MITT.ÖSTERR.MINER.GES. 167 (2021)

FROM A GARNET INCLUSION TO THE VARISCAN EVOLUTION:IMPLICATIONS FOR THE POLYMETAMORPHIC HISTORY OF THE
BOHEMIAN MASSIF
Sorger, D.1,2, Hauzenberger, C.A.1, Finger, F.3, Linner, M.4, Fritz, H.5, Sizova, E.1,
Skrzypek, E.1, Iglseder, C.4, Schorn, S.1
NAWI Graz Geocenter, University of Graz, Universitätsplatz 2, 8010 Graz, Austria
Present address: Geoscience Center, Georg-August-University Göttingen, Goldschmidtstraße 1, 37077
Göttingen, Germany
3
Department of Geography and Geology, University of Salzburg, Hellbrunnerstraße 34, 5020 Salzburg, Austria
4
Department of Hard Rock Geology, Geological Survey of Austria, Neulinggasse 38, 1030 Vienna, Austria
5
NAWI Graz Geocenter, University of Graz, Heinrichstraße 26, 8010 Graz, Austria
e-mail: dominik.sorger@uni-goettingen.de
1

2

The Central European Variscan orogen consists of a mosaic of various peri-Gondwana terranes,
which separated from Gondwana at various times during the Cambrian to Devonian. Later,
during the Devonian-Carboniferous they were between the converging continents of Gondwana
and Laurussia as the Rheic ocean closed. While the major part of the Bohemian Massif belongs
to the so-called Armorican terrane, some eastern parts are assigned to the Avalonian terrane,
which amalgamated with the southern margin of Laurussia in the Silurian. The major phase of
the regional metamorphism affected the rocks of the Bohemian Massif in the Visean at ~340
Ma and is thought to correspond to the final collision of Avalonia/Laurussia andArmorica/Gondwana (FINGER & STEYRER, 1995; KRONER & ROMER, 2013). Evidenceof this predominant metamorphism is typically observed in the Bohemian Massif, while somerocks have remnants of an older metamorphism and/or were affected by a younger metamorphic
overprint. The investigated part of the Bohemian Massif can be assigned to the high-grade
Moldanubian zone, which is traditionally assigned to the Armorican terrane and is subdivided
into several tectonostratigraphic subunits that were juxtaposed into their present relative
positions during the Variscan orogeny. The high-grade Gföhl unit overlies both, the Drosendorf
and Ostrong units. Although the Drosendorf unit was traditionally assigned to be part of theArmorican terrane, a detrital zircon study revealed zircon ages at ~1.2 Ga, ~1.5 Ga and ~1.8
Ga, which confirms an Avalonian affinity of the Drosendorf unit (SORGER et al., 2020). The
youngest detrital zircon generation suggests a Neoproterozoic deposition age of the precursor
siliciclastic sediment. These findings are in good agreement with recent zircon studies oforthogneisses from the Drosendorf unit (LINDNER et al., 2020). The area in the south-westernpart of the Moldanubian zone, which is characterized by a low-pressure–high-temperature (LP–HT) metamorphism associated with granitic plutonism, is referred to as the Bavarian unit.
Polyphase garnet growth, remnant mineral inclusions and textural relations in samples fromthree prominent localities located in the Austrian part of the Bohemian Massif allowed us todecipher three different Variscan metamorphic events: an early Variscan event in the Devonian(event1, ~370 Ma), the predominant metamorphism in the Visean (event2, ~340 Ma), both withcollisional P–T characteristics and a Pennsylvanian LP–HT overprint (event3, ~315 Ma).
The Devonian event1 can be observed in metapelitic paragneiss from the southern Drosendorf
unit, which exhibit two chemically and texturally different garnet generations that provide

67evidence of a polymetamorphic evolution. Both garnet generations carry abundant inclusions,the most important are monazite, rutile, kyanite, staurolite (limited to the second garnet
generation) and crystallized melt droplets. The latter is indicating a peritectic growth of the hostgarnet in the presence of a melt phase. Thermodynamic modelling combined with various
geothermo- and barometers allow the reconstruction of the complex evolution of two garnetforming metamorphic events (SORGER et al., 2020). The metamorphic conditions for the firststage of garnet growth are estimated with 0.7–0.8 GPa at 680–700 °C and 0.95–1.10 GPa at
745–785 °C (Fig. 1). A Late Devonian age (373 ± 9 Ma) for this first metamorphic event(event1) was obtained from chemical dating of monazite inclusions in grt1. Generally, monazite
has Y- and U-rich core domains that were overgrown by Th enriched domains. The latter may
contain inclusions of crystallized melt droplets indicating a peritectic growth of monazite
contemporaneous with garnet. Additionally, a significantly older monazite generation (654 ±17 Ma) enriched in U and Y appears as inclusions in grt1 and can be interpreted as inherited
grains of a Cadomian metamorphic event.
Subsequent exhumation after event1 placed these rocks in a shallower position. A second garnet(grt2) started growing in the amphibolite facies reaching peak conditions in the granulite facies
with 0.95–1.10 GPa at 745–785 °C (Fig. 1), which are similar to those of the first garnet forming
event. Subsequently, the rocks experienced a near isothermal decompression to 0.5–0.8 GPa
accompanied by sillimanite and ilmenite growth in the matrix. A Visean age (343 ± 3 Ma) of
monazite inclusions in grt2 and matrix grains correlates the second garnet forming event withthe predominant metamorphism in the Bohemian Massif (event2). Similar ages are known forthe metamorphic peak conditions of the rocks from the adjacent Gföhl unit, which includes
high-pressure–ultra-high-temperature (HP–UHT) felsic granulite, orthogneiss and paragneiss.
Aluminous paragneiss from the Loosdorf complex (south-eastern Gföhl unit), which constitutes
the hangingwall part of the large granulite bodies, provide some new insights on the exhumation
history of these high-grade rocks at the end of the Visean metamorphic event (event2). The
paragneiss commonly show reaction coronas of complementary cordierite moats and cordierite+ spinel symplectites located at former garnet-sillimanite interfaces. Garnets and embedded
rutile ± kyanite are relics of the previous peak assemblage and record the metamorphic
conditions of 0.8–1.1 GPa and 770–820 °C. The reaction textures formed in the course of anearly isothermal decompression (ITD) path at LP–HT of ∼0.5 GPa and ∼750 °C. The inferred
P–T evolution suggests prograde metamorphism reaching granulite facies metamorphism atlower crustal depth of ∼35 km subsequently followed by the ITD to the upper/middle crustal
level (∼15 km depth). The P–T evolution emphasizes rapid exhumation of the Loosdorf
complex at the hangingwall position of the felsic granulite, which was most likely triggered by
the exhumation of the HP–UHT granulite itself. Monazite inclusions in garnet and matrix grains
yielded a slightly younger age of ∼335 Ma. Although ages are overlapping within errors they
may indicate the age of the retrograde LP–HT overprint during the exhumation subsequently
after the metamorphic peak of event2 at ~340 Ma.
The Bavarian unit in the south-western part of the Bohemian Massif is characterized by strong,late-Variscan, LP–HT metamorphism. Rare migmatite varieties hosting garnets record detailed
information regarding the regional P–T–t evolution. The garnet porphyroblasts preservecomplex three-phase growth zoning and variable mineral inclusions indicative of apolymetamorphic history (Sorger et al., 2018). Garnet cores (grt1) and related inclusions
yielded a medium-pressure–medium-temperature (MP–MT) metamorphic peak of 0.85–1.10
GPa at 720–780 °C (Fig. 1). Monazite inclusions in grt1 reveals an age of 340 ± 7 Ma indicatingthat the garnet cores are remnants of the predominant regional metamorphism (event2).
This first metamorphic stage was followed by a stage of decompression and cooling resulting
in a partial resorption of grt1. A second prograde metamorphic stage then caused additional
garnet growth, starting at 0.45–0.60 GPa at 580–630 °C (grt2 and inclusions) and leading to68

LP–HT peak conditions of 0.55–0.65 GPa and 830–900 °C (grt3 and matrix). Monazite
inclusion in grt2 yielded an age of 319 ± 6 Ma, matrix monazite and inclusions in grt3 produced
an age of 312 ± 5 Ma, which dates the pervasive LP–HT overprint (event3).
Our petrological and geochronological data suggest that Avalonian and Armorican terranes had
already collided in the late Devonian (event1), as proposed by KRONER & ROMER (2013).
However, this is important from the viewpoint of global plate tectonics, as it marks the closureof the Rheic ocean. The final architecture of the Variscan orogen was established considerably
later following a further strong collisional phase with regional high-grade metamorphism at~340 Ma (event2). This was most likely a short-lived tectonic event with HT–HP granulite
formation and a rapid exhumation thereafter. In the final stage of the Variscan orogeny someparts of the Moldanubian zone (Bavarian unit) were selectively reheated (event3). The isobaric
heating to granulite facies conditions at the middle crustal level point to a significant external
heat influx into the middle crust at this stage (e.g. mantle delamination).

