Mr Heatley told how he was from Onerahi, in Whangarei, and grew up 20km from the New Zealand Refining Company, which he said had been taking out a tanker full of oil a week for 50 years and nobody had noticed.
"They come in while you're sleeping and working and packing your kids off to school.
"They have done that on a beautiful coastline. On that coastline I collect pipi, I see orca, I see dolphins, I catch snapper and tarakihi and kingfish and lots of other stuff, all legally of course, and it's gone on for 50 years. Not a glimmer of worry from residents ..."
Mining could provide a badly needed step-change in the Northland economy to create jobs, he said.
"This is all about finding out what's down here and once we know what's down here we can have an intelligent conversation about how we access it safely, where we don't and where we do."
Mayor Brown said the initiative was about "jobs, jobs, jobs".
There were 6500 unemployed in Northland and 64 per cent of them were Maori. The median household income last year was $19,200. "Mining offers a step-change in GDP that others [industries] can't deliver."
Afterwards, Green MP Catherine Delahunty said this was not about local citizens but about "foreign mining companies ripping off the north, so it's a sad day for Northland".
Protesters - a range of greenies and local Maori and Pakeha - are concerned about the toxicity created from mining.
Tim Howard, from Minewatch Northland, said mining was being presented by politicians as a silver bullet. "But we don't want jobs at any cost, and toxic jobs are not the solution."
EXPLORATION
* Earlier reports have identified the likelihood of gold, silver, and copper deposits in Northland.
* An aerial survey was conducted last year to provide further information.
* Mining companies will analyse the results then decide whether to bid for exploration licences.