Clay Minerals - Science topic

Also, I suggest you consider the inverse where the microbial metabolic processes, specifically the electron transfer to electron acceptors modifies the surface chemistry of clay minerals. I have experienced this at in-situ bioremediation sites where the cohesiveness vs the uncontaminated and untreated clays was substantially decreased. Of course we did not have the option of evaluating the clays since we were working for other purposes.

Yes it does ! Thank you for your answer.

Any idea for the cylinder ones ?

The preparation process is straightforward. You should begin by drying the material and affixing it to a conductive substrate,fofr exapmle by carbon tape. Lastly, because your sample is non-conductive, it will require sputtering with another conductive material, typically carbon or gold.

Hello Andrey.

Thanks a lot for sharing your experience with this topic.

I will study carefully your comments and test it with our materials.

Best regards

Antonio

Atikur Rahman

Surprisingly, that microcline does not fit - it is his most intense reflex. In the picture you showed only rutile. You will not get the ratio of minerals, knowing only interplanar distances. Only qualitatively can you talk about the presence of phases.

Please find the attached article - Determination of Chloride Content in Cementitious Materials. (It may be helpful)

First, examining the .gpx file, it can be seen that in one go you imposed all 5 phases. Typically, each phase is added one at a time. Also, the diffraction pattern is not of good quality, the intensity of the maxima must be above 10000. That will make the refinement quite difficult, the pattern you show would be preliminary. You must repeat the measurement.

If you really need to work with this diffraction pattern, first do a Pawley or Le Bail refinement with GSASII without using the cell, to refine the instrumental parameters like U, V, W, X, Y and S (asymmetry), as well as the background. This is an advantage of GSASII, doing a refinement without including the cell parameters. Then, you carry out the rietveld refinement using the parameters obtained above and add each phase one at a time, starting with the highest composition. Finally, you proceed with refinement.

Without analyzing by XRD technique the parallelly oriented clay samples saturated with Ca and K ions and subsequent glycolation of Ca-sample and heating the K-sample , it not possible which clay mineral it is.

It's very interesting that in my research, this method in sandy soils gave a better answer and I have to say, definitely yes.....

Check these paper

1.

2.

After orienting on a glass slide , scan Ca-saturated, Ca-saturated-glycolated and K-saturated and heated clay samples to 110,300 and 550 deg C. By this way palygorskite may be better identified.

Clay samples usually contain different clay minerals which in turn are fine dispersive and have different defects (mixed-layering, stacking failts, microstrains, etc.). Therefore classical quantitative XRD methods are not useful for such samples. The effective way is the simulation of the XRD pattern for each individual clay phase in a sample (taking into account its actual crystal structure) and then comparison of the experimental XRD pattern with the optimal summation of the calculated XRD patterns. The best result could be obtaind for several state of a sample (air-dried after Na, Ca, Mg or K - saturation, glycol saturation, heating at different temperates etc.) if one and the same structural model for each phase was used for different sample teratment. Close ratio contents of clay minerals for each sample treatment also will indicate to realistic resuts.

If you have only kaolinite-group minerals and smectite-group minerals in your clay you might get an approximation as you know what the type of smectite is like (e.g, dioctahedral, trioctahedral , Mg- or Fe-enriched). If you have a kaolin mixed with smectite that contains in addition to those minerals some feldspar relics, quartz or even muscovite I do not see any realistic chance.

Hello,

distinguishing kaolinite and dickite by XRD is not that complicated. It is necessary to prepare the least structured preparation (cuvette filled from above or behind, powdered preparation, preparation mixed with plastic binder etc.) and possibly use the Rietveld method with the insertion of models of both minerals. The positions of relatively weak non-basal lines are decisive.

Nobody has an answer, so I'll write some observations. First of all, I would say that the phase analysis of clay minerals is one of the most complicated things that can be devised in mineralogy. Some clay minerals have virtually all the vices a mineral can have. Clay minerals show polytypism (all), often have a slightly or even strongly disordered or turbostratic structure, limited particle size and also display mixed layering too. All this affects not only (semi) quantitative but also qualitative analysis, and without a completely correct phase identification, quantitative analysis is meaningless.