Figure 1: Proposed P–T–t paths for the Late Devonian (event1), the Visean (event2) and the Pennsylvanian(event3) metamorphic events, modified after SORGER et al., 2018, 2020.

FINGER, F., STEYRER, H. P. (1995): Geol. Carpathica, 46, 137–150.
KRONER, U., ROMER, R. L. (2013): Gondwana Res., 24, 298–329.
LINDNER, M., DÖRR, W., REITHER, D., FINGER, F. (2020): Geol. Soc., London, Special Publ., SP5032019-232.
SORGER, D., HAUZENBERGER, C.A., FINGER, F., LINNER, M. (2020): Gondwana Res., 85, 124–148.
SORGER, D., HAUZENBERGER, C.A., LINNER, M., IGLSEDER, C., FINGER, F. (2018): J. Petrol., 59,
1359–1382.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

CERAMIC INVESTIGATIONS IN THE SYSTEM CaO-Al2O3-ZnO
Albertus, M.1, Kahlenberg, V.1
University of Innsbruck, Institute of Mineralogy and Petrography, Innrain 52, 6020 Innsbruck, Austria
e-mail: max.albertus@student.uibk.ac.at

1

The ternary system CaO-Al2O3-ZnO has been studied since the 1960s with a special focus on
the influence of zinc oxide on the properties of the calcium aluminates occurring in Portland
cement clinkers (AKATSU et al., 1968). In an investigation by BARBANYAGRE &TIMOSHENKO (1996), single crystals of two different calcium zinc aluminates(Ca14Al10Zn6O35 and Ca3Al4ZnO10, respectively) have been synthesized and their crystal
structures and crystallochemical properties have been determined. In recent years, bothternary compounds have seen a revival of interest. After doping with Ti4+, Ca14Al10Zn6O35 canbe used as an attractive material for phosphor production due to its very good luminescence
properties, environmental safety and low-cost components (WU et al., 2019). In addition, thephase offers an extraordinary potential as an optically transparent ceramic material for a wide
range of applications. However, previous studies also have shown that one of the major
requirements for optical ceramics - sufficient phase purity - has not been achieved yet.
In the course of this investigation, selected synthesis routes aiming on the preparation ofphase-pure Ca14Al10Zn6O35 (C14A5Z6) have been evaluated. First, a number of conventional
solid-state syntheses were performed using sinter temperatures between 1000 °C and 1250 °C.
Qualitative and quantitative phase analyses of the sinter pellets obtained were carried out bymeans of powder X-ray diffractometry (PXRD). While Ca14Al10Zn6O35 only occurs in small
proportions at temperatures below 1200 °C, sublimation of zinc oxide at higher temperatures
results in the formation of zinc-free secondary phases. The highest yield of the target phase(96 wt.-%) could be obtained in the sample fired at 1220 °C (4 x 16 h with intermediate
grinding). Furthermore, powder preparations using wet chemical methods based on solutionprecipitation as well as sol-gel syntheses were examined. Applying a modified sol-gel
process, also known as the Pechini or polymer precursor method, it was possible to obtain ahighly reactive amorphous precursor that yielded an almost phase-pure product (98 wt.-%)after a single run of 16 hours at the maximum temperature of 1220 °C. Using this specificprecursor, in-situ high-temperature PXRD experiments indicate that the sintering temperature
can possibly be further reduced to 1150 °C.
AKATSU, K., IKAWA, K., MAEDA, K. (1968): Cem. Assoc. Japan, 22, 40-43.
BARBANYAGRE, V.D., TIMOSHENKO, T.I. (1996): Powder Diff., 12, 22-26.
WU, X., LIU, L., XIA, M., HUANG, S., ZHOE, Y., HU, W., ZHOU, Z., ZHOU, N. (2019): Cer. Internat., 45,
9977-9985.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

POLYSTAGE TUNGSTEN MINERALIZATION AT LIENZER SCHLOSSBERG,
EASTERN TYROL, AUSTRIA: EVIDENCE FROM MICRO-TEXTURES AND
LA–ICP–MS ANALYSES OF SCHEELITE
Altenberger, F.1, Hutter, F.1, Raith, J. G.1, Krause, J.2, Weilbold, J.3, Auer, C.3
Montanuniversität Leoben, Chair of Resource Mineralogy, Peter-Tunner-Straße 5, 8700 Leoben Austria
2Helmholtz-Zentrum Dresden-Rossendorf, Helmholtz Institute Freiberg for Resource Technology,
Department of Analytics, Chemnitzer Straße 40, 09599 Freiberg/Saxony, Germany
3
Geological Survey of Austria, Department of Mineral Resources, Neulinggasse 38, 1030 Wien, Austria
e-mail: florian.altenberger@unileoben.ac.at

1

At Lienzer Schlossberg, scheelite mineralization comprises several styles: (1) disseminations
in pyrrhotite-dominated massive Fe-Cu sulfide ores, (2) structurally controlled scheelite in a
fault zone within altered host rocks, (3) “wallpaper”-like coatings on joints and fractures as wellas (4) scheelite in small quartz veinlets. Scheelite has been studied by combining micro-texturesvisualized by cathodoluminescence (EPMA-CL) with LA-ICP-MS trace element analysis.
Mineralization occurs within the contact aureole but also in magmatic rocks of the Oligocene
Lienz/Edenwald tonalite intrusion. Host rocks in the contact metamorphic aureole include
metapelitic hornfels grading distally into regional metamorphic mica schists and gneisses.
Minor marbles, calc-silicate rocks and an up to 3 m thick massive sulfide horizon (FUCHS,
1982) are exposed in abandoned mine workings at Edenwald. Scheelite crystals (Scheelite 1
and 2) were found in the underground workings disseminated in the sulfide layer and in a fault
zone associated with strongly altered host rocks. Subsequent stages (Scheelite 3, 4?) arerestricted to the tonalitic intrusive rocks. The hypothesis that scheelite mineralization at Lienzer
Schlossberg is of magmatic-hydrothermal origin is tested by comparing the scheelite chemistrywith geochemical data of the Oligocene tonalite intrusion.
CL revealed internal micro-textures in scheelite which are dominated by oscillatory zoning thatreflects fluctuating fluid conditions in hydrothermal systems (POULIN et al., 2018). Continuinghydrothermal activity is indicated by dissolution-replacement and overgrowth textures affecting
the primary zonation. The correlation of CL-textures, trace element contents and Eu anomalies(EuA = Eu/Eu*) were examined along profiles in scheelite. The distribution of rare earth
elements (REE) from Scheelite 1 to 4 comprise convex (i.e., MREE-enriched) fractionation
patterns with distinct negative Eu anomalies, which grade into relatively flat REE profiles withvariable EuA that are replaced by similar flat patterns but lower ΣREE at the outermost rims. In
contrast, younger scheelites illustrate a HREE-depleted profile with negative EuA.
Scheelite at Lienzer Schlossberg has by far one of the highest ΣREE concentrations in the
Eastern Alps but contains minor Mo and the least Sr. High Nb contents and the positive
correlation of REE-Eu+Y vs. Nb+Ta suggest that the main exchange vector for REE
incorporation in scheelite is via the coupled substitution of Ca2+ + W6+ = REE3+ + Nb5+
(GHADERI et al., 1999).
FUCHS, H.W. (1982): Arch. f. Lagerstätt.forsch. Geol. B.-A., 2, 67-70.
GHADERI, M., PALIN, M., CAMPBELL, I.H., SYLVESTER, P.J. (1999): Econ. Geol., 94, 423-438.
POULIN, R.S., KONTAK, D.J., McDONALD, A., McCLENAGHAN, M.B. (2018): Canad. Mineral., 56, 265302.

