Sir @ Subhash Chavare rock identification is a systematic process, requiring concise, accurate descriptions of physical characteristics. This process is called petrography. Geologists use petrographic descriptions to communicate the essential features of rocks in writing (with illustrations / photographs if appropriate). Petrographic descriptions also summarise these characteristics for future reference. They should contain sufficient information to allow identification of the rock. Such type of data you should find for your research.

Dr. Atish Patil has rightly informed that petrography can be used for the identification of minerals and rocks. Usually petrographic microscope is used for this purpose.

Spectroscopy is also one of the best, quick and accurate method of identifying minerals and mineral composition of rocks.

If you can afford it, buy an XRF portable unit. These people below will sell you one (in Canada):

Karsh Scientific (Ken Mehta) and SciAps (Andrew Sommers)

Dear Dr. Chavare:

There are two crucial questions and the establishment of an all embracing platform

1. Do you want to determine the mineralogical composition in the field so as to “baptize” the rock and give it a name, e.g., granite, biotite-plagioclase augen gneiss or conglomeratic sandstone or can you avail yourself of some indoor- and laboratory tools such as a petrographic microscope, XRF, SEM etc. A good compromise between the two areas of investigation is a set of portable handheld devices from PIMA to the Kappameter combined with a portable XRF which, however, particularly in the range of major elements does not deliver to everybody´s satisfaction for physical reasons (capturing digital data in the field = put part of your lab into the field)

2. What type of rock do you deal with? Is it a coarse-grained rock amenable for an examination with the unarmed eye, e.g. an eclogite or with a hand lens or is it a massive dull rock such as an argillaceous or calcareous mudstone? In the latter case visual inspection will not get you closer to a solution and you will have to very soon shift your focus on laboratory analytical devices.

Whatever rock suite you treat you need reliable classification schemes which mostly are stored in textbooks on igneous, metamorphic or sedimentary petrology.

H.G.Dill

Simply by X-ray Diffraction, you can get an idea about the mineral composition

Most rocks are composed of minerals. Minerals are defined by geologists as naturally occurring inorganic solids that have a crystalline structure and a distinct chemical composition. Of course, the minerals found in the Earth's rocks are produced by a variety of different arrangements of chemical elements.

Over 2000 minerals have been identified by earth scientists. The Elements Group includes over one hundred known minerals. Many of the minerals in this class are composed of only one element. Geologists sometimes subdivide this group into metal and nonmetal categories. Gold, silver, and copper are examples of metals. The elements sulfur and carbon produce the minerals sulfur, diamonds, and graphite which are nonmetallic.

Para estudo dos minerais que compõe uma rocha é necessário o conhecimento das várias propriedades físicas, químicas e óticas desses, pois, genericamente uma rocha é composta por vários minerais, com poucas exceções.

Hello, first on the field, it is possible to identify some minerals in hand specimen. Take note of the minerals you can identify. Secondly, you have to cut thin sections of the rock sample and observe under the microscope. If you are not so sure after this, you can go ahead and carry out electron probe micro analysis of the rock sample ( mineral chemistry).

I recommend you consult this book: Atlas Of Rocks (Igneas, Metamorphic and sedimentary) and Their Textures (W.S Mackenzie, C.H Donaldson, C. Guiford).

If you can't access a petrographic microscope.

If you are on a field, the simplest way is to make a XRF-WholeRock analysis. Almost all of the conventional minerals will be checked out. Another simple way is to read the study report by the predecessors.

I recommend XRD analysis of bulk samples of the rock (WholeRock analysis) to have a better idea of its mineral composition when added to field macroscopic identification of mineral composition the particular rock obtained from literature. You can go further to confirm the minerals identified with petrography and electron micro probe analysis (EMPA). Rocks here, I mean both natural and synthesised (slags).

It depends on the type of rock of intended study

So kindly define the type of rock, then answers will be definite

Hello, the study of a rock starts from the field where you have to get a fresh hand specimen. from the specimen you have to identify the color, texture, degree of crystallinity and all possible observations so as to classify the rock whether it is plutonic or volcanic, acid, intermediate or basic.Then make a thin section for the rock to identify its mineral constituants of under the microscpe. Then follows is the chemical analysis of the rock (the whole rock analysis - here any chemical method can do the job but I recommend an XRF analysis), interpretation of the results and to be plotted into various diagrams. Further if you have some doughts about a certain mineral you can step to the scanning electron microprobe analysis. All the best.

