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1. Experimental determination of the effect of Cr on Mg isotope fractionation between spinel and forsterite

   https://doi.org/10.1016/j.gca.2020.12.028  

   Tang, Haolan; Szumila, Ian; Trail, Dustin; Young, Edward D. (March 2021, Geochimica et Cosmochimica Acta)

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2. Patchy Forsterite Clouds in the Atmospheres of Two Highly Variable Exoplanet Analogs

   https://doi.org/10.3847/1538-4357/acab58  

   Vos, Johanna_M; Burningham, Ben; Faherty, Jacqueline_K; Alejandro, Sherelyn; Gonzales, Eileen; Calamari, Emily; Gagliuffi, Daniella_Bardalez; Visscher, Channon; Tan, Xianyu; Morley, Caroline_V; et al (February 2023, The Astrophysical Journal)

   Abstract We present an atmospheric retrieval analysis of a pair of highly variable, ∼200 Myr old, early T type planetary-mass exoplanet analogs SIMP J01365662+0933473 and 2MASS J21392676+0220226 using the Brewster retrieval framework. Our analysis, which makes use of archival 1–15μm spectra, finds almost identical atmospheres for both objects. For both targets, we find that the data is best described by a patchy, high-altitude forsterite (Mg₂SiO₄) cloud above a deeper, optically thick iron (Fe) cloud. Our model constrains the cloud properties well, including the cloud locations and cloud particle sizes. We find that the patchy forsterite slab cloud inferred from our retrieval may be responsible for the spectral behavior of the observed variability. Our retrieved cloud structure is consistent with the atmospheric structure previously inferred from spectroscopic variability measurements, but clarifies this picture significantly. We find consistent C/O ratios for both objects, which supports their formation within the same molecular cloud in the Carina-Near moving group. Finally, we note some differences in the constrained abundances of H₂O and CO, which may be caused by data quality and/or astrophysical processes such as auroral activity and their differing rotation rates. The results presented in this work provide a promising preview of the detail with which we will characterize extrasolar atmospheres with JWST, which will yield higher-quality spectra across a wider wavelength range. 

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3. Vaporization and thermodynamics of forsterite-rich olivine and some implications for silicate atmospheres of hot rocky exoplanets

   https://doi.org/10.1016/j.icarus.2017.02.006  

   Costa, Gustavo C.C.; Jacobson, Nathan S.; Fegley Jr., Bruce (June 2017, Icarus)
4. Hydration-driven stabilization and volume collapse of grain boundaries in Mg2SiO4 forsterite predicted by first-principles simulations

   https://doi.org/10.2138/am-2021-7732  

   Ghosh, Dipta B.; Karki, Bijaya B.; Wang, Jianwei (April 2022, American Mineralogist)

   Abstract Grain boundaries in mantle minerals are of critical importance to geophysical and geochemical processes of the Earth’s interior. One of the fundamental issues is to understand how the water (H2O) component influences the properties of grain boundaries in silicate materials. Here, we report the results of the structure and stability of several tilt grain boundaries in Mg2SiO4 forsterite over the pressure range 0 to 15 GPa using density functional theory-based first-principles simulations. The results suggest greater energetic stability and hydration-driven volume collapse (negative excess volume) at zero pressure for the majority of hydrous grain boundaries relative to the anhydrous (dry) ones. All the hydrous grain boundaries become increasingly favorable at elevated pressures as the calculated hydration enthalpy systematically decreases with increasing pressure. The hydrous components at the interfacial regions are predominantly in the hydroxyl form and, to a lesser extent, in the molecular H2O form. Their calculated ratio ranges from 1.6 to 8.7 among the different grain boundary configurations. Our structural analysis also reveals that the hydroxyls are bound to either both Mg and Si or to Mg only. In comparison, the molecular species are bound only to Mg sites. Besides direct oxygen-hydrogen bonding, intermolecular hydrogen bonding becomes important with compression. On the basis of our results, we suggest that local atomic rearrangements caused by dissociative adsorption of water facilitate efficient compaction of the boundary interfaces, which, in turn, results in greater relative stability of hydrous grain boundaries. This means that water prefers to be incorporated within the grain boundaries over the bulk of silicate materials. 

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5. High precision Al–Mg systematics of forsterite-bearing Type B CAIs from CV3 chondrites

   https://doi.org/10.1016/j.gca.2016.12.006  

   MacPherson, G.J.; Bullock, E.S.; Tenner, T.J.; Nakashima, D.; Kita, N.T.; Ivanova, M.A.; Krot, A.N.; Petaev, M.I.; Jacobsen, S.B. (March 2017, Geochimica et Cosmochimica Acta)