Evidence for the existence of primitive life forms such as lichens and fungi can be based upon the formation of oxalates.
These oxalates form as a film like deposit on rocks and other host matrices. The anhydrous oxalate mineral moolooite CuC
2O
4 as the natural copper(II) oxalate mineral is a classic example. Another example of a natural oxalate is the mineral wheatleyite
Na
2Cu
2+(C
2O
4)
2·2H
2O.
High resolution thermogravimetry coupled to evolved gas mass spectrometry shows decomposition of wheatleyite at 255°C. Two
higher temperature mass losses are observed at 324 and 349°C. Higher temperature mass losses are observed at 819, 833 and
857°C. These mass losses as confirmed by mass spectrometry are attributed to the decomposition of tennerite CuO. In comparison
the thermal decomposition of moolooite takes place at 260°C. Evolved gas mass spectrometry for moolooite shows the gas lost
at this temperature is carbon dioxide. No water evolution was observed, thus indicating the moolooite is the anhydrous copper(II)
oxalate as compared to the synthetic compound which is the dihydrate.
Keywords copper(II) oxalate - evolved gas mass spectrometry - high resolution thermogravimetry - moolooite - oxalate - Raman spectroscopy - wheatleyite