Identification of organic material in Los Buitres 1 rock art shelter, Badajoz, Spain

This research aimed to characterize the chemical and mineralogical nature of prehistoric painted figures from the Los Buitres 1 rock shelter and to identify organic material from the pigment samples. MicroRaman spectroscopy and ATR-FTIR analysis were made. Four pigment samples were selected: three red and one dark-red granules of pigment. Micro-Raman spectroscopy was applied to determine the mineralogical composition of selected samples while ATR-FTIR was applied in order to identify organic material present in each. Samples 1 and 2 are almost identical and registered montmorillonite being present. Analyses by ATRFTIR points to organic components in sample 3 while sample 4 was identified as burnt umber. A comparison with a nearby shelter with the same organic compounds in the same type of figure causes some alarms to sound due to the possibility that a real pigment recipe has been in use in the same region for the same time spectrum.