Carletonmooreite, Ni₃Si, a new silicide from the Norton County aubrite meteorite
Abstract
Carletonmooreite (IMA 2018-68), Ni₃Si, is a new nickel silicide mineral that occurs in metal nodules from the Norton County aubrite meteorite. These nodules are dominated by low-Ni iron (kamacite), with accessory schreibersite, nickelphosphide, perryite, and minor daubréelite, tetrataenite, taenite, and graphite. The chemical composition of the holotype carletonmooreite determined by wavelength-dispersive electron-microprobe analysis is (wt%) Ni 82.8 ± 0.4, Fe 4.92 ± 0.09, and Si 13.08 ± 0.08 (n = 6, total = 100.81) giving an empirical formula of (Ni_(2.87)Fe_(0.18))_(Σ3.05)Si_(0.95), with an end-member formula of Ni₃Si. Further grains discovered in the specimen after the new mineral submission extend the composition, i.e., (wt%) Ni 81.44 ± 0.82, Fe 5.92 ± 0.93, Cu 0.13 ± 0.02, and Si 13.01 ± 0.1 (n = 11, total = 100.51 ± 0.41), giving an empirical formula (Ni_(2.83)Fe_(0.22)Cu_(0.004))_(Σ3.05)Si_(0.95). The backscat tered electron-diffraction patterns were indexed by the Pm3m auricupride (AuCu₃)-type structure and give a best fit to synthetic Ni₃Si, with a = 3.51(1) Å, V = 43.2(4) ų, Z = 1, and calculated density of 7.89 g/cm³. Carletonmooreite is silver colored with an orange tinge, isotropic, with a metallic luster and occurs as euhedral to subhedral crystals 1 × 5 µm to 5 × 14 µm growing on tetrataenite into kamacite. The dominant silicide in the Norton County aubrite metal nodules is perryite (Ni,Fe)₈(Si,P)₃, with carletonmooreite restricted to localized growth on rare plessite fields. The isolated nature of small euhedral carletonmooreite single crystals suggests low-temperature growth via solid-state diffusion from the surrounding kamacite and epitaxial growth on the tetrataenite. This new mineral is named in honor of Carleton B. Moore, chemist and geologist, and founding director of the Center for Meteorite Studies at Arizona State University, for his many contributions to cosmochemistry and meteoritics.
Additional Information
© 2021 Mineralogical Society of America. Manuscript received May 28, 2020; Manuscript accepted November 18, 2020; Manuscript handled by Simon A.T. Redfern. We are grateful to the staff and for the use of the facilities in the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University. We thank the associate editor Simon Redfern and Michael Zolensky and Thomas Zega for their timely reviews, which helped improve the quality of the paper. This work was in part funded by a NASA Emerging Worlds Grant NNX-17AE56G to L.A.J.G and supported in part by NASA Earth and Space Science Fellowship (NESSF) award 80NSSC18K1269 to S.R. and M.W. EBSD and EPMA were carried out at the Caltech GPS Division Analytical Facility, which is supported in part by NSF grants EAR-0318518 and DMR-0080065.Additional details
- Alternative title
- Carletonmooreite, Ni3Si, a new silicide from the Norton County aubrite meteorite
- Eprint ID
- 112035
- DOI
- 10.2138/am-2021-7645
- Resolver ID
- CaltechAUTHORS:20211124-154743604
- NNX-17AE56G
- NASA
- 80NSSC18K1269
- NASA Earth and Space Science Fellowship
- EAR-0318518
- NSF
- DMR-0080065
- NSF
- Created
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2021-11-24Created from EPrint's datestamp field
- Updated
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2021-11-24Created from EPrint's last_modified field