Age dating of basalt sending messages on dating sites
Potassium occurs in two stable isotopes (Ar atoms trapped inside minerals.
What simplifies things is that potassium is a reactive metal and argon is an inert gas: Potassium is always tightly locked up in minerals whereas argon is not part of any minerals. So assuming that no air gets into a mineral grain when it first forms, it has zero argon content.
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 selected size fraction is cleaned in ultrasound and acid baths, then gently oven-dried.
Then the gas sample is cleaned of all unwanted gasses such as H, nitrogen and so on until all that remains are the inert gasses, argon among them.The target mineral is separated using heavy liquids, then hand-picked under the microscope for the purest possible sample.This mineral sample is then baked gently overnight in a vacuum furnace.These steps help remove as much atmospheric Ar from the sample as possible before making the measurement.Next, the mineral sample is heated to melting in a vacuum furnace, driving out all the gas.