A Northern Territory heritage group is defending a decision to throw an old Chinese coin found on a remote island back into sand dunes, saying it did not have a choice.
The brass coin, thought to be from the Qing Dynasty and minted between 1736 and 1795, was found on Elcho Island last month by a group of heritage enthusiasts called Past Masters.
Group spokesman Mike Owen said they were following the instructions of the NT Government.
"They [the NT Government] said if we found anything it had to go back," he said.
"That was in discussions we had last year," he said.
The heritage group, which includes a geomorphologist, an anthropologist and several archaeologists, was on Elcho Island, about 600km east of Darwin off the coast of Arnhem Land when they made the discovery.
They located the coin using a metal detector and said they photographed the item before throwing it into the sand dunes where it had been found.
Reaction to Chinese coin discovery
News of its discovery sparked international interest, with some speculating on ancient links between China and northern Australia.
Others downplayed its importance, saying similar Chinese artefacts had been found around goldfields in the Northern Territory.
The decision to leave the coin in the sand was criticised.
"Chances are someone else would come by with a metal detector and grab it," said a post onReddit.com.
"Is there not a museum that would be interested in this?" asked another.
Others questioned whether the coin was really found at all.
"It reminds me of those guys that claimed to have shot a mythical wild Victorian panther, but decided to throw the carcass in the river after taking a photo," said one person posting on the site.
No requirement for valuables to be returned
A spokeswoman for the NT Department of Lands, Planning and the Environment, which deals with heritage matters, said there was no rule or requirement that valuable items be returned to their original location.
However, she said the research undertaken by Past Masters was conducted at a known Macassan archaeological site.
Macassan people are known to have visited Australia for hundreds of years from Indonesia to trade in trepang, or sea cucumbers, and there are legal protections for these sites.
"Such sites are automatically protected by the Heritage Act as heritage places. This means that a permit is required for any disturbance of the site," she said.
It is understood Past Masters did not have a permit to carry out their activities, although Mr Owen disputes that they were at a known Macassan site.
Coin should have been left where it was found
Curator of the Museum and Art Gallery of the Northern Territory, Paul Clark, said picking up a coin and taking it from where it was found would mean it lost its context.
"Metal detectorists and heritage enthusiasts and general members of the public are not encouraged to collect artefacts from the field," he said.
"Professional archaeologists, museum people etc, historians, anthropologists, they don't go willy-nilly into the field and just pick up any shiny pebble that they come across on the beach.
"Archaeology is about trying to understand past human behaviour and it is not really about antiquarian collecting."
Mr Clark said it was impossible to know how the Chinese coin came to be on the remote island.
'Finders keepers' for old coin?
An artefact dealer from Queensland, Arthur Palmer said he thought that Past Masters should have kept the coin.
"In my view it would have been better for research purposes if it had been kept safe," he said.
Mr Palmer said for isolated finds on beaches it was usually a case of "finders keepers".
Other coins have previously been found at the site.
In the 1940s a soldier found coins that were later shown to be 1000 years old and originally from the Tanzanian port city of Kilwa.