Fig. 2: Summary of fluorescence features across targets.

a, Histograms of the λ_max (measured from raw data) of four fluorescence features that were observed in survey scans in natural targets in Máaz (top, n = 84), abraded targets in Séítah (bottom, n = 82) and abraded targets in Máaz (middle, n = 1070). Bins of 1 nm show variation in band centres, y axes scaled to each dataset. b, Filtered mean spectra from each target representing each fluorescence feature category demonstrate characteristic band positions, normalized relative intensities and colocated features between targets. The range of the SHERLOC CCD is 250–354 nm. The rise in baseline below 270 nm is a boundary artefact introduced by the filter and not representative of the sample data⁴⁵.