SYDNEY (REUTERS) - An amateur Australian prospector who has not had much luck searching for gold has struck it rich, unearthing a nugget heavier than a newborn baby and worth more than US$300,000 (S$367,000).

The anonymous prospector discovered the 5.5 kg nugget near the country town of Ballarat and in an area known as the "Golden Triangle" due to its rich veins which sparked a gold rush in the 1850s.

The find came to light on Wednesday when the man walked into the Ballarat Mining Exchange Gold Shop and told owner Cordell Kent: "Mate, I found a good one". He then produced the nugget, adding that he had weighed it on the bathroom scales at home.

"It's a substantial nugget," Kent told Reuters.

The Y-shaped nugget, 22 centimetres long and 14 centimetres wide, was found by the prospector using an Australian-made gold detector.

"The intrinsic gold value is about A$286,000, but because it's a natural raw specimen and they're extremely rare, it's got a value far in excess of that," Kent said.

The southern state of Victoria's "Golden Triangle" is known for large nuggets, such as the massive 27.21 kg "The Hand of Fate" nugget, which is now housed in a Las Vegas casino.

Kent said the find was likely to create a new, mini gold rush. "It's given a lot of prospectors great hope that there are still great pieces out there," said Kent.