An ammonite mining company is offering a reward after a fossil worth thousands of dollars was stolen in broad daylight Thursday.

The heist took place shortly after miners recovered a rare piece of ammonite.

The workers were taking a lunch break, when they noticed a couple men at the opposite end of the open pit mine.

“An individual came down this 30 foot bank, and grabbed a fossil,” mine manager Michael Shideler told CTV Lethbridge reporter Terry Vogt, in an interview.

The man stuffed the piece of ammonite into his backpack and took off.

He ran, scrambling out of the pit mine, across a field, and down another embankment before crossing another river and into the Blood Reserve, where he raced to a waiting half ton truck that’s been identified as a silver and red 1988 Chevy extended cab long box.

The miners chased the man, but stopped when they were threatened with a pickax.

Once they crossed the river, the terrain made it difficult to track them down.

“There’s a lot of back roads,” said Shideler, “going through these ravines and coulees that they can go and hide."

The company searched the area by airplane and spotted the truck parked by another ammonite mine.

“They must have been quite desperate to do that,” said owner Tom Chant. “That was quite risky.”

The RCMP are appealing to the public to try to locate the truck, its owners and the missing fossil.

“It’s something that when it’s finished is probably worth in the area of thirty to forty thousand dollars, U.S. value,” Shideler said.

“It wasn’t just a piece of rock, piece of gem,” he added. “It was a full, intact fossil that was taken.”

The company is offering a $5,000 reward for information leading to an arrest and recovery of the fossil.