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Identity HelpSulphur?

2nd Jul 2019 19:06 BSTshaheer niazi

02659450015652049973324.jpg
Is this sulphur? the crystals have a light green hue. and the crust on the outside is very sulphur like.


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2nd Jul 2019 19:40 BSTMatt Ciranni

What does it SMELL like?


That should be the most obvious clue. Sulphur smells like, well, sulfur. That LOOKS like Sulfer, for what it's worth. Where abouts did you find that?

2nd Jul 2019 19:42 BSTPaul Brandes Manager

Agree.

The best way to know if it's sulphur (or a sulphur bearing mineral) is to sniff it.

2nd Jul 2019 21:41 BSTKevin Conroy Expert

Where is it from?

2nd Jul 2019 22:40 BSTAlfredo Petrov Manager

Sulphur will melt and catch fire in a match or candle flame, and release unmistakable SO2 fumes. But I suspect you really have a sulphate here rather than native sulphur.

3rd Jul 2019 01:13 BSTCecil Cosse

Or, it could be a corroded cadmium smithsonite. There are what appears maybe to be hemimorphite xls in the second photo. Especially if it doesn't smell or burn.


Cecil

3rd Jul 2019 04:01 BSTSteve Hardinger Expert

"he best way to know if it's sulphur (or a sulphur bearing mineral) is to sniff it."


Respectfully....no. Examples of odorless, sulfur-bearing minerals (ignoring decomposition): pyrite, arsenopyrite, chalcanthite, etc.

3rd Jul 2019 04:12 BSTKevin Conroy Expert

While we're waiting to get information on where this might be from... The photo of the crystals reminds me of the aragonite geodes, that sometimes have associated kutnahorite, from Valdarno, Italy.

3rd Jul 2019 04:20 BSTshaheer niazi

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its from the mountains in the nowshera region of kpk in pakistan, more specifically a village area called khawrai. from an abandoned coal mine.


here are picture of the inside taken by the person who went in. the sulfur he picked was from the rubble.


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3rd Jul 2019 04:24 BSTshaheer niazi

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also I dont smell anything. but other people in the house definitely smell something.


heres a picture of a large sulphur (if correct) vein on the wall. It appeared as though melted sulphur was driped along the wall and deposited there or it was by the action of water.



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3rd Jul 2019 07:03 BSTUwe Kolitsch Manager

The second photo shows probably halotrichite-pickeringite.

In a coal mine you often find iron/metal sulphates that formed by decomposition of pyrite/marcasite.


The first photo probably also shows some Fe sulphates.


Test solubility in water for both.

3rd Jul 2019 15:24 BSTPaul Brandes Manager

Steve Hardinger Wrote:

--------------------------------------------------

> Respectfully....no. Examples of odorless,

> sulfur-bearing minerals (ignoring decomposition):

> pyrite, arsenopyrite, chalcanthite, etc.


For a professional, no; there are much better ways to identify sulphur bearing minerals. But, for a beginner who is not as well versed in mineralogy as we may be, it is a great first step.

3rd Jul 2019 16:07 BSTKevin Conroy Expert

Place a drop or two of vinegar or hydrochloric acid on the specimen. If bubbles form, then you have a carbonate mineral.

4th Jul 2019 12:04 BSTshaheer niazi

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So I conducted some tests in my amateur lab.


I crushed a small bit of the mineral and it dissolved in water forming a pale yellow solution. it was cloudy so I filtered it off which left the solution a nice clear yellow. the powder left on the filter paper was yellow, but when i burnt it it became red and smelt like burnt rubber (though maybe that was the smell of some plastic bit burning in my lighter as I kept it on for too long). I am assuming whatever it was decomposed to Iron oxide. I had some sulphur lying around so i burnt and compared that with the yellow powder. the sulphur melted and I could smell the SO2.


the thin needle crystals most certainly contain iron. I performed the standard cation test with some sodium hydroxide. Got the green ppt which turns brown on contact with air. So Fe2+ is present.

the carbonate test was a nope,

I wanted to perform an anion test for sulphate but didnt have anay thing to make a ppt. Will get some barium salt soon. Though I did try using chromium 3+ ions. but it didnt produce any precipitate. One place on the internet mention that using Cr3+ should work. but chromium sulphates are water soluble.

