Chinese or Han Purple was a manufactured pigment used between about 1200 BC and 220 AD, most famously on the terracotta soldiers of the Qin emperor.
Han purple is a compound based on copper silicate, and the purple color derives from the red impurity of copper oxide. Like the other blue pigments developed by the Chinese (the others are Han Blue and Ultramarine), Han Purple has been found in objects in the Western Zhou dynasty (1207-771 BC), the Eastern Zhou period (770-221 BC) and the Qin and Han dynasties (220-207 BC and 206 BC-220 AD). Han Purple has been identified on the terracotta army; but not Han blue (the blue used was azurite).
Using historical records, a research team led by Zhi Liu has argued that the color was invented by Taoist alchemists to imitate jade, an important substance for the Taoist religion. Cullen, however, believes that the historical reference to the Tao (or Dao) is not necessarily a reference to the Taoist religion, but is currently understood to refer to a wide range of secular knowledge and philosophy. Liu points out that the use of jade in burials was banned at the end of the Han Dynasty by the Emperor Wen, along with other conspicuous consumption traits of the Han and Qin dynasties, as epitomized by the Emperor Qin's tomb.
The recipe for Chinese purple was lost, but recovered when modern day alchemists armed with high-resolution transmission electron microscopy, electron energy loss spectroscopy, and x-ray microanalysis, were able to reconstruct the pigment.
Stanford's exhibit on Chinese Purple is an excellent source for more information on the Liu research.
Berke, Heinz 2007 The invention of blue and purple pigments in ancient times. Chemical Society Reviews 36:15–30.
Cullen, Christopher in press Taoism (Daoism) and 'Chinese Purple': a note on some historical issues. Journal of Archaeological Science in press.
Liu, Zhi in press Reply to "Taoism (Daoism) and ‘Chinese Purple’: a note on some historical issues". Journal of Archaeological Science in press.
Liu, Z., et al. 2007 Influence of Taoism on the invention of the purple pigment used on the Qin terracotta warriors. Journal of Archaeological Science 34(11):1878-1883.
This glossary entry is part of the Dictionary of Archaeology.