Hi Christopher , Its a pleasure to share these with excellent people of APUG.

I had been posted a multispectral virtual restorated Mona Lisa picture and colors were like Velvia mostly.

I read Magnesium Oxide pigment plus linseed oil glazes used at Mona Lisa. There are two Anatolian connections. First magnesium word comes from old South West Anatolian city Magnesia , second Mona Lisas husband was an silk merchant and Chinese Silk Road was under control of Turks at the west end.

Well , I researched some little bit about Magnesium Oxide and I learned it is main reference white color for spectrophotometers.

And other famous faces like Maiden on the Rocks , was glazed with copper pigment.
Copper was a Egyptian recipe also and blue. Some of the Michelangelo frescoes bright green color comes from natural copper mineral Malachite.

I wanted to put Wiley , Revealing the sfumato Technique of Leonardo da Vinci by X-Ray Fluorescence Spectroscopy , paper on to forum but cost is 35 dollars.

I will ask my sister , She is an doctorate student at France to find me this paper free. Than We will dscuss more.

Best ,

Mustafa Umut Sarac