But you can't say that it's not possible at all, it's just extremely complicated and you need to combine more techniques. The results of the Reynold Cup, which was organized by the Clay Minerals Society in the past, also prove that this is realistic.

In such diluted NaCl solution, Na may not replace any substantial amount of interlayer cations of 2:1 layer silicate minerals. Clays are generally preserved in Na form after removing excess chloride. You may refer to the following publication.

Jackson, M. L., Soil Chemical Analysis – Advanced Course, University

of Wisconsin, Madison, USA (Published by the author),

1979, 2nd edn.

Hi dear Muhammad

I m agree with Doriana Vinci

You must add standard & new databases like (pdf2-pdf4-COD).

COD databases are free and you can download that from this site --> http://www.crystallography.net/cod/

PDF 2 & PDF 4 are better databases but unfortunately, they are not free.

Dear Muhammad Sarim ,

At such a low angle, 3^o 2theta, the source (X-ray tube) directly aligns with the detector. It doesn't matter if in a theta-theta or theta-2theta configuration.

The direct detector irradiation is inevitable. If no reason indicates the necessity to star at such a low angle, standing at about 5^o 2theta will promote a high decrease in the effect and reduce the direct detector's irradiation.

Concerning your sample, 4.5^o 2theta is going to work very well.

The setup may use filters; however, the result is only partial; the best solution is to increase the starting angle.

Best regards,

WNM

P.S. Please find attached an interesting review article entitled

"CLAYS, CLAY MINERALS AND CORDIERITE CERAMICS - A REVIEW"

In this review article "The nomenclature and characteristic structural properties of clays, clay minerals talc, kaolin, vermiculite, ceramic raw materials, cordierite ceramics, cordierite and cordierite polymorphs were summarized.

Mineral phases in clay mixtures and cordierites sintered at 1300°C were compared."

Thank you very much for the precision, I want to synthesize zeolite type A.

Dear Anupam, The percentages of clay minerals can be determined using the Rietveld program very precisely or using the semi-quantitative method

Basically secondary minerals: Consider the Ferro-magnesian and Alumino oxides or oxy-hydroxides.

Dear Soumaya,

You may refer to the document attached. You may find it useful for your intended purpose. Good day!

Link will be helpful to smooth XRD data by removing signal noise

Dear Dr. Aldhahi,

instead of writing a lengthy text I attach a sequence of minerals based upon which you can easily decide in which level of sugergene alteration you are.

DILL, H.G. (2020) A geological and mineralogical review of clay mineral deposits and phyllosilicate ore guides in Central Europe - A function of geodynamics and climate change.- Ore Geology Reviews 119 (on-line)

DILL, H.G. (2017a) Residual clay deposits on basement rocks: The impact of climate and the geological setting on supergene argillitization in the Bohemian Massif (Central Europe) and across the globe.- Earth Sciences Reviews 165: 1-58.

DILL, H.G. (2017b) An overview of the pegmatitic landscape from the pole to the equator – Applied geomorphology and ore guides.- Ore Geology Reviews 91: 795 – 823.

This sequence is explained in more detail in Dill (2017a). You will find more information also on more exotic minerals in ore deposits in the above papers Dill (2017b, 2020).

DILL, H.G., WEBER, B. and BOTZ, R. (2013) Metalliferous duricrusts (“orecretes”) - markers of weathering: A mineralogical and climatic-geomorphological approach to supergene Pb-Zn- Cu-Sb-P mineralization on different parent materials.- Neues Jahrbuch für Mineralogie Abhandlungen, 190: 123-195.

Dill et al. (2013) also provides you with thermodynamic calculations.

All paper are available for download on the RG server.

These papers are written from a mineralogical , geomrrphological and pedological point of view.

Kind regards

H.G.Dill

Can someone please provide me the structure file for clay minerals like '' Smectite, Chlorite, Kaolinite and Illite'' Our TOPAS database somehow lost those files. It would be highly appreciated if anyone can provide these files.

Agree with Dr. Doriana

no problem dear Doriana Vinci ,

thank you ver much!

regards

The viruses have no activity because they are only proteins and RNA or DNA and become active inside alive cells only but if you mean the possibility of adsorption on clay minerals surfaces I guess it's possible with high energy bonding which means that the viruses become unable to transport

Above link is useful.

