What is potassium argon dating used for
However, because each of these parameters is difficult to determine independantly, a mineral standard, or monitor, of known age is irradiated with the samples of unknown age.
The individual ages from each heating step are then graphically plotted on an age spectrum or an isochron.
The method most commonly used to date the primary standard is the conventional K/Ar technique.
The primary standard must be a mineral that is homogeneous, abundant and easily dated by the K/Ar and Ar methods.
However, the Argon, a noble gas, constitutes approximately 0.1-5% of the Earth's present day atmosphere.
Because it is present within the atmosphere, every rock and mineral will have some quantity of Argon.