Glauconite is rarely a homogeneous micaceous phyllosilicate in arenites but mostly a mixture or mixed-layer of white mica and smectite-group minerals. The amount of mica in the composite increases with increasing burial depth and diagenesis. Making use of a simple XRD analysis will give you no proper information because you might get an X-ray pattern of a mixture of glauconite mixed-layers shaped as green to bluish pellets and of the detrital flakes of smectite-group minerals and/or white micaceous clay minerals. To avoid that erroneous results which lead to a totally wrong interpretation of the geological environment I suggest a separation of these two groups by the grain morphology in a panning or jigging system. The green aggregates can subsequently be investigated and quantified with regard to the smectite-mica ratio using the Rietveld method. Heavy liquids to not provide reliable results because of the overlap of the specific gravity values of the clay minerals in question.

I suggest reading the two papers of mine where you find more about glauconite as environment indicator and tool for age determination (K/Ar, Ar/Ar):

DILL H.G., KÖTHE A., GRAMANN, F. and BOTZ, R. (1996) A palaeoenvironmental and palaeoecological analysis of fine-grained Palaeogene estuarine deposits of North Germany.- Palaeogeography, Palaeoclimatology, Palaeoecology, 124: 273-326.

DILL H.G. SCHEEL M., KÖTHE A., BOTZ R. and HENJES-KUNST F. (1997) An integrated environment analysis-lithofacies, chemofacies, biofacies-of the Oligocene calcareous-siliciclastic shelf deposits in northern Germany.- Palaeogeography, Palaeoclimatology, Palaeoecology, 131: 145-174.

H.G.Dill

Vivek P. Malviya

Glauconite is a clay mineral belonging to the illite group of clay mineral as they both have quite similar XRD peaks. Muscovite, biotite are two mica minerals which also show almost similar peaks. So care must be taken while carrying out XRD analysis. Quantification and identification of glauconite can be done with the aid of the following literatures:

Moore, D. M., & Reynolds Jr, R. C. (1989). X-ray Diffraction and the Identification and Analysis of Clay Minerals. Oxford University Press (OUP).

Odin, G. S., & Matter, A. (1981). De glauconiarum origine. Sedimentology, 28(5), 611-641.

Banerjee, S., Farouk, S., Nagm, E., Choudhury, T. R., & Meena, S. S. (2019). High Mg-glauconite in the Campanian Duwi Formation of Abu Tartur Plateau, Egypt and its implications. Journal of African Earth Sciences, 156, 12-25.

Li, X., Cai, Y., Hu, X., Huang, Z., Wang, J., & Christidis, G. (2012). Mineralogical characteristics and geological significance of Albian (Early Cretaceous) glauconite in Zanda, southwestern Tibet, China. Clay minerals, 47(1), 45-58.

Clay minerals and micas with similar structures are generally differentiated first under the microscope and then using XRD. Even if petrography is not possible (for fine grain size), XRD should be the first analysis because without the idea of the structure of the clay, no other analytical method can precisely determine which clay mineral is present. If carefully done, in different orientation, XRD will be enough for differentiating those minerals.

Completely agree with previous comments...

However, if I undertood well what you want is identify/quantify the different clay minerals in the sample, not only the interstratified glauconite-smectite. To do that, you could use the XRD patterns of oriented aggregates (clay fraction separated from the bulk sample). If you just want to characterise the interstratified glauconite-smectite, you need more specifications. I could provide also some references from our Research Group.

Best,

Adrián

For the quantification of normal phyllosilicates you can use the Rietveld Methode. In some cases you need , however, additional information provided by IR sepctroscopy.

You can try XRD-Rtietveld full-spectrum fitting method~

Thank you so much Harald G. Dill Adrián López-Quirós Tathagata Roy Choudhury and Hong-yu Wan for giving me valuable suggestions and information on proper identification of glauconite mineral.

Harald G. Dill

Adrián López-Quirós Tathagata Roy Choudhury Please send me related papers at [email protected]

Thank you so much in advance

Regards

Vivek

Vivek P. Malviya

I will send you the papers but I do not own an e-book of Moore and Reynolds (1989). Please try to find the book online or buy one from Amazon.in (hard copy). I am sending you the remaining papers but I beg your pardon for not being able to send you the book that will clear your basics about XRD of clay minerals.

Feel free to ask any question related to glauconite or related clay minerals. Will be happily answer to all your queries.

Thank you very much for showing interest.

Tathagata Roy Choudhury

Thank you so much@ Tathagata

Probably our paper translated in English (the original was written in Russian) may be useful for you. It is published in:

Lithology and Mineral Resources, 2013, Vol. 48, No. 6, pp. 489–513.

Boris Sakharov please share your paper

regards

Vivek

Dear Dr. Malviya,

you can use the intensity ratio of 001/002 peaks in oriented XRD patterns for a rough estimation of Fe content in mica group minerals, which may help you if your sample has a low number of clay phases. However, in more complex mineral assemblages XRD full profile techniques provide better results.

You can also combine XRD results with other techniques to determine Fe content in clays, like XRF (in bulk samples), TEM-EDS (in single mineral grains) or even Mössbauer spectroscopy.

See the papers I and colleagues published as examples:

Article Sequential mineral transformation from kaolinite to Fe-illit...

Article Transformation of clay minerals in salt-affected soils, Pant...

Best regards

Gabriel Ramatis Pugliese Andrade Thank you very much

For a detailed analysis of glauconite sandstone or so-called green sandstone which are very common in the Paleogene, I can only repeat and place emphasis on a preparatory stage involving heavy liquid separation and separation based on the morphology and grain size of glauconite. The quality of the separated mineral assemblage qualifies even for radiometric age dating and the analysis of stable isotopes. Any other method cannot distinguish between authigenic glauconite and detrital flakes of mica. The different clay minerals tell you a completely different story of evolution and also yield different ages, one for the evolution of provenance area and the other one for the diagenetic overprinting of the host sandstone.

Dear Dr. Malviya:

The QEMSCAN (Quantitative Evaluation of Minerals by SCANning electron microscopy) is a good alternative to identify (100-200 EDX determinations per second) and quantify (mineralogy percentages) clay minerals.

Here I put two examples of how the QEMSCAN works (see the link of the first paper):

1) Mineralogy and Geochemistry of the Main Glauconite Bed in the Middle Eocene of Texas: Paleoenvironmental Implications for the Verdine Facies (Harding et al., 2014).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3913656/

2) Diagenetic and sedimentary controls on porosity in Lower Carboniferous fine-grained lithologies, Krechba field, Algeria: A petrological study of a caprock to a carbon capture site (Armitage et al., 2010).

Best Regards,

F. Stange

Harald G. Dill Thank you so much Sir for your valuable suggestions Fredy Stange thanks

Tathagata Roy Choudhury Please share the title of the book...

Thanks

MG

@Mukhtiar Ghani

Moore, D. M., & Reynolds Jr, R. C. (1989). X-ray Diffraction and the Identification and Analysis of Clay Minerals. Oxford University Press (OUP).

Thanks Tathagata Roy Choudhury

By using ceramic disk covered mud or clay minerals and analyze via XRD twice glycerated and non glycerated