Dear Mr. Aldhahi

Separation of different size of clay particles using sedimentation technique has to be done in different steps.

The method of choice is the settling tube method („Atterberg”) which is performed following the Stokes ‘Law.

1. Remove from your sample organic matter and soluble salt minerals by hydrogen peroxide and washing, respectively.

2. For mud-low or mud-free sample you can immediately dry the sample at approx. 70°C. For those samples enriched in mud pass your sample by wet-sieving to a set of sieves where the sand particles are retained as a function of mesh- or sieve size

3. The remaining fraction less than 20µm or 63µm is saved for the settling tube method. You must disperse the fine-grained matter, pour the slurry into the settling tube shake it and let it separate the coarser-grained matter from the finer one in a laboratory room under constant temperatures. In a view plain words, the finer and the purer the fraction you want to achieve the longer the time span necessary to attain these results. You can well be separate the < 2µm fraction and even better (<0.63µm). The latter procedure takes you more than 24 hrs.

4. As an alternative you can speed up the process using ultracentrifugation which can be handled with water similar to the settling tubes or even with heavy liquids (Attention: imbalanced loading of the centrifuge)

5. The various fractions are dried mildly. Do not use to high temperatures so as to alter the structure of the phyllosilicates (clay mineralogy). Smectite used to be in the finest fraction of sediments can easily by separated from the rest of the sample and enriched so as to determine these complex phyllosilicates in more detail.

I wish you much success

HGD

Farnood Sobhbidari Google is your friend...

You may also wish to make friends with someone in the electron microscopy department of your school. You say you're in the Geology department so there's sure to be someone with microtome experience. Float the sections off - perhaps onto mica - if this is suited to your AFM

Farnood Sobhbidari

Carbon will always be there if a sample is stored in air. ESCA/XPS will confirm this - indeed the contaminant C signal at ~ 285 eV is used to correct for charging in XPS samples. You can argon ion etch or use a plasma etch to remove both the top layers and carbon. Then you'll need to preserve your specimen in vacuo or in a reducing atmosphere.

Dear Dr. Al-Wotaify,

Dioctahedral and trioctahedral clay minerals are described in the most simple way by the difference in the charge balance of dioctahedral and trioctahedral clay minerals and can easily be documented by the two important clay mineral groups of the mica and smectite groups.

Muscovite is dioctahedral showing the chemical composition KAl₂[(OH, F)₂|AlSi₃O₁₀], biotite is trioctahedral with the chemical composition K(Mg,Fe²⁺,Mn²⁺)₃[(OH,F)₂|(Al,Fe³⁺,Ti³⁺)Si₃O₁₀].

The dioctahedral phyllosilicate muscovite needs to accommodate a monovalent cation K ⁺ and two trivalent cations of Al ⁺⁺⁺ in its lattice to achieve charge balance, whereas biotite needs three bivalent cations (Mg⁺⁺, Fe^++, Mn⁺⁺) and one monovalent cation (K⁺). For trivalent Al also trivalent Fe can substitute.

The same approach can be taken for another more complex clay mineral group called smectites. Saponite has the chemical formula (Ca/2,Na)_0.3(Mg,Fe²⁺)₃(Si,Al)₄O₁₀(OH)₂.4(H₂O). It is as far as the crystallographic structure is concerned similar to biotite (trioctahedral), whereas another Fe-bearing smectite , called nontronite is dioctahedral Na_0.3Fe³⁺₂ Si₃AlO₁₀(OH)₂.4(H₂O). The latter clay mineral couple can be used as a geo-redox marker. Nontronite is common to environments of oxidizing regimes due to the trivalent Fe , whereas bivalent Fe-bearing saponite is typical of reducing environments.

Kind regards

H.G.Dill

p.s. compilation given in the file below

Dear Niclas Münch!

In this area, very few minerals are reflected. There are about a dozen of them. The most common = is smectite, vermiculite, chlorite, mixed-layer such as smectite-illite, and smectite-chlorite and sepiolite with palygorskite. For a more accurate diagnosis, it would be good to check the ​​small angles area of of 2-5 degrees.

With respect

Using plates of high conductive materials could lead to errors since the temperature differences on the 2 sides of the outer plates will be small and thus small measurement errors could lead to important errors of the computed conductivity.

