XRD can provide qualitative information on the mineral content of a rock and if you're lucky, you are also able to quantify the amounts of various minerals. In your case you may use XRD as a tool for mineral identification.

XRD, by itself, does not tell you about the p-T-conditions of rock formation. This needs a much more complex investigation - including parameters such as rock chemistry (e.g., XRF), textural relationships of different mineral species (thin section), and is sometimes really challenging...

If you then know what minerals occur in chemical equilibrium in your rock, take any textbook on metamorphic petrology and check to which 'metamorphic facies' regime your sample belongs.

In my shelf I see for example: "J.D. Winter: An introduction to igneous and metamorphic petrology" and "Bucher & Grapes: Petrogenesis of metamorphic rocks" but all such introductory boos should contain the information you need to start with.

Good luck, Simon

XRD can provide qualitative information on the mineral content of a rock and if you're lucky, you are also able to quantify the amounts of various minerals. In your case you may use XRD as a tool for mineral identification.

XRD, by itself, does not tell you about the p-T-conditions of rock formation. This needs a much more complex investigation - including parameters such as rock chemistry (e.g., XRF), textural relationships of different mineral species (thin section), and is sometimes really challenging...

If you then know what minerals occur in chemical equilibrium in your rock, take any textbook on metamorphic petrology and check to which 'metamorphic facies' regime your sample belongs.

In my shelf I see for example: "J.D. Winter: An introduction to igneous and metamorphic petrology" and "Bucher & Grapes: Petrogenesis of metamorphic rocks" but all such introductory boos should contain the information you need to start with.

Good luck, Simon

Dear Mr. Singh,

XRD alone is no way to go for getting precise information on the P-T regime. You have to go through the minerals. In some cases XRD may be the method of choice, e.g., phyllosilicates and very fine-grained rocks, which escape any precise identification of minerals under the petrographic microscope or even SEM.

Let us know what type of rocks or minerals you work with and what the final goal of your study is ? Based upon that information one can tailormade your family tree of investigation to get a proper answer for you issue.

Looking forward to a more precise description of your issue.

Best regards

Harald G. Dill

Dear  Dill Sir,

I have quartz grains of sedimentary origin from different regions of India and I want to do two things-:

Firstly, I want to quantify the defects, i.e. want to know the amount of defects. Actually I have samples from the northern India whose source lies in the Himalayas and anothern sample from southern India. i know that the grains from the southern India have more lattice defects (I don't knowwheter it is intrinsic or extrinsic) compared to that from northern India. I want to do a compartitive study but don't know which approach to use.

Secondly, I want to relate these defects to the P-T condition of formation of its source rock and also want to know how the P-T condition control the formation of defects in lattice.

Best regards,

Atul

Dear Mr. Singh,

thank you for your more detailed account on your samples.

Defects of the lattice may be induced by mechanical affects, e.g., the well known "Boehm´s stripes". Another group is caused by radiation damage, the classical type is the mineral coloration of quartz which turns the mineral into smokey quartz. Apart from that you might find some phase transition which are caused by subsequent heating , e.g. above 573°C.

You mentioned in your first statement that your main interest lies within constraining the p-T conditions.

I can offer you a way to get good results on the T of  formation of quartz, using the Ti-in geothermometer. The way how to obtain these data has been eloborated by:

WARK, D.A.& WATSON, E.B. (2006): TitaniQ: a titanium-in-quartz geothermometer. Contributions to Mineralogy and Petrology 152: 743-754.

I have applied this method to quartz pegmatites and I good very good results usefull for an assessment of the temperature of formation and for a correlation of quartz modifications and generations.

I refer to two of my publications in which I used this method successfully:

DILL, H.G., SKODA, R., WEBER, B., BERNER, Z., MÜLLER, A.& BAKKER, R.J. (2012): A newly-discovered swarm of shearzone-hosted Bi-As-Fe-Mg-P aplites and pegmatites in the Hagendorf-Pleystein Pegmatite Province, SE Germany: A step closer to the metamorphic root of pegmatites. Canadian Mineralogist, Special Volume dedicated to Petr Černý 50: 943-974.

