Story: Gold and gold mining
Page 5 – Coromandel Peninsula
The first rumours of gold in New Zealand came from the Coromandel Peninsula in the 1820s. Nothing came of the reports for decades. Then in 1852 some Aucklanders offered a reward of £100 for the discovery of a payable goldfield near Auckland. When the reward was increased to £500, a sawmiller named Charles Ring claimed it after he found golden flakes in his pan at Driving Creek, near Coromandel town. His find led to only a small patch of alluvial gold – by April 1853 less than £1,200 worth had been won. But even a small strike attracts prospectors, and if the original strike fails they search again. Prospectors found little until quartz reefs were uncovered in the hills of Coromandel Peninsula in the early 1860s. But extracting gold from quartz was difficult.
Hard rock at Thames
The first big strike was near Thames in August 1867, when a speck of gold was seen in the rock face of a waterfall in Kuranui Stream. Other reefs were uncovered, and within months the Thames foothills swarmed with men. Mining quartz reefs needed capital investment to tunnel, mine the ore, crush it and separate the gold. This type of mining favoured larger companies and gradually they took control of production.
Some reefs were spectacularly wealthy. In 1870 the Caledonian mine in just over a year produced 140,000 ounces (3,969 kilograms) of bullion (silver and gold). At the peak of the rush in 1868, 18,000 people were living in Thames. Other very rich reefs were soon discovered and quickly worked out so that by the 1890s the big gold rushes were over. Miners now knew where the gold was, but they needed to find an economic way to mine it.
Recovering the gold
Machines called stamper batteries, which crushed quartz into powder, were set up in the Coromandel ranges. Most mines were steadily producing ore, but the recovery methods were highly inefficient (only 45% of the gold and barely any silver was recovered).
In 1889 the cyanide process was trialled by the New Zealand Crown Mines Company at Karangahake – the first time in the world cyanide had been used on a large scale for commercial mining. Cyanide was added to crushed quartz ore. Gold and silver dissolve in cyanide, allowing more of these metals to be recovered (about 90% of gold and 50% of silver). They are extracted from the cyanide solution using chemical processes.
The new process was a leap forward as it made lower-grade deposits profitable. Previously, much fine gold had been lost, and in places it paid to rework tailings (waste rock) with cyanide to recover the lost gold. Cyanide recovery stimulated investment. Mining continued successfully until the 1920s, by which time many ore reserves were depleted. The depression saw a brief flurry of new mines but nothing came of them.
A handful of very rich mines dominated production. One was the Martha mine at Waihī, which when it closed in 1952 had produced a total of 992,233 kilograms of bullion. Waihī was the site of a large miners’ strike in 1912 – a bitter wrangle that lasted six months and resulted in New Zealand’s first death in an industrial dispute.
In the late 1960s the Tui mine at Te Aroha and the Ohinemuri gold and silver mine at Maratoto reopened. They did not last. Both closed in the 1970s after producing a further 5,018 kilograms of mainly silver, and some gold.