Hello Hamed,

I have studied Brazilian kaolins in this regard. For the crude ore, we found that the mineralogical content has a stronger relation with brightness than the total oxide content. It is even possible (although not always easy) to model this relation using the Kubelka-Munk theory. Particle size can be a potential complicator.

Regards,

Ítalo

Article Quantification of Hematite and Goethite Concentrations in Ka...

Brightness decreases with the amount of

impurities, particularly feldspars, smectite and vermiculite. On the other hand brightness increases with increasing structural

order in kaolinite (Bundy et al.  1965;

Johns & Murray 1959, Velho & Gomes 1991, Galán et al. 1998)

Article Contribution of multivariate analysis to the correlation of ...

Hello dear Patricia;

Thank you for your comments and paper which it seems it is really impressive and I have just downloaded that and it could be useful for my study.

I will come back to you when I read the document.

Regards,

Hamed

Thanks for that report too.