The new specimen, from the Victorian goldfields, weighs 2 tonnes and fingers are crossed it won't need to be replaced.

"We hope it will be harder for someone to take it away," garden chairman Professor Brad Pillans said.

"Our stonemason has assured us it will be secured firmly."

Thieves caused thousands of dollars of damage when they stole the 1-tonne rock from the garden's Federation Rocks display.

The sandstone and quartz rock from a goldmine in Bendigo featured prominent gold-flecked quartz veins.

Although a spectacular geological specimen, its value in terms of how much gold it could yield was minimal.

Professor Pillans said the 1-tonne boulder might have had $100 worth of gold in it.

"We have to assume that whoever took it has crushed it up and tried to extract the gold," he said.

"It is a pretty hard way to make a living.

"The original rock had quite a lot of fool's gold in it – what is called pyrite - so maybe they really were fools."

The new rock has been donated by Castlemaine Goldfields mining company.

Transport and installation costs are being paid for by the Victorian state government.

The new specimen is from Ballarat, one of Victoria's most famous gold towns.

"Learning from our past experience, although we wanted to replace it with something similar, we were very keen on having a rock with no gold in it," Professor Pillans said.

"That will restore the Victorian Federation Rocks display back to its former glory."

The display was first opened by former chief minister Katy Gallagher in October 2013 and was designed to commemorate Australia's Federation.

Each state donated rocks that symbolised their history.

The next phase of the National Rock Garden will be to populate its 2-hectare site with other spectacular geological items.