In search of a good hydrous ferric oxide

[dawncruth]

Hi all,
I have a user who will need a good hydrous ferric oxide standard. Of course these are difficult to polish and find, but I thought I would ask to see if anyone knows of a good source.

Thanks!

[Probeman]

Is this for EPMA? Can I ask why they will need a good hydrous ferric oxide standard?

Is this for some kind of peak shift/shape problem?

[dawncruth]

It is for EPMA.
I have a user who is studying hydrous ferric oxides and would like to have a recognized standard for QC monitoring.

[Probeman]

Huh, what elements are they measuring that they want to check against a secondary standard?

I ask because I suspect that they are going to find (as is the case with most of these materials) is that they are not as well characterized as we might think they are, e.g., the Smithsonian mineral standards which are heterogeneous and full of inclusions.

If testing for oxygen and iron accuracy, then any iron oxide, for example a synthetic Fe2O3 might be good, as they are readily available and in fact is one of the materials Will Nachlas is looking into for the FIGMAS project.

The most important point is to be sure to include water calculated by stoichiometry:

https://probesoftware.com/smf/index.php?topic=92.msg8485#msg8485

and possibly also calculate the ferrous-ferric ratio using the Droop method in Probe for EPMA:

https://probesoftware.com/smf/index.php?topic=40.msg10869#msg10869