FMF - Friends of Minerals Forum, discussion and message board

[Roger Warin]

Cabochon.
Ambatovita, Madagascar.

[Gail]

Fabulous! We are quite avid collectors of Pezzotaite ourselves. Nice to see your images.

[Roger Warin]

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.

[Matteo_Chinellato]

some photos

https://www.mindat.org/photo-438347.html
https://www.mindat.org/photo-246355.html
https://www.mindat.org/photo-244596.html
https://www.mindat.org/photo-236249.html
https://www.mindat.org/photo-205984.html
https://www.mindat.org/photo-205766.html
https://www.mindat.org/photo-115744.html
https://www.mindat.org/photo-118513.html

[Roger Warin]

Wonderful collections and outstanding pictures.
One advantage of being close to the sources.
Congratulations.
Roger.

[John S. White]

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?

[Matteo_Chinellato]

[Roger Warin]

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.

[Riccardo Modanesi]

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.

[osman khattak]

Dear Roger Warin , thanks for sharing more than precious information from Pezzotaite:

with best regards

[Roger Warin]

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.

[Riccardo Modanesi]

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.

[Matteo_Chinellato]

some other photos of other specimens

[Roger Warin]

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

[Roger Warin]

Pezzottaite in its environment:
Rock : albite (hardly visible on the photo)
Mica (muscovite) and licorice tourmaline (in French, Malagasy people say tourmaline reglisse).
Roger.