¹Francis M. McCubbin,¹, Jonathan A. Lewis,², Jessica J. Barnes,¹, Jeremy W. Boyce,^1,3Juliane Gross, ⁴Molly C. McCanta,^5,6Poorna Srinivasan, ⁷Brendan A. Anzures,¹Nicole G. Lunning,¹, Stephen M. Elardo,¹Lindsay P. Keller,⁹Tabb C. Prissel,^5,6Carl B. Agee
American Mineralogist 108, 1185-1200 Link to Article [http://www.minsocam.org/msa/ammin/toc/2023/Abstracts/AM108P1185.pdf]
¹NASA Johnson Space Center, Mailcode XI, 2101 NASA Parkway, Houston, Texas 77058, U.S.A.
²Lunar and Planetary Laboratory, University of Arizona, 1629 E University Boulevard, Tucson, Arizona 85721, U.S.A.
³Department of Earth and Planetary Sciences, Rutgers University, Piscataway, New Jersey 08854, U.S.A.
⁴Department of Earth and Planetary Sciences, University of Tennessee, Knoxville, Tennessee 37996, U.S.A. 5
⁵Institute of Meteoritics, University of New Mexico, 200 Yale Boulevard SE, Albuquerque, New Mexico 87131, U.S.A.
⁶Department of Earth and Planetary Sciences, University of New Mexico, 200 Yale Boulevard SE, Albuquerque, New Mexico 87131, U.S.A.
⁷Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, Texas 77058, U.S.A.
⁸Department of Geological Sciences, University of Florida, Gainesville, Florida 32611, U.S.A.
⁹Jacobs, NASA Johnson Space Center, 2101 NASA Parkway, Houston, Texas 77058, U.S.A.
Copyright: The Mineralogical Socuety of America

We conducted a petrologic study of apatite within one LL chondrite, six R chondrites, and six CK
chondrites. These data were combined with previously published apatite data from a broader range of chondrite meteorites to determine that chondrites host either chlorapatite or hydroxylapatite with ≤33 mol% F
in the apatite X-site (unless affected by partial melting by impacts, which can cause F-enrichment of
residual apatite). These data indicate that either fluorapatite was not a primary condensate from the solar
nebula or that it did not survive lower temperature nebular processes and/or parent body processes.
Bulk-rock Cl and F data from chondrites were used to determine that the solar system has a Cl/F ratio of
10.5 ± 1.0 (3σ). The Cl/F ratios of apatite from chondrites are broadly reflective of the solar system Cl/F
value, indicating that apatite in chondrites is fluorine poor because the solar system has about an order
of magnitude more Cl than F. The Cl/F ratio of the solar system was combined with known apatite-melt
partitioning relationships for F and Cl to predict the range of apatite compositions that would form from
a melt with a chondritic Cl/F ratio. This range of apatite compositions allowed for the development of a
crude model to use apatite X-site compositions from achondrites (and chondrite melt rocks) to determine
whether they derive from a volatile-depleted and/or differentiated source, albeit with important caveats
that are detailed in the manuscript. This study further highlights the utility of apatite as a mineralogical
tool to understand the origin of volatiles (including H2O) and the diversity of their associated geological
processes throughout the history of our solar system, including at its nascent stage.

¹Christiaan P. A. van Buchem,^1,2Yamila Miguel,¹Mantas Zilinskas,³Wim van Westrenen
Meteoritics & Planetary Science (in Press) Open Access Link to Article [https://doi.org/10.1111/maps.13994]
¹Leiden Observatory, Leiden University, Leiden, The Netherlands
²SRON Netherlands Institute for Space Research, Leiden, The Netherlands
³Faculty of Science, Earth Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
Published by arrangement with John Wiley & Sons

To date, over 500 short-period rocky planets with equilibrium temperatures above1500 K have been discovered. Such planets are expected to support magma oceans,providing a direct interface between the interior and the atmosphere. This provides a uniqueopportunity to gain insight into their interior compositions through atmosphericobservations. A key process in doing such work is the vapor outgassing from the lavasurface. LavAtmos is an open-source code that calculates the equilibrium chemicalcomposition of vapor above a dry melt for a given composition and temperature. Resultsshow that the produced output is in good agreement with the partial pressures obtainedfrom experimental laboratory data as well as with other similar codes from literature.LavAtmos allows for the modeling of vaporization of a wide range of different mantlecompositions of hot rocky exoplanets. In combination with atmospheric chemistry codes,this enables the characterization of interior compositions through atmospheric signatures.