Radiometric dating calculator uranium
With 238U the Pb/U ratio grows much more slowly with age, but the idea is the same.
If you took rocks of all ages and plotted their two Pb/U ratios from their two isotope pairs against each other on a graph, the points would form a beautiful line called a concordia (see the example in the right column). First, its chemical structure likes uranium and hates lead.
Carbon-14 dating can only be used to determine the age of something that was once alive.
Lead atoms created by uranium decay are trapped in the crystal and build up in concentration with time.