Argon argon dating lab
A strong and emerging component of the lab activity is also concerned with exploring the rare-gas isotope behavior in natural/synthetic minerals by means of P-T-).
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.
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.
That is, a fresh mineral grain has its K-Ar "clock" set at zero.
The rock sample to be dated must be chosen very carefully.