Table 1 Mineralogical composition (wt %) of Oudam, Marimba, Quela, and Sebina with 1σ errors.

Detection limits for crystalline materials are 0.5 wt %.

MineralOudamMarimbaQuelaSebina
Andesine27.8 ± 0.514.0 ± 0.913.5 ± 0.710.7 ± 0.4
Hematite13.9 ± 0.46.4 ± 0.47.1 ± 0.46.9 ± 0.2
Ca-sulfate6.3 ± 0.37.0 ± 0.65.5 ± 0.47.4 ± 0.6
Sanidine2.4 ± 0.62.3 ± 0.51.4 ± 0.4
Pyroxene5.3 ± 0.90.7 ± 0.62.7 ± 0.72.8 ± 0.4
JarositeAt detectionAt detection0.9 ± 0.2
Quartz0.7 ± 0.1At detectionAt detectionAt detection
Clay minerals3 ± 128 ± 516 ± 319 ± 4
Amorphous43 ± 2040 ± 2052 ± 2551 ± 25