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4th Jul 2019 12:08 BSTshaheer niazi

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Also heres my mini setup on my floor.

4th Jul 2019 23:00 BSTshaheer niazi

this might be copiapite with sulphur and botryogen being the orange powder. and melanterite being the needle crystals?

5th Jul 2019 01:30 BSTCecil Cosse

I suggest x-ray analysis rather than trying (guessing, speculating) what it is.


Cecil

5th Jul 2019 16:15 BSTSteve Hardinger Expert

Shaheer, congratulations on performing these historically- important wet chemical tests. You would benefit from Don Peck's book if you don't already own a copy. Yes modern instrumental methods are quicker and leave less doubt, but the wet chemistry is so much more fun.

5th Jul 2019 18:10 BSTshaheer niazi

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Yes! it was fun. Sadly i dont have any facility around which would allow for an xray analysis.


here are some macro shots

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5th Jul 2019 18:38 BSTFranz Bernhard Expert

Sure these are post-mining sulphates! Several possibilities, but halotrichite-pickeringite is a good guess of Uwe. Melanterite, Copiapite, Slavikite and many others may also occur.

Btw, congrats to your good pics and the wet chemical tests!

Franz Bernhard

5th Jul 2019 19:33 BSTCecil Cosse

You can use Mr. Attard's website to get x-ray analysis done on specimen.

6th Jul 2019 16:26 BSTshaheer niazi

So I contacted the local physics department with which I performed some amateur research, They have X ray fluorescence spectroscopy available, Is it better than x ray diffraction?

6th Jul 2019 16:50 BSTDonald B Peck Expert

Shaheer,


Welcome to mindat. And congratulations on your wet chemistry attempt at identification. I may be wrong, but I think you will learn much more about minerals by doing your own ID (or at least attempting it) than by sending a sample off for x-ray analysis. And you will have a lot more fun. I don't want to disparage instrumental analysis, but for me it is kind of a last resort.


Don


Steve, thank you!

6th Jul 2019 16:50 BSTLouis Zulli

Roughly, XRF provides the mineral's chemical formula, whereas XRD determines its crystal structure with great accuracy. So XRD can distinguish graphite from diamond, for example, whereas XRF says 100% carbon for each.


If XRF is available and XRD is not, then XRF is clearly better!

6th Jul 2019 17:26 BSTshaheer niazi

Thanks, I got a time for August to use it. I will keep you all posted!

6th Jul 2019 18:16 BSTUwe Kolitsch Manager

XRF is not a good option for such sulphates. Raman might be better, if you don't have access to powder XRD.


EDIT: Typo.

6th Jul 2019 22:37 BSTFrank K. Mazdab Manager

Louis Zulli Wrote:

-------------------------------------------------------

> Roughly, XRF provides the mineral's chemical

> formula, whereas XRD determines its crystal

> structure with great accuracy. So XRD can

> distinguish graphite from diamond, for example,

> whereas XRF says 100% carbon for each.

>

> If XRF is available and XRD is not, then XRF is

> clearly better!


Except few XRF detectors are even sensitive to elements as light as carbon, so hopefully your graphite or diamond are distinctive enough to identify by more conventional means... ;-)


All light-heartedness aside, Raman or perhaps one of those handheld or small desktop ASD-type near-IR instruments (if your physics or geology dept. has one) may be more effective.

