Radioactive isotope used in geological dating Avatar chat 3d xxx
Zircon has a high hardness (7.5) which makes it resistant to mechanical weathering, and it is also very resistant to chemical weathering. Chemically, zircon usually contains high amounts of U and low amounts of Pb, so that large amounts of radiogenic Pb are produced.Other minerals that also show these properties, but are less commonly used in radiometric dating are Apatite and sphene.
U would have been stable in the crystallographic site, but the site is now occupied by by Pb.
We can also construct a Concordia diagram, which shows the values of Pb isotopes that would give concordant dates.