A mining company which claims that hundreds of millions of dollars worth of gold is waiting to be recovered from the seabed off the West Coast is to start an exploration voyage on Monday.
New Zealand prospecting company Seafield Resources has contracted a subsidiary of South African diamond-mining giant De Beers to use a vibracoring rig - a seabed sampling tool - to cut as many as 400 holes 12 nautical miles offshore.
The sampling is expected to show the concentration of heavy minerals in the area.
Seafield Resources was granted a prospecting permit, prospecting licence and resource consent in 2006 to prospect for gold on the Westland continental shelf between Karamea and Jackson Bay.
The company will test the seabed off Westland over two months, but has said that if a worthwhile deposit is found, it will need to seek separate permits and consents for mining.
The sampling will be over a 2000-square-kilometre area, and Seafield director Grant Stubbs told Radio New Zealand that finding a concentration of just one gram of gold per tonne of sediment may be enough to make mining economic.
"It will have to be substantial enough to recover the capital cost of getting the equipment in and putting a whole mining operation in place ... we would be probably talking tens to hundreds of millions of dollars," he said.
The Green Party has said it will oppose mining of the West Coast seabed because of potential environmental damage.
The project was thought up by John Youngson, a Dunedin-based geologist and and specialist in "placer" or alluvial gold deposits.
His company, Placer Solutions (2004) Ltd, initially approached De Beers Marine to fund and develop the project.
Historically, about 227 tonnes of placer gold have been recovered from rivers and beaches in the adjacent onshore West Coast region, and Mr Youngson said it is likely that glaciers and rivers from the Southern Alps carried gold onto the continental shelf during glacial periods when sea was as much as 120m below present levels.
The company's main permit covers 8689 sq km of foreshore and seabed, extending from the low water line to 12 nautical miles offshore, and runs from Karamea in the north to Jackson Bay south of Haast.
A separate prospecting licence, under the Continental Shelf Act, covers 1490 sq km and contains three separate sections, the largest of which runs from north-west of Westport to north-west of Karamea.
The second largest section lies off Ross and Hokitika with a third narrow section off Greymouth.
Both the permit and licence give prospecting rights, not only for gold, but for ilmenite, rutile, platinum group metals, zircon, magnetite, and garnet.