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CONTRASTING RARE METAL POTENTIALS INTWO SOUTHERN ALPINE VEIN DEPOSITS
Angerer, T.1, Poniewas, T.1, Profanter, L.1, Braetz, H.2, Tribus, M.1
1

Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria
2
Geozentrum, Erlangen University, Schlossplatz 4, 91054 Erlangen, Germany
e-mail: thomas.angerer@uibk.ac.at

Investigating rare metal potentials of the Alpine regions is of great importance to progress
towards future supply independence. Sphalerite is an important carrier of Co, In, Ga, Ge, andSb, and we know from the Eastern Alps, that vein deposits roughly host 66 % of the Co, 18 %of the Ga and 4 % of the In resources (MELCHER & ONUK, 2019). Here, we present data of
sphalerite (and chalcopyrite) from two contrasting vein deposits in the Southern Alpine
basement: the Pfunderer Berg Cu-Zn-Pb-Ag mine near Klausen and the Rabenstein F-Zn minein the Sarn Valley. Both abandoned mines used to be important pre-industrial, and to someextent post-industrial metal or fluor suppliers.
The Pfunderer Berg mine is a Permian intrusion-hosted vein deposit with a chalcopyritesphalerite-galena-sulphosalt paragenesis (KRISMER et al., 2011). The Rabenstein mine is avein deposit with fluorite-sphalerite paragenesis, probably related to the Periadriatic fault(HEIN et al., 1990).
The two ores show contrasting textures and chemistry of sphalerite, which are primarily related
to formation temperature: at Pfunderer Berg high-T ZnS is black and homogeneous andenriched in Fe-Mn-Cd-Cu-Se-Co-In-Sn, while at Rabenstein low-T ZnS is honey-coloured andzoned and enriched in Pb-As-Ag-Sb-Hg-Tl-Ga-Ge. Rare metal medians at Pfunderer Berg are
303, 124, and 187 µg/g for Co, In, and Sn. At Rabenstein medians for Ga, Sb, Ag, and Ge are383, 203, 85, and 9.1 µg/g. Spot analyses can reach higher values, either related to mineralinclusions (Pfunderer Berg) or to zoning (Rabenstein). Across zoned ZnS grains, co-variations
with Fe-content (0.3 to 6 wt.%) or Cu (70 to 5000 µg/g) are related to an evolving hydrothermal
pulse. Results demonstrate significant rare metal variations across deposit types, but also
complexities of fractionation within given deposits.
HEIN, U., LÜDERS, V., DULSKI, P. (1990): Mineral. Mag., 54, 325-333.
KRISMER, M., VAVTAR, F., TROPPER, P., SARTORY, B., KAINDL, R. (2011): Austr. J. Earth Sci., 104, 3648.
MELCHER, F., ONUK, P. (2019): BHM Berg- und Hüttenmännische Mh., 164, 71-76.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

CONSTRAINING TIME SCALES OF THE DECOMPRESSION OF
MANTLE ROCKS FROM SECONDARY CHEMICAL ZONING OF GARNET
FROM THE GFÖHL-UNIT, MOLDANUBIAN ZONE
Asenbaum, R.1, Racek, M.2, Petrishcheva, E.1, Abart, R.1
1

Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
2Charles University, Praha, Institute of Petrology and Structural Geology,
Albertov 6, 128 43 Praha 2, Czech Republic
e-mail: rene.asenbaum@gmx.at

Up to 100 m sized mafic-ultramafic lenses, considered as mantle fragments, are embedded infelsic granulites of the Gföhl unit, Moldanubian zone, which were incorporated into mid-crustal
rocks during the Variscan orogeny. We investigated a garnet-pyroxenite occurrence pertaining
to these lenses. The primary mineral assemblage comprises Ca-rich garnet (XGrs = 0.4),
kyanite, and Al-rich clinopyroxene (XCaTs = 0.23), indicating pressures of about 1.9 GPa andtemperatures of 1100 °C. Towards the margins of the mafic lens, destabilization of theseprimary mineral assemblages during overprint at lower pressure conditions of about 1.0 GPa isevident. A first decompression phase is represented by sapphirine-spinel-plagioclase
symplectites, which presumably replace kyanite and clinopyroxene. A second phase is evident
from the partial resorption of garnet by plagioclase and clinopyroxene in the form of "corrosion
tubes" that penetrate the garnet in a worm-like fashion. At pressures of about 0.8 GPa andtemperatures of about 800 °C, the garnet was partially replaced by plagioclase-orthopyroxenespinel symplectites at the rim. Along with this, garnet shows a pronounced secondary
compositional zoning towards the decompression products. For the sapphirine-spinelplagioclase symplectites and the plagioclase-clinopyroxene corrosion tubes, the secondary
zoning is characterized by a decrease in the Ca content and a simultaneous increase in the Mg
and Fe content. Secondary zoning toward the plagioclase-orthopyroxene spinel symplectites
shows an increase in the Fe content and a simultaneous decrease in the Mg content with constant
Ca content. By fitting a multicomponent diffusion model to the secondary zoning patterns, timescales for the duration of decompression were estimated. These vary, depending on the choiceof experimental calibrations of the diffusion coefficients, from a few 1000 to several 100,000
years. Here, the early decompression reactions show the longest time scales of several 100,000
years and are up to five times longer than those obtained from the corrosion tubes and about
ten times longer than the late plagioclase-orthopyroxene spinel symplectites. These time scales
reflect the duration of the process from the beginning of the decompression reaction until the
rocks have cooled below about 700 °C, when the compositional patterns of the garnet wereeffectively frozen due to increasingly sluggish diffusion towards lower temperatures. In thecontext of the evolution of the Moldanubian Zone, these time scales are short and indicate rapidtransport of mafic-ultramafic lithologies from mantle to intermediate crustal levels andsimultaneous integration into a predominantly felsic environment, accompanied by immediatecooling.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

TRAPPING OF HETEROGENEOUS FLUIDS
Bakker, R.J.1
1

Resource Mineralogy, Department of Applied Geosciences and Geophysics, Montanuniversity Leoben,Peter-Tunner-Straße 5, 8700 Leoben, Austria
e-mail: bakker@unileoben.ac.at

In theory, the formation of a fluid inclusion assemblage from a multi-phase state (i.e.
heterogeneous entrapment) is a common process at natural geological conditions. The
immiscibility of multi-component fluids may occur at high temperatures and pressures and is
not restricted to diagenetic conditions. Specific fluid systems are even immiscible atGreenschist-, Amphibolite-, Blueschist-, and Granulite-facies metamorphic conditions. The
identification of a heterogeneous fluid inclusion assemblage in natural rock is a major challenge
in fluid inclusion research, and it is expected to be a common phenomenon. There is only little
experimental knowledge about the formation of heterogeneous fluid inclusion assemblages.
The synthesis of these assemblages has been used in only a few experimental studies toinvestigate the boundary conditions of fluid immiscibility fields. These studies included theanalyses of only a few fluid inclusions (between 1 and 10 per experiment), but do not reveal
the variability of the assemblage or systematics on the distribution or deviations of distinct fluidinclusion types. One inclusion is not representative for specific experiments that usually resultin a variety of fluid properties. Fluid inclusions are synthesized at approximately 600 ˚C and 80
MPa, from a 30 mass% NaCl aqueous solution (SR-020) and a 10 mass% NaCl aqueous
solution (SR-019). For both experiments, the conditions are within the two-fluid phase field,
and both should result in the formation of similar liquid-rich inclusions and similar vapour-richinclusions, but in different proportions. Due to the unmixing at experimental conditions, two
fluids are present in the capsules, i.e. a liquid-like fluid relatively enriched in NaCl (40.42 to
41.40 mass%) and a vapour-like fluid relatively depleted in NaCl (2.41 to 2.71 mass%). The
measured dissolution and homogenization temperatures are not consistent with values
calculated with the thermodynamic model (Fig. 1). These preliminary results of experiments in
the H2O-NaCl fluid system have illustrated that predicted fluid properties do not correspond tothe observed assemblage. Therefore, the processes
that are involved during heterogeneous entrapment
need to be investigated in greater detail bysystematic analyses of entire fluid inclusion
assemblages to be able to predict fluid entrapmentin natural systems, and to be able to deduce natural
trapping
conditions
fromthe observed
assemblages.

Figure 1. Microthermometric results of liquid-rich fluidinclusions from SR-019 and SR-020. The expected values areillustrated by the black box.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

THE ECCENTRIC CONE MOUNTS DE FIORE, MONTE ROSSI,MONTE SPAGNOLO, AND THE 2002/03 LAVA FLOW, MT. ETNA:EVIDENCE FOR MAGMA MIXING
Bauer, M.1, Ntaflos, Th.1, Abart, R.1, Giacomoni, P.P.2, Ferlito, C.3, Coltorti, M.2
1
Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Wien, Austria
Department of Physics and Earth Sciences, University of Ferrara, Via Savonarola, 9, 44121 Ferrara, Italy
3
Department of Biol., Env. and Geol. Sciences, University of Catania, Piazza Università, 2, 95124 Catania, Italye-mail: moritz.bauer96@gmail.com
2

