Crystallographic orientations of magnesiochromite inclusions in diamonds: what do they tell us?
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We have studied by X-ray diffractometry the crystallographic orientation relationships (CORs) between magnesiochromite (mchr) inclusions and their diamond hosts in gem-quality stones from the mines Udachnaya (Siberian Russia), Damtshaa (Botswana) and Panda (Canada); in total 36 inclusions in 23 diamonds. In nearly half of the cases (n = 17), mchr is parallel within error to diamond, but the angular misorientation for other crystallographic directions is generally significant. This relationship can be described as a case of rotational statistical COR, in which inclusion and host share a single axis (1 df). The remaining mchr–diamond pairs (n = 19) have a random COR (2 df). The presence of a rotational statistical COR indicates that the inclusions have physically interacted with the diamond before their final incorporation. Of all possible physical processes that may have influenced mchr orientation, those driven by surface interactions are not considered likely because of the presence of fluid films around the inclusions. Mechanical interaction between euhedral crystals in a fluid-rich environment is therefore proposed as the most likely mechanism to produce the observed rotational COR. In this scenario, neither a rotational nor a random COR can provide information on the relative timing of growth of mchr and diamond. Some multiple, iso-oriented inclusions within single diamonds, however, indicate that mchr was partially dissolved during diamond growth, suggesting a protogenetic origin of these inclusions.
KeywordsDiamond Magnesiochromite Inclusion Crystallographic orientation Syngenesis Protogenesis
This research was supported by ERC Starting Grant INDIMEDEA to FN (agreement n. 307322). MA was supported by ERC Horizon 2020 research and innovation programme (agreement n. 714936 for the project TRUE DEPTHS). JWH thanks the Diamond Trading Company (a member of the DeBeers Group of Companies) for the donation of the diamonds used in this study. We acknowledge the Paul Scherrer Institut, Villigen, Switzerland, and the Diamond Light Source, UK, for provision of synchrotron radiation beamtime at the TOMCAT beamline of the SLS (experiment e15427) and at the I15 beamline of the DLS (experiment EE7616), respectively. We are grateful to M. Bruno for reviewing an early version of the manuscript and useful discussion, and to O. Navon and an anonymous reviewer for their formal reviews, which helped us improve the paper.
- Frank-Kamenetsky VA (1964) The nature of structural impurities and inclusions in minerals. LGU Press, Leningrad (in Russian)Google Scholar
- Futergendler SI, Frank-Kamenetsky VA (1961) Oriented inclusions of olivine, garnet and chrome-spinel in diamonds. Zapisky Vsesoyuznogo Mineralogicheskogo Obshestva 90:230–236 (in Russian)Google Scholar
- Habler G, Griffiths T (2017) Crystallographic orientation relationships. In: Heinrich W, Abart R (eds) Mineral reaction kinetics: microstructures, textures, chemical and isotopic signatures, chap 15. EMU Notes in Mineralogy, vol 16. Mineralogical Society of Great Britain & Ireland, London, pp 541–585CrossRefGoogle Scholar
- Harris JW (1968) The recognition of diamond inclusions. Part 1: syngenetic mineral inclusions. Ind Diamond Rev 28:402–410Google Scholar
- Harris JW, Gurney JJ (1979) Inclusions in diamond. In: Field JE (ed) The properties of diamond. Academic Press, London, pp 555–591Google Scholar
- Harris JW, Henrique R, Meyer HOA (1967) Orientation of silicate mineral inclusions in diamonds. Cryst Growth 7:118–123Google Scholar
- Hartman H (1954) A discussion on ‘Oriented olivine inclusions in diamond’. Am Mineral 39:674–675Google Scholar
- Hwang SL, Yui TF, Chu HT, Shen P, Zhang RY, Liou JG (2011) An AEM study of garnet clinopyroxenite from the Sulu ultrahigh-pressure terrane: formation mechanisms of oriented ilmenite, spinel, magnetite, amphibole and garnet inclusions in clinopyroxene. Contrib Mineral Pet 161:901–920. https://doi.org/10.1007/s00410-010-0571-6 CrossRefGoogle Scholar
- Hwang SL, Shen P, Chu HT, Yui TF, Iizuka Y (2013) A TEM study of the oriented orthopyroxene and forsterite inclusions in garnet from Otrøy garnet peridotite, WGR, Norway: new insights on crystallographic characteristics and growth energetics of exsolved pyroxene in relict majoritic garnet. J Metamorphic Geol 31:113–130. https://doi.org/10.1111/jmg.12002 CrossRefGoogle Scholar
- Meyer HOA (1985) Genesis of diamond: a mantle saga. Am Mineral 70:344–355Google Scholar
- Meyer HOA (1987) Inclusions in diamond. In: Nixon PH (ed) Mantle xenoliths. Wiley, London, pp 501–523Google Scholar
- Mitchell RS, Giardini AA (1953) Oriented olivine inclusions in diamond. Am Mineral 38:136–138Google Scholar
- Orlov JL (1977) The mineralogy of diamond. Wiley, New YorkGoogle Scholar
- Pokhilenko NP, Sobolev NV, Boyd FR, Pearson DG, Shimizu N (1993) Megacrystalline pyrope peridotites in the lithosphere of the Siberian platform: mineralogy, geochemical peculiarities and the problem of their origin. Russ Geol Geophys 34:56–67Google Scholar
- Proyer A, Krenn K, Hoinkes G (2009) Oriented precipitates of quartz and amphibole in clinopyroxene of metabasites from the Greek Rhodope: a product of open system precipitation during eclogite–granulite–amphibolite transition. J Metamorphic Geol 27:639–654. https://doi.org/10.1111/j.1525-1314.2009.00844.x CrossRefGoogle Scholar
- Royer L (1928) Recherches expérimentales sur l’épitaxie ou orientation mutuelle de cristaux d’espèces différentes. Bull Soc Fr Min 51:7–159Google Scholar
- Schulze DJ, Helmstaedt H, Cassie RM (1978) Pyroxene-ilmenite intergrowths in garnet pyroxenite xenoliths from a New York kimberlite and Arizona latites. Am Mineral 63:258–265Google Scholar
- Wiggers de Vries DF, Drury MR, de Winter DAM, Bulanova GP, Pearson DG, Davies GR (2011) Three-dimensional cathodoluminescence imaging and electron backscatter diffraction: tools for studying the genetic nature of diamond inclusions. Contrib Mineral Petrol 161:565–579. https://doi.org/10.1007/s00410-010-0550-y CrossRefGoogle Scholar
- Zyuzin NI (1967) On nature of orientation of garnet inclusion from Yakutian diamond. Geol Geofiz 8:126–128 (in Russian)Google Scholar