The CNN article doesn't but it's a detrital zircon. It essentially has to be of terrestrial origin.
In other words, the zircon grain was found in what was at one point a sedimentary rock (now metamorphosed).
It formed in an igneous rock, was eroded, transported, deposited, lithified, buried, heated up, converted to a metamorphic rock, and then exhumed (actually all of this multiple times).
The zircon survived through all of that. (Which is why there's so much interest in making sure that the U/Pb ratio hasn't been altered by all of the rounds of deformation.)
However, extraterrestrial zircons have been found, and date back even farther.
This is the oldest piece of anything found that we know with reasonable certainty had to come from Earth.
Comments
The CNN article doesn't but it's a detrital zircon. It essentially has to be of terrestrial origin.
In other words, the zircon grain was found in what was at one point a sedimentary rock (now metamorphosed).
It formed in an igneous rock, was eroded, transported, deposited, lithified, buried, heated up, converted to a metamorphic rock, and then exhumed (actually all of this multiple times).
The zircon survived through all of that. (Which is why there's so much interest in making sure that the U/Pb ratio hasn't been altered by all of the rounds of deformation.)
However, extraterrestrial zircons have been found, and date back even farther.
This is the oldest piece of anything found that we know with reasonable certainty had to come from Earth.