Mt. Etna, located in Sicily, Italy, is Europe’s most active volcano and its geodynamic setting
and plumbing system have been in the centre of many extensive studies. The 6 stages of
eruptive activity from the past to the present are: (1) ‘Tholeiitic Stage’ between 600-320 kaago, (2) ‘Timpe Stage’ 220-110 ka ago, (3) ‘Ancient Alcaline Volcanism’ 110-65 ka ago, (4)‘Ellittico Stage’ 57-15 ka ago, (5) ‘Mongibello Stage’ from 15 ka ago until 1971, and (6) the‘post -1971 Stage’ comprising the volcanic activity since 1971 (CASETTA et al., 2019).
The lava propagating through the Etna plumbing system generated a complex network of sills
and dykes and is responsible for the formation of the summit craters and a plethora ofeccentric cones that cover the flanks of the volcano.
We studied whole rock and mineral chemistry of the lavas from three eccentric cones (Monte
Spagnolo, Mounts de Fiore and Monte Rossi) and the 2002/03 southern flank lava flow. Alllavas are trachybasalts with trachytic texture and variable modal composition of olivine,clinopyroxene and plagioclase phenocrysts. The Monte Spagnolo whole rock composition has
the most primitive lavas of all the sampled outcrops with Mg# between 55-57.5 and 10.7 wt%
CaO, whereas the Monte Rossi lavas are the most evolved ones with a Mg# between 48.3 and49.3 and a CaO content between 10.44 and 10.48 wt%. Mounts de Fiore and the 2002/03 lava
flow are more evolved than the Monte Spagnolo lavas, as they have a Mg# of around 51 to
52. The corresponding CaO concentration is around 11.2 wt% and 10.62 wt% respectively.
Deviating from the trend of the corresponding whole rock composition, the most MgO-richolivine (Fo = 88.9 %) was found in the Monte Spagnolo lavas. Due to its low NiO content(0.17–0.2 wt%) and high CaO content (0.25–0.26 wt%) this olivine is apparently of magmaticorigin. Considering that the olivine, which could be in equilibrium with these lavas, has Fo=82.2, it is evident that the olivine with Fo=88.9 points to magma mixing with high MgO-richlavas. The most evolved lavas from Monte Rossi have the lowest Fo-content (Fo = 67-75 %).
In conclusion, olivine and pyroxene with inverse zoning and a higher Mg# in the rims than in
the cores indicate extensive magma mixing in all locations except for Monte Rossi. These Focontent differences from core to rim are in the range of 4%.
Monte Spagnolo lavas, compared to the other studied eccentric cones, represent the mostprimitive magma formed at high temperatures (avg. 1166 °C) and the Monte Rossi lavas themost evolved magma formed at lower temperatures (avg. 1138 °C). In comparison, the lavasof Mounts de Fiore and of the 2002/2003 eruption show a mediate grade of evolvement andaverage formation temperatures (avg. 1156 °C).
CASETTA, F, GIACOMONI, P.P., FERLITO, C., BONADIMAN, C., COLTORTI, M. (2019): Internat. Geol.
Rev., 62, 338-359.

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INVESTIGATING THE EFFECTS OF METAMORPHISM ON THE
SEDIMENT-HOSTED Cu-Co DOLOSTONE ORE FORMATION, NAMIBIA,USING GEOCHEMISTRY OF COEXISTING IRON-SULFIDES
Bertrandsson Erlandsson, V.1, Wallner, D.1, Ellmies, R.2, Melcher, F.1, Raith, J.G. 1
Montanuniversität Leoben, Peter-Tunnerstraße 5, 8700 Leoben, Austria
2
Gecko Namibia, Einstein 10, 8912, Swakopmund, Namibia
e-mail: viktor.erlandsson@unileoben.ac.at

1

The Dolostone Ore Formation (DOF) is a sediment-hosted Cu-Co mineralization in the Kunene
Region, northwestern Namibia. The DOF is hosted in Neoproterozoic calcareous siltstones andcarbonates of the Ombombo Subgroup (MILLER, 2008). The main ore minerals of the DOF
are sphalerite, chalcopyrite, linnaeite, pyrite and pyrrhotite; with subordinate, galena andcobaltite. These sulfides occur in six major mineralization styles: mono-sulfide disseminations,poly-sulfide clusters and nodules, clasts with prominent strain shadows, veins, and the so-called“events”. The “event” mineralization style resemble slump-like structures with both brittle andductile components, but may also be some sort of crack-seal veins.
Trace element analyses were carried out by LA-ICP-MS to better understand the geochemistryof the sulfides of this sediment-hosted mineralization. Pyrite and pyrrhotite coexist exclusively
within the “events”, where euhedral to subhedral pyrite is surrounded by anhedral pyrrhotite.
The “event” pyrrhotite is associated with anhedral and intergrown sphalerite, chalcopyrite, andgalena. Trace element analyses show that the “event” pyrite is enriched in Cu, As, Sb, Tl, andPb, compared to the “event” pyrrhotite. Whilst concentrations of elements such as Co, Ni, andSe are relatively similar between the coexisting “event” iron-sulfides.
LARGE et al. (2007) demonstrated that trace elements such as Cu, Zn, Ag, Au, Te, and Pb
would be depleted in greenschist facies recrystallized pyrite, compared to theunmetamorphosed pyrite. During metamorphism, the depleted elements would be liberated
from the pyrite crystal lattice and form new separate phases, e.g. sphalerite and chalcopyrite.
Elements that typically are more tightly incorporated into the crystal lattice of the iron-sulfides(e.g. Co, Ni, and Se) remain at similar concentrations after metamorphism (HUSTON et al.,2017; LARGE et al., 2007). These trends are what we observe in the DOF “event” iron-sulfides.
Textural relationships between the “event” pyrite and the pyrrhotite, along with their traceelement trends, propose the possibility that early pyrite was a source for Zn, Cu, and Pb thatlead to the precipitation of sphalerite, chalcopyrite, and galena that are associated with thepyrrhotite during metamorphism. Preliminary EMPA results indicate that early framboidal
pyrite is enriched in, at least, Zn, suggesting framboidal pyrite being a possible source of themetals of the DOF mineralization.
HUSTON, D.L., MERNAGH, T.P., HAGEMANN, S.G., DOUBLIER, M.P., FIORENTINI, M., CHAMPION,
D.C. (2017): In: Ore Geol. Rev., 76, 168–210.
LARGE, R.R., MASLENNIKOV, V.V., ROBERT, F., DANYUSHEVSKY, L.V., CHANG, Z. (2007): In: Econ.
Geol., 102, 1233–1267.
MILLER, R.M. (2008): The geology of Namibia. 3 Volumes, Geol. Surv. Namibia, 1564.

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SYSTEMATICS OF FACETED INTERFACES BETWEEN ORIENTEDMAGNETITE MICRO INCLUSIONS AND PLAGIOLCASE HOST
Bian, G.1, Li, C.2, Ageeva, O.1,3, Habler, G.1, Abart, R.1
Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
2
University of Antwerp, 2020 Antwerp, Belgium
3
IGEM RAS, Staromonetnyi 35, 119017 Moscow, Russia
e-mail: rainer.abart@univie.ac.at

1

Oriented needle- and lath-shaped magnetite (Mt) micro-inclusions in plagioclase (Pl) arerobust carriers of natural remanent magnetization. Systematic crystallographic and shapeorientation relationships (CORs, SORs) between Mt and Pl may lead to magnetic anisotropy
and thus are of pivotal importance for paleomagnetic reconstructions. The unusual needle orlath morphology of the Mt inclusions and their SORs and CORs are due to the alignment ofimportant oxygen layers across the Mt-Pl interfaces that are parallel to the inclusion
elongation direction. Typically, the Mt needles are elongated parallel to Mt<111>, andMt{222} is parallel to one of several oxygen layers in Pl, including Pl(112), Pl(3̅ 12), Pl(150),
Pl(15̅ 0). All these lattice planes have nearly identical d-spacings so that they are coherent
across the Mt-Pl interfaces (AGEEVA et al., 2020). This alignment allows one rotational
degree of freedom around the needle elongation direction. The rotation is, however, notcontinuous, but clusters around several specific positions. In this context, the atomic
structures of Mt-Pl interfaces are of key interest. We used high angle annular dark fieldscanning transmission electron microscopy (HAADF-STEM) to determine the atomic
structure of the Mt-Pl interfaces of two needles with Mt<111> parallel to the normal direction
to Pl(3̅ 12). In projections parallel to the needle elongation directions, one inclusion has ahexagonal cross section and, in addition to Mt<111>//Pl(3̅ 12), satisfies the relation
̅̅̅̅,10,7̅ ]. This ensures perfect fit of FeO6 octahedra of Mt in channels of the Pl
Mt<100>//Pl[14crystal structure, which is considered an important match during the nucleation phase anddefines the nucleation orientation. The other inclusion has a quadrilateral cross section and, in
addition to Mt<111>//Pl(3̅ 12), satisfies Mt{220}//Pl(150), where both planes form facets of
the Mt-Pl interface. This is likely the energetically most favourable configuration and defines
the main orientation. The interface facets can be rationalized based on a modified exact phaseboundary model. In nucleation orientation, Mt{220}//Pl(131) and Mt{220}//Pl(23̅ 4). In mainorientation, Mt{220}//Pl(112) forms the facets or meets Pl(150) with a ratio of 4:3. For the
inclusion in nucleation orientation, the elongation direction Mt<111> deviates by <1° fromthe normal direction to Pl(3̅ 12), while in main orientation the deviation is up to ~6°. The
transition from the nucleation to the main orientation corresponds to a two-step rotation: (i)~6° rotation around Pl(150)n, (ii) ~30° rotation around the inclusion elongation direction.
This transition is probably driven by minimizing interfacial energy while keeping the coherent
oxygen layers across the Mt-Pl interfaces along the needle elongation direction aligned.
AGEEVA, O., BIAN, G., HABLER G., PERTSEV, A., ABART, R. (2020): CMP, 175(10), 1-16.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

