Helicopter hunts for minerals

A low-flying helicopter dominating the airway between Invercargill and Bluff last week was searching for gold, platinum and other minerals below the earth's surface.

Australian-based company Thomson Aviation used a helicopter to do an aerial geophysical survey for Hatfield Resources, which holds a prospect permit in the 150-square-kilometre area.

The helicopter flew back and forth in imaginary lines about 100 metres apart and 45 metres above the ground to cover the permit area in three days. Such surveys are done by exploration or mining companies over ground they believe may contain economic minerals below the ground.

Last week's deep-south mineral search was funded by British-based company South Island Developments, with its consultant Shaun Clements saying the helicopter used specialised equipment to search for minerals such as gold, platinum, zirconium, and ilmenite.

A geophysicist would now interpret the data, which could take one to three months, before a decision was made on whether to continue with the mineral hunt, he said.

If the results were positive, the company would approach land-owners in the search area, who include the Invercargill City Council, to seek permission to go on to the land and drill for minerals.

"It's still very, very early days; if nothing comes out of the survey we walk away and surrender our permits and go somewhere else," Mr Clements said.

"It's a risky game. It's quite rare that you find economic deposits and even if you do find them you need permission to get on to the land from the various authorities and land holders."

Thomson Aviation geophysical airborne survey director Paul Rogerson said the helicopter doing the survey carried instruments on board called a magnetometer and a spectrometer which measured the natural variations in the earth's magnetic field and natural background radiation.

Minerals distorted the earth's magnetic signature and when the geophysical survey results were mapped a geologist would use this information, together with other relevant information, to work out what areas of the survey might be worth exploring further, he said.

Venture Southland group manager of enterprise and strategic projects Steve Canny said aerial geophysical surveys did not give an absolute understanding of the minerals underground but they did indicate what the geological structures were and the likelihood of whether minerals were in those structures.

Venture was looking at doing aerial geophysical surveys for water in Southland, he said.

The Southland Times