Zircon radiometric dating
It suffers from the problem that rubidium and strontium are very mobile and may easily enter rocks at a much later date to that of formation.
The time that it takes for half of a sample to decay is known as the half life of the isotope.
Carbon dating works on organic matter, all of which contains carbon.
However it is less useful for dating metal or other inorganic objects.
To date older fossils, other methods are used, such as potassium-argon or argon-argon dating.
Other forms of dating based on reactive minerals like rubidium or potassium can date older finds including fossils, but have the limitation that it is easy for ions to move into rocks post-formation so that care must be taken to consider geology and other factors.