood damage is increased by underground mining : Water that eventually floods the mine workings brings more pressure through cracks and fissures increasing the likelihood of slips after heavy rainfall especially in steep rugged water catchments.

Dr Rachel Garden

Notice-board

Headlines

The difference between Quarrying & Mining

current mining  background

Environment Court decision pdf(526kb)

Mark & Nedilka roast Coffee as well as Miners -- from the Thames Organic Co-op shop or below