I would suggest ceramic plates with about 23 W/m°K for instance.

Only a remark my suggestion is NOT a single sided but a double sided (3 layers). Which I already used for other measurements as "ceramic- stuff-ceramic".

Dear Mr. Aldhahi,

I learnt from your question that you separated your soil sample and selected the finest particle size for XRD. Despite this grain size fractionation you identified besides phyllosilicates also feldspar, quartz and calcite. They will not make up the majority of the mineral assemblage but traces are not uncommon there.

I suggest to make two principal suites, one called phyllosilicates or sheet silicates (I would not use in this case the technical term clay minerals for size and crystallographic reasons), the other non-phyllosilicates. This subdivision can also be used for quantification using methods like Rietveld. If you are able to determine the accessory minerals of this size fraction use words like tectosilicates (e.g. feldspar) and carbonate minerals (e.g. calcite). You can also go a step further and describe them more precisely as calcite, or alkaline feldspar.

As long as you can put them into a tripartite classification scheme you can also plot them in triplots, e.g. phyllosilicates-carbonate minerals - tectosilicates.

I wish you much success

H.G.Dill

No because after heating kaolinite structure is totally destroyed.

Dear Mr. Aldhahi,

the major driver for the CEC in rocks and soil is the smectite content. With this in mind high smectite contents will also yield high CEC. This is a correlativ relationship it does not compensate for a precise determination of the CEC as shown in

Meier, L.P., Kahr, G., 1999. Determination of the cation exchange capacity (CEC) of clay

minerals using the complexes of Copper (II) ion with triethylenetetramine and

tretraethylenepentamine. Clay Clay Miner. 47, 386–388

H.G.Dill

Many thanks for the exposure to literature.

Dear Mr. Li,

You mentioned only smectite. Is there any other clay mineral, e.g., illite or muscovite? How precisely did you investigate smectite? There exists a wide range of smectite-mica mixed layers. The only recommendation I can give to you is:

1. Investigate meticulously the clay mineral association. Do not use a bulk composition but split it into different grain size fractions, because smectite is very grain-size-sensitive and mainly accumulated in the finest grain-size fraction

2. Try and find K-bearing micaceous clay minerals as individual grains or in mixed-layers with other clay minerals such as smectite and carry out K/Ar or Ar/Ar dating and compare the data with those of the host rock sediments and the provenance area

3. Determine the chemistry of clay minerals not only with regard to the major elements, e.g., K, Al, Fe but also with regard to minor elements such as Cr, V and Ni which are accommodated in some clay minerals and used as marker phyllosilicates for supergene and hypogene processes, processes which you might not expect in the coastal environment of deposition under study.

4. Do not only focus on clay minerals but also take a keen eye on heavy minerals and light minerals which may be detrital but also may form in-situ (“do not put all your eggs in one basket”)

With kind regards H.G.Dill

Dear Mr. Ungewitter,

it may have find an explanantion in the slip- and twinning system of minerals (Etheridge, Hobbs and Paterson 1973). Slip was formely called translation gliding which in mica or phyllosilicates, in general, is exclusively controlled by the (001) plane. Other rock-foming minerals such as quartz or calcite have different ones.

H.G.Dill

Factors that control the dissolved minerals in groundwater include:

(1) the types of minerals that make up the aquifer.

Different rocks, e.g., sandstone, limestone and basalt all have different minerals and therefore, groundwater in contact with these materials will have different compositions.

(2) the length of time that the water is in contact with the minerals.

The longer the groundwater is in contact with the minerals, the greater the extent of its reaction with those minerals and the higher will be the content of dissolved minerals.

(3) the chemical state of the groundwater.

The chemical state of groundwater is usually defined in terms of pH, temperature and oxidation-reduction potential. These parameters control and are influenced by chemical reactions. As temperatures change seasonally, as the water table rises and falls, or as recharge rates vary, the chemical state will change and, as a result, so will the composition of groundwater.

Reference:

Mr. Markus Christ is right. Alternatively, you may use a mechanical tablet press tool http://chinacoolgadgets.com/2017/08/06/pill-tablet-press-machine-manual-steel-pill-tablet-maker/

Good discussion.. following

Dear Mr. Fereidooni,

it strongly depends on your rocks. The slake durabilty can't be explained by only one factor. Influencing factors are the overall structure of the rock, induration, mineralogy, climate etc.

