After the alluvial deposits were exhausted the large companies continued to recover gold by the mercury-amalgamation process. By 1890, however, many people feared for the industry's future. In 1889 the cyanide process was successfully tested in New Zealand and, before long, there was a revival of activity on the Thames and Ohinemuri fields. The new process also enabled the Waihi Co. to develop the low-grade gold and silver ores near Waihi and begin a “boom” period which lasted well into the present century.

In Otago and the West Coast, sluicing became the normal method of recovering gold. By 1890, when returns were again declining, dredging became the principal mode of production. In 1886 the Dunedin, the first steam bucket dredge, was built, and during the next decade, as technical difficulties were overcome, many dredges appeared on Otago rivers. The dredging boom lasted from 1898 to about 1913. In 1903, the peak year, there were 201 dredges working in Otago-Southland, the majority on the Clutha and its tributary, the Kawarau. There were also a further 63 on the West Coast. Today the Kaniere dredge, which works the river near Kumara, is the sole survivor of this era.

Between 1857 and 1960 over 27 million ounces of gold were exported from New Zealand. This has been valued at nearly £125 million.

by Bernard John Foster, M.A., Research Officer, Department of Internal Affairs, Wellington.

• A History of Goldmining in New Zealand, Salmon, J. H. M. (1963)
• Heart of the Desert, Parcell, J. C. (1951)
• History of Otago, McLintock, A. H. (1949)
• Charleston — its Rise and Decline, Faris, I. (1941)
• The West Coast Gold Rushes, May, P. R. (1962)
• The Prerogative Right of the Crown to Royal Metals, Parcell, J. C. (1960)
• Kawarau Gold, Sinclair, R. S. M. (1962).