At the Puhipuhi Mercury Mines, a jumble of WWII-era industrial equipment is hidden amongst the regenerating native vegetation.

Warning: The Puhipuhi Mercury Mine site is not developed for visitors. There are no signs, tracks, or other visitor facilities. The site contains multiple hazards, including unstable structures, machinery parts, steep slopes and possible mercury contamination.

The ruined machinery, overgrown roads and railway tracks, and tumble-down buildings are testimony to all the hard work and money invested in the operation.

Puhipuhi Mercury Mine: history and site description (PDF, 3,058K)

Heritage values

The Puhipuhi Mercury Mines (1907 – 1945) were a notable failed experiment in New Zealand’s industrial history.

(The image on the right shows the processing plant in 1968: the building with the vertical terracotta pipes is part of the cooling system to condense vaporised mercury into its liquid form. The towers are visible in the bottom left corner)

Mercury was only every commercially extracted from three places in New Zealand: Puhipuhi, Ngawha (Northland), and Mackaytown (Coromandel Peninsula).

The Puhipuhi site is unique, because there remains a great deal of the processing plant machinery – such as the metal cooling towers 12 metres high, a cast iron extractor fan, and part of a giant rotating furnace.

For the cost of £2 000, a dam was built across Waikiore Stream to ensure a water supply. The dam and the lake it created are present at the site today.

The mercury mines were not a pleasant place to work. The men who operated the processing plant were in constant danger of inhaling toxic mercury vapour. In 1935 they were suffering from highly inflamed gums and loose teeth – symptoms of mercury poisoning.

During WWII, the daughter of one of the workers remembers her father being very ill, waking up with his mattress soaked in sweat. Excessive sweating is another symptom of mercury poisoning, along with tremors, lung damage, kidney damage, nausea, emotional upheaval, and even death.

The men who invested in the mining venture were not slowly poisoned like some of their employees, but they did suffer in terms of their finances. Like any business, the succession of companies who operated at Puhipuhi generated a lot of paperwork over the years.

The scientific and technical reports, business documents, and correspondence paint a picture of an on-going failure to make money out of mercury.

Even during WWII – when mercury was in great demand for compasses and munitions – the mine failed to prosper because the right equipment was in short supply.

The final straw came after WWII ended, and the price of mercury collapsed so that it was not worth the effort.

View a map of the mercury mine in the 1940s (GIF, 141K)

Conservation work

Conservation work has only just begun at the Puhipuhi Mercury Mines. Recording all of the ruins is a challenging task, made all the more complicated by the dense undergrowth.

Once the site has been properly recorded, DOC will monitor the historic ruins to see whether any stabilisation work needs to be done.

The Puhipuhi Mercury Mines is not a visitor site at present. There is potential to develop walking tracks along the existing benched formations, which used to be roads and railway tracks. This would require the removal of rather a lot of gorse and native undergrowth.

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