# K ar dating

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.

It might be 1 gram, kilogram, 5 grams-- whatever it might be-- whatever we start with, we take e to the negative k times 1.25 billion years. So you get the natural log of 1/2-- we don't have that N0 there anymore-- is equal to the natural log of this thing.Time since recrystallization is calculated by measuring the ratio of the amount of The quickly cooled lavas that make nearly ideal samples for K–Ar dating also preserve a record of the direction and intensity of the local magnetic field as the sample cooled past the Curie temperature of iron.The geomagnetic polarity time scale was calibrated largely using K–Ar dating.his document discusses the way radiometric dating and stratigraphic principles are used to establish the conventional geological time scale.It is not about the theory behind radiometric dating methods, it is about their , and it therefore assumes the reader has some familiarity with the technique already (refer to "Other Sources" for more information).