The man has already received offers of $160,000 and he has dubbed his nugget "You Wouldn't Believe It", according to a press release distributed by Aussie metal detecting technologies firm Minelab via AAP.
Mark Day — who operates metal detector retailer Gold Ballarat — said the nugget was unique in its size and that the prospector had dabbled in metal detecting on and off for "some time".
"I've been in this business for 25 years and this is the biggest find we have seen by one of our customers — that they've told me about anyway," he said.
Mr Day said the retiree had visited the store soon after finding the nugget to ask if he was interested in buying some "big gold".
"I said I wasn't a buyer and asked him what he meant by big. He said two kilos and I just said 'You've got to be kidding'," he said.
"When he showed me the nugget here in the store he was shaking like a leaf. He didn't know what to do with it. He hadn't slept in three days."
While the man is remaining tight-lipped about the nugget's exact location, it was reportedly found a metre below the surface in old pasture land within 150km of Ballarat.
The exact location is top-secret.
"He told me the detector made a noise and when he dug down a short way and found a .22 lead bullet and thought that was that. But the detector kept insisting there as something there, so he dug further and — bang — there it was," Mr Day said.
"History tells us that big finds like this have happened in this area before, and even though they've been digging gold in this region for 150 years, it's still out there.
"People collect nuggets, they don't want them melted down. And this one has real character to it. We were in awe when he brought it in. It really looks good."
Mr Day said the prospector was convinced "there's more gold out there".
The incredible find comes just months after a Bendigo man found a 624g gold nugget worth $35,000 while walking his dog in May.
The local man, who asked to remain anonymous, was walking the family dog — fittingly named Lucky — on the outskirts of town on a Sunday morning when his daughter kicked something hard lying on the ground.
At first, the father and his two daughters were unsure of what they had found — but it has since been confirmed by experts as a 624 gram gold nugget.
Last September, a huge gold nugget worth at least $110,000 was uncovered by a retired prospector in remote Western Australia.
And in 2017, Surfers Paradise gold digger Greg Cooke made headlines after finding several gold nuggets on a northern Gold Coast beach over several visits.
