SOMBA K'E/YELLOWKNIFE - The man who discovered the world's oldest rock says it is "amusing" that the ancient granite is back in the media spotlight.

Mark Brown is selling the world's oldest known rock through his website, Rock of Ages. - Jeanne Gagnon/NNSL photo

Sam Bowring, a geology professor at the Massachusetts Institute of Technology (MIT), was doing geological surveys north of Yellowknife in the 1980s when he noticed an intriguing outcrop near the Acasta River. His team moved their work to that area in 1985.

By 1987, Bowring and his team had dated rocks in the area at about four billion years old - the oldest known rocks in the world. The Earth itself is about 4.5 billion years old.

Now, Mark Brown a Yellowknifer with a prospecting claim to the site has started a business selling bits of the rock, making headlines across Canada.

"I find it amusing, actually," said Bowring. "Because we went through this already in 1990."

Indeed, Brown is not the first to sell the rock. Walt Humphries, a long-time Yellowknife prospector and columnist, staked a claim to the area in 1989.

"We thought, 'we flew all the way up there, we might as well sell the rock and that'll pay for the flight.' Which it did," said Humphries.

"A lot of people in town wanted a piece of it."

Museums and universities around the world were also interested in the rock, so Humphries and his partner provided it to the institutions at a price. Members of a Japanese university flew up and purchased four tons of it for a geological wall.

"That was the biggest single order by far," said Humphries.

All the other orders combined came to about two tons, generally fist-sized chunks of the rock, selling for $20 apiece. There wasn't much reaction then, said Humphries.

"We had a little flak from the government but I guess we proved to them we weren't doing anything dastardly," the prospector said. "We didn't touch the outcropping, were just going out to pick up boulders, it was pretty small stuff."

Brown was instantly intrigued when he found an old map that mentioned the Acasta River site, he said.

"I have been in the mining exploration business for 12 years and never heard of such a thing," Brown said. "The oldest rock in the world!"

He staked a claim in the area and is now selling bits of the granite on his website, Rock of Ages NWT. A customer can purchase a small chunk on its own for $149.99 or $249.99, with a display case.

"I guess I have mixed feelings about it," Bowring said of the rock for sale. "On one hand it would be nice to preserve it in perpetuity. On the other hand, there's nothing to say that three hills over, there aren't rocks that aren't even older."

It's unlikely that Brown's business will cause much damage, he said.

"Short of them creating a giant scar on the earth - and I can't imagine there'd be demand for it - it doesn't disturb me that much," Brown said.

According to Bowring, it's unlikely to be a huge consumer hit. "One always thinks of the pet rock," he said. "For one year somebody made a lot of money and then interest dropped off. We'll see, but the prices seem quite high."

Another problem is that it is extremely difficult and expensive to check the age of each individual piece of rock, Bowring said. "I could go out there and pick up a whole bunch of rocks and there'd be a whole range of ages."

Regardless of the sense of deja-vu, Humphries said it's nice to put a spotlight on geology.

"Any geological interest is good. It gets people thinking about things and paying more attention to rocks around them," he said. "Every rock has a story to tell, it's all part of the history of the planet."

Some geologists have suggested creating an eco-tourism attraction at the Acasta River site. Humphries isn't so sure about that.

"It's a very expensive trip, and it's very nice and everything else, he said. "But the oldest rock - it looks much like any other rock."