The zircon has been cut and polished, then treated with high-temperature annealing and chemical abrasion with hydrofluoric acid.
The crystal interior parts affected by lead loss have been "mined out" in the process, allowing uranium/lead dating to provide a more accurate measure of its age.
Welcome to the K12 section of the Radiocarbon WEBinfo site.
This technique is widely used on recent artifacts, but educators and students alike should note that this technique will not work on older fossils (like those of the dinosaurs alleged to be millions of years old).The age of the carbon in the rock is different from that of the carbon in the air and makes carbon dating data for those organisms inaccurate under the assumptions normally used for carbon dating.This restriction extends to animals that consume seafood in their diet.To date, zircons - known to many as a semiprecious stone and December's birthstone - have often produced confusing and inaccurate results.A secondary electron microscopy image of a zircon from volcanic ash, about four thousandths of an inch (100 microns) across.
Carbon-14 cannot be used to date biological artifacts of organisms that did not get their carbon dioxide from the air.