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The Lengenbach Quarry in Switzerland: Classic Locality for Rare Thallium Sulfosalts


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Minerals 2018, 8, 409; doi:10.3390/min8090409
The Lengenbach Quarry in Switzerland: Classic
Locality for Rare Thallium Sulfosalts
Thomas Raber 1,* and Philippe Roth 1,2
1 Lengenbach Research Association (Forschungsgemeinschaft Lengenbach, FGL), Gemeinde Binn,
Dorfstr. 11, 3996 Binn, Switzerland
2 Swiss Seismological Service, ETH Zurich, Sonneggstr. 5, 8092 Zurich, Switzerland;
* Correspondence:
Anniversary publication60 years of continuous mineral search at Lengenbach and 15 years of FGL.
Received: 11 July 2018; Accepted: 6 September 2018; Published: 14 September 2018
Abstract: The Lengenbach quarry is a world-famous mineral locality, especially known for its rare
and well-crystallized Tl, Pb, Ag, and Cu bearing sulfosalts. As of June 2018, it is the type locality for
44 different mineral species, making it one of the most prolific localities worldwide. A total of 33
thallium mineral species have been identified, 23 of which are type minerals. A brief description of
several thallium species of special interest follows a concise and general overview of the thallium
Keywords: Lengenbach; Binn valley; thallium; sulfosalts; hutchinsonite; fangite; richardsollyite;
sartorite; routhierite-stalderite; chabournéite-dalnegroite
1. Introduction
The Lengenbach quarry in the Binn valley, Valais, Switzerland (Figures 1 and 2) is located in
Triassic meta-dolomites of the Penninic zone in the Swiss Alps. Metal extraction for economic
purposes never occurred in the quarry, but specimen extraction has been continuously carried out
since 1958. The quarry is currently operated by the Forschungsgemeinschaft Lengenbach (FGL,
literally: Lengenbach Research Association), financed by a group of idealistic collectors and by the
local community of Binn. The purpose of the research association is to promote scientific research on
the unique minerals of the Lengenbach deposit and of other dolomite localities in the Binn valley. An
intermittent, measured specimen extraction during the snow-free summer months shall guarantee
the potential for scientific investigations on the one hand and deliver dolomite material for a
publicly accessible dump, serving as an attraction to equally eager tourists and mineral collectors, on
the other hand.
This brief review gives a glimpse at the current status of the mineralogical research with regard
to the thallium mineralization at the locality. For further information about history, geology, and
mineral extracting work we recommend References [1,2].
Minerals 2018, 8, 409 2 of 16
Figure 1. The upper part of the Lengenbach quarry in the Binn valley, view to the east.
Figure 2. Ralph Cannon, technical head of the Forschungsgemeinschaft Lengenbach (FGL) research
association, at the entrance of the quarry in front of the concrete hall, where the current
mineral-extraction activities are carried out at the lowest dolomite level.
2. Geochemical Setting and Formation of the Lengenbach Locality
The Lengenbach ore body is located within the Penninic Monte Leone nappe, at the Northern
front and subvertical hinge zone of a large fold. The stratabound mineralization occurs in the
stratigraphically uppermost part of the 240 m thick dolomite sequence.
The formation of the highly complex mineralization in the Lengenbach deposit is not yet
completely understood. While Graeser [3] suggested a late introduction of As, Tl, and Cu into a
pre-existing Fe-Pb-Zn mineralization during Alpine metamorphism from the underlying gneissic
basement, Hofmann and Knill [4] proposed a pre-Alpine origin of those elements and a subsequent
isochemical Alpine metamorphism, under upper greenschist to lower amphibolite facies.
Minerals 2018, 8, 409 3 of 16
According to Hofmann and Knill [4], the distinct mineral associations in the different parts of
the Lengenbach dolomite can be understood as a result of slow crystallization processes in two
different redox environments. One is based on graphite and/or pyritepyrrhotite, leading to
zerovalent arsenic. The other, which was essential for the rare sulfosalts’ formation, is controlled by
baryte (sulfate)pyrite (sulfide), leading to trivalent arsenic. Accordingly, the As(III)-rich zone in the
central part of the quarry shows an enrichment in baryte and hosts the coveted Tl-Pb-Ag-Cu bearing
Graeser [3] as well as Hofmann and Knill [4] have each proposed a zonation scheme for the
different types of mineral assemblages. While the former considers in essence only mineralogical
and spatial criteria, the later rely on geochemistry and there is no obvious link between the two
zonations. However, it is clear that the Tl-rich zone is restricted to the central part of the quarry.
While on a broad scale the different bedding-parallel zones containing the different assemblages
strike subvertically in an eastwest direction (Figure 1), on the more local scale, they can be
subdivided into ribbons and ellipsoidal lenses that thicken, to a maximum thickness of 0.5 m, and
pinch out.
The FGL has been working for a few years on three such ribbons in the Tl-rich central zone
(Figure 3). They are spaced approximately 1 m apart, measure a maximum of 4 m × 2 m and are
designated, from north to south as ribbons 1, 1/2, and 2. Structurally, they are ellipsoidal in shape,
with a sharp contact to the surrounding, mineral-poor dolomite. The contrast is essentially a
mineralogical-geochemical, not a lithological contrast. Thanks to their high realgar contents, all three
ribbons are easily identified in situ. But while ribbon 1 is very rich in thallium species, the very
brittle and orpiment-rich dolomite of ribbon 1/2 is poorer in Tl while the realgar-richest ribbon 2 is
almost bare of any thallium-species. Table 1 summarizes all species found in ribbon 1; 18 species
containing thallium as one of main constituents are marked in bold characters.
Figure 3. Three realgar-rich ribbons in the central dolomite zone in the lower part of the quarry.
Ribbon 1 (red) is very rich in thallium species, ribbon 1/2 (yellow) contains much orpiment in a brittle
dolomite and is poorer in thallium, ribbon 2 (orange) is the realgar-richest ribbon, but almost bare of
any thallium species. The maximum ribbon thickness is about 0.5 m. Dashed lines show the expected
extension of the ribbons below the debris.
Minerals 2018, 8, 409 4 of 16
Table 1. Species constituting the mineral assemblage of ribbon 1 in the Lengenbach quarry. Tl
minerals are marked in bold, modified after reference [5].
Adularia and hyalophane
Canfieldite (Te-rich)
3. Overview of Thallium Minerals at Lengenbach
As of June 2018, the Lengenbach quarry hosts 160 different mineral species, with sulfides and
sulfosalts being the major group representing 57% of these species (Table 2 and Figure 4). Forty-four
minerals are so called type minerals as they have been found and described for the first time from
this locality. Twenty-three of them are thallium minerals. Table 3 lists all known Lengenbach
thallium minerals as of today.
Table 2. Mineralogical overview of the Lengenbach quarry.
* IMA (International Mineralogical Association) approved.
Minerals 2018, 8, 409 5 of 16
Figure 4. Distribution of mineral classes at Lengenbach.
Table 3. Thallium minerals at Lengenbach.