Please have look at the following publications:

Chai, Z. Y.; Zhang, Y. T.; Zhang, X. Y. (2015): Experimental investigations on correlation with slake durability and mineral composition of mudstone, Journal of the China Coal Society, 40/5, p. 1188–1193

Engin Ciftyürek Thank you for your help and recommendations. I want to measure friction in small scale (micron and nano). Therefore, I need to find some areas that contain specific minerals such as clay minerals. I tried SEM/EDS before. I think as the grain size of the clay minerals is too small, it is a time consuming process to find those areas on the surface of my samples. The area of my samples are approximately 1 square centimeter. I tried also Raman Spectroscopy, and I got better results.

As first step I would proceed to identify the single clay phases by the standard procedure suggested by USGS:

https://pubs.usgs.gov/of/2001/of01-041/htmldocs/flow/index.htm

There is little chance to misdiagnose kaolinite as muscovite, but is quite possible to misinterpret it as chlorite in complex mixtures, or it's other polymorphs (i.e. dickite, halloysite).

Dear Adeda,

I don't know what you are after, is it the chemical composition or crystal structure of the zeolite type?

I suggets you first do a thin section & identify textural characteristics of zeolites & any associated minerals.

After that you can go ahead with XRD, EMPA, SEM & XRF depending on what you primary objective is.

Regards

Shad

The minerals are the result of changes in the chemical systems; they try and get adjusted to the existing physical-chemical regime (P, T, chemical composition of soluble compounds). As such processes are reversible through time and space. It is, however, a question of the reactivity of the compounds involved if the reaction works its way swiftly or is retarded.

With kind regards

H.G.Dill

One cannot get very much from chemical analyses alone, orientatively the Al:Si ratio equals 1 for kandites (kaolinite) > illite > smectites (montmorillonite). Illite typically contains K, while smectites contain Na and Ca. For reliable diagnostic purposes, as suggested above, XRD is the recommended method, using bulk and treated (heated, glycolated) material.

Dear Ms Marshal,

Less resistive clays rich horizon over more resistive sedimentary layer can limit the GPR investigation depth. Clayey layers are conductive and attenuate the radar signals. GPR is not appropriate in areas where the surface layer resistivity is less than 100 Ohm. m, that is the case of most clay rich soil horizons. Regards, Anicet

I recommend Amit Anand 's answer, but recognize that 200 C is the limit for a teflon lining. Other linings can get you to higher temperatures. If you have the funds, Hastalloy has a number of variants that will work.

An Amott cell is usually done for this. The expelled phase is then collected at the top of the cell and the volume is measured as corresponding to imbibed volume. If you need mass, just apply the density. If you consider gas, then the procedure can be done in a similar way if the system is pressurized and density changes are negligible. You could likely also just keep track of the liquid phase which is of negligible compressibility.

Kind regards,

Pål

Thanks to everyone for your kind answer.

Doriana Vinci I tried your suggestions and I managed to have some good samples, thanks again!

Robert Möckel unluckily your sample preparation does not avoid particle segregation and, as a consequence, it is not really suitable for the quantitative analysis I would like to run. But thanks again for spending some time answering my question

same as for Robert Mockel: I would like to avoid segregation, I am not sure I fully get what you are suggesting though. If your suggestion is to drop the suspension on a glass slide then this is not good enough for quantitative analysis. But sincerly thanks for your suggestion and for answering

Dilip Kumar Pal Thank you for the reference, I am going to read it as soon as possible. Thanks again.

i am still confused that how to apply H2O2 for diatom samples. what is basic methodology. either other methods are much better. very confused

I checked with High score (database PDF 2). It is likely some sort of hydrated form an hydroxide.

Sorry it will be Dear Sajjad

We can keep speculating on what the peak mean and not get any meaningful thing done. Mathias has really nailed this. All the requirements to do better justice is not extractable from the image. Did you change the slides for the bulk? Or you used glass for all different measurements? The hump can be very informative on amorphous situations / disorder.

