Dalnegroite, Tl5-xPb2x(As,Sb)21xS34, a new thallium sulphosalt from Lengenbach quarry,
Binntal, Switzerland
F. Nestola*, A. Guastoni*, L. Bindi** and L. Secco* * Dipartimento di Geoscienze, Università degli Studi di Padova, Via Giotto 1, I-35137 Padova, Italy ** Museo di Storia Naturale, sezione di Mineralogia, Università degli Studi di Firenze, Via La Pira, 4, I-50121 Firenze, Italy Published in Mineralogical Magazine; December 2009; v. 73; no. 6; p. 1027-1032.
Dalnegroite, ideally Tl4Pb2(As12Sb8)Σ20S34, is a new mineral from Lengenbach, Binntal, Switzerland. It occurs as anhedral to subhedral grains up to 200 μm across, closely associated with realgar, pyrite, Sb-rich seligmanite in a gangue of dolomite. Dalnegroite is opaque with a submetallic lustre and shows a brownish-red streak. It is brittle; the Vickers hardness (VHN25) is 87 kg mm–2 (range: 69–101) (Mohs hardness ~3–3 1/2). In reflected light, dalnegroite is highly bireflectant and weakly pleochroic, from white to a slightly greenish-grey. In cross-polarized light, it is highly anisotropic with bluish to green rotation tints and red internal reflections.
According to chemical and X-ray diffraction data, dalnegroite appears to be isotypic with chabournéite, Tl5–xPb2x(Sb,As)21–xS34. It is triclinic, probable space group P1, with a = 16.217(7) Å, b = 42.544(9) Å, c = 8.557(4) Å, α = 95.72(4)°, β = 90.25(4)°, γ = 96.78(4)°, V = 5832(4) Å3, Z = 4.
The nine strongest powder-diffraction lines [d (Å) (I/I0,) (hkl)] are: 3.927 100 (-2 10 0); 3.775 (45) (2-22); 3.685 (45) (-460); 3.620 (50) (440); 3.124 (50) (-2-82); 2.929 (60) (4-22); 2.850 (70) (-442); 2.579 (45) (0 -14 2); 2.097 (60) (024). The mean of 11 electron microprobe analyses gave elemental concentrations as follows: Pb 10.1(1) wt.% , Tl 20.4(1), Sb 23.0(1), As 21.3(8), S 26.2(8), totalling 100.6 wt.%, corresponding to Tl4.15Pb2.03(As11.86Sb8.20)S34. The new mineral is named for Alberto Dal Negro, Professor in Mineralogy and Crystallography at the University of Padova since 1976.
The sample studied was collected by Luca De Battisti, an amateur collector in the summer of 2006 .
Binn Mineralienbörse and VFL meeting by Claudio Albertini
Claudio Albertini.- Saturday July 25 th 2009 has been held, in the Burgersaal der Gemeinde Binn, the annual meeting of the VFL (Verein Freunde Lengenbach) with numerous participants. After the presentation of some new partners, the examination of some proposals and the administrative matters, Ralf Cannon has talked about the actual works in the Lengenbach quarry and prof. Stefan Graeser has spoken about the analyses developed on the mineral recovered.
At the end of the meeting, prof. Graeser has introduced a film performed in the Lengenbach quarry and in the Mineralogical Institute of the Basel University in the years between 1969 to 1983. Later, the Italian mineralogist Claudio Albertini has reported and shown all the images of a photographic album, casually recovered by him this year and belonged to the famous English mineralogist Richard Harrison Solly. This album contains images of the works in the Lengenbach quarry in the years between 1901 and 1906 and besides images of Binn in that times. At the end of the presentation, Albertini has made gift to the Commune of Binn of a digital copy of the photos.
The projection of the film and the presentation of the Solly's photo-album have been gatherings with great enthusiasm and interest from the participants.
Therefore all participants are transferred in the rooms of the
Regionalmuseum where were exposed, in an exhibition entitled show "Ein
Schritt in der Vergangenheit- das Binntal zu Beginn des 20. Jahrhunderts: das Photo-album von Richard Harrison Solly", the most beautiful photos of the Solly's album. The traditional raclette and the drawing of some Lengenbach specimens, held in proximity of the tent of the Mineralienborse, have concluded the beautiful day.
The following day has been held the Mineralienborse, where were offered as every year, interesting specimens from the Lengenbach quarry, Binntal and Swiss Alps. Very good was the special display of the collector Martin Andres that in a showcase presented the most beautiful minerals from his personal collection: the giant Armenites from Wasenalp, beautiful Cafarsites from Wannigletscher, stupendous specimens of the classical minerals from Lercheltini region, a great fluorite from Gischigletscher and many others.
Binntal and the Lengenbach quarry in the beginning of 20th Century.
