SOL-GEL SYNTHESIS OF INTERMEDIATE COMPOSITION, NANOCRYSTALLINE OLIVINE

Olivine, (Mg,Fe)₂SiO₄, is one of the most important rock forming minerals in our solar system, and forms in a solid-solution series between a magnesium end member forsterite, Mg₂SiO₄ (Fo₁₀₀), and an iron end member fayalite, Fe₂SiO₄ (Fo₀₀). Most naturally occurring olivine on Earth is ~Fo₉₀, however, olivine compositions on the Moon, Mars, and other solar system bodies can vary throughout the solid-solution series. Since there is a scarcity of iron-rich olivine on Earth available for use in planetary analog experiments and analyses, production of synthetic, intermediate composition olivine is desirable.

Previous studies have used the sol-gel technique to produce pure forsterite (Park et al., 1993; Anovitz et al., in prep) and pure fayalite (DeAngelis et al., 2012). The goal of this project was to build on those previous studies, and develop a new synthesis method to target specific intermediate olivine compositions. Several batches (~10 g per batch) of intermediate composition olivine were generated using this new method, including: Fo₁₀₀ – Fo₇₅ – Fo₅₀ – Fo₂₅ – Fo₀₀. Chemical composition, crystalline structure, surface area, and porosity of the material produced were analyzed using X-ray diffraction, energy dispersive spectroscopy, and surface area analysis. Though synthesis technique refinement continues (see Manley et al. presented at this conference), we believe that this new method can be used to generate any desired intermediate composition olivine.