Palmierite (and atacamite?)

[Jorge_Stolfi]

replacing information from a technical report by an opinion of a non-expert. 

My opinion is based on the data included in the report.  I understand enough of the physics and chemistry involved to see how they got that palmierite diagnostic.  The report includes a noisy X-ray diffraction spectrum and the output of a software that looks for the best match to the spectrum in a large library of spectra of minerals.  The software said "palmierite", and the technician simply copy-pasted that into the table at the end of the report.  He obviously did not even bother to check the Wikpedia article about that mineral.  If he had, he surely would have felt the need to explain how that exotic mineral, found only around fumaroles in a handful of places in the world, could have found its way in that paint.

the whole article says noting at all

The reference in that article has a bit more information.

In earlier days there was a similar discussion about atacamite.

Natural atacamite was discovered in South America, but there are medieval recipes for creating a green copper pigment that turns out to be (synthetic) atacamite.  

So at least atacamite is something that could have been used in a paint at the likely dates when the VMS was painted -- which means any date before Voynich got it.  

However, I personally don't think that is likely in the case of the VMS, specifically, since the recipe for synthetic atacamite is not trivial (expose a plate of copper covered in honey to vapors from vinegar for months), and the Painter seems to have been very amateurish.  It seems that he did not even have a decent brush.  I can't see him making his own pigments according to obscure alchemical recipes.

Besides, the Painter already had a green pigment, which he used liberally all over the VMS. The McCrone technician could not identify this pigment beyond saying that it contained copper but was not crystalline; hence he guessed "a copper resinate", which does not mean much actually.

All the best, --stolfi