Corrosion analysis of unearthed jade from Daye Zhen Tomb of Northern Zhou Dynasty

Abstract X-ray fluorescence spectroscopy, scanning electron microscopy energy spectrum, excitation-emission matrix spectroscopy, and Fourier transform infrared spectroscopy was applied to the unearthed jade with multilayered corrosion, to reveal the microstructure, composition structure, and distribution of organic matters. Our results showed that the interior of the jade was mainly composed of layered serpentine with a regular structure, while the white layer structure on the surface is scattered and irregular, and the content of calcite formed by elements Ca and C increases significantly; between the green matrix and the white layer on the surface, there are brown corrosion zones with obvious fluorescence effect and mainly composed of humic acid, which continuously extends inward along the corrosion cracks for accelerating the internal corrosion. This article, for the first time, argued for the corrosive and fluorescent humic acid bands that appear inside serpentine jade and cautions its role in investigating the corrosion of jade.