The difficulty you face is to some degree related to the often general nature of the definition of illite that is in common use ...mica like clay size consitituent....and the other frequent use which is to label a peak near 10 angstroms in a diffraction patterns of a clay size fraction 'illite'. In reality the 10 angstrom peak and mineral group it represents in many sediments, rocks and soils is a heterogenous mixture of micaceous minerals. So your 'illite' may often include some micaceous components that could also be classified as muscovite if we have some means to determine their characteristics. In practical terms in a bulk sample where I assume you are looking at random powder XRD data, you might try to make a distinction bassed on polytype, e.g. a true muscovite will likley be a 2M1 polytype, whereras illites are usually 1 layer polytypes often with various degrees of dissorder. However, it is not a trivial matter to try to include models for illite structures in Rietveld codes.

Further to Dr Towe's suggestion the book by Moore and Reynolds (1997 (2nd ed)) is a great place to start.

sincerely,

steve

Dear Dr. Batabyal,

After 40 years in the business, I know that it is often an uphill battle to persuade geoscientists to follow a simple “chain of command” in geoscientific studies:

1. (Field) geology (good mapping and sampling)

2. Mineralogy from the hand specimen to the nanoscale

3. Chemistry from the simple method, e.g., from the XRF to the mass spectrometry of isotopes.

Geophysics may take the same level in the hierarchy as No. 1 and 2.

Each case history has its own rules according to which you have to use and adjust indices like those or even come to the conclusion and decide to omit them because of enough information already collected in one of the predecessor investigations or after some forward modeling find out that it is not worth the trouble to use this or that method or any index.

Too many put the cart before the horse because they think it speeds up the process and they will make faster progress. But this is certainly not a realistic approach and may only help for a while to ride the “paper tiger”.

Sorry for that piece of advice from a “vintage geologist”

With kind regards

H.G.Dill

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 Professor

The materials are sourced from an Andesite quarry.

Samples are oriented on 2.54 cm slides that were prepared after three stages of pre-treatment procedure to isolate clay-sized particles. I presented the XRD results on air-dried samples. I also have the XRD test results for sample which are glycolated at 60 degree of Celsius for 20 hours and the heated sample as well (45 minutes at 550 degree of Celsius). I can provide them in the case of need.

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.

I would highly recommend to define your own database and only use these confirmed phases for further interpretation. You can in case of new phases start a new search considering all other databases again. Since you obviously did XRD indexing in the past I would not expect that you are exactly running now into a trap as pointed out by K. M. Towe, however, his recommendation you should always take into account. You can measure perfectly but not exactly that what you want or need to measure.

Another option is to use instead of Match the free software BGMN. If you look into the ranking of the Reynolds cup, BGMN always was very successful for clay minerals. This should ave some reason :-). From my point of view the fundamental parameters approach which does not enable a "meaningful" optimization of the peak widths which is essential in case of numerous overlapping reflections.

BGMN even has a free GUI developed by N. Döbelin:

https://profex.doebelin.org/?page_id=404

I am sure that he would help you during the first steps...

Good luck!

CIA = {Al2O3 / (Al2O3 + CaO* + Na2O + K2O)} x 100

PIA = {(Al2O3 – K2O) / ((Al2O3 - K2O) + CaO* + Na2O)} x 100

CIW = {Al2O3 / (Al2O3 + CaO* + Na2O)} x 100

CIW´ = {Al2O3 / (Al2O3 + Na2O)} x 100

In the above equations the major oxides are expressed in molar propotions and CaO* is the content of CaO incorporated in silicate fraction. McLennan (1993) proposed an indirect method for quantifying CaO content of silicate fraction assuming reasonable values of Ca/Na ratios of silicate material. Procedure for quantification of CaO content (CaO*) of silicate fraction involves subtraction of molar proportion of P2O5 from the molar proportion of total CaO. After subtraction, if the “remaining number of moles” is found to be less than the molar proportion of Na2O, then the “remaining number of moles” is considered as the molar proportion of CaO of silicate fraction. If the “remaining number of moles” is greater than the molar proportion of Na2O, then the molar proportion of Na2O is considered as the molar proportion of CaO of silicate fraction (CaO*).

@ Jhedy Amores

Dear Sir

I think the links below will benefit you in your search

Best Regards