Carbon dating uranium
With the exception of Carbon-14, radiometric dating is used to date either igneous or metamorphic rocks that contain radioactive elements such as uranium. Now when the uranium or thorium disintegrates, the alpha particles which are emitted are slowed down by the crystals in which the grains of the uranium- or thorium-bearing minerals are embedded.
And even though various radioactive elements have been used to "date" these rocks, for the most part, the methods are basically the same. This means that if you had some pure uranium-238 with no lead in it, 4.5 billion years later one half of it would have decayed into its stable daughter product (lead-206). Where these alpha particles finally stop, crystal deformation occurs (and) shows up as a discolouration or a darkening of the crystals.
In other words, the magnitude of the radius of a pleochroic halo in a particular crystal depends on the half-life of the decay responsible for the alpha particle emission. the radii of pleochroic haloes corresponding to a definite decay in a particular mineral are ...
(the same) size, then it can be safely assumed that the half-life of that decay is a constant.
The four isotopes are uranium-235, uranium-238, lead-207, and lead-206.
The process of dating finds the two ratios between uranium-235 and lead-207; and uranium-238 and lead-206.
This will be covered in the chapters, Primitive Environment (chapter 9), and DNA (chapter 10).
Most people are not aware of the many processes that take place in lava before it erupts and as it solidifies, processes that can have a tremendous influence on daughter to parent ratios.
The reason for stopping at lead is because lead is not radioactive and will not change into a different element.
It may sound straight-forward, but there are many variables that have to be considered.
To me it has been a real eye opener to see all the processes that are taking place and their potential influence on radiometric dating.
Radiometric dating is largely done on rock that has formed from solidified lava.
The radiometric dater then uses the half-life of all four isotopes to find an age range the rock should be in.