X-ray study of the graphite-bearing rocks from the Pestpaksha ore occurrence and structural features of graphite
Tóm tắt
Graphite-bearing rocks and graphites from the Precambrian metamorphic sequence of the Pestpaksha ore occurrence, Murmansk district, have been studied by the X-ray method. It was determined that the rocks have a complex polycomponent composition. Graphite is associated with garnet-quartz, pyroxene-amphibole, and biotite-quartz with an admixture of pyrrhotite, kyanite, chlorite, and other minerals. In terms of mineral composition, the studied samples are subdivided into five groups. The structural characteristics of graphite—parameters a
0 and c
0, the degree of structural perfection (U), the content of rhombohedral phase (R), and others—were found to be different for each group. The U value varies from 1.04 to 1.56 (with predominant values from 1.4 to 1.5), while the content of rhombohedral phase in samples is no more than 18%. This fact indicates a relatively high 3D order, which is typical of graphites from metamorphic rocks. Graphites from metasomatites have the lowest U value, while those from weathering zones are characterized by a small value of the coherent scattering domain (CSD). It was established that interplanar spacing d
002 of graphite correlates with depth, while the degree of ductility and flexibility of the graphite is defined by conditions of its retrograde metamorphism.
Tài liệu tham khảo
Biske, N.S., Results of the X-ray and Thermographic Study of Graphites of the Ladoga Complex, Zap. Vses. Mineral. Obshch., 1982.
Chukhrov, F.V., Zvyagin, B.B., Zhukhlistov, A.P., et al., Characteristics of Structural Peculiarities of Natural Graphite, Izv. AN SSSR. Ser. Geol., 1986, no. 7, pp. 3–15.
Crystal Structures of Clay Minerals and Their X-ray Identification, Brindley, G.W. and Brown, G., Eds., London: Mineral. Soc., 1980.
Korshunov, A.B., Analytical Method for the Determination of Parameters of Fine Crystal Structure Based on the Broadening of X-ray Lines, Zavod. Lab., Diagn. Mater., 2004, vol. 70, no. 2, pp. 27–32.
Kwiecinska, B., On the Rhombohedral Modification in Natural Graphites and Semi-Graphites, Min. Pol., 1978, vol. 9, pp. 3–13.
Lygina, T.Z., Volkova, S.A., Gubaidullina, A.M., et al., Sulfide Minerals of Iron and Their Role in the Typification and Estimation of Ore Formation Conditions in the Graphite-Bearing Rocks, Otechest. Geol., 2009, no. 1, pp. 69–73.
Svoistva konstitutsionnykh materialov na osnove ugleroda (Properties of Constitutional Materials Based on Carbon) Sosedov, V.P., Ed., Moscow: Metallurgiya, 1975.