7th Jul 2019 01:26 BSTDana Morong

Actually, it might be educational to do more wet chemical tests, as Don Peck has mentioned (if you have not yet gotten his book, I would suggest getting a copy). I recall once finding some odd yellow material under the overhang of a roadcut where there were pyrites in nearby matrix, and the specimen was so yucky-looking that the professor would have nothing to do with it! It had lots of yellow stuff on it, which under the microscope were tiny squarish flakes. So I took it home and as I had plenty of material to test, thought to see what it might have in it. It was water-soluble. This makes wet testing easy, if one has lots of material. It had sulfur in it. It was a hydrated sulfate (I suspect from decomposed pyrites). Other tests showed iron, but not much of anything else (I did several to make sure). It was copiapite.

I suspect that some geology students, finding sulfur in a yellow mineral, suspect elemental sulfur, but elemental sulfur has several different properties than oxidized sulfur such as a sulfate

For such do-it-yourself testing, one has to have a basic understanding of basic philosophy of scientific method, and of chemistry, and experience in the specific tests (it is very educational to first try out a known to see how the test works, and when interfering ions may change results, and how to avoid that). Also recording what you do, when you do it - which, as you have shown, you already do. Recording while doing can be a great benefit, as Michael Faraday once mentioned (it can also be useful in other fields, such as the time I did a tricky piece of car mechanics while laying on my back under the car - always forgot the exact procedure, so I took notes while under the car! This was not only possibly useful later, but led to some humorous philosophical meanderings as well).

7th Jul 2019 08:18 BSTshaheer niazi

Yes I do plan on doing some more tests as I am an impatient soul, and leaving my sample untested till august is brrrr. waiting for a barium salt for confirming the sulphate ion, I get it tomorrow, will post the results soon.

Also I suspect it to be a hydrate too, so Ill be doing a test to find the xH2O in the compound. I observed when heating the crystals they do release a lot of water.

I dont have the book, I searched online but it wasnt available on Amazon either. So im relying on the chemical analysis techniques taught in college.


Thank you sir Don for the kind words, I agree with using direct techniques as last resort as it saps the fun out of mineral identification. Being a person who always tries to replicate the original procedures to achieve maximum involvement with the object in question, like doing oil painting because its more complicated and involves me with the pigments, it will give me the most satisfaction to do my own analysis and guessing (based on experimental evidence).

All for the experience!

7th Jul 2019 13:20 BSTKeith Compton Manager

Shaheer,

Don's book is available from the Mineralogical Record in USA

7th Jul 2019 21:19 BSTFrank K. Mazdab Manager

I agree that doing these wet chemistry tests are great. It's a lost art (as someone emphatically insisted on reminding me a few months ago) and indeed it's very educational.


Such tests could be a bit challenging in this case, however, because among these secondary sulfates that I think the consensus here has tentatively ascribed as an ID for this sample, many are very chemically similar and may differ not so much in the kinds of components, but more so in the amounts of those components... for example in the number of waters of hydration, or in the iron:sulfur ratio. So qualitative testing alone may not differentiate some of these minerals, and in some cases quantitative testing, by gravimetric analysis, may be necessary. Of course, such testing is also not necessarily out of the reach of a careful home chemist with a good balance, an ample supply of material to test, and the time and patience to conduct the experiments, but here there are some challenges as well.


A carefully weighed sample heated to drive off loosely-bound water can be re-weighed to ascertain lost water of hydration, but one must be careful because some minerals lose different amounts of water at different temperatures (this in itself can be distinctive, but it may be difficult for the home chemist to control the temperature so carefully). There's also a risk that in some of these minerals with Fe2+ that heating can oxidize the iron to Fe3+ and offset some of the water weight loss with essentially oxygen gain. The sulfate test mentioned above could also be done quantitatively rather than qualitatively, but that might require some specialized equipment and may not be especially definitive here, since the differences in sulfate contents among many of these minerals may be well within the measurement error best attainable by a home chemistry lab set-up.


Another quantitative test of value for these secondary sulfates can be solubility... not simply that the mineral is water soluble, but more characteristically how many grams of it can you dissolve in 100 g of water? Quantitative data on mineral solubility is overall pretty poor, but fortunately the chemists have done the work for us on their synthetic analogs... the CRC is a decent source for these data; there may be better ones.


