However, because each of these parameters is difficult to determine independantly, a mineral standard, or monitor, of known age is irradiated with the samples of unknown age.
The monitor flux can then be extrapolated to the samples, thereby determining their flux.
Ca F is also routinely irradiated and measured to determine the Ar technique relies on ratios instead of absolute quantities, we are able to extract and measure multiple aliquots of argon from a single sample.
Multiple argon extractions can be performed on a sample in several ways.
This imprecision (and inaccuracy) is transferred to the secondary minerals used daily by the Ar age equation will become continually more refined allowing much more accurate and precise ages to be determined.
Because the J value is extrapolated from a standard to an unknown, the accuracy and precision on that J value is critical.
For example, laser spot sizes of 100 microns or less allow a user to extract multiple argon samples from across a small mica or feldspar grain.
Laser probes also allow multiple ages to be determined on a single sample aliquot, but do so using accurate and precise spatial control.
Traditionally, this primary standard has been a hornblende from the Mc Clure Mountains, Colorado (a.k.a. Once an accurate and precise age is determined for the primary standard, other minerals can be dated relative to it by the Ar technique (e.g. However, while it is often easy to determine the age of the primary standard by the K/Ar method, it is difficult for different dating laboratories to agree on the final age.
Likewise, because of heterogeneity problems with the MMhb-1 sample, the K/Ar ages are not always reproducible.
The method most commonly used to date the primary standard is the conventional K/Ar technique.
The primary standard must be a mineral that is homogeneous, abundant and easily dated by the K/Ar and Ar methods.