The infrared spectroscopy of biotic and abiotic minerals: its relevance to Mars studies

Abstract. The evidence of water erosion on Mars is particularly interesting since present climatic conditions are such that liquid water cannot exist at the surface. But, if water was present on the planet in the past, there may have been life, too. Since the discovery of carbonates on Mars also may have very important implications on the possibility that life developed there, we have studied a mineral that can have biotic or abiotic origin: aragonite, a metastable state of calcium carbonate (CaCO3). We have analysed biomineral aragonite, in form of shells, along with crystals of mineral aragonite. Infrared spectroscopy in the 2-25 µm wavelength range shows that, after heat treatment, the biotic samples and the abiotic ones have a different spectral behaviour. The importance of such differences is discussed in the framework of the present exploration of the Planet Mars. 1