SYNTHETIC PYROXENES: STRENGTHENING THE FOUNDATION OF REMOTE GEOCHEMICAL ANALYSIS

Pyroxene is one of the most commonly used minerals for remote analysis of mineralogy and composition of planetary bodies. This is in part due to the prevalence of pyroxene on the surfaces of objects in the inner solar system, but also due to the fact that pyroxene exhibits a distinctive reflectance spectrum in the near-infrared that is highly sensitive to its specific composition, structure and cation site occupancy.

To push the boundaries of what can be learned from remote detections of pyroxenes, we have working to characterize and document a suite of 91 synthetic pyroxenes, whose compositions span the entire Ca-Mg-Fe pyroxene quadrilateral. We have conducted spectral measurements from the visible through far-infrared using reflectance spectroscopy, and we have also collected mid-infrared thermal emission data, Raman spectra, attenuated total reflectance, electron microprobe data, and variable-temperature Mossbauer spectra on ~40 key samples. We will present the results of this integrated study, focusing on how crystal structure, composition, and cation site occupancy in pyroxenes is reflected by different remote or in-situ measurement techniques, and how these techniques can be used to assess the cooling regime of extraterrestrial pyroxenes.