Australian authorities have found the missing radioactive capsule on a remote highway in the desert. “Locating this object was a monumental challenge – the search groups have quite literally found the needle in the haystack,” said Emergency Services Minister Stephen Dawson said in a news conference.

The capsule is believed to have fallen off a truck driving from a mining site owned by the company Rio Tinto in northern Western Australia, to Perth, CNN writes. The capsule was just six millimeters by eight millimeters, making the search highly difficult across an 870-mile stretch of road. It was found using special radiation-detecting equipment in a search vehicle, which identified the area the capsule was dropped. Then, portable detection equipment found the capsule about 6.5 feet from the side of the road, NPR explains.

“When you consider the challenge of finding an object smaller than a 10-cent coin along a 1,400-kilometer stretch of Great Northern Highway, it is a tremendous result,” remarked Fire and Emergency Services Commissioner Darren Klemm. The search took six days.

The capsule contained trace amounts of Cesium-137, a highly radioactive isotope that can cause radiation sickness and burns. “The simple fact is this device should never have been lost,” said chief executive of Rio Tinto Simon Trott. A government investigation has been launched into the incident and Rio Tinto could face prosecution. 

Under Australian law, the maximum financial penalty for mishandling radioactive material is around $700, which many including Australian Prime Minister Anthony Albanese call “ridiculously low.” Chief Health Officer Andy Robertson explained that they “have the ability to prosecute under the Radiation Safety Act” and “will certainly look at such prosecutions.”

“While the recovery of the capsule is a great testament to the skill and tenacity of the search team, the fact is it should never have been lost in the first place,” said Trott.