Thames, Thames-Coromandel District, Waikato Region, New Zealandi

Regional Level Types
Thames	- not defined -
Thames-Coromandel District	District
Waikato Region	Region
New Zealand	Country

Gold was discovered in Kuranui Creek on 10 August 1867 by Hunt, White, Clarkson and Cobley at what would become the Shotover claim. The discovery led to a gold-rush, and by the end of 1868, the Thames area held 1200 claims, with about 800 working, and 600 of those on gold to variable degrees. There were also 27 batteries, with 13 more under construction. By this stage the field had produced 83 000 ounces of gold.

Like many goldfields, leases passed from prospectors to small local companies, reaching a maximum output by 1871. This was largely to do with the bonanza discovery in the Caledonian Mine. The quartz reefs in the Thames area were generally low in gold, except where veins intersected, at which point there were at times rich gold specimens. The central area of the mines produced half a dozen bonanzas of this kind, overall contributing to about 40% of the gold produced.

Gold production gradually decreased, and the English capital boom of the 1890's did little to arrest the slide. The vast sums of money spent by English investors was not warranted, often leading to the early ceasing of operations, sale of the properties, and the companies liquidated. The Waiotahi bonanza discovery of 1904 was the last hurrah, and major mining had ceased by the World War One years. Minor intermittent mining and prospecting continued until the 1940's.

A major structural feature is the north north-west to south-south-east Moanataiari Fault, which divides the goldfield into an upland, and lowland area. The fault traverses the mountains behind Thames, and can be seen as a stepped feature. Parallel to this is the beach slide, a fault following the former foreshore, and now crossing the middle of the Thames town-site, and marking the western limit of the goldfield. More minor faults include Collarbone, a north-south feature from Shortland Flat in the south to the head of the Waiotahi Valley, and the Hague Smith Fault, also north-south trending further inland.

The majority of the quartz reefs trend north-east to south-west, and are majorly thrown at the Moanataiari Fault, to the point many have separate names either side of the fault. Reefs on both sides can be gold bearing, and the fault effectively divides the goldfield in two. The reefs are often highly lenticular, show for a short distance, and go to no depth. The quartz is finely crystalline, shows many small cavities near surface, often stained black or brown in the upper areas by manganese oxides/pyrolusite/manganite and limonite, but is otherwise white, or bluish-white, with also chalcedony and jasper in some of the veins.

The reefs are hosted by variably propylitised altered andesite. The alterated andesite is soft white, light grey, purplish-grey or greenish, with chalky feldspars, secondary pyrite, leucoxene, siderite, and minor epidote. The major components of the andesite include hornblende, augite, pyroxene, and hypersthene. Inamongst this is harder dark un-altered andesite. Also found is breccia, the quartz veins being more defined and usually holding more gold where they cross the altered andesite, rather than breccia. Clay, quartz grit, sandy material, fragmentary country rock fill the faults.

Gold and silver is found in electrum, as jagged shreds, filaments, plates, and granular aggregates. Gold-silver may also be found in relatively minor tellurides. The northern section of the Thames field contains the most tellurides, with hessite the main ore component of the Waitangi Mine. Sulphides include major amounts of pyrite, some galena (often low grade argentiferous), sphalerite, chalcopyrite, and minor arsenopyrite and molybdenite, associated with gold in the veins across most of the goldfield, however again more prevalent in the northern sections. Minor enargite can be associated with gold in clay areas.

Of other species, calcite and aragonite is found in small quantities; selenite and chalcanthite as major recent encrustations in old workings that are almost impossible to access now; ankerite common in the Una Hill and Karaka Stream areas; chlorite the Tararu Stream area, pyrargyrite in the Kuranui-Caledonian mine area; minor copper oxidation products like bornite, malachite, and cuprite; common rhodonite and rhodochrosite in the northern sections of the goldfield, giving the reefs a pinkish tinge.

Specimens likely seen from the goldfield are attractive stibnite crystal aggregates, with yellow cervantite as an alteration product. Clear barite transparent plates and rhombic prisms attached on edge to quartz and pyrite in cavities. Gold specimens are generally found in local museums, being a few saved that were not processed.

Mindat only lists the most major of the mines for the Thames area. The town has the Thames School of Mines, which includes a mineral display, and attached rock shop, although its selection of New Zealand specimens is limited. The Thames Gold Mine Experience, includes an operational stamp battery, and underground tours. The pumphouse, and technological museum may also be worthwhile. Most have limited opening times, especially in winter.

References

Localities in this Region

Other Regions, Features and Areas containing this locality