Ebrahim,

the peaks which move between treatments indicate that you have a clay in your sample. In the glycolated trace you have a peak at about 10.3 2theta Copper so about 8.5 Angstroms in terms of d-spacing. This looks like an 002 of a smectite (or at least very smectitic clay), the 001 is probably just off scale as you have started you trace at 5 degrees 2theta (just about where the smectite 001 would occur) start a bit lower if you can, 2 degrees is usally ideal, but sometimes difficult to achieve because of instrument geometry. The other peaks in you pattern that don't move about look like they are mostly from feldspars, but the sharp peak near 22 degrees is almost certainly due to cristobalite rather than a feldspar since it is more intense (larger peak height) than other peaks attributed to feldspar. Hope that helps.

steve

dear Ebrahim Sangsefidi

To help you,Is it possible to explain the type of sample?

Thank you for your attention dear Abbas R. Ali

The materials are sourced from an Andesite quarry.

Samples are oriented samples on 2.54 cm slides that were prepared after three stages of pre-treatment procedure to isolate clay-sized particles. First an air-dried analysis was carried out on the sample, then to recognize the clay phases the sample was glycolated at 60 degree of Celsius for 20 hours. I have the XRD test results for the heated sample as well (45 minutes at 550 degree of Celsius).

please let me know if you need more information.

Kind regards,

Ebrahim

Both the peaks one at 6 degree and 10 degree indicate the presence of layer silicates in your samples. Please indicate which metal target you have used for Xray examination. Once the target is known the specific mineral can be identified.

Hi Dilip Kumar Pal

Experiments were run using a PANalytical Empyrean X-ray diffractometer operating at 45 kV and 40 mA. The diffractometer employs a Cu K-alpha radiation (Kα1/Kα2 = 0.5) with a 1.5406 Å wavelength (Kα1) and has a graphite monochromator with a PIXcel Detector. Fresh bulk materials scans were run at a 2θ angle from 4 to 70°, with a 0.013° step size and an integrated 100 s dwell time.

Thank you for your time.

Dear Ebrahim Sangsefidi!

Typically, a diffraction peak at 10 degrees indicates the presence of clay (eg, montmorillonite, smectite, illite). An unique identification is rather difficult, since the peak position also depends on the degree of ordering.

For example, it is known that the peak d001 of montmorillonite under heating expands and shifts towards larger angles and, and at temperatures over 500 C completely disappears. In addition, the interaction of glycerin with montmorillonite leads to a shift of the peak d001 in the region of small angles and the appearance of the lines d002 (8.93 Å), d003 (5.90 Å), d005 (3.54 Å) d006 (2.95 Å) due to the ability of the structural cell of montmorillonite expands. This is a diagnostic feature of montmorillonite.

Consequently, it can be assumed that your initial sample contains some montmorillonite. The peak d001 is shifted towards large angles in the heated sample. In opposite, this peak is shifted to smaller angels under the treatment with ethylene glycol.

Please follow the analytical protocol to identify the layer silicates. Samples need to be parallel oriented on a glass slide and scan in Xray after various treatments. Please refer to the book ' Jackson, M. L., Soil Chemical Analysis – Advanced Course, University of Wisconsin, Madison, USA (Published by the author), 1979, 2nd edn.

dear Ebrahim Sangsefidi

(6 and 10) degree peaks indicate the presence of silicates layer in your samples.

with my best regard

Ebrahim,

the peaks which move between treatments indicate that you have a clay in your sample. In the glycolated trace you have a peak at about 10.3 2theta Copper so about 8.5 Angstroms in terms of d-spacing. This looks like an 002 of a smectite (or at least very smectitic clay), the 001 is probably just off scale as you have started you trace at 5 degrees 2theta (just about where the smectite 001 would occur) start a bit lower if you can, 2 degrees is usally ideal, but sometimes difficult to achieve because of instrument geometry. The other peaks in you pattern that don't move about look like they are mostly from feldspars, but the sharp peak near 22 degrees is almost certainly due to cristobalite rather than a feldspar since it is more intense (larger peak height) than other peaks attributed to feldspar. Hope that helps.

steve

Hi Professor Kenneth M Towe

Thank you for your attention.

The sample is a low quality aggregates to be used in the pavement structure. I did the XRD test to make sure the presence of clay minerals and the type of them in the structure of aggregates. I have done XRF and Thin Section tests as well.

Please let me know if you need more information.

Cheers

Should be montmorillonite or some other clays lone that.

Need to see your d-spacing data.

Good kuck

Hi Ali Yaraghi

I have added the d-spacing data.

Cheers,

Need look at the excitation of these electron produces diffractions which characteristics of the elements and compounds.

Dear Ebrahim:

I only have this to add to all previous answers: if your andesites are fairly young and not metamorphosed, then the K-feldspar you should have cannot be microcline, but sanidine, probably Na-rich. In the Guiana Shield, in southern Venezuela, we have very old trachytes and rhyolites (Paleo to Mesoproterozoic) in which, due to low grade metamorphism and their great ages, all sanidine has developed microperthites and became microclinized. But these are rocks at least of 1.8 Ga of age. Also you cannot have peaks of albite and anorthite separated, usually andesites have strongly zoned plagioclase, with Ca-rich cores and Na-rich bordes, of even more complex inverse or oscillatory zoning patterns, due to magma mixing, and other open-system magmatic processes. Regards, Sebastián.

