FMF - Friends of Minerals Forum, discussion and message board

[Herwig]

[Cesar M. Salvan]

In our observations, we didn't observe a specific pattern in the fluorescence under UV at different wavelengths.

I rarely recommend those quick test to identify species that forms series. It is uncommon that a species prone to form series appears as a pure end. In this case, the different proportions of Zn, Mn and Fe lead to a complex fluorescence response (which is already complex by itself).

To properly assign a label to specimens of these minerals, what we've done is a ternary diagram (see image) where it is possible to define regions of predominance.
Also, after analyzing a number of samples, we already know the relationship between Raman shifts and relative proportions of Fe, Mn and Zn, which simplifies a lot the identifications.
In my opinion, if someone wants to put a precise label on an specimen, that should be the workflow. Otherwise, the specimens should be labeled as the series. I noted that collectors have some aversion to labels like "genthelvite-helvine series". Well, if one wants to put a single name, some effort should be done.

(as a curiousity, the data for the ternary plot shown were obtained using an experimental APXS system similar to those aboard the Mars exploration rovers)

[Herwig]

¡Muchas gracias por su respuesta, Cesar!

Very interesting to see the diagram, and the compositions of the analyzed specimens. AFAI can see, there are 4 specimens in this diagram.
The one called "Sample" is IMHO pretty close to being and end-member. :-)

FYI:I will never state that the luminescence of a specimen is the ONLY parameter to positively identify a mineral specimen.
But it can be one of the parameters that will help to identify a specimen.

If I understand correctly, there are no data about the reactions of the four specimens in the diagram to any kind of UV light, right?
Please correct me if I'm wrong (and let us know your observations if available).
Cheers, Herwig