Clay minerals have an average grain size of

Dear Dr. Kundula,

the procedure applied to clay mineral analysis depends upon the goals of your studies. Is it more related to an environment analysis, devoted to economic geology or a provenance study of fine-grained sedimentary rocks? I was faced with all of these problems. Even if you speak about clay minerals I would not cast aside the coarser particle sizes such as silt and sand. Focusing on the clay minerals which needs to be defined first (phyllosilicates or a technical term used to describe a grain size interval). Some strictly focus on < 2µm or an evens smaller (smectite) grain size others prefer < 20µm with an option for further grain size separation (settling tube, centrifuge).

The mineralogical work encompasses some routine techniques such as XRD (power samples, oriented/random) which can be up-graded up to a quantitative analysis by means of Rietveld-refinement and different types of spectroscopy. Cation exchange capacity studies for expandable phyllosilicates, such as the smectite group, are a must. SEM/EDX and SEM/WDX will be helpful for chemical and morphological studies.

Thermo-physical techniques (e.g. differential thermo analyses) are useful if your focus lies within the final use of clay minerals. The techniques are sometime very specific.

If you want to capture digital data in the field, e.g. for mapping and cross sectioning use a portable XRD, combined with IR mineral analyzers, and a kappameter, gamma-spectrometry and conductivity meter determining the relative resistivity (smectite/ silica ratio) according to the Wenner Array.

I exclude age dating of clay minerals using the K/Ar and Ar/Ar method. We did it by you can write a book about how to prepare the sample most suitable.

This is a first-hand introduction based upon my knowledge and practical experience which I collected in the field and the laboratory aimed a tackling problems in the three approaches taken above.

The lacustrine environment should always been looked at in context with the fluvial and aeolian environment dependent upon whether you deal with an ephemeral or perennial lake.

DILL, H.G., DOHRMANN, R., KAUFHOLD, S. and TECHMER, A. (2014) Provenance analysis and thermo-dynamic studies of multi-type Holocene duricrusts (1700 BC) in the Sua Salt Pan, NE Botswana.- Journal of African Earth Sciences, 96: 79-98.

DILL, H.G., BALABAN, S.- I., WITT, B. and WERSHOFEN, H. (2014) Capturing digital data of rock magnetic, gamma-ray and IR spectrometry for in-situ quality control and for the study of the physical-chemical regime of residual kaolin deposits, SE Germany.- Ore Geology Reviews, 57: 172-190.

DILL, H.G., KAUFHOLD, S., LINDENMAIER, F., DOHRMANN, R., LUDWIG, R. and BOTZ, R. (2012) Joint clay-heavy-light mineral analysis: A tool to investigate the hydrographic-hydraulic regime of the Late Cenozoic deltaic inland fans under changing climatic conditions (Cuvelai-Etosha Basin, Namibia).- International Journal of Earth Sciences, 102: 265-304.

These papers are first and foremost to give you an idea what the technical approaches are like. Sedimentological studies on lacustrine environments and adjacent ones are countless.

Best regards

Harald G. Dill

Dear Mr. Gautam, be aware that probably only clay minerals from the smectite group (e. g. montmorillonite) can be found solely in the grain size fraction of

First you may need to separate the clay fraction from the bulk sediments if your samples are organic laden or dominated by coarse grained sediments (poor clay amount). You can do it by mechanical sieving (wet or dry) or pipette method. Extract size fraction with < 2 micron. Then, you may further pulverised the samples prior to sending it for XRD analysis. XRD analysis coupled with some minerals identification software allows us to know exactly what kind of clays that present in the sample. For visual confirmation of your clay samples, it is also recommended that you sampled an aliquot of the < 2 micron samples and send it for SEM-EDX examination. The EDX system provides you the chemical composition of the samples which may be helpful to know what kind of clay is in the samples. Good luck!

Dear Renata !

I agree to your thoughts.