On the last day, finally some results.
The last sample of the 15 we analyzed was a red rock, most likely the Moenkopi sandstone, with lichens growing on the outside - the grayish layer in the picture.
Although the title of the plot is not correct (this was not a soil sample), the data are. The plot below shows a compilation of some of the masses we are interested in (please note which trace goes with which y-axis).
The large green peak between 400 and 550 °C is CO2 - the majority of this peak (>80%) is CO2 evolved from the carbonates in this sample (either calcite: CaCO3, or dolomite: (MgCa)(CO3)2). These minerals decompose at a relatively low temperature under vacuum.
The yellow and very wobbly brownish plots (27, 78) are representative fragments from decomposition of organic material. These compounds are most likely from the lichen decomposition.
The blue line is water that is part of hydrated minerals. Adsorbed water would evolve at temperatures around 100°C, hydrated water at 300-600°C, depending on the mineral.
These are the results from a first quick look, next step, explaining all the other traces we find.