After a tiny, dangerously radioactive capsule was lost in the Western Australian desert in mid-January, authorities feared that it could take weeks or even months to find it. The device was smaller than a penny, while the search zone was an 870-mile stretch of highway cutting across vast tracts of desert.

But the search took just six days, with authorities announcing Wednesday afternoon that the capsule had been recovered in what they called an “extraordinary result.”

“The search crews have literally found the needle in the haystack,” said Stephen Dawson, the emergency services minister for Western Australia.

Authorities had launched the large-scale search, involving the defense force, emergency services and radiation experts, after the capsule was discovered to be missing last week.

A small silver cylinder measuring 0.3 inches by 0.2 inches, the device contains a small amount of cesium-137 that makes it dangerously radioactive, officials said. An hour of exposure to it from a meter away is the equivalent of receiving 10 X-rays, and prolonged exposure can burn the skin, and, in severe cases, cause acute radiation sickness, they said.

The capsule was discovered Wednesday morning, after a vehicle equipped with radiation detection equipment picked up a signal not far from the start of the truck’s journey, according to Dawson.

A search team was then deployed and soon found the capsule, about 6.5 feet from the side of the road, he said.