Rocks that a family found on a beach in Cape Porcupine, Labrador, turned out to be the explosive material dunnite, police say. (RCMP)

A family collecting unusual beach stones in Labrador on Labour Day weekend ended up bringing home a dangerous find.

The family members from Cartwright, a small Labrador community, were enjoying a day on the beach at nearby Cape Porcupine Sept. 1 when they came upon what seemed to be an unusual rock.

The rock was rusty, but much lighter than normal. When they broke portions off the rock, they discovered yellow powder inside.

Curious about the rock, they brought home five kilograms of it. But after researching their find on the internet, they suspected it might be dunnite, an explosive used during the world wars, and they contacted local police.

Cartwright RCMP Cpl. Wendy Martin said the rock was confirmed as dunnite, and the RCMP explosives disposal unit was called in from St. John's to blow it up.

"[In] my experience, my limited experience, it was certainly a sizable explosion for each piece. It had the full mushroom cloud of smoke and percussion. It was very interesting to observe it being safely destroyed," she said.

The explosives unit searched the Cape Porcupine area, and found significant remains of exploded large and small artillery shells.

Unit members also found the remains of a large artillery shell, measuring nearly a metre long and 30 cm across, which had washed ashore within the last week. According to the police, the shell was empty. They also found more dunnite, which was removed and exploded.

The RCMP are warning the public not to touch the material if they come across it, and to call the police.