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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Jan 31, 2013 09:07 Post subject: Pezzottaite: some aspects |
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Cabochon.
Ambatovita, Madagascar.
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Pezzotaite Ambatovita, Madagascar |
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Rough pezzottaite, Ambatovita. Transmitted light. |
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Rough pezzottaite, Ambatovita. Transmitted light through a dichroscope |
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Rough pezzottaite Ambatovite. Reflected light. |
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Gail
Joined: 21 Feb 2008
Posts: 5839
Location: Texas, Lone Star State.
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Posted: Jan 31, 2013 09:56 Post subject: Re: Pezzottaite: some aspects |
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Fabulous! We are quite avid collectors of Pezzotaite ourselves. Nice to see your images.
_________________ Minerals you say? Why yes, I'll take a dozen or so... |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Jan 31, 2013 11:59 Post subject: Re: Pezzottaite: some aspects |
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Pezzottaite is a “new” gem mineral discovered in November 2002. It is the Cs,Li – rich member of the beryl group.
Its ideal formula is Cs(Be2Li)Al2Si6O18. It was sold during de Tucson Show as some trivial names as « Raspberry beryl ». In September 2003 it is named after Dr Federico Pezzotta (NHMuseum, Milan, It.) which was one of the first to study this mineral.
The photo shows the typical crystal growth of pezzottaite. Its prismatic habit is similar to morganites, very slightly elongated along the c axis.
Here we observe an inverted pyramid developed from a germ. A possible extension results from an oscillating growth.
If you want, I can discuss the general morphology and this point.
Roger.
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Pezzottaite Ambatovita (Mandrosonoro) - Mad. 4.5 x 5.5 mm Oscillating growth |
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24960 Time(s) |
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Matteo_Chinellato
Joined: 12 Dec 2011
Posts: 115
Location: Venice, Italy
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Jan 31, 2013 14:37 Post subject: Re: Pezzottaite: some aspects |
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Wonderful collections and outstanding pictures.
One advantage of being close to the sources.
Congratulations.
Roger.
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John S. White
Site Admin
Joined: 04 Sep 2006
Posts: 1295
Location: Stewartstown, Pennsylvania, USA
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Posted: Jan 31, 2013 14:37 Post subject: Re: Pezzottaite: some aspects |
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Is there any possibility that it grew this way because it crystallized simultaneously with feldspar until the very end where the termination was free to form unobstructedly?
_________________ John S. White
aka Rondinaire |
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Matteo_Chinellato
Joined: 12 Dec 2011
Posts: 115
Location: Venice, Italy
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Posted: Jan 31, 2013 15:06 Post subject: Re: Pezzottaite: some aspects |
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John S. White wrote: | Is there any possibility that it grew this way because it crystallized simultaneously with feldspar until the very end where the termination was free to form unobstructedly? |
Unique its ask to Federico when come in Tucson
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Jan 31, 2013 16:44 Post subject: Re: Pezzottaite: some aspects |
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I do not think. I believe the tan silicated impurities are caused by a exsolution process at the end of pezzottaite crystallization. I think I can relate this phenomenon to the formation of “trapiches” emeralds.
Roger.
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Riccardo Modanesi
Joined: 07 Nov 2011
Posts: 618
Location: Milano
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Posted: Feb 04, 2013 09:08 Post subject: Re: Pezzottaite: some aspects |
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Hi to everybody!
If you write or talk with the German Gemmological Institute in Idar-Oberstein as well as any other gemmological institute in the world, you may achieve all of the information about this mineral you like to get!
Greetings from Italy by Riccardo.
_________________ Hi! I'm a collector of minerals since 1973 and a gemmologist. On Summer I always visit mines and quarries all over Europe looking for minerals! Ok, there is time to tell you much much more! Greetings from Italy by Riccardo. |
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osman khattak
Joined: 31 Jul 2012
Posts: 18
Location: Peshawar
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Posted: Feb 05, 2013 06:34 Post subject: Re: Pezzottaite: some aspects |
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Dear Roger Warin , thanks for sharing more than precious information from Pezzotaite:
with best regards
_________________ KHATTAK |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Feb 05, 2013 10:44 Post subject: Re: Pezzottaite: some aspects |
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As you enjoy this mineral, here is another specimen.
Contrary to appearances, pezzottaite isn’t a beryl! It belongs to the trigonal crystal system, space group R3 (a very low symmetry).
Roger.
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Pezzottaite Ambatovita, Madagascar Euhedral crystal |
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Riccardo Modanesi
Joined: 07 Nov 2011
Posts: 618
Location: Milano
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Posted: Feb 06, 2013 05:36 Post subject: Re: Pezzottaite: some aspects |
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Hi to everybody!
Roger is right: in one publication of the German Gemological Institute there are the complete analyses of pezzottaite, and it is quoted it belongs to trigonal system (i.e. not hexagonal). It WAS believed as a beryl variety because of its specific weight which is about 2,75, therefore very close to the beryl one, and because od its birefrangence, 0.006 to 0.009, also close to the beryl one. The only (and very interesting!) difference is (or better: ARE) the refraction indexes, 1.600 to 1.610, significantly higher than the typical beryl ones, 1.560 to 1.595 in some emeralds. That's why this stone was so deeply studied, apart from the gemmological worth itself.
Last but not least: the right spelling is PEZZOTTAITE, with double Z and double T.
Greetings from Italy by Riccardo.
_________________ Hi! I'm a collector of minerals since 1973 and a gemmologist. On Summer I always visit mines and quarries all over Europe looking for minerals! Ok, there is time to tell you much much more! Greetings from Italy by Riccardo. |
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Matteo_Chinellato
Joined: 12 Dec 2011
Posts: 115
Location: Venice, Italy
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Posted: Feb 06, 2013 06:44 Post subject: Re: Pezzottaite: some aspects |
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some other photos of other specimens
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Feb 06, 2013 11:13 Post subject: Re: Pezzottaite: some aspects |
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Nice Matteo’s photos and very interesting specimens showing very well the trigonal R3 crystallization.
One 3-fold rotation axis is the only symmetry, without mirror plane or center of symmetry. This is the trigonal-pyramidal class.
It clearly explains the odd forms of some equant crystals (photos “Pezzo-monoxl#3 and Mado14”).
Roger
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Roger Warin
Joined: 23 Jan 2013
Posts: 1176
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Posted: Feb 06, 2013 11:30 Post subject: Re: Pezzottaite: some aspects |
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Pezzottaite in its environment:
Rock : albite (hardly visible on the photo)
Mica (muscovite) and licorice tourmaline (in French, Malagasy people say tourmaline reglisse).
Roger.
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Pezzottaite, muscovite, tourmaline Ambatovita, Madagascar |
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Pezzottaite Ambatovita, Madagascar |
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Matteo_Chinellato
Joined: 12 Dec 2011
Posts: 115
Location: Venice, Italy
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Posted: Feb 06, 2013 12:08 Post subject: Re: Pezzottaite: some aspects |
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classic matrix of Pezzottaite
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