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.One out of every 10,000 Potassium atoms is radioactive Potassium-40 (K-40).
The quantity of potassium in a rock or mineral is variable proportional to the amount of silica present.
Therefore, mafic rocks and minerals often contain less potassium than an equal amount of silicic rock or mineral.
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Argon-Argon dating is similar to Potassium-Argon dating, but it requires less material.
Potassium can be mobilized into or out of a rock or mineral through alteration processes.