Due to the relatively heavy atomic weight of potassium, insignificant fractionation of the different potassium isotopes occurs.However, the Argon, a noble gas, constitutes approximately 0.1-5% of the Earth's present day atmosphere.Thus, the ratio of argon-40 and potassium-40 and radiogenic calcium-40 to potassium-40 in a mineral or rock is a measure of the age of the sample.The calcium-potassium age method is seldom used, however, because of the great abundance of nonradiogenic calcium in minerals or rocks, which masks the presence of radiogenic calcium.
Following death, however, no new carbon is consumed.
It is based on measurement of the product of the radioactive decay of an isotope of potassium (K) into argon (Ar).
Potassium is a common element found in many materials, such as micas, clay minerals, tephra, and evaporites.
Therefore, mafic rocks and minerals often contain less potassium than an equal amount of silicic rock or mineral.
Potassium can be mobilized into or out of a rock or mineral through alteration processes.