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Resources - Alluvial Gold
- Gold eroded from veins has been concentrated in sediments in valleys, basins and coastal plains as alluvial gold deposits in all gold bearing areas of New Zealand.
- These alluvial gold deposits have been, and are, an important resource especially in Otago and Southland.
- see The Gold Cycle (Southern Alps) and Gold at St Bathans
Mercury (Hg) in alluvial gold
- Alluvial gold in some Southland valleys has recently been found to contain a high mercury content.
- Mercury sulphide (cinnabar, HgS) from hydrothermal veins (see map) is commonly found with alluvial gold in gravels.
- Dissolved mercury in streams is elevated above background but is lower than drinking water limits.
- Miners melting recovered gold have inadvertently inhaled and ingested high levels of mercury.
