The Colour of Pine Needles and Nightingales. A Traditional Japanese Copper-based Green Pigment

Abstract The article describes a historic Japanese green pigment which was identified in a painting attributed to the Kano school, dating to the Edo period. According to literature, malachite – which is the common translation of the Japanese term rokushō – has been the most widely used green pigment in Japan over a long period of time. Its colour shade could be modified by the use of different degrees of grinding and by heating the pigment. The green paint layer found in the painting was examined using XRF, SEM-EDS and XRPD, and cross sections. Examinations revealed a heterogeneous paint layer which consists of a mixture of various natural copper-containing minerals, some of which also contain arsenic and other elements. A concluding discussion of pigment nomenclature in Japan raises the question if rokushō may in fact be equated with pure malachite.