New Mineral: Edscottite
The first natural occurrence of the iron carbide Fe
5C
2 has been identified in the Wedderburn iron meteorite [Data link from the
Meteoritical Database] and has been named edscottite, as reported in the
European Journal of Mineralogy (issue 31) and
American Mineralogist (volume 104, issue 9). Approved by the
International Mineralogical Association's Commission on New Minerals, Nomenclature, and Classification, the name honors Dr. Edward R. D. Scott, Emeritus Professor at the Hawaii Institute of Geophysics and Planetology (
HIGP) at the University of Hawaii at Mānoa. Dr. Scott is a leading authority on the geochemistry, mineralogy, and petrology of iron meteorites, and also a friend of
PSRD whose research and writing on meteorites have appeared in our pages.
Edscottite formed as lath-shaped or platy single crystals (15–40 µm long) in kamacite (an iron-nickel mineral with low nickel content that, along with taenite, is responsible for the
Widmanstätten pattern in iron meteorites). The edscottite crystal shapes suggest they grew rapidly after supersaturation of carbon.
Dr. Scott and Dr. Stuart O. Agrell identified the Fe
5C
2 iron carbide chemically while studying Wedderburn in 1971, but the technology was not yet available to thoroughly characterize its structure and associated phases. Dr. Chi Ma of Caltech and Dr. Alan Rubin of the University of California at Los Angeles performed the new analyses needed to verify and name the new mineral.
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[LEFT] Backscatter electron microscope image of new mineral, edscottite, from a sample of the Wedderburn iron meteorite. Image courtesy of Chi Ma, Caltech. [RIGHT] Dr. Edward Scott, namesake of new mineral. Image courtesy of HIGP.
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(pdf version)
See References:
· Ma, C. and Rubin, A. E. (2019) Edscottite, Fe5C2, A New Iron Carbide Mineral from the Ni-rich Wedderburn IAB Iron Meteorite, American Mineralogist,, v. 104(9), p. 1351-1355, doi: 10.2138/am-2019-7102. [abstract]
· Ma, C. and Rubin, A. (2019) Edscottite, IMA 2018-086a. CNMNC Newsletter No. 47, February 2019, page 202; European Journal of Mineralogy, v. 31, p. 197-202, doi:10.1127/ejm/2019/0031-2839. [open access pdf]
See also:
· Edward R. D. Scott publications on Google Scholar.
· Scott E. R. D. and Agrell, S. O. (1971) The Occurrence of Carbides in Iron Meteorites (abstract). 238 Meteoritics, v. 6, p. 312-313. [NASA ADS entry]
Written by Linda Martel, Hawaii Institute of Geophysics and Planetology, for
PSRD.