Authorities in Australia are searching for a tiny capsule containing radioactive material that went missing during transport, and they're urging anyone who finds it to keep their distance.

The round, silver capsule — measuring roughly a quarter of an inch in diameter by a third of an inch tall — is posing a radioactive substance risk in the regions of Pilbara, Midwest Gascoyne, Goldfields-Midlands and Perth, officials said.

"Exposure to this substance could cause radiation burns or severe illness – if people see the capsule or something that looks similar, stay away from it and keep others away from it too," Dr. Andrew Robertson, Western Australia's chief health officer and radiological council chair, said in a statement.

Inside the capsule is a small amount of radioactive Caesium-137, which is used in mining operations.

Authorities said the capsule can't be used to make a weapon, but it can cause health problems, such as radiation burns to the skin.

According to the state's Department of Fire and Emergency Services, the capsule was packed up on Jan. 10 for transport by road, and the shipment arrived in Perth on Jan. 16.

But when the gauge it was part of was unpacked for inspection on Jan. 25, workers discovered that the gauge had broken apart and the capsule was missing.

The capsule belongs to the mining company Rio Tinto, which said in a statement that it was sorry for the alarm caused by the missing piece.

The company said it had hired a third-party contractor to package the device and was working with that company to figure out what went wrong. Rio Tinto said it had also conducted radiological surveys of areas where the device had been as well as roads in and leading away from the Gudai-Darri mine site.

The more than 700-mile route from Perth to Newman is now the subject of a massive search. Officials from Western Australia's government as well as radiation specialists are slowly driving up and down the Great Northern Highway on the hunt for the capsule roughly as wide as a pencil eraser.

Authorities are warning anyone who may come across the capsule to stay at least 16 feet away from it and not to touch it but rather to call the fire and emergency services agency. [Copyright 2023 NPR]