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Concretions: The Other Valuable Mineral

by Darrell Hookey

    As round as a bowling ball and just as heavy, a concretion is "the other valuable mineral" found in the Yukon.

    Unlike its more famous and sexier cousin, gold, a Yukon concretion tends to be bigger and more plentiful than most others found in the world. Yet it shares the same mystery and intrigue. If it weren't so useless it could have inspired Service-esque poetry.

    Sitting on the front, right corner of the receptionist's desk, a concretion is the first rock that greets visitors to the Economic Development's Yukon Geology Program. Upstairs at the non-descript building at Second and Elliott, are the geologists who can explain the true value of a concretion.

    "It's neat," says Grant Lowey with an apologetic shrug. Other than pebbles worn round by tumbling down a stream or shot-sized spherical meteorites, they are one of the few mineral aggregates that grows round. There is an area west of Haines Junction that is littered with these concretions. More hang exposed in a cliff face high above awaiting erosion to set them free to tumble to the base.

    As the Yukon's placer geologist, Lowey also investigates unusual rocks found in the territory. But as neat as they are, they don't answer geology's big questions: They don't indicate where to find bodies of precious minerals and fuel sources, they can't help re-construct the paleo-geography of the world and they do not advance knowledge of predicting natural disasters. As a result, Lowey's time and efforts are devoted elsewhere, mostly to placer gold.

    But a personal interest was piqued when he first encountered a concretion in a Haines Junction gift shop. From a photo of the area it was found in, he was able to deduce its location. The shop owner wasn't about to make it any easier for him. Like many Haines Junction residents, he wanted to protect the area from scavengers.

    At one time there were thousands of the concretions exposed on the ground. Now there are hundreds. The cliff face that surely hides more is of a finite size ... when they are gone they are gone.

    Depending on who you talk to, Haines Junction resident Doug Makkonen is either a hero or a villain. He staked a placer claim on the area three years ago. He was able to stake a claim because, after much deliberation, the mining recorder decided if a concretion could be sold, it qualifies as a valuable mineral or a precious stone. Environmental groups, politicians and local residents writhed in angst thinking he would move in heavy machinery to tear up the land that has been so popular with hikers. He hasn't nor does he intend to, he says. Since he is a helicopter pilot, many assumed he would fly the concretions out.

    "It's not my helicopter," he explains, adding he would not want to risk his job by dragging his employer into a controversy. Besides, he says, if he wanted to take a load out he would just drive his truck in.

    Makkonen is frustrated that he is painted as the bad guy. He would like to see the area preserved and enjoyed by future generations. Perhaps there is a tourism potential there. At least the area will be protected for the next four years because he owns the claim. It is now illegal to remove the concretions by anyone but him. Yet despite signs warning hikers, they have been disappearing. Makkonen sees them on the front stoops of his neighbours' homes. He has heard of his concretions being sold at flea markets in Vernon, British Columbia. Although he has taken some out, he has never sold any. He may have given some away to friends and clients, but he has never earned money from the concretions, he says.

    Concretions can be found anywhere in the world. But the Yukon's are impressive because all of the elements necessary for their formation came together here. Lowey hefts a concretion to his lap from his office floor. In the centre of the cement-like rock is likely a leaf or a twig. It fell into a stream running off of a retreating glacier and was swept into a fan-delta, an accumulation of sediments where the stream slowed as it entered Glacial Lake Alsek some five to eight thousand years ago. Rain water percolated into the ground absorbing minerals along the way until it met up with the leaf or twig. Being carbon material, it is positively charged and thus attracted the negatively charged minerals. The bigger areas on top of the leaf or twig have more of a positive charge so it built up minerals at a faster rate until it was finally perfectly round.

    The size of the Haines Junction concretions owes to the thick layers of sediments and ground water, says Lowey. There must have been a lot of water passing through virgin territory to make the conditions just right. Some local hiking guides claim the concretions are actually millions of years old and were formed by tumbling inside a glacier. And they are incorrectly identified as "thunder eggs", which is actually another type of rock called a "geode".

    A lesson learned from gold: There is nothing like mis-information to add to a valuable mineral's mystery and intrigue.

Photo of concretions found in the Haines Junction, Yukon area.
Photo courtesy of the Yukon Territorial Government