Mineral Species
Chemical Formula
Year of First Description
from Lengenbach
Reference for the Occurrence
at Lengenbach
Graeser (in Hofmann et al.) [6]
Roth [7]
Dalnegroite *
Nestola et al. [8]
Dekatriasartorite *
Topa et al. [9]
Edenharterite *
Graeser & Schwander [10]
Enneasartorite *
Topa et al. [11]
Erniggliite *
Graeser et al. [12]
Roth [13]
Ferrostalderite *
Biagioni et al. [14]
Gabrielite *
Graeser et al. [15]
Hatchite *
Solly & Smith [16]
Hendekasartorite *
Topa et al. [11]
Heptasartorite *
Topa et al. [11]
Hutchinsonite *
Solly [17]
Imhofite *
Burri et al. [18]
Incomsartorite *
Topa et al. [19]
Jentschite *
Graeser & Edenharter [20]
Graeser [21]
Raber [22]
Philrothite *
Bindi et al. [23]
Roth [24]
Raberite *
Bindi et al. [25]
Roth [26]
Ralphcannonite *
Bindi et al. [27]
Rathite *
Baumhauer [28]
Richardsollyite *
Meisser et al. [5]
Roth [29]
Sicherite *
Graeser et al. [30]
Spaltiite *
Graeser et al. [31]
Stalderite *
Graeser et al. [32]
Cannon [33]
Wallisite *
Nowacki [34]
Raber & Roth [35]
* Type minerals from the Lengenbach quarry.
From the 73 valid mineral species containing essential thallium worldwide (according to [36]), the striking number of 33 species (45.2%) could be found at Lengenbach.
Sulfides &
Sulfates & molybdates
Phosphates &
Minerals 2018, 8, 409 6 of 16
4. On Some Special Thallium Minerals from the Lengenbach Quarry
We focus here on a few thallium species of special interest, as a discussion of all thallium
sulfosalts would be beyond the scope of this brief note.
4.1. HutchinsoniteThe First of Its Kind
The first thallium mineral from Lengenbach, hutchinsonite, TlPbAs5S9, was found in 1903, when
the English expert of Lengenbach minerals, Richard Harrison Solly (18511925), during one of his
many trips to this remote Binn valley, recognized that the red to greyish-black, often flattened
orthorhombic crystals probably were belonging to a new species. He briefly described it in 1904 [37],
without giving it a name. In 1905, his colleague at the British Museum, G.T. Prior was able to reveal
the presence of 20 wt % Tl in hutchinsonite. This was of “especial interest”, as Solly [17] wrote in his
following detailed description, in which he named the mineral after Arthur Hutchinson (18661937).
Prior’s discovery of thallium in hutchinsonite was important enough to result in a short note in
Nature [38], as it was only the third mineral worldwide (after crookesite and lorándite) to contain
thallium as an essential constituent.
Hutchinsonite is the most common thallium species in the deposit and represents the type
structure of a family of complex sulfosalts. Its crystals are commonly transparent and prismatic, due
to an elongation parallel to the c axis (see Figures 57), or, rarely, more or less isometric.
Hutchinsonite may contain antimony that contributes the crystals to be darker and opaque. The two
varieties, prismatic Sb-free and more isometric Sb-bearing hutchinsonites, may be closely associated.
The crystals reach 2 mm in size.
Figure 5. Dark wine-red, transparent, lath-like hutchinsonite crystals on dolomite. Field of view 1.4
mm. Photo: Edgar Müller.
Minerals 2018, 8, 409 7 of 16
Figure 6. Translucent aggregate of parallel-oriented, red, flattened hutchinsonite crystals with pyrite
on dolomite. Field of view: 2.5 mm. Photo: Stephan Wolfsried.
Figure 7. Prismatic dark-red to grey crystals of hutchinsonite. Field of view: 1.5 mm. Photo: Stephan
4.2. FangiteThe Thallium-Richest
Well-developed crystals of fangite, Tl3AsS4, could recently be identified for the first time
[13]to our knowledge, the first microscopically visible crystals of this species worldwide. They are
small, deep red, and very shiny (Figure 8). With more than 75 wt % Tl, fangite is the thallium-richest
mineral discovered at Lengenbach up to now.
A morphological study of the small crystals [26] showed them to display different combinations
of crystal forms, irrespective of the fact that the prismatic habit is always approximately the same
(Figure 9).
Minerals 2018, 8, 409 8 of 16
Figure 8. Tiny, prismatic, lustrous, red fangite crystals on dolomite. Field of view: 0.75 mm. Photo:
Mischa Crumbach.
Figure 9. Fangite crystals showing different combinations of forms but similar habits. A distinct
color is assigned to each crystal form. The Miller indices of the different forms are given without
brackets FACES drawings [39].
4.3. RichardsollyiteHonoring a Pioneer
In 2015, the FGL extracted two specimens with an unknown mineral from the very Tl-rich
dolomite ribbon 1 (Figure 3) in the center of the quarry. Its chemistry, as first determined by Energy
Dispersive X-ray Spectroscopy (EDXS) measurements in two independent institutes, showed the
presence of Tl, Pb, As, and S in a simple, yet unknown ratio of 1:1:1:3. Also the powder X-ray
diagram did not match with any known listed natural or synthetic chemical compound in the
relevant databases. One year later, Meisser et al. [5] could describe this mineral as a new species with
the name richardsollyite (Figure 10), TlPbAsS3, honoring the aforementioned pioneer of Lengenbach
investigations at the dawn of the twentieth century, R.H. Solly. The crystal structure of
richardsollyite is new in nature, being previously known only in some synthetic alkali sulfosalts [5].
Minerals 2018, 8, 409 9 of 16
Figure 10. Holotype specimen of richardsollyite (dark grey) with hutchinsonite (dark red) and
realgar. Field of view: 3.5 mm. Mineralogical Collection of the Musée cantonal de géologie (MGL no.
080126), photo: Stefan Ansermet.
4.4. The New Sartorites”—From a Species to a Group
Sartorite, PbAs2S4, was first described by vom Rath as scleroclase in 1864 [40], and shortly
after renamed by Dana [41] to honor Wolfgang Sartorius von Waltershausen (18091876), a professor
of mineralogy in Göttingen, Germany. In 1919, Smith and Solly [42] recognized that sartorite
hasdespite its simple chemical formula—a quite unique and complex crystal structure: sartorite
appears to rank with the telluride of gold, calaverite, in the peculiarity of its atomic arrangement, since in
certain at least of his crystals there exist simultaneously two or even three incongruent space-lattices, which
may be supposed derivable from one another by a slight shear.” It is quite remarkable that they were able,
with the limited methods of their timein essence only crystal-morphological investigationsto
recognize the so-called complex and incommensurate nature of both the calaverite and, partly,
sartorite structures.
After the introduction of X-ray investigations in crystallography, several different monoclinic
super cells (superstructures) were described [4346]. Berlepsch et al. [46] pointed to the
crystallographic consequences of the complex correlated atomic substitution by which substantial
amounts of thallium are incorporated into the sartorite structure. They found a so-called 9-fold
superstructure for a sartorite with up to 6.5 wt % Tl and discussed this as a “lock-in” structure with a
commensurate lattice, for a species that they regarded as usually incommensurate.
The true nature of sartorite was finally resolved by Topa et al. [9,11,19]. Based on a systematic
combination of electron microprobe measurements and crystal structure determinations they
showed that sartorite actually represents a group of different mineral species with distinct crystal
structures and distinct chemical compositions. According to their different superstructures, the new
sartorites were named by adding a Greek prefix, which corresponds to an integral multiple of the
basic sartorite substructure with 4.2 Å (Table 4).
Minerals 2018, 8, 409 10 of 16
Table 4. The new sartorite minerals.
Mineral Name
Chemical Formula
Superstructure of the Sartorite Subcell (4.2 Å)
Heptasartorite [11]
Enneasartorite [11]
Hendekasartorite [11]
Incomsartorite [19]
11-fold (incommensurate)
Dekatriasartorite [9]
These species are not visually distinguishable. The crystals are lead-grey with a metallic luster.
Well-developed crystals show a prismatic habit with more or less distinct striation parallel to the
longitudinal axis (Figure 11). Their length reaches several centimeters.
