New Discoveries in the Maijishan Grottoes: Identification of Blue-Green Pigments and Insights into Green Pigment Application Techniques

The application techniques and composition of green and blue-green pigments in the Maijishan Grottoes were explored by utilizing microscopic observation, Raman spectroscopy, and SEM-EDX analysis. For the first time, lavendulan and high-purity botallackite were identified in these grottoes, in addition to the commonly found malachite and atacamite. These discoveries suggest that several caves in the Maijishan Grottoes were originally painted in blue-green tones, which have since altered to the current green or dark green hues. It was also revealed that the application of green mixed pigments involved layering malachite over basic copper chloride, rather than blending them together. Moreover, variations in the composition and placement of white ash layers indicate that the use of mixed pigments was likely due to repainting rather than initial decorative purposes. These findings significantly enhance our understanding of ancient painting techniques and provide crucial data for the conservation and restoration of cultural heritage in the Maijishan Grottoes.