for National Geographic News
An object that struck the high plains of Peru on Saturday, causing a mysterious illness among local residents, was a rare kind of meteorite, scientists announced today.
A team of Peruvian researchers confirmed the origins of the object, which crashed near Lake Titicaca, after taking samples to a lab in the capital city of Lima (see Peru map).
Nearby residents who visited the impact crater complained of headaches and nausea, spurring speculation that the explosion was a subterranean geyser eruption or a release of noxious gas from decayed matter underground.
But the illness was the result of inhaling arsenic fumes, according to Luisa Macedo, a researcher for Peru's Mining, Metallurgy, and Geology Institute (INGEMMET), who visited the crash site.
The meteorite created the gases when the object's hot surface met an underground water supply tainted with arsenic, the scientists said.
Numerous arsenic deposits have been found in the subsoils of southern Peru, explained Modesto Montoya, a nuclear physicist who collaborated with the team. The naturally formed deposits contaminate local drinking water.
"If the meteorite arrives incandescent and at a high temperature because of friction in the atmosphere, hitting water can create a column of steam," added José Ishitsuka, an astronomer at the Peruvian Geophysics Institute, who analyzed the object.
By Wednesday, according to Macedo, all 30 residents who felt ill reported feeling better.
"People Were Extremely Scared"
Locals described the meteorite as a bright, fiery ball with a smoke trail. The sound and smell rattled residents to the point that they feared for their lives, Ishitsuka said.
The meteorite's impact sent debris flying up to 820 feet (250 meters) away, with some material landing on the roof of the nearest home 390 feet (120 meters) from the crater, Ishitsuka reported.
"Imagine the magnitude of the impact," he said. "People were extremely scared. It was a psychological thing."
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