Figure 11. Lead-grey, metallic, prismatic crystal of dekatriasartorite. Field of view 4.8 mm. Photo:
Mischa Crumbach.
4.5. The Routhierite-Stalderite GroupComplex Substitutions
The routhierite-stalderite series is a group of thallium arsenio-sulfosalts with, in addition,
monovalent (Me1: Cu+, Ag+) and bivalent metal ions (Me2: Hg2+, Zn2+, Fe2+) and the generic formula
TlMe1+Me22+As2S6. Accordingly, six different combinations, and thus six distinct mineral species are
theoretically possible in this group (Table 5, Figure 12). Five could indeed be found in nature:
arsiccioite, routhierite, stalderite, ralphcannonite, and ferrostalderite. The latter four occur in the
Lengenbach quarry, the type-locality for the latter three. Routhierite and arsiccioite are red to
dark-red in color, the other three are dark grey with a metallic luster, but they all show the same
pseudo-cubic to prismatic morphology (≤1 mm).
Minerals 2018, 8, 409 11 of 16
Table 5. Routhierite-stalderite group minerals.
Mineral Species
Chemical Formula
Figure 12. The minerals of the routhierite-stalderite group in a block diagram. The six distinct
species are the result of the six possible combinations of monovalent (Ag+, Cu+) and bivalent metal
ions (Zn2+, Hg2+, Fe2+). Modified after Reference [27].
In the frame of a series of EDXS analyses on Lengenbach samples from the mineralogical
collection of the Eidgenössiche Technische Hochschule (ETH) collection in Zurich, we recently
identified what to our knowledge are the first completely idiomorphic crystals of routhierite
worldwide (Figure 13).
Arsiccioite has not yet been found at Lengenbach. However, a single EDXS analysis of a minute
crystal indicated a possible dominance of silver and iron, and thus, the possible existence of the last
unreported member of this group in the quarry.
Minerals 2018, 8, 409 12 of 16
Figure 13. Idiomorphic, pseudo-cubic crystals of routhierite from the mineralogical collection of the
Eidgenössiche Technische Hochschule ETH in Zurich.
4.6. Chabournéite-DalnegroiteAnd Possibly More
Dalnegroite was described as a new mineral species from Lengenbach in 2009 [8]. It is
considered the As-analogue of chabournéite. The latter was also recently identified in one single
specimen showing what appears to be the first distinct crystals for the species: They are very similar
to the dalnegroite crystals and also show a strong similarity to lengenbachite crystals, which may
imply that the two rare species may have been mistaken for lengenbachite in the past (Figure 14).
Both dalnegroite and chabournéite are Pb-bearing species. In ribbon 1/2, however, the FGL has
recently found a few samples of a Pb-free dalnegroite (Figure 15), the equivalent of the Pb-free
chabournéite from Jas Roux, France [47,48]. The Pb-free species may well be distinct minerals
(Figure 16). Their study needs to be refined and completed.
Figure 14. Black, stellar aggregates of chabournéite on dolomite. Field of view 1.2 mm. Photo: M.
Minerals 2018, 8, 409 13 of 16
Figure 15. Aggregate of small acicular crystals of “Pb-free dalnegroite” from ribbon 1. Field of view
0.6 mm.
Figure 16. Diagram of Jas Roux and Abuta (France, resp. Japan, open diamonds)
chabournéite,Monte Arsiccio (Italy, open circles) protochabournéite and Lengenbach (open squares)
dalnegroite, modified after Reference [48], with copyright permission from Mineralogical
Association of Canada, 2013. Dalnegroites are located in the As-dominated left part of the diagram,
chabournéites and protochabournéites in the right part with Sb-dominance. The Pb content
increases along the y-axis. The new Lengenbach samples (analyzed by EDXS) are shown as red
squares. Lengenbach chabournéite is located in the Pb-rich part of the diagram (the cross gives the
1 sigma of all measurements), showing a higher Sb content than the samples from Jas Roux. The
nearly Pb-free dalnegroite seems to be clearly isolated from the holotype material of this species
(open squares).
Minerals 2018, 8, 409 14 of 16
5. Summary and Perspective
Since 1958 an uninterrupted prospection for and extraction of mineral specimens has been
performed in the Lengenbach quarry. Three working collectives have been successively in charge of
these purely non-profit operations, aimed at providing interesting specimens to both science and
collector communities. The Arbeitsgemeinschaft Lengenbach (AGL, literally: Lengenbach Working
Association) was active from 1958 to 1997 and extracted 28,422 specimens in total. It was followed by
the Interessengemeinschaft Lengenbach (IGL, literally: Lengenbach Interest Association), active from
1998 to 2002. The IGL produced 2424 specimens. The Forschungsgemeinschaft Lengenbach (FGL),
which was founded in 2003 and celebrates its 15th anniversary in 2018, has been extremely
successful. The association could ensure the collaboration of several experts as Preferred Associated
Scientists, who performed countless investigations to increase our knowledge of the Lengenbach
mineralogy, and to contribute with many publications and the description of several new mineral
species to further enhance Lengenbach’s reputation as an eldorado for rare and complex sulfosalts.
In these 15 years, 43 new mineral species have been described from the Lengenbach quarry,
including 17 new type minerals.
As a consequence of the specimen extraction performed since 2014 in the Tl-rich dolomite
ribbon 1, the number of thallium-bearing mineral samples extracted in the quarry has significantly
increased recently, as it was already the case in the late eighties and early nineties when the AGL
also worked in this zone (Figure 17). The FGL plans to continue the mineral prospection and
extraction during the next two or three years in this fascinating part of the deposit. Consequently,
there is a good chance to find additional rare thallium sulfosalts andwho knowseventually also
new mineral species.
Figure 17. Number of thallium bearing samples officially cataloged by the three working
associations, since 1958.
Author Contributions: Both authors (T.R. and P.R.) contributed to varying degrees to all the different aspects
of the work that led to this article. This includes conception, investigations, formal analyses, validation, draft
preparation, review and editing, as well as administration.
Funding: This research received no external funding.
Acknowledgments: We would like to thank the Verein Freunde Lengenbach” association, for its yearly financial
contribution, and their members for their active support to the operational work in the quarry during their
summer holidays. Special thanks go to FGL’s Scientific Head, Nicolas Meisser (Lausanne, Switzerland) and to
our Preferred Associated Scientists who are always willing to investigate interesting mineral samples from the
quarry, and without whom the incredible mineralogical success of the Lengenbach as worldwide-renowned
sulfosalt locality would not have been possible: Fabrizio Nestola (Padua, Italy), Jakub Plášil (Prague, Czech
Republic), Dan Topa (Vienna, Austria). Thanks also go to three anonymous reviewers who substantially
helped improve this work. We are also grateful to the Minerals editors for their thorough and thoughtful
Minerals 2018, 8, 409 15 of 16
Conflicts of Interest: The authors declare no conflict of interest.
1. Graeser, S.; Cannon, R.; Drechsler, E.; Roth, P.; Raber, T. Faszination LengenbachAbbau, Forschung,
Mineralien; KristalloGrafik Verlag: Achberg, Germany, 2008; p. 192. (In German)
2. Roth, P.; Raber, T.; Drechsler, E.; Cannon, R. The Lengenbach Quarry, Binn Valley, Switzerland. Mineral.
Rec. 2014, 45, 157196.
3. Graeser, S. Die Mineralfunde im Dolomit des Binnatales. Schweiz. Mineral. Petrogr. Mitt. 1965, 45, 597795.
(In German)
4. Hofmann, B.A.; Knill, M.D. Geochemistry and genesis of the Lengenbach Pb-Zn-As-Tl-Ba-mineralisation,
Binn Valley, Switzerland. Miner. Depos. 1996, 31, 319339.
