Meet the man with NZ's largest gemstone collection

Vince Burke first became fascinated with gemstones fishing for groper with his dad at Birdlings Flat, near Christchurch.

"As a child, I'd sit on the beach with dad, and I'd pick up the coloured stones."

Now Burke, 85, has amassed a collection numbering 10,000 that is on display at his Birdlings Flat Gemstone and Fossil Museum.

The beach there is rich with gemstones carried down by Canterbury's rivers, he told RNZ's Nights.

"The ancient volcanoes going way back the head of the Rangitata, the Hinds, the Ashburton, Mount Somers, Mount Barrosa, were all agate bearing volcanoes."

Agate is silica hardened over time that becomes a gemstone, he said.

"There's a lava flow, and there's an air pocket in the lava flow, the silica flows into that pocket and starts to fill it up, so do the minerals.

"It's very, very hot, and while it's swirling around, the colours all mix, so the beauty of a gemstone is you don't know, once you take the crust off the outside, or you'll cut it in half, exactly what's inside."

Back in the day, gemstone hunting was a relaxed affair, he said.

"In the early days before the Department of Conservation took over the Crown land, you just ring the farmer and get the key to the gate, and you could fill your pack up and carry it out back to the car, so you could get quite a bit of material."

Now he's looking to sell his collection, the asking price is $140,000.

"The main reason for the price is because you're not going to get it again. Mount Somers and Mount Barrosa been taken over by the Department of Conservation.

"To pick up anything off Crown land and walk away, you've got to have a permit. And if you want to pay $1,300 for a permit to pick up one rock, people just don't do it."

The collection is simply too big for the local museum to handle, he said.

"I would honestly donate this whole collection to the Canterbury Museum, but once again, it's pretty big, and they have nowhere to store it."