FLUID PRODUCTION CONDITIONS MANIFESTED IN MINERALPRECIPITATES FROM GEOTHERMAL POWER PLANTS
Boch, R.1,2, Kluge, T.3, Szanyi, J.4, Leis, A.5, Mittermayr, F.6, Dietzel, M.1
Graz University of Technology, Institute of Applied Geosciences, Rechbauerstraße 12, 8010 Graz, Austria
2
Geoconsult ZT GmbH, Wissenspark Salzburg Urstein, 5412 Puch bei Hallein, Austria
3
Karlsruhe Institute of Technology, Inst. of Applied Geosciences, Adenauerring 20b, 76131 Karlsruhe, Germany
4
University of Szeged, Dept. of Mineralogy, Geochemistry & Petrology, Egyetem u. 2, 6722 Szeged, Hungary
5
JR-AquaConSol GmbH, Steyrergasse 21, 8010 Graz, Austria
6
Graz University of Technology, Institute of Technology & Testing of Building Materials,
Inffeldgasse 24, 8010 Graz, Austria
e-mail: ronny.boch@tugraz.at
1

Fluid circulation and fluid-solid interaction are critical constituents during sustainable andrenewable geothermal energy production (heat, electricity) and gas storage (H2, CO2, CH4). The
occurrence and extent of unwanted processes (scaling, corrosion, plugging) depends on theprevailing natural and technical environmental and fluid production conditions. Differentiatedaqueous solutions and gases streaming in subsurface reservoir rocks and boreholes as well as
surface infrastructure (pipelines, heat exchangers) lead to successive mineral precipitation andmaterial alteration. This includes mineral (scale) deposits, corrosion products, cements in porespaces, veins in fractures as well as altered rock and construction materials. Production
conditions and potential mineral formation vary across the fluid flow route and with time.
The unwanted mineral precipitates (carbonates, sulfides, sulfates) are originating from thethermal fluid and constitute a chemical-sedimentary archive evolving continuously and/or
episodically. Applying some forensic approach (“Scaling Forensics”) an advanced process
understanding emerges from the solid deposits. This is based on a steadily growing set oflaboratory analytical methods targeting mineralogical, petrographic, chemical, and isotopic
compositions. The reconstruction of relevant processes involves the interpretation of indicativeminerals and inclusions, crystal growth mechanisms, chemical tracers, and the role of specificinterfaces, substrate effects and microbial contributions. Distinct phases and sections of thefluid circuit can further be interrelated by computer based numerical modeling.
Considering novel geochemical tracers, “clumped isotopes” (multiply-substituted
isotopologues) in solids (scale deposits, rocks) and gases, hold a highly attractive potential asgeothermometer, fluid provenance and evolution tracer and for kinetic effects related to mineral
precipitation. In particular, carbonate scales reflecting a broad range of physicochemical growth
conditions are promising materials for the evaluation and calibration of the new isotopic tool.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

ORE PETROGRAPHIC AND GEOCHEMICAL ANALYSIS OF THE
POLYMETALLIC COPPER DEPOSIT WALCHEN NEAR ÖBLARN, STYRIA
Brandner, P.1, Melcher, F.1, Onuk, P.2, Skrzypek E.2
1

Montanuniversität Leoben, Leoben, Lehrstuhl für Geologie und Lagerstättenlehre, Peter-Tunner-Straße 5,8700 Leoben, Austria
2
Universität Graz, Graz, Austria, Institut für Erdwissenschaften, Universitätsplatz 2, 8010 Graz, Austria
e-mail: brandner.peter@live.at

The stratiform sulfide deposit Walchen is an Fe-rich, polymetallic sedimentary-exhalativemineralization, which occurs in greenschist facies metamorphic sedimentary host rocks. The
east-west trending orebodies are located in a transition zone between the Wölz Micaschistcomplex and the Ennstal phyllite zone. A total of five ore types can be distinguished, i.e.
pyrite, pyrrhotite, chalcopyrite, sphalerite impregnation ore, and massive pyrrhotite ore. The
main ore minerals, in decreasing order of frequency, are pyrite, pyrrhotite, chalcopyrite,
sphalerite, and galena. Minor and trace minerals are arsenopyrite, stannite, Ag-bearing
fahlore, boulangerite, bournonite, ullmannite-willyamite, jamesonite, cassiterite, ilmenite,
gudmundite, Bi-Sb alloys, and Ag-Au-Hg phases.
The gangue is composed of non-sulfidic minerals with the majority being quartz, alkali
feldspar, phyllosilicates and carbonates (dolomite-ankerite, siderite). Monazite and xenotimegroup minerals, rutile, ilmenite, uraninite and zircon are accessories. The host rock generally
consists of the same minerals except of Fe-rich carbonates. Whereas only minor mineralogicaland geochemical differences are found between footwall and hanging wall rocks of theorebody, a significant difference is visible in the trace element contents (i.e. Cr, Ni).
LA-ICP-MS trace element analyses of pyrite, pyrrhotite, chalcopyrite, and sphalerite were
evaluated. Pyrite shows a strong accumulation of Co (543 ppm) and As (1099 ppm).
Chalcopyrite reveals increased median contents for Ag (190 ppm) and In (51 ppm). In
sphalerite Fe (8.4 %), Cd (0.16 %), and In (111 ppm) are accumulated. Preferred
accumulation of trace elements in a certain ore type could not be recognized. However,
sphalerite and chalcopyrite in massive ore samples (Ph-DE) often show elevated trace element
concentrations.
Mineral chemical analyses indicate that the metamorphic overprint of the deposit took placeat temperatures of at least 350 °C at pressures around 3.8 kbar. Uranium-lead measurementswith the electron microprobe on micro-uraninites from the impregnation ores show a mean
age of 93 Ma which is interpreted as the age of the last metamorphic overprint.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

DISTRIBUTION OF CO2 IN THE LITHOSPHERIC MANTLE BENEATHNORTHERN VICTORIA LAND (ANTARCTICA): INSIGHTS FROM PETROLOGY,FLUID INCLUSIONS CHEMISTRY AND X-RAY µCT IN MANTLE XENOLITHS
Casetta, F.1, Rizzo, A.L.2,3, Faccini, B.2, Ntaflos, T.1, Lanzafame, G.4, Faccincani, L.2,
Mancini, L.5, Giacomoni, P.P.2, Coltorti, M.2,3
Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, 44122, Ferrara, Italy
3
Istituto Nazionale di Geofisica e Vulcanologia, Sezione di Palermo, Via Ugo La Malfa 153,
90146 Palermo, Italy
4
Department of Biological, Geological and Environmental Sciences, University of Catania,
Corso Italia 57, 95129 Catania, Italy
5
Elettra-Sincrotrone Trieste S.C.p.A., s.s. 14 km 163,500 in Area Science Park, 34149 Basovizza, Trieste, Italye-mail: cstfrc@unife.it
12Modelling the carbon cycle in Earth’s deepest reservoirs is crucial for enhancing ourcomprehension of the evolution of our planet. In fact, geodynamic processes are intimately
linked to the storage and mobility of volatiles in the Earth’s mantle, as C-O-H species play animportant role in driving melt extraction, metasomatism and refertilization. A powerful way toinvestigate where and how carbon is stored in the deep Earth, and especially in the SubContinental Lithospheric Mantle, is the combined application of petrology, fluid inclusions
geochemistry and high-resolution imaging techniques to mantle-derived xenoliths.
In the present study, modally and/or chemically heterogeneous mantle xenoliths brought to thesurface by Cenozoic lavas in northern Victoria Land (Antarctica) were investigated by meansof mineral chemistry, fluid inclusions composition and 3D textural/volumetric characterizationsof intra- and inter-granular microstructures performed by X-ray computed microtomography(µCT).
Fluid inclusions are volumetrically abundant in both olivine and pyroxenes, and often
associated with inter-granular reaction zones. Olivine-hosted fluid inclusions have the lowest
CO2 concentrations, ranging from 0 to 39 µg(CO2)/g(sample), while amphibole- and pyroxenehosted FI are typified by the highest contents [up to 187.3 µg(CO2)/g(sample)].
X-ray µCT was used to image and quantify the abundance, connectivity, and density ofglass/fluid components as well as to speculate about their origin and relationships with the
networks of secondary fractures, likely formed during decompression, that sometimes pervade
the rocks. In general, glass/fluid components have tetrahedral to prismatic shape and sizes
between 2 and 50 μm.
Together with mineral chemistry data and T-fO2 models, fluid inclusions chemistry and X-rayµCT results were used to: i) model the storage and distribution of carbon in intra- and intergranular zones in mantle xenoliths; ii) relate the occurrence/mobility of carbon to the melt
extraction and enrichment episodes that affected the Sub-Continental Lithospheric Mantle
beneath Antarctica; iii) understand the role played by fluids during the major geodynamic
processes.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