5. Meisser, N.; Roth, P.; Nestola, F.; Biagioni, C.; Bindi, L.; Robyr, M. Richardsollyite, TlPbAsS3, a new
sulfosalt from the Lengenbach quarry, Binn Valley, Switzerland. Eur. J. Mineral. 2017, 29, 679688.
6. Hofmann, B.; Graeser, S.; Imhof, T.; Sicher, V.; Stalder, H.A. Mineralogie der Grube Lengenbach, Binntal,
Wallis. Jahrb. Naturhist. Mus. Bern 1993, 11, 390. (In German)
7. Roth, P. Chabournéit, eine weitere interessante Neuentdeckung. Schweizer Strahler 2017, 51, 3638. (In
German and French)
8. Nestola, F.; Guastoni, A.; Bindi, L.; Secco, L. Dalnegroite, Tl5-xPb2x(As,Sb)21xS34, a new thallium sulphosalt
from Lengenbach quarry, Binntal. Mineral. Mag. 2009, 73, 10271032.
9. Topa, D.; Stoeger, B.; Makovicky, E.; Stanley, C. Dekatriasartorite, IMA 2017-071. In IMA Commission on
New Minerals, Nomenclature and Classification (CNMNC) Newsletter 40, 2017; p. 1579. Available online:
difications (accessed on 11 July 2018).
10. Graeser, S.; Schwander, H. Edenharterite (TlPbAs3S6): A new mineral from Lengenbach, Binntal
(Switzerland). Eur. J. Mineral. 1992, 4, 12651270.
11. Topa, D.; Makovicky, E.; Stoeger, B.; Stanley, C. Heptasartorite, Tl7Pb22As55S108, enneasartorite,
Tl6Pb32As70S140 and hendekasartorite, Tl2Pb48As82S172, three members of the anion-omission series of
‘sartorites’ from the Lengenbach quarry at Binntal, Wallis, Switzerland. Eur. J. Mineral. 2017, 29, 701712.
12. Graeser, S.; Schwander, H.; Wulf, R.; Edenharter, A. Erniggliite, (Tl2SnAs2S6), a new mineral from
Lengenbach, Binntal (Switzerland): Description and crystal structure determination based from data
synchrotron radiation. Schweiz. Mineral. Petrogr. Mitt. 1992, 72, 293305.
13. Roth, P. Fangit: Neue Mineralart für die Schweiz und die ersten Kristalle. Schweizer Strahler 2017, 51, 3537.
(In German and French)
14. Biagioni, C.; Bindi, L.; Nestola, F.; Cannon, R.; Roth, P.; Raber, T. Ferrostalderite, CuFe2TlAs2S6, a new
mineral from Lengenbach, Switzerland: Occurrence, crystal structure, and emphasis on the role of iron in
sulfosalts. Mineral. Mag. 2016, 80, 175186.
15. Graeser, S.; Topa, D.; Balić-Žunić, T.; Makovicky, E. Gabrielite, Tl2AgCu2As3S7, a new species of thallium
sulfosalt from Lengenbach, Binntal, Switzerland. Can. Mineral. 2006, 44, 135140.
16. Solly, R.H.; Smith, G.F. Hatchite, a new (anorthic) mineral from the Binnenthal. Mineral. Mag. 1912, 16,
17. Solly, R.H. Some new minerals from the Binnenthal, Switzerland. Mineral. Mag. 1905, 14, 7282.
18. Burri, G.; Graeser, S.; Marumo, F.; Nowacki, W. Imhofit, ein neues Thallium-Arsensulfosalz aus dem
Lengenbach (Binnatal, Kt. Wallis). Chimia 1965, 19, 499500. (In German)
19. Topa, D.; Stoeger, B.; Makovicky, E.; Stanley, C. Incomsartorite, IMA 2016-035. In IMA Commission on
New Minerals, Nomenclature and Classification (CNMNC) Newsletter 33, 2016; p. 1136. Available online: (accessed on 11 July 2018).
20. Graeser, S.; Edenharter, A. Jentschite (TlPbAs2SbS6)A new sulphosalt mineral from Lengenbach, Binntal
(Switzerland). Mineral. Mag. 1997, 61, 131137.
21. Graeser, S. Ein Vorkommen von Lorandit (TlAsS2) in der Schweiz. Contrib. Mineral. Petrol. 1967, 16, 4550.
(In German)
22. Raber, T. Neufunde von der Grube Lengenbach im Binntal: Parapierrotit. Schweizer Strahler 2016, 50, 2425.
(In German and French)
23. Bindi, L.; Nestola, F.; Makovicky, E.; Guastoni, A.; De Battisti, L. Tl-bearing sulfosalts from the
Lengenbach quarry, Binn valley, Switzerland: Philrothite, TlAs3S5. Mineral. Mag. 2014, 78, 19.
24. Roth, P. Neufunde von der Grube Lengenbach im Binntal: PicotpaulitEine weitere Thallium-haltige
Seltenheit. Schweizer Strahler 2015, 49, 3031. (In German and French)
Minerals 2018, 8, 409 16 of 16
25. Bindi, L.; Nestola, F.; Guastoni, A.; Peruzzo, L.; Ecker, M.; Carampin, R. Raberite, Tl5Ag4As6SbS15, a new
Tl-bearing sulfosalt from Lengenbach quarry, Binn valley, Switzerland: Description and crystal structure.
Mineral. Mag. 2012, 76, 11531163.
26. Roth, P. FGL (Forschungsgemeinschaft Lengenbach). Available online:
(accessed on 5 May 2018).
27. Bindi, L.; Biagioni, C.; Raber, T.; Roth, P.; Nestola, F. Ralphcannonite, AgZn2TlAs2S6, a new mineral of the
routhierite isotypic series from Lengenbach, Binn valley, Switzerland. Mineral. Mag. 2015, 79, 10891098.
28. Baumhauer, H. Über den Rathit, ein neues Mineral aus dem Binnenthaler Dolomit. Z. Kristallogr. 1896, 26,
593602. (In German)
29. Roth, P. Neufunde von der Grube Lengenbach im Binntal: Die Mineralien der
Routhierit-Stalderit-Gruppe. Schweizer Strahler 2016, 50, 2831. (In German and French)
30. Graeser, G.; Berlepsch, P.; Makovicky, E.; Balić-Zŭnić, T. Sicherite, TlAg2(As,Sb)3S6, a new sulfosalt
mineral from Lengenbach (Binntal, Switzerland): Description and structure determination. Amer. Mineral.
2001, 86, 10871093.
31. Graeser, S.; Topa, D.; Effenberger, H.; Makovicky, E.; Paar, W.H. Spaltiite, IMA 2014-012. In IMA
Commission on New Minerals, Nomenclature and Classification (CNMNC) Newsletter 20, 2014; p. 557.
Available online:
minmag.2014.078.3.05/minmag.2014.078.3.05.pdf (accessed on 11 July 2018).
32. Graeser, S.; Schwander, H.; Wulf, R.; Edenharter, A. Stalderite TlCu(Zn,Fe,Hg)2As2S6A new mineral
related to routhierite: Description and crystal structure determination. Schweiz. Mineral. Petrogr. Mitt.
1995, 75, 337345.
