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Mineralogical ClassificationIMA 2011-109 = tubulite

21st Feb 2014 17:28 UTCMarco E. Ciriotti Manager

Reference:

▪ Moëlo, Y., Pecorini, R., Ciriotti, M.E., Meisser, N., Caldes, M.T., Orlandi, P., Petit, P.-E., Martini, B., Salvetti, A. (2014): Tubulite, Ag2Pb22Sb20S53, a new Pb-Ag-Sb sulfosalt from Le Rivet quarry, Peyrebrune ore field (Tarn, France) and Biò, Borgofranco mines, Borgofranco d’Ivrea (Piedmont, Italy). European Journal of Mineralogy, 25, 1017-1030.

Abstract:

Tubulite, ~ Ag2Pb22Sb20S53, is a new Pb–Ag–Sb sulfosalt discovered at Le Rivet quarry, Peyrebrune ore field (Tarn, France) and Biò, Borgofranco mines, Borgofranco d’Ivrea (Piedmont, Italy). As indicated by the name, it forms very thin perfect micro-tubes, 100 to 600 micron in length, 40 to 100 micron in diameter, and only 1 to 2 micron in thickness; a hair-like variety is also present at Biò. At Le Rivet, it is associated with galena, pyrite, pyrrhotite, arsenopyrite, stibnite, and various Sb sulfosalts of Pb, Ag and Cu, in a gangue of quartz, baryte and carbonates. At Biò, it is associated with galena, sphalerite, chalcopyrite, pyrite, marcasite, and various Sb sulfosalts of Pb, Ag and Cu, within the same type of gangue. Tubulite is metallic black; optical properties could not be observed under the microscope, due to the crystal morphology. Electron microprobe analysis gave (wt.% - average of 8 anal.): Ag 2.7(2), Pb 46.6(9), Sb 26.1(8), S 17.8(5), Total 93.2(2.1). The low total is due to the thinness of the tube wall. According to crystallographic study (electron and X-ray diffraction), tubulite is monoclinic (space group Pc, P2/c or P21/c) with unit-cell parameters a 4.132(2), b 43.1(2),c 27.4(1)A°, beta 93.2°, V 4872(40)A°3, with Z=2. Weak reflections in the <010> electron diffraction pattern indicate a 2a superstructure. Main diffraction lines are : 3.99 (35), 3.69 (60), 3.36 (100), 3.28 (55), 2.99 (55), 2.912 (55), 2.063 (75). The unit cell of tubulite is very close to those of sterryite and parasterryite; like these sulfosalts, tubulite is probably an expanded derivative of owyheeite. Its peculiar tubular morphology is discussed within the general framework of crystals whose habit presents a circular symmetry. It is proposed that micro-tubes were initiated by capillary forces acting on very thin lamellar crystallites around gas bubbles or liquid droplets.

22nd Feb 2014 01:57 UTCReiner Mielke Expert

" It is proposed that micro-tubes were initiated by capillary forces acting on very thin lamellar crystallites around gas bubbles or liquid droplets."

It only took 37 years for someone to see the merits of my theory! Attached are some pages from my 1977 BSc thesis :Boulangerite and Associated Minerals of the Rogers Mine, Madoc, Ontario" in which I proposed a similiar mechanism for the formation of rings and tubes. Unfortunately I was not able to attach the entire thesis as it is too large ( 8.2MB) If someone wants the entire thesis let me know and I will send it to you.

More to follow:

22nd Feb 2014 02:04 UTCReiner Mielke Expert

Interestingly in 1982 I wrote an article for the Mineralogical Record based on my thesis which was rejected because they didn't like my theory of ring formation HA!!! See the attached rejection letter, very amusing.

22nd Feb 2014 12:11 UTCMarco E. Ciriotti Manager

Yes Reiner, we agree with your thesis, which is cited in the references.

Thank you.

Marco

22nd Feb 2014 12:13 UTCReiner Mielke Expert

Thank you Marco!

22nd Feb 2014 13:01 UTCJakub Plasil Expert

Dear Reiner,

would you mind sending me your thesis? I am at the email address plasil@fzu.cz. Many thanks and regards! Jakub

23rd Feb 2014 13:25 UTCLuís Martins 🌟

Marco,

Could you please provide the PDF?

Best regards, Luís Martins.

23rd Feb 2014 16:37 UTCRob Woodside 🌟 Manager

Me too! Please Marco? My email address is rwmw@telus.net. Now Moello's Van Silver owyheeite ID is making more sense.;-)

24th Feb 2014 09:34 UTCMarco E. Ciriotti Manager

Sent!

Enjoy!

24th Feb 2014 12:27 UTCJoel Dyer

Interesting stuff & wouldn't mind reading both papers, if possible to send to joeldyer (at) hotmail.com. Of course, I'm only a amateur but keenly like reading various kinds of texts.

Are there other minerals possibly formed this way? I assume for instance some cylindrical Tochilinite's construction is due to other reasons: the laminate composition? (American Mineralogist, Vol 71, pp 1201-1209, etc)

Thanks.

24th Feb 2014 13:29 UTCMarco E. Ciriotti Manager

Sent, Joel.

In the paper you can find some other examples of similar stuff.

Cheers. Marco

24th Feb 2014 19:00 UTCJean-Marc Johannet Manager

Hi Marco,

Please, could you send me too this paper.

I've taken this photo for Yves and Robert to be use in this article but in fact, I don't know if they did or not.

http://www.mindat.org/photo-473282.html

24th Feb 2014 20:55 UTCPeter Haas

Reiner,

Dont't be too disappointed. A rejection and a 37 years latency are certainly bad, but in another century, they might have burned you on a stake ...

25th Feb 2014 00:40 UTCReiner Mielke Expert

Good point Peter :-)

25th Feb 2014 07:55 UTCMarco E. Ciriotti Manager

Sent Jean-Marc!

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