Argon-argon dating

Argon-argon dating is a method used to determine the age of rocks and minerals. It measures the ratio of two isotopes of argon: argon-40, which occurs naturally in rocks, and argon-39, produced by irradiating a sample in a nuclear reactor. When rocks form, they contain little argon-40, but over time, it accumulates as radioactive potassium-40 decays. By comparing the amounts of these isotopes, scientists can calculate the time that has passed since the rock was formed. This technique is particularly useful for dating volcanic rocks and provides insights into geological events and the age of the Earth.