33. Cannon, R. Mineral-Neufunde aus dem Dolomit am Lengenbach, Binntal (Wallis)/Schweiz. Aufschluss
2005, 56, 375390. (In German)
34. Nowacki, W. Über einige Mineralfunde aus dem Lengenbach (Binnatal, Kt. Wallis). Eclogae Geol. Helv.
1965, 58, 403406. (In German)
35. Raber, T.; Roth, P. Neufunde von der Grube Lengenbach im Binntal: Weissbergit, ein
Thallium-Antimon-Sulfosalz. Schweizer Strahler 2014, 48, 1819. (In German and French)
36. Available online: (accessed on 5 May 2018).
37. Solly, R.H. On some minerals from the Binnenthal, Switzerland. Proc. Cambridge Phil. Soc. 1904 (read
October 1903), 12, 277.
38. Prior, G.T. A new thallium mineral. Nature 1905, 71, 534, doi:10.1038/071534b0.
39. Favreau, G. The FACES Software, version 4.2; A User-Friendly Tool for Crystal Modeling; Yearly
Symposium, Cleveland Mineralogical Society: Cleveland, OH, USA, 2003.
40. Rath, G. vom. IV. Mineralogische Mitteilungen: Über den Dufrénoysit und zwei andere im rhombischen
Systeme krystallisirende Schwefelverbindungen (Skleroklas und Jordanit) aus dem Binnenthale. Pogg.
Ann. 1864, 122, 371400. (In German)
41. Dana, J.D. System of Mineralogy, 5th ed.; John Wiley & Sons: Hoboken, NJ, USA, 1868; p. 88.
42. Smith, G.F.; Solly, R.H. On sartorite and the problem of its crystal-form. Mineral. Mag. 1919, 18, 259316.
43. Bannister, F.A.; Pabst, A.; Vaux, G. The Crystallography of Sartorite. Mineral. Mag. 1939, 25, 264270.
44. Nowacki, W.; Bürki, H.; Iitaka, Y.; Kunz, V. Structural investigations on sulfosalts from the Lengenbach,
Binn Valley (Ct. Wallis). Part 2. Schweiz. Mineral. Petrogr. Mitt. 1961, 41, 103116.
45. Pring, A.; Williams, T.B.; Withers, R. Structural modulation in sartorite: An electron microscope study.
Am. Mineral. 1993, 78, 619626.
46. Berlepsch, P.; Armbruster, T.; Makovicky, E.; Topa D. Another step toward understanding the true nature
of sartorite: Determination and refinement of a ninefold superstructure. Am. Mineral. 2003, 88, 450461.
47. Johan, Z.; Mantienne, J.; Picot, P. La chabournéite, un nouveau minéral thallifère. Bull. Minéral. 1981, 104,
1015. (In French)
48. Orlandi, P.; Biagioni, C.; Moëlo, Y.; Bonaccorsi, E.; Paar, W.H. Lead-Antimony sulfosalts from Tuscany
(Italy). XIII. Protochabournéite, Tl2Pb(Sb9-8As1-2)Σ10S17, from the Monte Arsiccio Mine: occurrence, crystal
structure and relationship with Chabournéite. Can. Mineral. 2013, 51, 475494.
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access
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... According to their structure types, seven archetypes (SnS, PbS, sphalerite, Tl-rich structures, structures of combination of two archetypes, chain structures, and layer structures with thallium-rich layers) have been categorized, and detailed crystal structures and crystal-chemical generalizations have been made [54]. Tuscany in Italy and Lengenbach in Switzerland are two classic localities for these rare thallium sulfosalt minerals [35,55]. Metamorphic overprint upon previous hydrothermal deposits is responsible for the complex thallium mineralization [55,56]. ...
... Tuscany in Italy and Lengenbach in Switzerland are two classic localities for these rare thallium sulfosalt minerals [35,55]. Metamorphic overprint upon previous hydrothermal deposits is responsible for the complex thallium mineralization [55,56]. ...
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Thallium is a highly toxic metal and is predominantly hosted by sulfides associated with low-temperature hydrothermal mineralization. Weathering and oxidation of sulfides generate acid drainage with a high concentration of thallium, posing a threat to surrounding environments. Thallium may also be incorporated into secondary sulfate minerals, which act as temporary storage for thallium. We present a state-of-the-art review on the formation mechanism of the secondary sulfate minerals from thallium mineralized areas and the varied roles these sulfate minerals play in Tl mobility. Up to 89 independent thallium minerals and four unnamed thallium minerals have been documented. These thallium minerals are dominated by Tl sulfosalts and limited to several sites. Occurrence, crystal chemistry, and Tl content of the secondary sulfate minerals indicate that Tl predominantly occurs as Tl(I) in K-bearing sulfate. Lanmuchangite acts as a transient source and sink of Tl for its water-soluble feature, whereas dorallcharite, Tl-voltaite, and Tl-jarosite act as the long term source and sink of Tl in the surface environments. Acid and/or ferric iron derived from the dissolution of sulfate minerals may increase the pyrite oxidation process and Tl release from Tl-bearing sulfides in the long term.
... The presence of Tl-As-Hg-Sb-(Te) geochemical signature, including those belonging to the same paragenesis as gold, is also characteristic for Carlin-style gold deposits [22,23]. However, thallium minerals are also widely distributed in deposits associated with the metamorphosed carbonate strata composed of limestone and dolomite [24][25][26] with the formation of mineralized bodies according to the principle of alpine-type veins. However, in these deposits, the thallium mineralization is not accompanied by gold mineralization. ...
... In general, the presence of thallium mineralization in ore bodies of different genetic types can be explained by actively developed models of the magmatic formation of Carlinstyle deposits [22][23][24][25][26][27][28][29][30][31][32][33]. Within these models, thallium mineralization can be localized at a maximum distance from the magmatic source in the zone of intermediate argillic alteration and the distance from the magmatic source can reach more than 5 km. ...
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This paper describes native gold in ore-bearing breccias with realgar-orpiment cement from the Vorontsovskoe gold deposit (Northern Urals, Russia). Particular attention is paid to the morphological features of native gold and its relation to other minerals. The latter include both common (orpiment, barite, pyrite, prehnite, realgar) and rare species (Tl and Hg sulfosalts, such as boscardinite, dalnegroite, écrinsite, gillulyite, parapierrotite, routhierite, sicherite, vrbaite, etc.). The general geological and geochemical patterns of the Turyinsk-Auerbakh metallogenic province, including the presence of small non-economic copper porphyry deposits and general trend in change of the composition of native gold (an increase in the fineness of gold from high-temperature skarns to low-temperature realgar-orpiment breccias) confirm that the Vorontsovskoe deposit is an integral part of a large ore-magmatic system genetically associated with the formation of the Auerbakh intrusion.
... We defined nine major ore mineral assemblages, including seven related to carbonate breccias, and described 210 mineral species reliably identified at the deposit (Kasatkin et al. 2022b). By this number, the Vorontsovskoe deposit is noticeably ahead of three other deposits famous for their Tl-Hg-As-Sb-mineralization: Lengenbach in Switzerland (160 species -see Raber and Roth 2018), Allchar in North Macedonia (85 species -see Boev et al. 2012; and Jas Roux in France (53 species -see Bourgoin et al. 2011;www.mindat. ...
... There are only few larger Tl accumulations in the world (always accompanied by As mineralization) that could potentially serve as sources of this rare and toxic metal. The most important ones comprise the famous Xiangquan and Lanmuchang deposits in China (Liu et al. 2019(Liu et al. , 2020Lee et al., 2019;Lin et al., 2020), several Carlin-type gold deposits in Nevada, USA, the famous Lengenbach deposit in Switzerland (Hofmann and Knill, 1996;Raber and Roth, 2018), the Jas Roux occurrence in the French Alps (Johan und Manntiene, 2000), and the Allchar (Carlin-type Tl-As-Sb-Au) deposit in North Macedonia (Janković, 1993;Rieck, 1993;Percival and Radtke, 1994;Strmić Palinkaš et al., 2018). ...
