Gold mine stamper preserved in situ
Restoration team members put the finishing touches on the massive beams they replaced under the stamper. From left, John Taylor, Justin Adams, Steve Bagley (archaeologist standing on the top of the machine) and Matt Page. The bundle of gear in the foregro
A fascinating piece of Golden Bay’s industrial heritage has been preserved, thanks to the extraordinary efforts of some Department of Conservation experts.
The Johnston’s United gold mine stamper battery at Decimal Creek near Wakefield Gulley was in use for about 20 years until the late 1890s. During that time, about 30,000 ounces of gold were extracted from the mine in the hills behind Rockville.
The process of extraction in the steep and isolated country was painstaking, to say the least. The quartz ore was dug out of the mine in the hill above the creek. It was transported on a bush tramway along the side of the hill to a point directly above the stamper battery, where it was taken straight downhill on a gravity incline. Men unloaded the ore and shovelled it into chutes on the back of the stamper box. The stamper rods were attached to a steam-powered camshaft. The rods crushed the rocky quartz ore into a fine flour. It is hardly surprising that the men who worked on or near the stamper batteries were all clinically deaf within a couple of months.
The steam to drive the machine was generated in a boiler-house next to the battery, and the boiler was in turn fuelled by firewood cut from the surrounding hillsides. The flour from the stamper box was washed over a copper bed, where mercury was introduced into the mix so that some of the gold would attach itself. At the end of this process, the fine material was washed into verdans [large, steel mechanical pans with gears on their bases], which sloshed the mix around again to get more gold to attach itself to the introduced mercury. Finally the mix - was released into the creek. The extracted mercury/gold amalgam was condensed to separate the gold again, and the gold was assayed and transported out of the hills.
While the Johnston’s United mine was in its heyday, there was a thriving settlement in Bedstead Gully nearby, and in fact the stamper originally stood in Bedstead Gulley before being moved to the Decimal Creek site.
Local historian Denny Giloolly says that he first went looking for the original stamper site in the late 1960s or early 1970s.
“They had a lot of houses in there. You used to be able to see the mound where each house’s fireplace used to be. In the spring, bulbs used to come up and show you where the gardens used to be. The settlement obviously had a bakery, because my brother and I found the old baker’s oven.”
The disused stamper battery had stood in the bush at the bottom of the gulley near Decimal Creek for over 100 years, understandably deteriorating. It is the last standing 20-head in situ gold-stamping battery in the country. DOC has an interest in developing cost-effective methods of stabilising heritage machines on the site where they stand. They acknowledge that that there is a strong role for museums in preserving old machinery in controlled indoor environments, but they also wish to preserve interesting machines on the sites on which they worked.
Constructing the Johnston’s United stamper battery and transporting it to its site would have been an amazing feat in its day. The recent preservation work was accomplished with the assistance of a fair amount of modern technology, but it was hardly less remarkable.
The work required the four-man team of skilled restorers - John Taylor, Justin Adams, Matt Page, and Kim Forbes with help at times from Willy Abel and Tony Hitchcock - to work 12-hour days for six days at a time over several visits to the site late last year. The men were chosen for the job because of their range of skills and their interest in this kind of heritage restoration work. The project was a serious undertaking for DOC and had a budget of tens of thousands of dollars.
The massive timber supports under the steelwork were seriously compromised, so the DOC restoration team was confronted with the task of digging out around the base of the battery to expose the beams. This work was done as an archaeological investigation with authority from the New Zealand Historic Places Trust. Next, they undid the king-post stay-nuts that had been sitting outside for a century. This required two special spanners. One was borrowed from the Collingwood Museum at Rockville, and the other was especially manufactured by Waitapu Engineering. Having removed the bolts, the team carefully jacked up the entire steelwork so they could remove the beams from underneath. Then the new 17 x 24 inch beams, each weighing between 800kg and a tonne, were manoeuvred into place, and the steelwork was lowered back down onto them. The beams were so heavy that they were transported one at a time to the site by heavy-lift helicopter.
Because of the restoration work, the stamper battery is now likely to survive for many decades and be a landmark for visitors who make the effort to visit the site. Access is a little difficult. It is about a 20-minute, steep, downhill clamber off a four-wheel-drive track that begins just past the Devil’s Boots. The men involved in the restoration project hope that access to the site might be improved so that people visiting the stamper can get there more easily.
DOC archaeologist Steve Bagley explained the significance of the project.
“The Collingwood gold-field is a significant archaeological landscape. It encompasses some of the earliest alluvial workings as well as the some of the earliest hard-rock mining. The Johnston’s United battery is an important part of the story. It’s great that future generations will be able to see this interesting machine in its upright state. It has been identified as having national significance because it is the last of its size standing on site in New Zealand.
Neil Wilson
