Lipid abundances (ppm) from three different mineralogies. The core displayed, with increasing depth, a microbial mat, a goethite-rich sediment from the flowing acidic ferric sulfate-rich stream (FlowMG1a – FlowMG1c) and underlying quartz sands and clays (comprised of minor kaolinite and microcline). Lipid classes are indicated by different colored backgrounds and categorised as follows: green, saturated fatty acids; purple, unsaturated fatty acids; yellow, branched fatty acids; blue, cyclopropyl fatty acids; pink, hydroxy-fatty acids; brown, phytosterols. Lipid abundances are much greater within the goethite-rich section compared to the clay-rich section of the core. FAME = Fatty Acid Methyl Esters. Note the logarithmic scale.