Radiometric dating or radioactive dating is a technique used to date materials such as rocks or carbon, in which trace radioactive impurities were selectively incorporated when they were formed. Some of its cons are:
1. Expensive, because you have to determine the isotope of very trace quantities of radioelements, and not just the concentration of the element, in a mass spectrometer
2. Requires highly skilled specialists
3. Will not work for fossils or sedimentary rocks