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Identity HelpMagnetite complex pseudo-prismatic twins?

29th Dec 2021 17:20 UTCMarco Bonifazi

Corbolone, Variante quarry, Leghorn, Tuscany, Italy. These extremely rare crystals have been found in a serpentinite associated with mainly bi pyramidal, but also more complex, magnetite crystals and also with superficial growth streaks. I believe it is magnetite, but I have not found in the literature and in my research, any examples of elongated pseudo-prismatic crystals like these. Strange development of some faces or multi-twinned crystals? other ideas? other mineral that would not be known in the quarry? Thanks in advance for your ideas. In the photo, fov 3mm

Questions Answered
Can it scratch glass? : Unable to test
Can you scratch it with your fingernail? : Unable to test
Is it light/heavy for the size? : Unable to test

29th Dec 2021 17:39 UTCPavel Kartashov Manager

From my point of view, it is more similar to hematite.

29th Dec 2021 18:04 UTCMarco Bonifazi

Thank you for the comment, I agree that is more similar to hematite. My true question is if it could be possible to be magnetite? That are the other crystals shapes on the same sample, to show.

PS the quarry is closed since 40 years, not new material escavated, nobody had never found at now ematite, but it could be possible it is right.

29th Dec 2021 18:52 UTCGiuliano Bettini

There is no hematite there. Full stop.

29th Dec 2021 19:01 UTCMarco Bonifazi

You're right, it is known that there is no hematite there ... For that I believe it to be a very strange magnetite complexe twin

29th Dec 2021 20:47 UTCHarold Moritz 🌟 Expert

Perhaps ilmenite, or, since it is in a serpentinite, chromite?

29th Dec 2021 21:11 UTCMarco Bonifazi

Thanks for the guesses. A question, at the crystallographic level, what would be the difference between chromite and magnetite? if chromite is hypothesized, I believe that magnetite can equally be hypothesized?

29th Dec 2021 21:26 UTCKevin Conroy Manager

Locality page:

https://www.mindat.org/loc-54354.html

29th Dec 2021 23:03 UTCMarco Bonifazi

That is the second only sample found if it can help. Fov 3mm

30th Dec 2021 10:14 UTCPavel Kartashov Manager

This obviously NOT magnetite. This is rather escolaite (which belongs to hematite group and has identical crystallography). Or may be even some of krichtonite group member. In any case these crystals are something much more interesting than simply distorted magnetite.

I don't think that this is iron analogue of langbanite or gaudefroyite, but without any doubts something interesting.

You may to crush about 50 gr piece of such rock up to size 0.3 mm, wash out heavy fraction and divide it by magnet. You'll see that there are 3-4 different black minerals. You would to use them for analyses and save your good crystals.

30th Dec 2021 12:08 UTCMarco Bonifazi

Thanks for the ideas,

I will try to remove a crystal and send it for SEM-EDS and micro Raman analysis. I'm even more curious than before to know the results. Will come back in a few months.

31st Dec 2021 18:20 UTCNick Gilly

Very interesting. The crystals clearly have the same trigonal form of corundum and haematite. Eskolaite would be an excellent find if Pavel Kartashov is correct.

I look forward to reading the results.

31st Dec 2021 21:38 UTCRalph S Bottrill 🌟 Manager

Wurtzite?

1st Jan 2022 21:11 UTCUwe Kolitsch Manager

I'd guess either ilmenite or hematite.

2nd Jan 2022 02:54 UTCKeith Compton 🌟 Manager

I'd lean to an elongated hematite. In some ways a bit like those produced at the Wessels Mine in South Africa.

3rd Jan 2022 22:01 UTCDean Allum Expert

Magnetite is the simplest mineral to check for. Since you do have multiple samples, break one off the matrix, and see if it is attracted to a magnet covered by a plastic bag.

4th Jan 2022 11:32 UTCMarco Bonifazi

I removed a fragment and now need to send for analys. For the magnetic check, I tried, they look magnetic, but not too much, ilmenite? We see...

13th Apr 2022 20:21 UTCMarco Bonifazi

Dear friends, You were right, the analyzes confirmed that it is hematite, the first finding in the region. An article will be published in a few days in the Libvrna magazine number 5 and then I will add it to the list of minerals of the locality on Mindat

13th Apr 2022 22:17 UTCFrank K. Mazdab 🌟 Manager

thanks for following up, as it's always nice to get closure for these kinds of more academic ID threads.

And so it looks like someone from earlier in the thread might be having crow for dinner... "full stop". Science and absolutism rarely go well together... maybe, it could be that absolutism may not go well with much of anything... 🤔

14th Apr 2022 00:52 UTCEd Clopton 🌟 Expert

One of my duties at work (I'm a hospital emergency department technician) is teaching cardiac rhythm recognition (making sense of the wiggly lines on heart monitors) to newly hired nurses, a subject that is touched on only briefly in nursing school. A student in a recent class was frustrated because so often I say things like "this kind of wave probably indicates" this or that condition; she wanted clear-cut rules that she could hang her hat on (and could depend on to pass the course exam), and as you say, that certainty is hard to provide in science.

10th Jun 2022 17:39 UTCMarco Bonifazi

I would like to add these photos in the locality, but Mindat say to me i can't as that are double with these inside that discusion, Somebody could help me? Thanks

10th Jun 2022 17:50 UTCUwe Kolitsch Manager

Did you try the option "Edit this photo"?

10th Jun 2022 19:44 UTCDon Windeler

To build on Uwe's comment, click on your photo in the thread above and choose Edit. That will give you the regular photo submission screens where you can add locality, size, description, etc. Then it'll go into the usual review and submission process.

I didn't know about this functionality for a long time, but it solves the problem of turning a message image (user-only / other) into a formally-approved one.

Cheers,

20th Jun 2022 13:09 UTCMarco Bonifazi

Thank you both, I tried just now to edit with locality, will se if it appear inside the galletry, thanks.

24th Jun 2022 16:09 UTCMarco Bonifazi

I did it but it is for user gallery only, not in public galery? I would wait until do the same with the others hematites

24th Jun 2022 16:13 UTCUwe Kolitsch Manager

Any editing of photos must be re-approved - done now.

Move photo https://www.mindat.org/photo-1188328.html also to quarry?

24th Jun 2022 16:17 UTCMarco Bonifazi

Thank you Uwe

25th Jun 2022 18:55 UTCHerwig Pelckmans

Uwe Kolitsch Manager ✉️

Move photo https://www.mindat.org/photo-1188328.html also to quarry?

Right now that photo does not show any info ...

Cheers, Herwig

8th Aug 2022 16:23 UTCMarco Bonifazi

I don't know

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