Secondary minerals could be effective scavengers of toxic arsenic (As) and thallium (Tl). In environments polluted by mining, these elements are abundant both in acid rock/mine drainage scenarios, as well as in carbonate-buffered environments. In this study we have investigated the behavior of As and Tl during weathering in mine waste dumps and an associated technosol sample from the Crven Dol locality (Allchar Tl-As-Sb-Au deposit, North Macedonia) contaminated with up to 142 g∙kg–1 of As and 18 g∙kg–1 of Tl, making it an As- and Tl-extreme environment. We identified As and Tl reservoirs and discuss their difference from those observed in other naturally As- and Tl-rich environments. The pore waters show high concentrations of As (up to 196 mg·L⁻¹) and Tl (up to 660 μg·L⁻¹). Mild extractions mobilized up to 46% of the total Tl and 11% of the total As, indicating that a large amount of these toxic elements is weakly bound and can be easily mobilized into the environment. Apart from the recognition of Tl storage in several secondary phases (mainly as Tl(I) in members of the pharmacosiderite and jarosite groups, as well as Mn oxides, but also as very minor Tl(III) in other secondary phases), this study also provides the first evidence of Tl uptake by previously unknown thallium arsenate phases (with Tl:As ratios ∼ 2 and 4), detected in carbonate-buffered (near-neutral pH) As- and Tl-rich technosols and waste dumps. These results indicate the need for further studies on Tl speciation in extremely As- and Tl-rich environments.
... The Lengenbach quarry is well-known worldwide for its sulfosalt assemblages, typically characterised by the presence of Pb-As-Tl-Ag-Cu (e.g. Roth et al., 2014;Raber and Roth, 2018). Hofmann and Knill (1996) reported a 100-to 1000-fold higher content of Hg in the mineralised metadolostone than in the unmineralised one, similar to the enrichment factors of some other elements, e.g. ...
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Tennantite-(Hg), Cu 6 (Cu 4 Hg 2 )As 4 S 13 , was approved as a new mineral species (IMA2020-063) from the Lengenbach quarry, Imfeld, Binn Valley, Canton Valais, Switzerland. It was identified as an aggregate of black metallic tetrahedral crystals, less than 0.1 mm in size, intimately associated with sinnerite, and grown on realgar. In reflected light, tennantite-(Hg) is isotropic, grey in colour, with creamy tints. Minimum and maximum reflectance data for COM wavelengths in air are [λ (nm): R (%)]: 470: 29.1; 546: 29.1; 589: 28.5; 650: 27.7. Electron microprobe analysis gave (in wt.% – average of 7 spot analyses): Cu 32.57(42), Ag 6.38(19), Tl 0.29(14), Zn 0.04(5), Hg 17.94(2.27), Pb 0.70(51), As 17.83(61), Sb 0.34(8), S 24.10(41), total 100.19(1.04). The empirical formula of the sample studied, recalculated on the basis of Σ Me = 16 atoms per formula unit, is (Cu 4.69 Ag 1.04 Tl 0.03 ) Σ5.76 (Cu 4.35 Hg 1.58 Pb 0.06 Zn 0.01 ) Σ6.00 (As 4.20 Sb 0.05 ) Σ4.25 S 13.26 . Tennantite-(Hg) is cubic, I $\overline 4$ 3 m , with a = 10.455(7) Å, V = 1143(2) Å ³ and Z = 2. The crystal structure of tennantite-(Hg) has been refined by single-crystal X-ray diffraction data to a final R 1 = 0.0897 on the basis of 214 unique reflections with F o > 4σ( F o ) and 22 refined parameters. Tennantite-(Hg) is isotypic with other members of the tetrahedrite group. Mercury is hosted at the tetrahedrally coordinated M (1) site, in accord with the relatively long M (1)–S(1) distance (2.389 Å), similar to that observed in tetrahedrite-(Hg). Minor Ag is located at the triangularly-coordinated and split M (2) site. Other occurrences of tennantite-(Hg) are briefly reviewed and the Lengenbach finding is described within the framework of previous knowledge about the Hg mineralogy at this locality.
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The sediment-hosted As-Sb-Tl-Pb±Hg±Au Janjevo occurrence is located in the southern part of the Kizhnica-Hajvalia-Badovc ore field, in the Trepça (Trepča) Mineral Belt (TMB) in Kosovo. The As-Sb-Tl-Pb±Hg±Au mineralization is hosted by Upper Triassic marbles and occurs in the form of quartz-stibnite veins and dolomitized irregular pockets associated with jasperoid rocks. The main sulfide most widespread in the mineralization studied is pyrite which is the main carrier of thallium. A wide range of techniques was used to characterize the geochemistry and textural evolution of pyrite/ marcasite from Janjevo: polarized reflected-light microscopy, electron microprobe (EPMA), laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), X-ray powder diffraction (XRPD), Mössbauer spectroscopy, and isotopic studies. The study of 42 thin and polished sections resulted in the identification of 4 generations of pyrite/ marcasite. The first generation of pyrite related to the pre-ore stage occurs as framboidal pyrite with different degrees of evolution (Py1a), as well as recrystallized pyrite/ marcasite (Py1b). Au-enriched pyrite (Py2) occurs as elongated fibrous aggregates and is genetically associated with the formation of stibnite veins (Sb stage). As-Tl-Sb-Hg pyrite (Py3) forms irregular colloform aggregates which fill the stylolites and also overgrow older generations of pyrite. The youngest generation is represented by marcasite (Py4), which forms euhedral crystals. Co/Ni ratio <1 in all pyrite/ marcasite generations implies a sedimentary fingerprint. On the other hand, δ³⁴S isotopic studies confirm a magmatic sulfur source for As-Tl-Sb-Hg pyrite (Py3), as well as co-occurring stibnite and realgar. The most important minor and trace elements in pyrite/ marcasite are As (up to 14.1 %), Tl (up to 3.94 %), Sb (up to 3.73 %), and Hg (up to 0.55 %), which are mainly hosted by Py3. In addition to arsenic, thallium, antimony, and mercury, other generations of pyrite show enrichment in Ni, Co, and Cu (framboidal pyrite Py1), Au, and Se (Au-enriched pyrite Py2), and Se (marcasite Py4). The highest gold content of up to 6.08 ppm was recorded at Py2. Studies on Py3 geochemistry confirm the presence of 2Fe²⁺ ↔ Tl⁺ + Sb³⁺ heterovalent substitution in pyrite. As-Tl-Sb-Hg pyrite (Py3) is the main thallium host mineral in the mineralization studied, with significantly less thallium present in the Pb-Sb±Tl±As sulfosalts. In addition, the high arsenic content of Py3 is due to the presence of arsenic in the form of As¹⁻ and As⁰ related to amorphous arsenic-rich nanoparticles. The reported Py3 is the best phenomenon of the crystallization of colloform As-Tl-Sb-Hg-rich pyrite under hydrothermal conditions. Pyrite-rich sediment-hosted As-Sb-Tl-Pb±Hg±Au mineralization from Janjevo is associated with the distal manifestation of a concealed porphyry system.