DILL, H.G., SKODA, R., WEBER, B., MÜLLER, A., BERNER, Z.A., WEMMER, K. and BALABAN, S.-I. (2013) Mineralogical and chemical composition of the Hagendorf-NorthPegmatite, SE Germany – a monographic study.- Neues Jahrbuch für Mineralogie Abhandlungen, 190: 281-318.

Maybe for the moment this answer may be of assistance in two different directions , for the quartz failure and for the temperature of formation.

I would suggest to go both ways. Crystal defects and trace element analysis.

I also recommend the publication to get an overview of silica:

Ullmann´s Encyclopedia of industrial chemistry ,1993. Silica. A 23, 583-660, Verlag-Chemie, Weinheim, Germany.

Best regards

Harald G. Dill

Hi,

With XRD you can identify the minerals which consist the rock or sediment sample. Generally, in magmatic (igneous and ploutonic) and metamorphic rock samples, once you know the mineral composition, you can check out the formation properties for each mineral and in combination with some other factors such as the quantity of each mineral in your sample, you can deduce the formation conditions of the specific rock.

Nevertheless, there is a total different situation in sedimentary rocks. Indicating the minerals and their participation, and checking their properties is not enough. For understanding the formation processes of a sedimentary rock (diagenesis), you also need  to identify the deposition enviroment and the sedimentation processes through laboratory sedimentological analysis (grain size analysis, visual observations, statistical analysis, CM diagram etc), geochemical analysis (pH, secondary chemical structures, TOC, CaCO3, XRF etc) and texture analusis as well (X-radiography, matrix composition, detrital parts etc). These factors define the mineral synthesis of a sedimentary rock. The key is to identify in which stage of the petrological circle (erosion and re-sedimentation in sedimentary rocks cases), are the mineral that you recognize with the XRD method.

Best regerds,

Spiros Sergiou

What types of lattice defects do you expect? You can quantify things like dislocation densities, crystallite shape and size distribution, stacking faults by analysing diffraction peak profiles.

Thanks Roman,

I don't know which kind of defects are there but I want to know about all kind of defects. Can I  know about the extrinsic defects also through XRD?

Dear Mr. Singh,

I think it is important to define the technical term "defect", otherwise the discussion may run the risk of spiraling a bit out of control into general characteristics or features. I would like to saddle the horse from the opposite side and raise the question: What kind of defects to you expect based upon your knowledge about the potential provenance area? In simple words, if you expect a high-grade metamorphic terrain in the hinterland to have supplied a sufficient amount to your detrital fractions the situation will be strikingly different from a magmatic source area. I think you should always look at the issue from two or even more than two angles. Otherwise we are revolving around ourselves. I think this may get you faster and closer to a solution than only focusing on the object of study. Let me know your ideas?

Harald G. Dill

the XRD conduct to identification of phases, the phase diagrams show the temperature of formation of these phases

Dear Dill Sir,

The sediments from the southern part are from the deccans which are volcanic rocks known as Deccan traps in Indian stratigraphy whereas the sediments in the northern part are from the Himalayas which are probably metamorphic or plutonic igneous rocks.

Dear Mr. Singh,

that may narrow down the field of speculation. The Deccan Traps are a high-T environment with all their hallmarks imprinted onto the quartz grains, even if the tholeiites and andesites which make up the lion share of the flood basalt carry quartz only in their interstices as rather late-stage minerals. For the "Lesser" and the "Higher Himalayas" it will be rather difficult, but strain-related defects should be present and strongly contrast with what we might expect from the specimens of the flood basalts. Another part which you should pay attention to is the wide range of fluid inclusions which are the most diagnostic features in my opinion. You will have the entire spectrum from primary to secondary F.I. Owing to these stark contrasts in the lithologies of the provenance areas I am more optimistic that your approach will bear fruits.

There is a method which I can recommend for the quantification of quartz grains and to single out different suites. It is the color of the quartz grain. You may use the natural color of the quartz or irradiate them. It is a process similar to CTL analysis. The lattice defects  respond in a different way as do the mineral and fluid inclusions. Quartz color analysis has been successfully applied to Triassic epicontinental / platform sediments. You may swiftly get good and statistically reliable results and I am sure it will work in this case for provenance analysis.

Best regards

Harald G. Dill