Cave Art is a fragile testimony of past humans societies and the development of modern behaviours. In limestone caves, moonmilk commonly endanger the artworks. It is a calcite-deposit known to present a large variability of chemical composition and morphological structures, hosting numerous microbial communities. The possibility to characterize this deposit on the field would help to get a better understanding of the cave behaviour and set up proper conservation measures. The present study analyses the variability of a moonmilk strip of metric size in the Leye Cave. This cave located in the Vézère valley (Dordogne, France) is not ornate, and has been selected to become a laboratory cave in which in-situ observations and micro-sampling can be carried out, before performing them into cavities hosting parietal artworks. SEM observations of twenty-four samples allowed investigating, for the first time, the variability of the moonmilk deposit over a same wall of few meters dimension. Our observations highlight low variability of moonmilk at the microscopic scale regarding the chemical composition and the morphological structures despite significant macroscopic diversity, thus providing insights to optimize the sampling strategy of moonmilk in ornate caves.Read less <