How does one best subdivide nature into kinds? All classification systems require rules for lumping similar objects into the same category, while splitting differing objects into separate categories. Mineralogical classification systems are no exception. Our work in placing mineral species within their evolutionary contexts necessitates this lumping and splitting because we classify “mineral natural kinds” based on unique combinations of formational environments and continuous temperature-pressure-composition phase space. Consequently, we lump two minerals into a single natural kind only if they: (1) are part of a continuous solid solution; (2) are isostructural or members of a homologous series; and (3) form by the same process. A systematic survey based on these criteria suggests that 2310 (~41%) of 5659 IMA-approved mineral species can be lumped with one or more other mineral species, corresponding to 667 “root mineral kinds,” of which 353 lump pairs of mineral species, while 129 lump three species. Eight mineral groups, including cancrinite, eudialyte, hornblende, jahnsite, labuntsovite, satorite, tetradymite, and tourmaline, are represented by 20 or more lumped IMA-approved mineral species. A list of 5659 IMA-approved mineral species corresponds to 4016 root mineral kinds according to these lumping criteria. The evolutionary system of mineral classification assigns an IMA-approved mineral species to two or more mineral natural kinds under either of two splitting criteria: (1) if it forms in two or more distinct paragenetic environments, or (2) if cluster analysis of the attributes of numerous specimens reveals more than one discrete combination of chemical and physical attributes. A total of 2310 IMA-approved species are known to form by two or more paragenetic processes and thus correspond to multiple mineral natural kinds; however, adequate data resources are not yet in hand to perform cluster analysis on more than a handful of mineral species. We find that 1623 IMA-approved species (~29%) correspond exactly to mineral natural kinds; i.e., they are known from only one paragenetic environment and are not lumped with another species in our evolutionary classification. Greater complexity is associated with 587 IMA-approved species that are both lumped with one or more other species and occur in two or more paragenetic environments. In these instances, identification of mineral natural kinds may involve both lumping and splitting of the corresponding IMA-approved species on the basis of multiple criteria. Based on the numbers of root mineral kinds, their known varied modes of formation, and predictions of minerals that occur on Earth but are as yet undiscovered and described, we estimate that Earth holds more than 10 000 mineral natural kinds.
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The Vorontsovskoe gold deposit (Northern Urals) is unique in both Russia and the world because of the diverse and original Tl–Hg–Mn–As–Sb–S mineralization. Based on the available literature and our data, we present a list of 210 minerals found at this deposit. Eight of them are new minerals discovered by the authors: vorontsovite, ferrovorontsovite, tsygankoite, gladkovskyite, luboržákite, pokhodyashinite, gungerite, and auerbakhite. In addition, 41 minerals are found for the frst time in the Russian Federation and 89 minerals are new for the deposit. We defned nine major ore mineral assemblages, including seven ones related to carbonate breccias. They contain more than 70 rare sulfdes, tellurides and sulfosalts, including 31, 12, and 9 minerals with Tl, Hg and Mn, respectively, as species-defning elements. The paper also describes these mineral assemblages and minerals of the Vorontsovskoe deposit. Keywords: Vorontsovskoe deposit, Northern Urals, ore mineral assemblage, carbonate breccia, Tl-Hg-Mn sulfosalt, new mineral, frst fnd in Russia.
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This review offers an update on arsenic-bearing minerals and pigments with the aim of serving as a guide for the study of Cultural Heritage materials in which these materials can be found. The different As-bearing mineral phases (realgar, pararealgar, orpiment, anorpiment, alacranite, dimorphite, bonazziite, uzonite, wakabayashilite, duranusite, arsenolite and claudetite) and some of their light-induced products are examined. The occurrence of As-sulfides and their trade, use, alteration and degradation are also reviewed. Finally, the analytical techniques commonly used for the identification of arsenic-containing pigments are discussed. The manuscript concludes with a good-practice guide and a summary of key concepts for use by those working in the field of cultural heritage.
The new mineral species richardsollyite, TlPbAsS 3, was discovered in the Lengenbach quarry, Imfeld, Binn Valley, Canton Valais, Switzerland, intimately associated with hutchinsonite and baryte. It occurs as grey-black crystals, up to 750 μm, with a metallic lustre. Under the reflected-light microscope, richardsollyite is grey, with bright-red internal reflections; anisotropy is distinct, with greyish-white to bluish rotation tints. Reflectance values for the four COM wavelengths are [ R min, R max (%), (λ)]: 27.9, 29.8 (471.1 nm); 27.8, 31.0 (548.3 nm); 27.3, 30.8 (586.6 nm); and 27.0, 30.5 (652.3 nm). Electron microprobe analysis gave (in wt%): Tl 34.72(51), Pb 35.45(20), As 12.80(14), Sb 0.04(1), S 16.22(13), total 99.24(47). On the basis of 6 atoms per formula unit, the chemical formula is Tl 1.001Pb 1.008(As 1.007Sb 0.002) Σ1.009S 2.982. The main diffraction lines [ d in Å (intensity) hkl] are: 4.23 (80) 1 ⁻ 0 2; 3.875 (70) 2 ⁻ 1 1; 3.762 (100) 2 1 0, 1 2 0; 3.278 (70) 1 0 2; 2.931 (70) 0 2 2; 2.714 (70) 1 ⁻ 1 3; and 2.622 (80) 3 ⁻ 1 2. Richardsollyite is monoclinic, space group P2 1/ c, with a = 8.8925(2), b = 8.4154(2), c = 8.5754(2)Å, β = 108.665(3)°, V = 607.98(3)Å ³, Z = 4. The crystal structure was solved and refined to R 1 = 0.0242 on the basis of 1590 reflections with F o>4σ( F o). It can be described as formed by (1 0 0)[Pb(AsS 3)] ⁻ layers sandwiching Tl ⁺ cations, and is isostructural with synthetic ABCX 3 ( A = K, Rb, Cs; B = Eu, Ba; C = As, Sb; X = S, Se) compounds. The new mineral is named after Richard Harrison Solly (1851–1925) for his outstanding contribution to the knowledge of the Lengenbach mineralogy during the first flourishing period of Lengenbach investigations, at the beginning of the 20th Century.
The Lengenbach Pb-Zn-As-Tl-Ba mineralisation is located in Triassic dolostones of the Pennínic zone in the Swiss Alps where Alpine metamorphism reached upper greenschist to lower amphibolite grade. Geochemical data are used to constrain the origin of this unique occurrence. Two metamorphic redox environments are present: the As(III)-rich zone is controlled by barite-pyrite while the reduced zone contains graphite or pyrrhotitepyrite and formally zerovalent As. The As(III)-rich zone is characterised by a mineral assemblage consistent withfO2 in the stability field of barite + pyrite. An As-(Pb, Tl)-rich sulphide melt coexisted with a hydrothermal fluid at > 300 °C in this zone. Mineralised dolostones are anomalous in As, Pb, Ag, Tl, Hg, Zn, Ba, Cd, Fe, Cu, Mo, U, V, B, Ga, Cr and possibly Sri and Au (in order of decreasing enrichment). As, Pb and Zn are present in the 0.1 to 1% range, Tl and Ag reach several hundred ppm. Uraninite is concentrated in silicate-rich bands and yields a late Alpine U-Pb age of 18.5 ± 0.5 Ma. Pb- and S isotopic variations are interpreted by metamorphic overprinting and re-equilibration within an isochemically metamorphosed mineralisation. Hydrothermal sulphides are more strongly affected by uranogenic Pb than massive Pb-As-sulphides representing a former sulphide melt. The least overprinted mineralisation is characterised by206Pb/204Pb = 18.44 – 18.56,207Pb/204Pb = 15.60 – 15.75,208Pb/204Pb = 38.44 – 38.84 and δ34S (sulphide) = − 25 ± 2%. S isotopic variations are largely a result of sulphide-sulphate re-equilibration yielding temperatures of 450 ±30 °C.87Sr/86Sr ratios of mineralised samples are lower than or equal to host dolostones, precluding major infiltration of basement-derived fluids during Alpine metamorphism. The Sr source (87Sr/86Sr close to 0.708) probably was seawater with a radiogenic, detrital mineral component. The genesis of the unique Lengenbach mineralisation is interpreted as the result of isochemical metamorphic overprinting of a carbonate hosted stratiform sulphide mineralisation. Well-crystallised sulphide minerals in fissures and druses formed during retrograde cooling of a sulphide melt in equilibrium with a hydrothermal fluid. The primary mineralisation was probably formed at or close below the sea floor and fed by sulphide-poor hydrothermal fluids. Sulphide was largely derived from seawater by open system bacterial sulphate reduction. U, V and Mo may be seawater-derived.