147Sm–143Nd SYSTEMATICS FOR TRACING HYDROTHERMAL ALTERATIONAND U MOBILIZATION IN PROTEROZOIC JABILUKA UNCONFORMITYRELATED URANIUM DEPOSIT (NORTHERN TERRITORIES, AUSTRALIA)

Chernonozhkin, S.M.1,2,3, Luais, B.3, Reisberg, L.3, Brouand M.4, Cuney, M.2, Mercadier, J.2
Current address: Chair of General and Analytical Chemistry, Montanuniversität Leoben,
Franz-Josef-Straße 18, 8700, Leoben, Austria
2
Université de Lorraine, CNRS, CREGU, GeoRessources Lab, Campus Aiguillettes,
Faculté des Sciences et Technologies, rue Jacques Callot, Vandoeuvre-lès-Nancy, 54506, France
3
Centre de Recherches Pétrographiques et Géochimiques (CRPG), CNRS, Université de Lorraine, UMR 7358,
15 rue Notre Dame des Pauvres, Vandoeuvre lès Nancy, 54501, France
4
Orano Mining, 125 Avenue de Paris, 92320 Châtillon, France
e-mail: stepan.chernonozhkin@gmail.com
1

Jabiluka unconformity-related U deposit (Alligator Rivers Uranium Field, Northern
Territories, Australia) was formed at the unconformity between the Kombolgie sedimentarybasin and the Archean-Paleoproterozoic crystalline basement, as a result of percolation of hot
U-rich brines. The basement lithologies are characterized by massive hydrothermal alteration
linked to these brines, leading coevally to precipitation of U oxides and an illite/chlorite clay
alteration. Although the primary mineralization in the form of U oxides should at first glancebe easy to date using U-Pb method, this approach is jeopardized by mobilization and loss of
Pb and the fact that uraninite is easily dissolved by fluid circulation. U-Pb ages of the uranium
minerals provide a broad spectrum of ages with peaks between ca. 1680 - 1300 Ma.
This work revisits the temporal sequence of orogenic events leading to formation of the
Jabiluka unconformity-related U deposit using whole rock 147Sm-143Nd systematics. A seriesof samples taken from a single drill hole intersecting fresh to hydrothermally altered basement
lithologies and the U orebody were investigated. The REE contents and patterns strongly varywith the development of alteration and mineralization, demonstrating that this alteration
episode was large enough to isotopically homogenize the ~250 m layer of the basement, suchthat the 147Sm-143Nd system can be applied. The petrographic and geochemical features showthat the initial mineralogy, with the REE balance largely controlled by monazite, wasmodified such that clays, phosphate and uranium oxides became the main REE-bearing
phases. The 147Sm-143Nd isotope data demonstrate that U oxides and the hydrothermallyaltered silicate basement lithologies are formed in a single event. The inferred Sm-Nd age at
1545±27 Ma suggests that this massive alteration episode is not co-eval with the primary U
deposition at ca. 1680 Ma, but occurred nearly 100 million years later. The high initial143
Nd/144Nd shows that Nd evolved in an environment with high Sm/Nd ratio, which could
derived from the primary generation of the Jabiluka U oxides, dissolved and re-mobilized ca.
100 Ma after their initial formation.
This work demonstrates therefore the relevance of the application of the Sm-Nd system forstudying hydrothermal deposits in context of succession of multiple fluid episodes, andencourages for the development of dedicated applications.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

TOWARDS AN ANALYTICAL PROOF OF ORIGINFOR NATURAL GRAPHITE DEPOSITS
Dietrich, V.1, Melcher, F.1, Rantitsch, G.1
1

Department of Applied Geosciences and Geophysics, Montanuniversität Leoben,Peter-Tunner-Straße 5, 8700 Leoben
e-mail: valentina.dietrich@unileoben.ac.at

Raw material supply chains are complex systems. They build on the presence of economicallymineable mineral commodities that will undergo several steps until they are finally being used
as consumer products. Trustworthiness into the transparency of a supply chain is of increasing
importance, both to upstream and downstream companies. Any deviation from best-practiceand quality standards in mining, processing and production is critically looked by consumers,
especially nowadays. Therefore, certification and proof of origin concepts have emerged within
the past years, aiming at providing transparency to supply chains (MELCHER et al., 2021).
30 raw materials have been classified as critical by the EU; some of which are particularly
relevant for the Green Deal and the digital transformation, including graphite. The classification
as a critical raw material is based on the assessment of whether longer interruptions or shortages
in supply could have a negative impact on technological progress and economic growth.
In addition to the well-known use of (microcrystalline) graphite in pencils, another very
important and currently highly sought-after application of large flake graphite in the electronic
industry is in lithium ion batteries and fuel cells. The demand is constantly increasing.
POHL (2020) distinguishes four major deposit types, namely regional metamorphic graphite
formed from coal or hydrocarbons; contact-metamorphic graphite formed from sedimentaryrock; hydrothermal graphite as a product of magmatic, hydrothermal or volcanogenic
processes; and supergene residual deposits. Large-flake graphite can be extracted at a minimumof 3–5 % graphite in rock, whereas fine-grained or microcrystalline graphite ore requires
grades >45 %.
The increasing demand for this raw material and the limited market with a small number ofplayers is also accompanied by concerns from industry and consumers about the origin of thisraw material. Therefore, different graphite deposits distributed worldwide are included in thepresent study. The analysis of fingerprints for graphite is favourable in order to check anddifferentiate between different origins, in particular from African countries (Mozambique,
Madagascar, and Zimbabwe), but also from Korea, China and others. Graphites offer several
options for an analytical proof of origin, for example the determination of trace elements using
ICP-MS and LA-ICP-MS, the 13C isotope ratio by MC-ICP-MS or gas mass spectrometry.
Another useful parameter is the degree of graphitization, which is analysed by Raman
spectroscopy. Also textural information, such as morphology and grain size, which is assessedby microscopy and scanning electron microscopy are useful parameters for the application of
fingerprinting techniques.
MELCHER, F., DIETRICH, V., GÄBLER, H.-E. (2021): Minerals, 11, 461, 1-16.
POHL, W., (2020): Economic Geology: Principles and Practice, 2nd revised edition, Schweizerbart´sche
Verlagsbuchhandlung, Stuttgart, Germany.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

RADIOMETRIC DATING OF THE
MOLYBDENUM DEPOSIT REICHENSPITZE, TYROL
Doppelmayer, D.1, Melcher, F.1, Gallhofer, D.2, Sorger, D.2,3
Lehrstuhl für Geologie und Lagerstättenlehre, Montanuniversität Leoben,Peter-Tunner Straße 5, 8700 Leoben, Austria
2Institute of Earth Sciences, Universität of Graz, Universitätsplatz 2/II, 8010 Graz, Austria
3
Present adress: Geoscience Center, Georg-August-University Göttingen,Goldschmidtstraße 1, Göttingen 37077, Germany
e-mail: frank.melcher@unileoben.ac.at
1

The occurrence of molybdenum at Reichenspitze in Salzburg and Tyrol is part of themolybdenum ore province Zentralgneis Supersuite in the Tauernfenster. At the Reichenspitze,
molybdenite (MoS2) is restricted to aplitic intrusions in the Zentralgneis. These aplitic granites
are also referred to as Reichenspitz granite. Up to now no reliable age of the Reichenspitz
granite has been published. In this study, U-Pb zircon dating (LA-ICP-MS) yields acrystallization age of 292.2 ± 0.68 ǀ 3.9 Ma for the aplitic granites. This puts the Reichenspitz
granite directly into relation with the Lower Permian I-Type granitoids of the ZillertalVenediger-Tux magmatic suite. Geochemical analyses of the aplitic granite show high SiO2
contents (77 to 79 wt.%), barium contents of 141 to 233 µg/g, and rubidium contents of 147 to
171 µg/g. Based on low CaO contents (< 1.65 wt.%), a negative barium anomaly (normalized
to ocean ridge granites), and high Rb/Sr ratios (up to 5.93), the Reichenspitz granite waspreviously interpreted as an A-type granite. The analyzed samples of the Reichenspitz granite
also show low CaO contents (< 0.8 wt.%), a weak negative barium anomaly, and high Rb/Sr
ratios (up to 4.25). However, a K/Rb - Rb discrimination diagram indicates a differentiation
trend from granites in the Tux Core to the Reichenspitz granite. The Reichenspitz granite istherefore interpreted as a highly differentiated granitoid of the Zillertal-Venediger-Tux
magmatic suite. Typological studies of the investigated zircons yield calc-alkaline, highly
fractionated magma sources. Crystallization temperatures of 600 to 650 °C are presumed.
Additionally U-Pb uraninite dating was carried out in this study. Though the crystallization ageof the uraninites could not be precisely determined, the polygenetic zircon grains show younger
ages than the published Lower Permian zircon age. The youngest uraninite generation shows
consistent ages of 29 ± 5 Ma, which dates the Oligocene Neo-alpine regional metamorphism.
Based on the new geochronological data a primary ore formation syngenetic with the intrusionof the Reichenspitz granite is proposed. In the highly fractionated melt, volatile elements (F,Cl) and molybdenum were enriched. This process generated metal-bearing, possibly
pneumatolytic fluids which overprinted the host rock and led to metasomatic ore formation.
Hydrothermal activity during the Alpine regional metamorphism remobilised the ore, which
locally led to molybdenite enrichment as aggregates along shear zones. The Reichenspitze
deposit strongly resembles the molybdenum deposit Ackley in Newfoundland, which is also
related to aplitic granites in the roof zone of a magma chamber. A genetic relation between the
Reichenspitze molybdenum occurrence and the molybdenum deposit Alpeinerscharte/Tyrol
dated at 305 Ma (Langthaler et al., 2004) cannot be excluded but calls for further investigations.
LANGTHALER, K., RAITH, J.G., CORNELL, D., STEIN, H., MELCHER, F. (2004): Miner. Petrol., 82, 33-64.

