Abstract
Iron-bearing olivine grains naturally altered by oxidation were examined in the transmission electron microscope to determine the precipitate phases and their crystallographic and morphological relationships to the host. Precipitate complexes heterogeneously nucleated on dislocations were composed of Si-rich, Mg-rich/Si-rich, and Fe-rich regions corresponding to α- tridymite, enstatite, and magnetite and/or hematite, respectively. The tridymite and magnetite (hematite) occurred as rod-like interleaved fingers, while the enstatite was more equidimensional. The crystal orientations of the precipitate phases with respect to the host structure, listed in Table 2, were well defined, but, in general, could not be simply related to the close packing of oxygen planes. Iron-rich (001) planar precipitates occasionally nucleated homogeneously in the host as well as heterogeneously on dislocations. Oxygen diffusion does not appear to be the rate-controlling process for precipitate nucleation and growth as precipitation kinetics in fresh olivine oxidized at 900 ° C would indicate an oxygen diffusivity of 10−8 cm2/sec, a value 10 orders of magnitude faster than determined previously.
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Barnard, R.S.: An attempt at measuring oxygen self-diffusion data in forsterite by proton activation Technique. Master of Science Thesis, Division of Metallurgy and Materials Science, Case Western Reserve University, 1974
Champness, P.E.: Nucleation and growth of iron oxides in olivines, (Mg, Fe)2SiO4 Mineral. Mag. (London) 37, 790–800 (1970)
Deer, W.A., Howie, R.A., Zussman, J.: An introduction to the rock forming minerals. London: Longman 1963
Durham, W.B., Goetze, C., Kohlstedt, D.L., Vander Sande, J.B.: Science (in press)
Fenner, C.N.: Stability relations of the silica minerals. Am. J. Sci. 4th per., 36, 331–384 (1913)
Francis, D.: Xenoliths and the nature of the upper mantle and lower crust. Doctor of Philosphy Thesis, Department of Earth and Planetary Sciences, Massachusetts Institute of Technology, 1974
Friedel, J.: Dislocations, pp. 37–38. New York: Pergamon Press 1967
Goetze, C., Kohlstedt, D.L.: Laboratory study of dislocation climb and diffusion in olivine. J. Geophys. Res. 78, 5961–5971 (1973)
Haggerty, S.E., Baker, I.: The alteration of olivine in basaltic and associated lavas. Part I: High temperature alteration. Contrib. Mineral. Petrol. 16, 233–257 (1967)
Koltermann, M.: Der thermische Zerfall fayalithaltiger Olivine bei hohen Temperaturen. Neues Jahrb. Mineral. Monatsh. 181–191 (1962)
Koltermann, M., Mueller, K.H.: DTA und Vakuum-DTA von Olivin, Fayalit, und Bronzit. Ber. Deut. Keram. Ges. 40, 20–23 (1963)
Nitzan, U.: Stability field of olivine with respect to oxidation and reduction. J. Geophys. Res. 79, 706–711 (1974)
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Kohlstedt, D.L., Vander Sande, J.B. An electron microscopy study of naturally occurring oxidation produced precipitates in iron-bearing olivines. Contr. Mineral. and Petrol. 53, 13–24 (1975). https://doi.org/10.1007/BF00402451
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DOI: https://doi.org/10.1007/BF00402451