A photographic exhibition by Claudio Albertini and Stefan Graeser
During the summer period, from mid-June to mid-October, will be held in the hall of the Regionalmuseum of Binn an important photographic exhibition organized by Claudio Albertini (Omegna, IT) and Prof. Dr. Stefan Graeser (Basel, CH).
In the exhibition, with the title “Ein Schritt in die Vergangenheit – das Binntal zu Beginn des 20.Jahrhunderts: das Photo-album von Richard Harrison Solly”, will be displayed the photos contained in a photo-album recovered in England by Claudio Albertini and belonged to the famous English mineralogist R. H. Solly.
Richard Harrison Solly (1851-1925) was a recognized mineralogist and crystallographer. He worked at the British Museum (Natural History) and the University of Cambridge. He is chiefly remembered for his studies of Cornwall and Binntal. The most important part of his scientific works were devoted to the minerals from the Grube Lengenbach, where he determined eight new species.
The photos are related to the works performed in the dolomite of the Grube Lengenbach between 1901 and 1906, some views of family groups and Binntal way of life. These photos are very important because are the most consistent historical evidence of the works performed in the Grube Lengenbach searching minerals in those years.
An article with the reproduction of several photos and historical events related to this album will soon be published on Mineralien Welt magazine (nr.6 - November-December).
July 25th, Saturday: VFL General Assembly: Burgersaal Binn - Hall close to the Binn Museum. 14:00h. After Assembly: Film screening by Prof. Graeser: "Die Grube Lengenbach 1969-1983" and a Diaposhow "Das Fotoalbum von R.H.Solly" by Claudio Albertini.
July, 26th, Sunday: Binn Mineral Show.
AVALANCHE!!!! Repairing winter snow damages...
As some of you have already heard or probably have seen, in the last week of April after two days of fresh snow again a major avalanche, the pit and surrounding area (up briefly approached the container) were largely completely buried. The snow avalanche reached in the pit about 8 to 10 meters.
The removal of the avalanche snow and free evacuation of the mine took the whole month of June. During last days of June the last blocks has been removed from the ramp acces working area. A problem arose in the first two weeks, the low availability of water for melting of the snow avalanche. With 4 pipelines we chanelled enough water and after a week we had access to pit hall again.
The avalanche have fortunately not caused many serious problems. But there was an abundance of small to moderate damages in the mine area, to the slopes and the trails, which are now largely resolved and repaired. This week is still the fitting and securing work on the body in the eastern mining pit area, so in the coming week works can be started.
In all these works we have had the appreciable help and assistance of Franz Guntern and Peter Strunz (VFL) highly active workers! Last week, we were helped by the Basel sutudent of Geology Fabian Müller.
Fascinating
Mineral finds in 2008 - VFL info (Dr Eva Drechsler)
The year 2008 brought a surprising and pleasing range
of various interesting and rare minerals. Marrites and especially Quadratites
are to be mentioned. There are very fine specimens among them, a few of them
freestanding. One specimen is a rather thick packet of crystals strongly parqueted
and with a dark-red play of colours. Another Quadratite found
nearly at the end of the season is one of the biggest ever seen (nearly 3 mm).
Among his share of minerals found in 2007 Philippe Roth could discover a tiny Quadratite-triplet – the
phenomenon of twinned minerals is impressively described and illustrated in the new
book.
Particular enthusiasm was caused (not for the first time)
by the so-called “Picassos”. In the last years rare minerals like Wallisite and Sinnerite could
be found on such pieces. The Hatchite-Wallisite-crystals of this year proved
to be mostly Wallisites. Additionally on two “Picassos” two tiny,
dark-red or nearly black coloured and peculiarly striated crystals reminding
of Jentschite could be discovered next to Edenharterite. And
the radiographic tests carried out by Prof. Graeser proved the crystals to be Jentschites indeed! Jentschite belongs to the small number of the most rare minerals
at Lengenbach. A few other “Picassos” are to be tested still and
might carry Jentschite also…
The tin-mineral Kesterite
is known at Lengenbach since several years, but has been found rarely. In this
year a few really good specimens could be discovered. Mostly Kesterite appears
in tiny crystals located in piles on Dolomite or sometimes on Pyrites. They are
grey-black and tend to encrustations. Distinctly better defined and bigger crystals
are located very rarely on Sphalerite. Epitaxial phenomena seem to exist at least
sometimes. Seligmannite could be found in very good crystals again: prismatic,
deep-black coloured with an intense metallic lustre.
Especially attractive is the combination with brownish crystals of Wurtzite.
Specimens of Apatite and Mimetite should
be mentioned also.