Firstly , collect the rock samples properly ( except weathered part) . Prepared a thin section to identify colour, texture , crystalline formation , if any micro deformation etc .

Then if you need to know the total mineral composition do XRF and If you are going to find out any particular mineral , go for SEM/EDX , you will get the composition , then use XRD analysis for % calculation and dominant mineral (you are scharcing for). All such extracted data may be plotted as graphical representation or use statistical techniques for further analysis.

Automated mineralogy methods, MLA, for example, is a very good way to obtain modal mineralogy.

Best regards,

Pedro

Dear Dr. Chavare,

I can offer you some kind of a flow sheet to obtain your mineralogical results from a combination of mineralogical and chemical analyses

1. A rock chip is used for thin section examination

2. Bulk chemical analysis of the rock sample using XRF

3. Part of the grinded material used for preparation of samples for XRF is shipped to a laboratory

for screening and to split into the particle range < 63 µm and 63 µm to 300µm.

4. The interval < 63 µm is suitable for XRD (in case of detailed clay mineral analysis the use of settling tubes is recommended)

5. The grain size interval 63 µm to 300µm forms the basis of the separation of heavy minerals and for further investigation see point 6

6. The fraction separated under point 5 can be used for XRD, EMPA, SEM-EDX (+MLA) or (micro) Raman analysis of accessory minerals

All data can be plotted into triplots and x-y plots for mineralogical and chemical discrimination.

Dependent upon the availability of devices you can stop and leave this sequence at any point.

I wish you much success H.G.Dill

I strongly recommend the answer of Dr. Harald G. Dill

Kind regards, M. Makadze

Dear Dr Chavare,

Mineral composition of any rock!! Are you refering to any rock types of Sedimentary or Igneous origin? If you are interested in mineral composition of sedimentary rocks you can apply the following methods:

Sandstone: sieving of grain sizes & seperation of accesory minerals if the sandstone is not pure. Thin section microscopy to identify accesories and secondary effects on the sandstone. Apply SEM to note any clay content between the quartz grains.

Siltstone: Do the same as sandstone but the grains are fine to very fine and could be time consuming. Thin section, XRF & XRD are applicable.

Claystone: XRF & XRD are applicable

Plot all suitable data into respective discriminatory diagrams/plots to understand the mineralogical and chemical composition of the rocks.

Prof. Dill outlines the analytical methods for Igneous and metamorphic rocks.

Regards,

Shadrach

I recommend the answer of Dr. Harald G. Dill and I would also like to add that the first step and the most important step is to collect unaltered fresh samples of rocks, in order to correctly analyze the results obtained using various analytical procedures mentioned by Dr. Harald G. Dill.

I really recommended using Fourier Fourier Transform Infrared Spectroscopy FTIR) and X-Ray Diffraction (XRD).

Dear Dr. Subhash Chavare

The minerals are formed by different methods:

1- Crystallization from magma: Crystallization is the transformation from

liquid state to solid state due to the cooling process and forming crystal.

2- Precipitation from chemical solutions by means of chemical reactions or

microfauna.

3- Minerals may be formed directly from gases by densification.

4- New minerals may be formed by the effect of pressure and temperature as

minerals forming metamorphic rocks.

There are many techniques that are used in order to investigate the mineral composition in rocks such as XRD, SEM-EDX .

Regards

Qasim Al-Obaidi

Dear Mr. Chavare,

As Dr. Richmond U Ideozu highlighted, it depends on the type of rock and purpose of intended study!!!!!!!!!!!!

However, in all cases, to obtain good results, as a first step, the freshest/unaltered rock samples need to be collected.

As a next step, for igneous and metamorphic rocks, I would highly recommend following Harald G. Dill 's answer. In the case of sedimentary rock, I would also suggest taking a look at the Shadrach K. Noku answer.

Best regards, HG

Base petrographic analyses could be useful for this. After that whole-rock etc.

Regards.

Instrumentation of choice has an impact on the results. Differing instruments have differing resolutions and may not “see” all elements present. The most complete quantity instrument may be some form of ICP, though it has problems with what occurs naturally in air.

EDS does well with the lighter elements but may not detect small amounts of the heavier elements.

Micro-XRF does well with heavier elements, but may miss lighter elements.

I have had a lot os success using EDS and Micro-XRF simultaneously (Within an SEM).

Care must be used with all instrument types And the chosen analysis technique.