Gold 'mother lode' unearthed underground in Kambalda delivers $15 million in just four days

Underground miners in outback Western Australia have unearthed rare gold specimens which geologists are calling a "once-in-a-lifetime discovery".

Workers at the Beta Hunt mine near the small town of Kambalda, 630 kilometres east of Perth, have brought more than $15 million worth of gold specimens to the surface in just four days.

The gold-encrusted rocks were found about 500 metres below the surface in an area just three metres wide and three metres high.

The largest specimen weighs in at 90 kilograms and took three men to lift it onto the back of a ute.

The quartz rock is covered in an estimated 2,300 ounces of gold worth about $3.8 million at today's gold price.

Another 60kg specimen is estimated to contain 1,600 ounces, or about $2.6 million in gold.

Senior geologist Zaf Thanos said in most mines around the world it is only possible to see gold through a magnifying glass.

"You might go your whole life and you'll never see anything like it. It's definitely a once-in-a-lifetime discovery," he said.

"This sort of bonanza zone is incredibly unique."

The rich cluster of high-grade gold has so far produced more than 9,000 ounces.

'I've never seen anything like this': miner

Kambalda miner Henry Dole is credited with the discovery, describing it as hitting the "mother lode".

Mr Dole had drilled holes into the wall of the mine and planted explosives which were fired once he was safely on the surface.

When he came back to the same area for his next shift, Mr Dole thought it was business as usual.

"I've been an airleg miner for 16 years. Never in my life have I ever seen anything like this.

"There was chunks of gold in the face, on the ground, truly unique I reckon.

"I nearly fell over looking at it … we were picking it up for hours."

Security tightened but temptation remains

A handful of gold rocks could be worth several thousand dollars, so security has been beefed up in the days since the find.

Armed guards have been transporting the gold to a secure vault.

Workers are under constant video surveillance and the area of the mine where the gold was found has been fenced off and padlocked.

The irony is that Beta Hunt has been mined for nickel, which is a key ingredient in stainless steel, since the 1970s, and gold has always played second fiddle.

There are stories among the workforce dating back to the early days of the mine which suggest similar bonanza finds may have been made in the past but were not considered significant at the time because of low gold prices.

There are also tales that workers in those days would bury bags of gold rocks in the event the commodity came back stronger.

Large specimens to be auctioned off to collectors

The mine's Canadian owners, RNC Minerals, are planning an auction for the large specimens.

RNC president Mark Selby said collectors in north America and around the world are known to pay up to a 50 per cent premium on the gold metal value for rare specimens.

"Given the rarity of the rock, and the physical beauty and presentation of the gold that's there, it's a very spectacular stone in multiple ways so we'll see whether 20, 30 or even 50 per cent premiums apply here," he said.

"We're really looking forward to auctioning the key stones off over the coming weeks.

"There's a pretty select group of collectors who this would appeal to.

"When you look at nuggets, which are a solid piece of gold, the biggest are around 2,000 ounces, so this is right up there in terms of the largest specimens we've ever seen."

Rich find will not stop sale of Beta Hunt

An interesting sub-plot to the discovery is the fact Beta Hunt's future had been in doubt.

The Toronto-based company was battling to keep it open and put Beta Hunt on the market several months ago.

The sale process is now in the final stages, but Mr Selby said the "world-class discovery" does not make RNC think twice about selling up.

"When we started the sale process it wasn't because we don't like the asset. We always believed that it had the potential to become a multi-hundred-thousand ounce mine, we just weren't able to raise capital required to do the exploration drilling," Mr Selby said.

"We believe that a different set of management should be running the asset with the right amount of capital to take it forward."

Are the miners just scratching the surface?

The question now is whether there is more bonanza gold waiting to be found at Beta Hunt.

In the eyes of Mr Dole, there is no doubt and he hopes it is just the beginning of a revival for the Kambalda community, which has been hit by multiple mine closures in recent years.

"It's no secret we were looking down the barrel for a while, but with this, it's picked everyone's morale up," he said.

"It's good for the town, the mine life, all of that.

"I reckon we're just on the fringe of it … and if we get deeper I reckon we'll find more."