How accurate is potassium argon dating
This mineral sample is then baked gently overnight in a vacuum furnace.These steps help remove as much atmospheric Next, the mineral sample is heated to melting in a vacuum furnace, driving out all the gas.But micas, plagioclase, hornblende, clays, and other minerals can yield good data, as can whole-rock analyses.Young rocks have low levels of The rock samples are crushed, in clean equipment, to a size that preserves whole grains of the mineral to be dated, then sieved to help concentrate these grains of the target mineral.The advantage is that all the information needed for dating the sample comes from the same argon measurement. This method is commonly called "argon-argon dating." The Ar-Ar method is considered superior, but some of its problems are avoided in the older K-Ar method.Also, the cheaper K-Ar method can be used for screening or reconnaissance purposes, saving Ar-Ar for the most demanding or interesting problems.These dating methods have been under constant improvement for more than 50 years.
The abundance of Ar is unlikely to provide the age of intrusions of granite as the age typically reflects the time when a mineral cooled through its closure temperature.A precise amount of argon-38 is added to the gas as a "spike" to help calibrate the measurement, and the gas sample is collected onto activated charcoal cooled by liquid nitrogen.