Particular enthusiasm was caused (not for the first time)
by the so-called “Picassos”. In the last years rare
minerals like Wallisite and Sinnerite could
be found on such pieces. The Hatchite-Wallisite-crystals of this year proved
to be mostly Wallisites. Additionally on two “Picassos” two tiny,
dark-red or nearly black coloured and peculiarly striated crystals reminding
of Jentschite could be discovered next to Edenharterite. And
the radiographic tests carried out by Prof. Graeser proved the crystals to be Jentschites indeed! Jentschite belongs to the small number of the most rare minerals
at Lengenbach. A few other “Picassos” are to be tested still and
might carry Jentschite also…
The tin-mineral Kesterite
is known at Lengenbach since several years, but has been found rarely. In this
year a few really good specimens could be discovered. Mostly Kesterite appears
in tiny crystals located in piles on Dolomite or sometimes on Pyrites. They are
grey-black and tend to encrustations. Distinctly better defined and bigger crystals
are located very rarely on Sphalerite. Epitaxial phenomena seem to exist at least
sometimes. Seligmannite could be found in very good crystals again: prismatic,
deep-black coloured with an intense metallic lustre.
Especially attractive is the combination with brownish crystals of Wurtzite.
Specimens of Apatite and Mimetite should
be mentioned also.
2008
Summer Binn holidays (July)- David Hospital & Joan Rosell
Like every year, David Hospital and I
have been in Switzerland, in the Binn valley (Binntal). We have had the chance
to visit the Binn mineral show (July 20th). David and I both decided to spend
some days there. We went out last July 17th from Barcelona to Geneva by flight
and then, after three hours drive, we arrived at Binn.
We get Binn in the afternoon and we went directly to the small Pius restaurant
in Imfeld where we reach Ralph Cannon, who works in the Lengenbach quarry (from
now LGB) during the skilful season. He told us that next day he would be in the
quarry.
The next day we went to the small quarry where Peter Strunz was helping Ralph
in the consolidation walls tasks for next extraction works. We give Ralph a hand
but we only could see they were working an area where we only saw “tourmalines” and
some quartz crystals. The next day attended the meeting of the Verein
Lengenbach Freunde (VFL) or LGB Friends Association that
since this year we are new members. We are the only members that are not either
from Swistzerland, Austria, Italy, france or Germany. The association has 60 members (2007)
giving their support to the LGB mineral research. We didn’t understand
anything about the meeting conferences because they were German spoken, but we
must thank one of its members, Thomas, for their translations on what they were
talking about and voting. The new two “foreign” members were kindly
accepted and everyone applauded the new way to expand its membership and nationalities
represented.
After the meeting Dr. Stefan Graeser made a guided tour (in German!) at the LGB
mineral showcases in the Binn museum. Dr. Graeser, aware of our linguistic ignorance,
gave us all kinds of post explanations in excellent English language, a luxury.
Following the visit and for our stomach enjoyment there was an excellent cheese “raclette” with
potatoes and good wine... and after the lunch they share out few rich-sulfosalt
dolomite batches to the members, prepared by Thomas and Eva. It was a surprise
which minerals could appear from these samples.
The reason
for our trip was the Binn mineral show that would take place on Sunday, but we
enjoyed soon the mineralogy of this area as one of the most recognized Binn strahlers,
André Gorsatt, put up for sale much of their material. We were able to
buy some uncommon minerals from the area as: Cafarsite, Davidite, Senaite, Crichtonite
or Asbecasite and other more usual but also very nice as: Rutile, Hematite and
of course, excellent Anatase specimens from Gorb, along with several LGB pieces.
Another reason for our trip was the presentation of the new book (in German!):
Faszination Lengenbach (1958-2008) (Authors: Graeser, Cannon, Drechsler, Roth & Raber,
ISBN 978-3-940814-16-6, Kristallografik Verlag, 2008). This book, with 192 color
pages, has been published to celebrate 50 years (1958-2008) from the exploitation
of this unique quarry by various communities: the Arbeitsgemeinschaft LGB (AGL,
1958-1997), the Interessengemeinschaft LGB (IGL, 1998-2002) and currently the
LGB Forschungs-gemeinschaft (FGL, 2002-present).
The book contains many photographs, some of them from our own archive, about
the deposit and the mining works. In addition, you could find the most complete
information about Lengenbach: geology, geochemistry, working methods, identification
and mineral catalogs, curiosities... there is a comprehensive index of all species
found in LGB, with many information and photos. Given our "insistent" request
to publish this book in English we have begun to talk to the editor to manage
the idea and edit, at least, a short supplement with English texts, but we would
like to publish all the book in English. It depends on mineralogical English
spoken community: you decide! A book highly recommended. Follow
this link...
