The discovery by CSIRO scientists of the richest gold, silver, copper and zinc sulphide deposit ever found on the ocean floor has led to the granting of what are believed to be the world's first deepsea exploration titles for these minerals.

The series of deposits was found by an international team aboard the CSIRO research vessel Franklin, led by Dr Ray Binns of CSIRO Exploration and Mining, at depths of 1200-1700 metres in the Manus Basin, part of the Bismarck Sea, off New Britain.

The discovery has sparked renewed international interest in the possibility of economic mineral production from the seabed, and resulted in the granting by PNG authorities of two underwater exploration and development licences to Nautilus Mineral Corporation PL.

"There are two fields which have proved so far to be rich in minerals, the PACMANUS hydrothermal field and the SuSu Knolls," Dr Binns says.

"The average compositions of research samples from PACMANUS and SuSu respectively include 10% and 15% copper, and 26% and 3% zinc. PACMANUS has 15 grams of gold and 200 grams of silver to the tonne, while the figures at SuSu are 21g/t and 130g/t.

"If you found this deposit on dry land, you'd call these bonanza figures. They could change the economics of sea-floor mining and cause it to be taken seriously," he says.

The Chief Executive of Nautilus, Mr Julian Malnic, says the deposits represent an entirely new kind of mining opportunity and may offer a viable alternative to mining on land.

Mr Malnic says he has been excited about the prospects of the deposits ever since he saw the first high-grade samples brought up from the bottom of the Bismarck sea in 1993.

"They were utterly compelling," he says. "And the fact we now have title to the deposits has galvanised the scientists, and mining industry into seeing the possibilities."

Mr Malnic says it is surprising how much technology already exists for undersea mining. The other surprise has been in modelling the mineral economics expected to apply and the big advantages of undersea mining which are already emerging.

CSIRO and Nautilus recently signed a strategic agreement to collaborate in research projects on seafloor exploration and mining methods for application to the Manus Basin region.

The high-grade sulphide discoveries are the fortunate byproduct of a six-year investigation by CSIRO, in collaboration with researchers from Canada, Germany, Japan, Papua New Guinea, and the United States, into how world class ore deposits like Mt Isa and Broken Hill originally formed on the sea floor.

This involved the study of a region of "black smokers" ­ sea floor chimneys where submarine volcanoes are belching out superheated clouds of dense mineral-laden fluid. On contact with the cold salt water the sulphide minerals coalesce to form deposits rich in gold, silver, copper, lead, zinc and other metallic elements.

Inspired by the eerie undersea landscapes their submarines and robot cameras revealed, the scientists dubbed them appropriately: "the Satanic Mills" was an area of active smokers, "the Roman ruins" a series of ragged natural columns protruding from the seabed, while "Snowcap" was a hill carpeted in snow-white bacteria dining on the rich nutrients.

"Every time we go up to the Manus Basin , we find something new and amazing. There have to be lots more similarly rich deposits in the area," says Dr Binns.

"Fields like this make the prospect of undersea mining look economic. It is already technically feasible and, in one sense, it is cheaper than mining on land because you don't need fixed infrastructure as you do on a terrestrial mine. Hauling the ore from the depths of the sea is no harder in theory than hauling it up from deep underground."

Dr Binns is optimistic the find will spark further research into mineral deposits that lie on the seabed and into innovative ways to develop and exploit them, perhaps with robots.

He believes it will give fresh focus on Australia's Exclusive Economic Zone (EEZ) ­ an area one-and-a-half times the size of the continent ­ and the prospect that it is endowed with other different, yet promising undersea mineral resources.

More information:
Dr Ray Binns, CSIRO 02 9490 8741 02 4883 6069 (ah)
Julian Malnic, Nautilus 02 9360 2941
Chris Priday, CSIRO 02 9887 8247

Pictures:
Picture and vision opportunities available from CSIRO and Nautilus. Betacam undersea footage available.