Dear Ebrahim,

Indeed, the peak at 6 degrees 2theta is the smectite. The presence of this mineral is confirmed by EG and heat treatment.

same thing for the peak of 9 degrees 2theta is a typical 002 reflection of a smectite;

in addition, the peak around 15 degrees 2theta in the sample and heated glycolated vanishes, suggesting the presence of kaolinite hallosite type because the intensity becomes zero with the treatment.

For more details, see Hotzapel, 1986. X-ray diffraction and identification and analysis of clay minerals.

Looks like montmorillonite

Deat Ebrahim:

I don't exactly know what are the objetives of your study of andesites, but I assume that one interesting thing would be to find out what is the origin of this "clay minerals" you have. They could have been formed by: andesitic glass devitrification; as a product of low temperature hydrothermal alteration, or even by simple surface weathering, or any combination of the three!

Regards, Sebastián.

Dear Sebastián Grande

These andesite materials are sourced from a quarry that produces road aggregates. They usually does not have appropriate engineering properties and I am looking to find a reason in their micro-scale characteristics. To this end, knowing what type of clay minerals and primary minerals exist in the texture of the aggregates is a matter of importance to me ...

Cheers,

Ebrahim

Hello, Ebrahim

Should be smectite group minerals (montmorillonite).The presence of this mineral is confirmed by EG and after heat treatment.You should prepare a diffractogram patterns from 2.0 not from 5.0 2theta.

I would need more information to give a definitive answers on the minerals.

There is definitely a lot of montmorillonite in the sample and it is the major mineral.

To identify other minerals, it would be useful if you could provide information on the following:

i) Sample preparation. Was it treated in any way to separate the clay-size fractions i,e. below 2 microns

ii) The temperature of heating. Was it heated only once say at 480 degrees or did you carry out additional heating beyond this value?

iii) The nature of the sample. Is it a product from hydrothermal alteration of the andesite or a product from simple weathering? This has import on the nature of the feldspars and other minerals indicated in your diagram.

Please find appropriate reference and reading materials.

1. D Carroll Clay (1970) Minerals: A Guide to Their X-ray Identification. Front Cover. Dorothy Carroll. Geological Society of America

2. G. W. Brindley and G. Brown (1980) Crystal Structures of Clay Minerals and their X-Ray Identification. Mineralogical Society

3. Klug H.E. and Alexander L.E. (1974): X-ray diffraction procedures for polycrystalline and amorphous materials. Wiley, New York

Hi Siyan Malomo

Thank you for your attention to this question. Please find the following information:

i) Yes, clay size fractions was separated.

ii) The sample was treated for 45 minutes in 550 degree.

iii) the sample was collected from a Quarry known to produce aggregates for the pavement structure.

Please let me know if you need more information.

Thank you for the the references.

Cheers,

I agree with answer of Dr. Ibrahim Sangsefidi

Regards

Dr.G.A.Khater

What about the corresponding reference JCPDS cards?

Please refer opinions from Ralf Berger, Rafi Ananth,Lawrence Marqulies and Romano Rinaldi. Thanks for share with me

Dear Ebrahim

The behavior observed is typical of a swelling clay mineral of the smectite type. This group of minerals include montmorillonite (Al,Mg-rich)but also beidellite (Al-rich) and nontronite (Fe-rich) (dioctahedral smectites) but also saponite (Mg,Al-rich), hectorite (Mg-rich) and stevensite (Mg-rich) (trioctahedral smectites). Thus, in air-dried, the major reflection (001) of a smectite with divalent cation (Ca or Mg) in interlayer domain (hydrated by 2 molecules of water) is close to 15.0 Å (5.0°2theta), after ethylene glycol saturation the position of this reflection moves close to 17 Å and (due to the increased order in the stack) its harmonic (002) appears to 8.5 Å (11.0°2theta), finally after heat treatment the interlayer domain collapses completely and the reflection (001) moves towards 10.0 Å (9 °2theta). From these basic treatments, the conclusion is that this phase is a smectite (without precision about species). The precise knowledge of the positions of reflections would make it possible to say whether it is a pure smectite end-member, a smectite / illite mixed-layer very rich in smectite or a mixture of the two.

On the other hand, the nature of the smectite crystallized during your experiment depends on the initial composition of your rock and in particular on the vitreous phase (clearly abundant in your case), but also on the operating mode adopted, open (lixiviation) or closed (batch), which controls the content of the most labile elements (Mg, Fe) available or not for the development of the structure of the neoformed smectite? By diffraction (powder mode), the study of the position of the reflection (060) (or (0633)) of this smectite will be able to know if it is a dioctahedral (1.49 - 1.51 Å) or a trioctahedral mineral (1.52 - 1.54 Å) or a mixture; because the Mg and Fe contents released by the alteration of hornblende and augite may be sufficient for this purpose. If you are in presence of the dioctahedral series (montmorillonite-beidellite), Hofmann -Klemen test will allow you to know what end-member you have. In any case, the precise determination of a smectite species requires knowledge of its chemical composition, which you can have by the EDX-SEM analysis of your material.

Cheers

Dear Ebrahim Sangsefidi ! Please do it for oriented samples from 2 degree (2O)/ It will be more reliable for identification of clay minerals.

Sincerely