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Cold cases. Yellow orange unidentified on hydrotermalite.

Last Updated: 9th May 2016

By Giuliano Bettini

Reasons for health and old age, my "mineralogical trips" to the island of Elba and Leghorn Mountains have stopped.
Now I'm doing photos.
I'm reordering my old collection.
Here I am referring to the locality Nibbiaia, Rosignano Marittimo, Livorno Province, Tuscany, Italy.
http://www.mindat.org/loc-252520.html
Locality description:
Radiolarites & Hydrotermalites, about 800m east-south-east of Nibbiaia.
Mineral list: Anatase, Brookite, Quartz. Millerite, etc.


I was examining some samples of this area. Here in the past were mainly found Anatase.
Carefully examining etched samples (cold dilute HCl), interesting "unknown" are appearing.


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

In the very first time, examining a sample under the microscope, I saw this acicular crystal (Field of View: 1.5 mm).






Subsequently, in fact, I have noticed that this and other samples contain rare fragments of a yellow-orange material.
So I decided to make a sweep analysis of different specimens.
I have thus noted the presence of other crystals, and yellow-orange crusts and coatings here and there on the specimens.

I show some pictures.


Crystals.


04744690014947705464564.jpg
FoV 1.5 mm.
01042760014947705473617.jpg
FoV 1.5 mm.
05465900014947705471477.jpg
FoV 1.8 mm.
02030580014947705481295.jpg
FoV 2 mm.
04744690014947705464564.jpg
FoV 1.5 mm.
01042760014947705473617.jpg
FoV 1.5 mm.
05465900014947705471477.jpg
FoV 1.8 mm.
02030580014947705481295.jpg
FoV 2 mm.
02690710014951201916979.jpg
FoV 1.5 mm.
07753530014962364295238.jpg
FoV 1.5 mm.
08929890014947705498960.jpg
FoV 1.8 mm.
01685990014961880965611.jpg
FoV 2 mm.


01627540014962364306287.jpg
FoV 1.5 mm.
01112920014952248908218.jpg
FoV 1.5 mm.
05343280014962364308502.jpg
FoV 2 mm.
01423620014962364317430.jpg
FoV 2 mm.
01627540014962364306287.jpg
FoV 1.5 mm.
06997630014962364318387.jpg
FoV 1.5 mm.
05343280014962364308502.jpg
FoV 2 mm.
01423620014962364317430.jpg
FoV 2 mm.
00041840014962364326752.jpg
FoV 1.5 mm.
01112920014952248908218.jpg
FoV 1.5 mm.
03677690014962364328398.jpg
FoV 2 mm.
09751810014962364324197.jpg
FoV 2 mm.



Small masses, coatings (very rare). FoV 3 mm.




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

Is it the same mineral?
I suppose yes, even if sometime the crystals appear slightly more orange, and the crusts slightly more yellow.
Comparison:


07005460014947705564166.jpg
FoV 3 mm.
05654310014962364331842.jpg
FoV 1.5 mm.
07005460014947705564166.jpg
FoV 3 mm.
05654310014962364331842.jpg
FoV 1.5 mm.
07005460014947705564166.jpg
FoV 3 mm.
05654310014962364331842.jpg
FoV 1.5 mm.



Yellow orange unidentified is unidentified. So far.




Article has been viewed at least 2922 times.

Discuss this Article

5th Apr 2016 10:04 UTCRiccardo Modanesi

Hi Giuliano!
Have you seen the colour of the streak? If it is yellow-orange, it could be crocoite! Is there any documentation about an occurrence of crocoite in that place? However... there is always a first time for everything!
Greetings from Lombardy by Riccardo.

5th Apr 2016 10:30 UTCGiuliano Bettini


Dear Riccardo,
thanks for your comment.
No, I have no idea of the streak, too small to test.
In my extensive research on the Interne, me too I thought to Crocoite. No, it's never been found, even in Tuscany as far as I know.
We'll see.
Cheers,
Giuliano.

8th Apr 2016 10:00 UTCSteve Sorrell Expert

Crocoite would seem unlikely given the geological environment - cherts with hydrothermal quartz veins? For crocoite, you would need both lead and chromium sources. The lead could come in through the hydrothermal veins, but the chromium would need to be from maybe an ultramafic source.

8th Apr 2016 17:08 UTCGiuliano Bettini

Hi Steve.
I agree that Crocoite would seem unlikely here, even because never found.
But as to the "ultramafic soils" (I'm not a geologist, I just gave a quick look to the Internet)
it seems ok, and Chromium seems to be present..

Example
http://link.springer.com/article/10.1007%2FBF02913340#page-1

Also quoted the "Livorno hills" (what I called "Leghorn mountains").
We are here.
Anyway, honestly IMO Crocoite would seem unlikely.
We'll see.
Many thanks for your comment.
Giuliano.

11th Apr 2016 23:41 UTCKeith Wood

Perhaps minium or litharge, both lead minerals.
 
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