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GEOGENIC THALLIUM-EXTREME ENVIRONMENTS:
IN WHICH SECONDARY PHASES IS Tl(I) INCORPORATED?
Đorđević, T.1, Drahota, P.2, Kolitsch, U.3,1, Majzlan, J.4, Kiefer, S.4, Tepe, N.5, Hofmann, T.5,
Serafimovski, T.6, Tasev, G.6, Boev, I.6, Boev, B.6
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University,
Albertov 6, 128 43 Prague 2, Czech Republic
3
Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum, Burgring 7, 1010 Wien, Austria
4Institute of Geosciences, Department of Mineralogy, Friedrich-Schiller-Universität, Carl-Zeiss-Promenade 10,07745 Jena, Germany
5
Centre for Microbiology and Environmental Systems Science, University of Vienna,
Althanstraße 14, 1090 Wien, Austria
6
Department of Mineral Deposits, Faculty of Natural Sciences, University “Goce Delčev”-Štip,Goce Delčev 89, 2000 Štip, North Macedonia
e-mail: tamara.djordjevic@univie.ac.at
12

Although the oxidation zones of the majority of naturally Tl-rich localities represent a great
threat to surrounding ecosystems, they have not been investigated so far in much detail. Since
the remediative treatment of highly Tl-contaminated soils depends on the character of the Tlbearing phases, it is necessary to fully characterize Tl retention through secondary minerals inaffected areas, in order to build a sound basis for successful remediation.
In this study we identified Tl reservoirs in waste dumps and soils of the naturally thallium
richest locality in the world, the Crven Dol locality (Tl-As-Sb-Au Allchar deposit, North
Macedonia). Tl speciation differs to a certain extent from that observed in similar localities, andis reflected by a very well-developed secondary mineralogy. Thallium dissolved during
weathering is precipitated mostly as novel poorly crystalline to amorphous thallium arsenatesor as dorallcharite (Tl-Fe sulfate). In traces, Tl also appears as a nano-sized Tl(I) oxide (Tl2O)
and as thalliumpharmacosiderite (Tl-Fe arsenate). Furthermore, Tl is accumulated in supergene
Mn oxides, pharmacosiderite, and jarosite.
Pore waters contain high aqueous concentrations of Tl (up to 660 μg/L) and As (up to 196
mg/L). Although these concentrations are low with respect to their total concentrations in thesolid phase (Tl: 0.07-1.44 wt%; As: 0.72-8.67 wt%), mild extractions mobilized up to 44 % of
the total Tl and 23 % of the total As, indicating that a large amount of these toxic elements isonly bound weakly (sorption) to solids and can be easily mobilized.
In general, in soil horizons lacking secondary Tl-bearing minerals, Tl(I) adsorption onto
micaceous phyllosilicates (mostly illite), followed by Tl(I) and Tl(III) adsorption onto Mn
oxides has previously been identified as the dominant Tl retention mechanism (WICK et al.,2018, 2019 and references therein). However, in Tl-extreme environments, when illite and Mnoxides are either absent or exhausted, discrete secondary Tl minerals form and store Tl.
This work was supported by the Austrian Science Fund (FWF) [grant number P 30900-N28 to T. Đorđević].
WICK, S., BAEYENS, B., FERNADES, M.M., VOEGELIN, A. (2018): Environ. Sci. Technol., 52, 571-580.
WICK, S., PEÑA, J., VOEGELIN, A. (2019): Environ. Sci. Technol., 53, 13168-13178.

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THE 4-CENTER 2-ELECTRON BONDED CLUSTER CATIONS[Ag3Hg]3+ AND [Ag2Hg2]4+
Effenberger, H.1
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
e-mail: herta.silvia.effenberger@univie.ac.at

1[Ag3Hg]3+ and [Ag2Hg2]4+ are rare cation complexes. The first evidence was found intillmannsite, [Ag3Hg][(V,As)O4], which was described from an old copper mine of Roua−
(Alpes-Maritimes, France): space group I 4 (SARP et al., 2003). Later on, WEIL et al. (2005)
synthesized the V-end member besides the compounds [Ag2Hg2]3[VO4]4 and[Ag2Hg2]2[HgO2][AsO4]2 (I−42d and P31c). Just recently, rudabányaite - [Ag2Hg2][AsO4]Cl
was found in cavities of siliceous sphaerosiderite and limonite rocks at the Rudabánya ore−
deposit (Adolf mine area, NE Hungary; F 43c; EFFENBERGER et al., 2019).
The M = (Ag, Hg) atoms in all these [M4] clusters are located at the corners of an empty
tetrahedron; the complex is stoichiometric with Ag:Hg = 2:2 or 3:1, respectively. The M
atoms are ~1.66 Å apart from their vacant centres; thus, the size of the [M4] tetrahedra
corresponds with the arsenate and vanadate tetrahedra. The M―M bond distances of ~2.60 to
2.72 Å suggest predominantly covalent bonding. Order between Ag and Hg atoms is notverified. The M atoms are [6] coordinated by each three M atoms and by three anions. In
rudabányaite a partial displacement of the M atoms was observed (about 0.5 Å). Remarkable
is the pronounced one-sided [3] coordination of the Cl- ions in rudabányaite.
Only in [Ag2Hg4][XO4]2 (X = P,As) (MASSE et al., 1978; WEIL, 2003) the Ag and Hg atoms
are ordered: each two [Ag2Hg2] tetrahedra share a common Ag―Ag edge forming an[Ag2Hg4]6+-cluster cation. The shared edge (~2.85 Å) is slightly shorter than in native silver
but larger than the M―M distance in the [Ag2Hg2] complex. The other M―M bond distances
are comparable to the [M4] clusters.
On interest are some crystal chemical, structural, and topological similarities: In kuznetsovite([Hg3][AsO4]Cl, space group P213; WEIL, 2001) trigonal [Hg3]4+ clusters substitute for thelarger [Hg2Ag2]4+ metal clusters of rudabányaite; the Cl atom is planar [3] coordinated. – Intillmannsite, two distinct column-like arrangements built solely by [Ag3Hg]3+ cation clusters
respectively [(V,As)O4]3- tetrahedra are running parallel to [001]; alternatingly arranged[Ag3Hg] clusters and [(V,As)O4] tetrahedra are verified parallel to <100>. In rudabányaite[Ag2Hg2] clusters and [AsO4] tetrahedra alternate due to the cubic symmetry in all <100>directions.
The dominance of acentric crystal structures in this group of compounds should be noted.
EFFENBERGER, H., SZAKÁLL, S., FEHÉR, B., VÁCZI,T., ZAJZON, N. (2019): Europ. J. Mineral., 31, 537547.
MASSE, R., GUITEL, J.-C., DURIF, A. (1978): J. Solid State Chem., 23, 369-373.
SARP, H., PUSHCHAROVSKY, D.Yu., MACLEAN, E.J., TEAT, S.J., ZUBKOVA, N.V. (2003): Europ. J.
Mineral., 15, 177-180.
WEIL, M. (2001): Zeitschr. Naturforschung, 56b, 753-758.
WEIL, M. (2003): Zeitschr. Naturforschung, 58b, 1091-1096.
WEIL, M., TILLMANNS, E., PUSHCHAROVSKY, D.Yu. (2005): Inorg. Chem., 44, 1443-1451.

