Isotopic systems that have been exploited for radiometric dating have half-lives ranging from only about 10 years (e.g., tritium) to over 100 billion years (e.g., samarium-147).For most radioactive nuclides, the half-life depends solely on nuclear properties and is essentially a constant.A commonly used radiometric dating technique relies on the breakdown of potassium (Ar in an igneous rock can tell us the amount of time that has passed since the rock crystallized.
It is therefore essential to have as much information as possible about the material being dated and to check for possible signs of alteration.
Precision is enhanced if measurements are taken on multiple samples from different locations of the rock body.
Radioactive elements were incorporated into the Earth when the Solar System formed.
All rocks and minerals contain tiny amounts of these radioactive elements.
Radioactive elements are unstable; they breakdown spontaneously into more stable atoms over time, a process known as radioactive decay.