AN EXTRATERRESTRIAL NUGGET — A SERICHO METEORITE

The Sericho pallasite formed at the mantle-core boundary of an asteroid about 4.5 billion years ago. Deep inside the asteroid, molten metal from the outer core mixed with chunks of the olivine mantle that had crystallized. Things remained quiet for Sericho until a major collision shattered the asteroid; this event and subsequent, less energetic collisions set Sericho pallasite material on a collision course with Earth — and more specifically, 200 miles northeast of what is now Nairobi, Kenya. The strewn field was discovered by camel herders, and the stony-iron rocks were first identified as meteorites in 2016; it is currently unclear when this meteorite shower occurred, but it is at least decades old.