Realgar

Brief description of Realgar:

Red orange natural pigment closely related to the yellow orpiment. The two minerals are often found in the same deposits. Although it occurs perhaps as widely in nature as orpiment, realgar appears not to have been used so widely. Realgar is a highly toxic arsenic sulfide and was the only pure orange pigment until modern chrome orange.

Names for Realgar:

Example of use by artists:

Realgar and Pararealgar, the unbreakable couple

Very rare, early 13th century, Byzantine Syriac Gospel lectionary, 1216–1220 AD, British Library Oriental and India Office Collection

This Gospel lectionary consists of 264 folios with text and sixty illuminations and is valued at more than US$1 million. The large number of illuminations distributed throughout a manuscript of this type is very unusual; they are of high quality and have a rich palette which includes vermilion, lazurite, orpiment, lead white, realgar and pararealgar. Some of the illuminations have suffered serious deterioration of the white pigment, which has turned black in parts. The phenomenon is most striking where the faces of the figures, apparently initially coloured with a mixture of white and red pigments, are affected, creating blackened areas.

Orpiment was used for the yellow areas but it was not the only yellow pigment used. Some very rich yellow colouration differs significantly in appearance from that of orpiment, which has a much lighter hue. Viewed through the microscope, the pigment appears to be dominated by yellow crystals with a significant number of orange ones. Analysis by Raman microscopy revealed that the orange crystals were realgar and that the yellow crystals were pararealgar a light-induced transformation product of realgar