A Systematic Spectroscopic Study of Four Apollo Lunar Soils

A systematic spectroscopic study including Raman, Mid-IR, NIR, and VIS-NIR, is used to investigate four endmember lunar soils. Apollo soils (< 45 μm) 14163, 15271, 67511, and 71501 were selected as endmembers to study, based on their soil chemistry, maturity against space weathering, and the sampling locations. These endmembers include an anorthositic highlands soil (67511), a low-Ti basaltic soil (15271), a high-Ti basaltic soil (71501), and a mafic, KREEPy, impact-melt-rich soil (14163). We used a laser Raman point-counting procedure to derive mineral modes of the soils and the compositional distributions of major mineral phases, which in turn reflect characteristics of the main source materials for these soils. The Mid-IR, NIR, and VIS-NIR spectroscopic properties also yield distinct information on mineralogy, geochemistry, and maturity among the four soils. Knowledge of the mineralogy resulting from the Raman point-counting procedure corresponds well with bulk mineralogy and soil properties based on Mid-IR, NIR, and VIS-NIR spectroscopy. The future synergistic application of these spectroscopy methods on the Moon will provide a linkage between the results from in situ surface exploration and those from orbital remote-sensing observations.