When a young boy swung a pick and struck gold in central Queensland more than 150 years ago, it changed the course of history for the then frontier town of Rockhampton.
The 12-year-old lad pulled away the grass on his father’s claim and found a log of gold measuring 23 centimetres long, 10 centimetres wide and so heavy (258 ounces and worth $628,000 at today’s prices) he couldn’t lift it.
The next few decades would see gold rushes across the district including New Zealand Gully, near Mount Chalmers, with the eventual discovery of a mountain of gold at Ironstone Mountain around 1878.
That mine became Mount Morgan, 40 kilometres south of Rockhampton, and would eventually yield a total of 225,000 kilograms of gold, 50,000 kilograms of silver and 360,000 tonnes of copper over 99 years.
But while gold has been the prime focus of exploration around Mount Chalmers over the past 100 years, it is the lure of copper and record high prices of around $10,000 a tonne that has seen a renewed spark in activity.
Evidence points to more rich deposits
With 73,000 tonnes of copper equivalent at the QMines-owned Mount Chalmers project, it is easy to see why geologist Hamish Grant is excited.
The copper is buried under the Cawarral Gold Trend, a narrow corridor 15 kilometres long and five kilometres wide, formed by an undersea volcanic eruption during the Triassic period about 250 million years ago.
While Mr Grant and teams of drillers and field technicians are excited by the size of the proven copper deposit, what interests them even more is the potential to find similar copper and gold discoveries in the vicinity and “grow the resource”.
Mr Grant holds up a cylinder-shaped ore core sample taken from a recent diamond drill and points to the strong colour, indicating high-grade copper.
“Mount Chalmers is good, but if we can find another Mount Chalmers that hasn’t been mined, that hasn’t been eroded, and is still intact, that’s the real upside,” he says.
“We believe Mt Chalmers could be one pod and in this basin there could very well be multiples, I don’t know how many, but we already know from some historic soil sampling that other companies did way back in the 1970s and 1980s that we have good copper, lead, zinc numbers in the soil – and you only get those numbers if there is something going on.”
The Mount Chalmers team have combined the results of their intensive exploration program with historic samples, and are digitising the findings to establish the current inferred copper and gold resource.
QMines boss Andrew Sparke said the company had only listed in May and the prospects of developing Mount Chalmers’ mine to production were encouraging just four months into a two-year exploration phase.
QMines has an objective of increasing the resource to around 200 kilotonne of copper equivalent over the next two years through a 30,000 metre drilling program.
Getting a thrill from the drill results
Just a short drive away is the mine camp, which is a low-set house on a level block. It sits on a hilltop with ocean views.
He turns on his computer to show what 73,000 tonnes of buried inferred copper looks like after the drill results were converted to a graphic.
The three-dimensional image displays the copper as a large green blob underneath the old open pit mine. It looks like a big green whale.
“All this stuff (old data) had never been digitised,” Mr Grant says. “We have asked some contractors to go through all the data, all the reports, maps, go through the coordinates to put into a grid we can use today with a GPS.
“The old boys (historic miners) were pretty good. In 1890 they found this thing and it was outcropping (on the surface) so they chased the higher grade massive sulphide (volcanogenic massive sulfide ore deposits, also known as VMS deposits, are a type of metal sulfide ore deposit, mainly copper-zinc associated with and created by volcanic events in submarine environments).
“In the late 1970s, GeoPeco (the former mine owner) came in here and did an open pit over the top of the underground workings and we have that digitised as well. The real upside now is finding more of them (copy cat mines).”
A pub on every corner
Just down the road at the Mount Chalmers Community History Centre, secretary Sue Hutchinson points out the fascinating array of mining photos and artefacts from the town’s gold rush days in the early 1900s when the population was 2000, serviced by five hotels.
“There was a pub on every corner,” she says of the boom-town period before the gold mine faded out.
A resident of 30 years, she has seen several mining companies come and go over the years as they try to revitalise the old mine.
“You get rumours that the mine is going to open up again. A few people come out drill some holes, they go away you hear nothing. Nothing happens,” she says.
As for the chances of the amateur prospector still striking it rich, she wished them the best.
“There is a group with metal detectors that come out,” she says.
“They politely ask if they can go for a wander around the school grounds, but I don’t think they ever find anything.”
She said some of the old claims, like those at New Zealand Gully, were impossible to get to and any would-be fossickers needed to get permission from property owners.
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