Irregular xray mapping of large crystals

[dawncruth]

Hi Probe users!

I am interested in collecting crystal sized (mm2) x-ray maps without collecting xrays on my epoxy.  I know of the irregular-shaped quantitative mapping possibilities, but was wondering if it can be done with regular x-ray mapping.  I can see how the quant maps can be useful, but they do take a long time, especially if there are two rounds of maps to collect per sample.

On a different, but related note.  If I wanted to use the quantitative mapping, is is possible to estimate the amount of Si, Al (for example) in a plag based on the Ca, Na, K values?  Or Si in olivine, etc.  In other words, is it possible to collect just the pertintent cations for An, Fo, Mg#, etc, and maybe some trace elements and then estimate Si from the rest? Perhaps this is a silly question...

 

Anyway, thanks for the input and glad to be a part of the forum!

Cheers,
Dawn

[John Donovan]

I am interested in collecting crystal sized (mm2) x-ray maps without collecting xrays on my epoxy.  I know of the irregular-shaped quantitative mapping possibilities, but was wondering if it can be done with regular x-ray mapping.  I can see how the quant maps can be useful, but they do take a long time, especially if there are two rounds of maps to collect per sample.

Hi Dawn,
Welcome to the forum!

I think you are referring to the polygon mapping in PFE as described here?

http://probesoftware.com/smf/index.php?topic=60.msg227#msg227

Yes, this is really best for trace element mapping because of the overhead of moving the stage to discrete positions. But with the MAN correction, described here:

http://probesoftware.com/smf/index.php?topic=4.0

It goes quite fast however.

But to answer your question directly, this is the very next feature we will be adding to Probe Image. Please stay tuned.

On a different, but related note.  If I wanted to use the quantitative mapping, is is possible to estimate the amount of Si, Al (for example) in a plag based on the Ca, Na, K values?  Or Si in olivine, etc.  In other words, is it possible to collect just the pertintent cations for An, Fo, Mg#, etc, and maybe some trace elements and then estimate Si from the rest? Perhaps this is a silly question...

Good question actually. I think you might be able to do this using the Stoichiometry To Another Element feature in PFE (and CalcImage), but please try it first on some point analyses to be sure it works to your satisfaction.

Here is an example I did for turquoise, which is of course different than your example, but maybe some combination of this option and one of the others might do the trick as shown here:

http://probesoftware.com/smf/index.php?topic=92.msg520#msg520

Of course for the purposes of a proper matrix correction, if the map is a fairly constant composition  you could very likely get away with just specifying a specified composition as described here:

http://probesoftware.com/smf/index.php?topic=92.msg519#msg519

Again, try the method on some point analyses and see what you can achieve.