Spectral Characteristics of Chemically Weathered Sandstones in the Yungang Grottoes, China

Reflectance spectroscopy offers a non-destructive method to monitor chemical weathering in sandstones at cultural heritage sites, including the Yungang Grottoes in China. This study identifies distinct spectral absorptions linked to different weathering stages—fresh, calcite-dissolved, and argillitic-altered—using specific wavelengths (e.g., 490, 675, 900 nm for hematite; 2330 nm for calcite). Calcite dissolution reduces absorption at 2330 nm, while argillic alteration diminishes hematite-related peaks. Shifts in kaolinite-related absorptions (1410, 2205, 2350, 2380 nm) correlate with increasing kaolinite content. These findings demonstrate spectroscopy's potential for long-term weathering monitoring, aiding heritage conservation and environmental policy.

Yang, H.-M., Qiu, J.-T., Yu, L., Li, P.-J., Xu, C.-B., & Li, W.-W. (2018). Spectral Characteristics of Chemically Weathered Sandstones in the Yungang Grottoes, China. Studies in Conservation, 64(2), 63–72. https://doi.org/10.1080/00393630.2018.1482707