Coal occurs in river and lake sediments resting on basement rocks in many parts of New Zealand. Most important mining areas are shown on the map below.
- Coal and associated sediments commonly contain sulphur in the form of pyrite (FeS2). Sulphur is highest in coals associated with sediments formed near the sea coast.
- Sulphurous coal exposed at the surface produces sulphuric acid during oxidation (acid rock drainage).
- Pyrite in coal generally contains traces of arsenic, which is released with the acid rock drainage.
- The acid also dissolves other metals from associated sediments. The most common metals dissolved in New Zealand coaly sediments are copper, nickel and zinc.
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Introduction
Overview: Geological setting for Metals in the New Zealand environment
- Epithermal Gold
- Mesothermal Gold
- Acid Rock drainage
- Coal
- Metals in groundwater
- Alluvial Gold
- Northland Mercury
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Hot Springs (in heavy metals)