The Mineralienbörse
Binntal was held on Sunday. We saw a lot of alpine material as each year,
but there were not many novelties. A beautiful and perfect shape Sphalerite crystal
(17 mm) almost black on a LGB Dolomite gray matrix. Also an exceptional well
defined and bright Tilasite 6 mm crystal, a very rare arsenate (CaMg[F/AsO4])
from the Wanni glacier (Wannigletscher, Binntal, Valais, CH). Individualized
Magnetite crystals, very bright and with exceptionaly sharp faces and edges from
Lercheltini area (Binntal).
As a novelties, we could talk about some
Bornite old samples (they said) coated by Malachite and with some Silver wires
from Ausserbinn area. Each year we enjoy the excellent specimens of Rutile and
Hematite iron-roses. Also the yellow to honey color Fluorite cubic crystals from
Orismühle Quarry (Basel-land, CH) with Calcite scalenohedral crystals.
From Lengenbach Grube we would like to emphasize on the new Quadratite crystals,
small crystals but high price. Some interesting samples of Sinnerite, Hatchite-Wallisite,
Liveingite or Baumhauerite, which LGB is type locality. Some new specimens of
Mimetite and Baileychlore, recently analyzed. We were talking with Dr. Graeser
about the new article about Struvite-(K) from LGB.
The next day, before leaving Binntal to Barcelona, we made one last visit to
the Toni Imhof mineral shop. Toni, always a gentleman, surprised us with some
old specimens from LGB quarry with an excellent quality, which almost makes us
miss our flight to Barcelona. Binntal is always a surprise and we will try to
come back soon.
2006
Summer Binn holidays - David Hospital & Joan Rosell
We planned to travel to Binn Valley a long time ago, in order
to spend some days there visiting the different quarries and deposits of the
area and, also, make a visit to the already famous Binn Mineral Show, at the
end of July.
Finally, this summer we got to arrange a trip to the valley. After doing the
trip from Barcelona to Binn in one day by car (about 1000 Km) we arrived to Ofenhorn
Hotel in Binn, the most famous hotel in the valley. This old-time hotel, opened
at the end of 19th century, still has an old-fashioned style, so our stage there
was a great pleasure.
Next day we went to the Binn Mineral Show, always the last weekend of July. It’s
a classical alpine-type show, with plenty of material from the area, that we
can’t find in other bigger shows, like Munich or Saint-Marie-aux-Mines
Shows. We saw a lot of material from the nearby Lengenbach quarry at a reasonably
prices, and we could also speak with the well-known swiss photographer Walter
Gabriel, whom an interview with him was published in a back issue of the Spanish
version of Mineral Up, Revista de Minerales (vol.VIII, num.3, 2002). We spent
the following days to go around the different places of interest in the valley.
Binntal is actually very small, being basically three towns: Binn, Giessen and
Imfeld, with some other very small inhabited places, being Binn the biggest of
all with a population of only 200 inhabitants. But, if you’re lacking of
time to search minerals in the area, you can buy them in shops. We advise you
to visit the Toni Imhof’s shop in the center of Binn, and the André Gorsatt
shop in Imfeld. Even though both shops are focused on tourist material, they
have a good offer for mineral collector’s. You can find here cafarsite,
cervandonite, asbecasite, senaite-crichtonite, tilasite, etc, all of them typical
from the valley.
Even more focused on tourists we have the MONIK shop in Imfeld. On the other
hand, most interesting is to visit directly the quarries. The most famous and
interesting of them is Lengenbach; you can reach it in a 20 minutes walk from
Imfeld. Even though entrace to the quarry is not allowed, you can find some good
micromount material in the dumps. Dolomite there is really fresh and has a good
potential of binnite, sphalerite, realgar, dravite and also some sulphosalts
like sartorite and baumhauerite. Just 100 meters west from Lengenbach we find
Messerbach, another dolomitic quarry where is much more difficult to find something.
We can say the same about the third quarry we visited, Turtschi, in the right
side of the road from Binn to Giessen. If you are interested in a harder excursion
like going to Alp Lercheltini (Gorb, Spiessen,…) we advise you to speak
with an alpine guide, the most famous of them is André Gorsatt, who guides
mineral-oriented excursions in the valley.
Last but not least, we want to pinpoint two small but very interesting mineral
museums. First in Binn Museum, next to the Offenhorn hotel where we find a good
selection of minerals from the valley, especially a complete room focused in
Lengenbach with 3D-maquettes of the different stages of the exploitation. Second,
the private museum of André Gorsatt, on the surroundings of Imfeld, that
surprised us for the big quality of the displayed minerals. But if you prefer
a good lunch after so many minerals, you can’t avoid a visit to the Restaurant
Imfeld, in Imfeld of course, where Pius, the picturesque sthraler owner, will
receive you with his savoir-faire and will allow you to take a photograph with
his most showy self-found minerals.
Finally, to close the trip with more mineral shows, going back to Catalonia,
you can stop at Chamonix (first week end of August) or even at Narbonne in the
same week end.
