Use of TEM‐EDX for structural formula identification of clay minerals: a case study of Di Linh bentonite, Vietnam

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Marco E. Ciriotti
Messaggi: 25339
Iscritto il: ven 25 giu, 2004 11:31
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Use of TEM‐EDX for structural formula identification of clay minerals: a case study of Di Linh bentonite, Vietnam

Messaggio da Marco E. Ciriotti » sab 02 feb, 2019 11:38

Prossima pubblicazione.

Referenza:
▪ Hoang-Minh, T., Kasbohm, J., Nguyen-Thanh, L., Thi Nga, P., Thi Lai, Le, Thuy Duong, N., Duc Thanh, N., Thi Minh Thuyet, N., Duy Anh, D., Pusch, R., Knutsson, S., Ferreiro Mählman, R. (2019): Use of TEM‐EDX for structural formula identification of clay minerals: a case study of Di Linh bentonite, Vietnam. Journal of Applied Crystallography, 75, (in press).

Abstract:
Transmission electron microscopy linked with energy‐dispersive X‐ray spectroscopy (TEM‐EDX) was applied to characterize mineralogical signals of weathering processes in the Di Linh bentonite deposit (Vietnam) and to visualize the effects of Na activation on the smectitic phases. Modelling of X‐ray diffraction patterns (oriented mount) was applied in order to refine the computed structural formula. X‐ray diffraction, X‐ray fluorescence and Fourier‐transform infrared spectroscopy (FT‐IR) methods were also applied to verify the TEM‐EDX results. An Excel‐based routine has been developed in this research to allow fast computation of structural formulae and classification of the investigated clay particles. This routine supports the acquirement of 100–300 TEM‐EDX analyses as a representative set of individual particles for each sample. The Excel‐based routine involves end members of different clay‐mineral groups and interstratifications with two or three members (e.g. illite–smectite interstratifications – IS‐ml; dioctahedral vermiculite–smectite interstratifications – diVS‐ml; and kaolinite–montmorillonite–dioctahedral vermiculite interstratifications – KSV‐ml). The routine is now freely available. According to the identification procedure, the <2 µm fraction of the Di Linh bentonite (Vietnam) is composed mainly of K‐ and charge‐deficient illite–smectite interstratifications (or diVS‐ml): montmorillonite‐rich randomly ordered (R0) type and illite‐rich regularly ordered (R1) type. Additionally, Fe‐poor KSV‐ml was identified. Industrial Na activation of the Di Linh bentonite resulted in an increase of the R1 diVS‐ml portion and dissolution of a large part of the smectite‐rich phases. The TEM‐EDX approach also gave analytical proof of a sedimentary process for Di Linh smectite. The parent muscovite was altered in two different environments: (i) K‐leaching and layer‐wise alteration into kaolinite (weathering), and (ii) further edge‐controlled alteration of mica into lath‐like montmorillonite particles associated with a dissolution of kaolinite layers from the former kaolinite–mica intergrowths by heat impact (basalt flow).
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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Marco E. Ciriotti
Messaggi: 25339
Iscritto il: ven 25 giu, 2004 11:31
Località: via San Pietro, 55 I-10073 Devesi/Cirié TO - Italy
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Re: Use of TEM‐EDX for structural formula identification of clay minerals: a case study of Di Linh bentonite, Vietnam

Messaggio da Marco E. Ciriotti » mar 05 feb, 2019 15:14

Pubblicazione effetuata.

Referenza:
▪ Hoang-Minh, T., Kasbohm, J., Nguyen-Thanh, L., Thi Nga, P., Thi Lai, Le, Thuy Duong, N., Duc Thanh, N., Thi Minh Thuyet, N., Duy Anh, D., Pusch, R., Knutsson, S., Ferreiro Mählman, R. (2019): Use of TEM‐EDX for structural formula identification of clay minerals: a case study of Di Linh bentonite, Vietnam. Journal of Applied Crystallography, 75, 133-147.
Marco E. Ciriotti

«Things are interesting only in so far as they relate themselves to other things»

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