Abstract: Detailed electron-microprobe investigations and crystal-structure determinations established that ‘sartorite’ represents a group of distinct mineral species, each with unique chemistry and crystal structure. These manifest themselves as the 7-, 9- and 11-fold P21/c superstructures of the basic 4.2Å substructure. Heptasartorite is Tl7Pb22As55S108 (based on 192 apfu, 84Me+108S) with a = 29.269(2), b = 7.8768(5), c = 20.128(2)Å, β = 102.065(2)° and unit-cell volume V = 4537.8Å3; enneasartorite is Tl6Pb32As70S140 (based on 248 apfu, 108Me+140S) with a = 37.612(6), b = 7.8777(12), c = 20.071(3)Å, β = 101.930(2)° and V=5818.6(15)Å3; hendekasartorite is Tl2Pb48As82S172 (based on 304 apfu, 132Me+172S) (empirical ΣMe = 132.48) with a = 31.806(5), b = 7.889(12), c = 28.556(4)Å and β = 99.034(2)° with V = 7076.4(15)Å3. Physical and optical properties (grey with metallic lustre, in polished section white with visible bireflectance, red internal reflections; reflectance curves span 28.7–42.5%; Mohs hardness 3–3½) of these phases are very similar so that chemical analysis and/or single-crystal X-ray diffraction is needed to distinguish them. A brief description of complicated AsmSn crank-shaft chains in the walls of double-ribbons which form the As-based slabs of these structures is given. The three new mineral species differ in their structures by 4.2Å modular increments, not just by cation substitutions. They represent anion-omission derivatives of the ‘ideal’ PbAs2S4 composition with an important role for thallium in charge compensation. The described minerals belong to the late sulfide phases in the Pb–Tl–Ag–As deposit of Lengenbach, Wallis, Switzerland.
The new mineral species ferrostalderite, CuFe2TlAs2S6, was discovered in the Lengenbach quarry, Binn Valley, Wallis, Switzerland. It occurs as minute, metallic, black, equant to prismatic crystals, up to 50 mu;m, associated with dolomite, realgar, baumhauerite (?) and pyrite. Minimum and maximum reflectance data for COM wavelengths in air are [λ (nm): R (%)]: 471.1: 24.2/25.4; 548.3: 23.7/24.7; 586.6: 22.9/23.8; 652.3: 21.0/22.0. Electron microprobe analyses give (wt.%): Cu 6.24(25), Ag 4.18(9), Fe 9.95(83), Zn 4.46(91), Hg 1.22(26), Tl 26.86(62), As 19.05(18), Sb 0.63(6),S 25.39(47), total 97.98(72). On the basis of 12 atoms per formula unit, the chemical formula of ferrostalderite is Cu0.75(2)Ag0.30(1)Fe1.36(10) Zn0.52(11) Hg0.05(1) Tl1.00(1)[As1.94(4)Sb0.04(1)]∑1.98(4)S6.04(4). The new mineral is tetragonal, space group I42 m, with a = 9.8786(5), c = 10.8489(8) Å, V = 1058.71(11) Å3, Z = 4. The main diffraction lines of the calculated powder diagram are [d (in Å), intensity, hkl]: 4.092, 70, 211; 3.493, 23, 220; 3.396, 35, 103; 3.124, 17, 310; 2.937, 100, 222; 2.656, 19, 321; 2.470, 19, 400; 2.435, 33, 303. The crystal structure of ferrostalderite has been refined by Xray single-crystal data to a final R 1 = 0.050, on the basis of 1169 reflections with F 0 > 4σ(F 0). It shows a three dimensional framework of (Cu,Fe)-centred tetrahedra (1M1 + 2 M2), with channels parallel to [001] hosting disymmetric TlS6 and (As,Sb)S3 polyhedra. Ferrostalderite is derived from its isotype stalderite M1Cu M2Zn2TlAs2S6 through the homovalent substitution M 2Zn2+ → M 2Fe2+. The ideal crystal-chemical formula of ferrostalderite is M 1Cu M2Fe2TlAs2S6.
The physical, optical and crystallographic properties of stalderite are described. A new Tl-sulfosalt mineral, stalderite TlCu(Zn,Fe,Hg)2As2S6, was found in small cavities of hydrothermal origin in a Triassic dolomite at the famous sulfosalt locality Lengenbach, Binntal (Ct. Valais, Switzerland). Structural determinations of stalderite and routhierite confirm the close relationship of both minerals -from Authors
The Lengenbach deposit has been famous among scientists and mineral collectors since the early nineteenth century. As the type locality for 31 new mineral species, the Lengenbach quarry ranks among the ten most prolific localities worldwide. But, unlike all the others, the mineralized body is small and has only been mined for scientific and collection purposes. Today it is still producing excellent specimens of rare species, primarily lead, thallium, silver, copper and arsenic sulfosalts.
The new mineral species ralphcannonite, AgZn2TlAs2S6, was discovered in the Lengenbach quarry, Binn Valley, Wallis, Switzerland. It occurs as metallic black equant, isometric to prismatic crystals, up to 50 μm, associated with dufrénoysite, hatchite, realgar and baryte. Minimum and maximum reflectance data for COM wavelengths in air are [λ (nm): R (%)]: 471.1: 25.8/27.1; 548.3: 25.2/26.6; 586.6: 24.6/25.8; 652.3: 23.9/24.8. Electron microprobe analyses give (wt.%): Cu 2.01(6), Ag 8.50(16), Zn 10.94(20), Fe 3.25(8), Hg 7.92(12), Tl 24.58(26), As 18.36(19), Sb 0.17(4), S 24.03(21), total 99.76(71). On the basis of 12 atoms per formula unit, the chemical formula of ralphcannonite is Ag0.63(2)Cu0.25(2)Zn1.35(5)Fe0.47(1)Hg0.32(2)Tl0.97(3)[As1.97(6)Sb0.01(1)]Σ1.98(5)S6.03(8). The new mineral is tetragonal, space group I42m, with a = 9.861 (2), c = 11.125(3) Å, V = 1081.8(4) Å3, Z = 4. The main diffraction lines of the calculated powder diagram are [d (in Å), intensity, hkl]: 4.100, 85, 211; 3.471, 40, 103; 2.954, 100, 222; 2.465, 24, 400; 2.460, 39, 303. The crystal structure of ralphcannonite has been refined by X-ray single-crystal data to a final R 1 = 0.030, on the basis of 140 observed reflections [F o > 4σ(F o)]. It shows a three dimensional framework of (Ag,Zn)-centred tetrahedra (1 M1 + 2 M2), with channels parallel to [001] hosting TlS6 and (As,Sb)S3 disymmetric polyhedra. Ralphcannonite is derived from its isotype routhierite M 1Cu M 2Hg2TlAs2S6 through the double heterovalent substitution M 1Cu+ + M 2Hg2+ → M 1Zn2+ + M 2Ag+. This substitution obeys a steric constraint, with Ag+, the largest cation relative to Zn2+ and Cu+, entering the largest M2 site, as observed in arsiccioite. The ideal crystal-chemical formula of ralphcannonite is M1Zn M 2(Zn0.5Ag0.5)2TlAs2S6.