Intermediate Infrared Spectroscopy of Pyroxene: Determination of Ca‐Mg‐Fe Composition in the 4–8 Micron Wavelength Range

Although pyroxene has been detected remotely across the Solar System, limited information is available from infrared remote sensing about Mg-Fe composition of pyroxene, and distinguishing between augite (20 < CaSiO3 45) diopside-hedenbergite (CaSiO3 > remains challenging. The characteristics in intermediate range (4–8 μm), meanwhile, have not documented. Using reflectance spectra 72 samples ranging quadrilateral, we investigate effect variations Mg# (Mg/[Mg + Fe] × 100) Ca-content on positions strong well-defined spectral bands at ∼5.1 ∼5.3 μm high-Ca ∼5.2 low-Ca pyroxene. We find that 5.1, 5.2, 5.3 move to shorter wavelengths as increases, whereas does significantly affect these bands, enabling determination directly band alone. also more distinctive so augite. Therefore, enable discrimination among diopside-hedenbergite, Additionally, direct within ±23, ±10, ±29 mol% Mg-Fe, respectively.