Finally, the greatest challenge of all (not only to the home chemist, but also to the professional analyst) can simply be that many times these secondary sulfates may be finely intergrown or admixed. No easy fix for that, but being as careful as possible in your sample preparation helps.

7th Jul 2019 22:50 BSTAlfredo Petrov Manager

In addition to losing water on heating, some of the secondary Al and Fe sulphates can lose SO2 on heating, leading the analyst to overestimate water loss.


The strangest overestimate of water loss I have heard of was a supposedly anomalous water content in sodalite from Bolivia, which was the result of loss of NaCl vapor on ignition. Kitchen chemistry can be a huge amount of fun, but also misleading at times.

7th Jul 2019 23:19 BSTDana Morong

Don Peck's book is really the best, I think, for what you want to do, but in the meantime you might look at a book that has been put available on internet (in Internet Archive) this is Identification and Qualitative Chemical Analysis of Minerals, by Orsino C. Smith, 1946 (this was the first edition, the second edition was 1953 I think).


There is another qualitative test for sulfur, for all forms (this is a very qualitative test), which is the Hepar test or reaction. This is usually in all the older books on mineralogy, at least the ones that contain tests. I once wrote an article about the test (history and such) but I think that the website it was posted on no longer exists, but I still have it in electronic form in my machine. However, if all you want is the basic information about it, it will be found in the chemical testing sections of older mineralogy texts, and very likely on the internet also. (and one does not need a silver coin to do the test - an old silver-plated spoon will work as well, although James Smithson, who invented the test, wrote that copper works as well, and I tried it, and found that copper does work when there is plenty of sulfur, but silver works better for trace amounts).

9th Jul 2019 17:05 BSTDonald B Peck Expert

I agree with Frank, and others, that simple chemistry may not yield an answer to an ID, especially with hydrated sulfates. But, discovering that one's sample contains Fe2+, and/or Fe3+, SO42-, and substantial H20 is a lot of fun and instructive. I submit that just looking up the approved hydrated iron sulfates and noting the differences will provide a bit of learning to the person doing it and greater understanding of the science.


Doing one's own chemical or optical analysis is no different from doing a hardness, specific gravity, or streak test. It is the same as learning to recognize crystal forms and systems. It is only a matter of how much one wishes to push one's knowledge and skills.


Curt Segeler (Segelerite) had his home lab on the second floor of his home in Brookline, NY. I spent hours there and learned much, most notably the use of the spindle stage (for RI and 2V) and the ring furnace (for chromatographic separations). He used all the techniques, including qualitative chem and optical. With a few chemicals and a few minutes looking through the microscope, he could have a result. He was good! (And he was not shy about informing authors or agencies when there was a mistake in their text.)


If I had a $200K instrument in my basement, or down the corridor where I worked, I would be inclined to use it, but I never did have that kind of access. The cost of services, like John Attard's, are affordable today, however they do add up. So for all the above reasons, that is why I still advocate for doing your own ID . . . at least for as far as you can go. Then the high energy instrumental approach.


Time to climb down from my "soap-box".


Keith and Dana; Thank you.

10th Jul 2019 07:42 BSTshaheer niazi

Thanks Dana for the reference to the book! I checked it out and it is exactly what I wanted!

Other than my home lab, I do have access to a university molecular biology lab which can be used for more precise experiments, but the comfort of home is something else entirely!

6th Aug 2019 12:07 BSTshaheer niazi

So I got the oppurtunity at a STEM school in the national center of physics here. Ill get the XRD soon, but for now I had LIBS performed (Laser Induced Breakdown Spectroscopy). My instructor has kept it a challenge for me to decode the peaks and identify the elements. Any software suggested to work with?

7th Aug 2019 21:08 BSTshaheer niazi

hmm this new forum format :/
 
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