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GREEN INHIBITORS AGAINST CaCO3 SCALE DEPOSITS – ON-SITE
ASSESSMENT AND TUNING IN TUNNEL DRAINAGES
Eichinger, S.1, Boch, R.1,2, Leis, A.3, Baldermann, A.1, Domberger, G.3, Schwab, M.4,
Dietzel, M.1
Institute of Applied Geosciences, Graz University of Technology & NAWI Graz GeoCenter,
Rechbauerstraße 12, 8010 Graz, Austria
2
Geoconsult ZT GmbH, Wissenspark Salzburg Urstein, Urstein Süd 13, 5412 Puch bei Hallein, Austria
3
JR-AquaConSol GmbH, Steyrergasse 21, 8010 Graz, Austria
4
ASFINAG Service GmbH Graz, Fuchsenfeldweg 71, 8074 Graz – Raaba, Austria
e-mail: stefanie.eichinger@tugraz.at
1

Calcium carbonate scale deposits (CaCO3 mineral formation from aqueous solution) ingroundwater drainage systems are a common and challenging issue, especially if depositionand clogging limit the continuous water transport. The mechanical or chemical removal of such
unwanted mineral deposits is highly cost and labor intensive arguing for optimized casespecific and sustainable prevention strategies. In the present study, a novel approach to prevent
tunnel drainages from CaCO3 scale formation was assessed on-site in two selected Austrianroad tunnels: The eco-friendly green inhibitor polyaspartate (PASP) was tested and evaluatedin order to significantly reduce and modify the (micro)structure and material consistency of thewidespread CaCO3 scale deposits. The application of minor amounts of PASP caused (i) asignificant inhibition of CaCO3 precipitation, (ii) a more porous or even loose consistency(calcareous mud) of the CaCO3 deposits, and (iii) a shift in CaCO3 mineralogy frompredominant calcite toward metastable aragonite and frequent vaterite formation. Even a very
low PASP concentration (few mg PASP L-1) induced a strongly elevated saturation index ofcalcite up to ~2, i.e. close to the saturation level of ACC (amorphous Ca-carbonate). The upperreasonable dosage level of PASP has to be adjusted by considering the local inhibition
requirements and regulative limits, as well as the case-specific microbial activity enabling theconsumption of PASP, e.g. by the common iron metabolizing microbial species Leptothrix
ochracea, which can reduce the effective PASP concentration and thus the anticipatedinhibition effect.

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COMPOSITION OF GOLD IN THE ROMAN GOLD MINING DISTRICT KARTH,
LOWER AUSTRIA
Elmer, S.1, Lockhoff, N.2, Melcher, F.1, Cech B.3
Montanuniversität Leoben, Peter-Tunner-Straße 5, 8700 Leoben, Austria
Curt-Engelhorn-Zentrum Archäometrie, D6, 3, 68159 Mannheim, Germany
3
Independant researcher, Quaringgasse 22/3/7, 1100 Wien, Austria
e-mail: simone.elmer@unileoben.ac.at
1

2

The Roman mining district Karth is located between Semmering Schnellstraße S6 andSüdautobahn A2 southwest of Wiener Neustadt, Lower Austria. It is situated on a wooded
plateau in a hilly territory and comprises an area of about 6 km length and 2.5 km width. The
terrain shows remarkable formations like tanks and leat channels which are the remains ofhydraulic mining of placer gold by the Romans as described by Pliny the Elder (CECH et al.,2013). The placer gold occurs in the Loipersbacher Rotlehmserie (also termed Loipersbach
Formation), which is composed of clay and embedded coarse gravel layers (CECH et al., 2019).
The data presented were collected as part of a master thesis (ELMER, 2020) in the context of
FWF Project P30790-G25 (www.karthgold.com). Morphological investigations of gold
particles from Karth using a digital microscope Keyence VHX-6000 based on the classification
scheme from YOUNGSON & CRAW (1999) show mainly equant and complex outlines as well
as mixed forms, whereas branched particles are unusual. Flattening, rounding and folded edgesof the gold particles indicate a distal primary mineralisation, but a statement about thetransported distance is not possible. Back-scattered electron images of polished sections usinga scanning electron microscope Zeiss EVO MA10 show the zoning of gold with high finenessnear the surface, in contrast the interior is rich in Ag; further elements have hardly been
detected. Additional LA-ICP-MS analysis at the CEZA Mannheim, Germany, provide traceelement data and help to gain more information about the composition of this placer gold. Even
though a wide range of elements was analysed, only a few reached the limit of detection. For
comparison with placer gold from Mur, Mürz, and Feistritz, core data of Cu, Cd, Sb, and Hg
are used as these elements are above the detection limit most frequently. Gold from the different
locations contain similar contents of Cu and Sb and therefore do not show cluster todiscriminate one from another. In the core areas of Karth gold, Cd is mainly above the detection
limit, whereas it is generally below in the comparison samples. Even though the reliability of
Hg data by LA-ICP-MS has been discussed (ŽITŇAN et al., 2010) there are significant
differences between the data from Karth and the compared rivers. Gold from Karth contains
mainly <1000 ppm, in the Mürz values are around 660 ppm, in contrast Feistritz and Murcontain higher contents of Hg that are usually >1000 ppm. Thus, in the data so far the greatest
geochemical similarities occur between gold of the Karth and that of the Mürz.
CECH, B., KÜHTREIBER, T. (2013): In: P. SCHERRER (ed.): Römisches Österreich. Graz: Uni-Press Graz
Verlag GmbH (Jahresschrift der Österreichischen Gesellschaft für Archäologie, 36, 1–94.
CECH, B., SCHOLGER, R., STREMKE, F., WEIXELBERGER, G. (2019): In: M. FRASS, J. KLOPF, M.
GABRIEL (Ed.): Erfinder - Erforscher - Erneuerer. 1. Auflage. Salzburg: Paracelsus (Salzburger
Kulturwissenschaftliche Dialoge, 5, 83–114.
ELMER, S. (2020): Masterarbeit. Montanuniversität Leoben, Leoben.
YOUNGSON, J. H., CRAW, D. (1999): Econ. Geol., 94, 615–634.
ŽITŇAN, P., BAKOS, F., SCHMIDERER, A. (2010): Miner. Slovaca, 42, 57–68.

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KOLLERITE, (NH4)2Fe3+(SO3)2(OH)∙H2O, A NEW SULFITE MINERAL
Ende, M.1, Effenberger, H.1, Fehér, B.2 Sajó, I.3, Kótai, L.4, Szakáll, S.5
University of Vienna, Institut für Mineralogie und Kristallographie, Althanstraße 14, 1090 Wien, Austria
2
Herman Ottó Museum, Department of Mineralogy, Kossuth u. 13, 3525 Miskolc, Hungary
3
University of Pécs, Szentágothai Research Centre, Ifjúság u. 6, 7624 Pécs, Hungary
4Institute of Materials and Environmental Chemistry, Hungarian Academy of Sciences, Research Centre for
Natural Sciences, Magyar tudósok u. 2, 1117 Budapest, Hungary
5
University of Miskolc, Department of Mineralogy and Petrology, 3515 Miskolc-Egyetemváros, Hungary
e-mail: herta.silvia.effenberger@univie.ac.at1

Sulfite ions are rare constituents of minerals; so far only eight minerals containing [SO3]2groups have been approved by the IMA-CNMNC. During field work in the coal open pit near
Köves Hill (Pécs-Vasas, Mecsek Mts., South Hungary) the new mineral kollerite was
detected: (NH4)2Fe3+(SO3)2(OH)∙H2O, Cmcm, a = 17.803(7) Å, b = 7.395(4) Å, c = 7.096(3)Å, V = 934.2(7) Å3, Z = 4. Data for structure investigation were collected on a Stoe StadiVari
four-circle diffractometer (Dectris Pilatus 300 K pixel detector, MoKα radiation, 100 W aircooled Incoatec IµS micro-focus X-ray tube, 50 kV, 1 mA).
The Fe3+ ion (<Fe[6]―O> = 1.963(2) Å) has site symmetry 2/m; the atoms S, O1, N, and twoof the H atoms belonging to the NH4 group are located at a mirror plane, the hydroxyl groupas well as the O atom belonging to the water molecule (Ow) have site symmetry m2m. The
water molecules exhibit an orientational disorder with (static or dynamic) half-occupied H
atom positions. However, there is no hint for a long-range order. Despite the small size of thecrystal used for data collection (6765 µm), the atomic coordinates and isotropic
displacement parameter of all H atoms could be refined without any restraints.
<S[3]―O> = 1.538(2) Å and O―S―O = 102.71(12) to 104.58(9)° accord with a sulfite
group. The [Fe(Os)4(Oh)2] octahedra are corner linked to buckled chains via the Oh atoms andrepresent the backbone of the [Fe(OH)(SO3)2]2- chains running parallel to [001]. Similar chain
topologies but with [XO4]2- tetrahedra instead of the [SO3]2- groups are known from theminerals tancoite, sideronatrit, and sideronatrite-2M.
Intercalated between the [Fe(OH)(SO3)2]2- chains are the water molecules and the ammonium
cations. Linkage is achieved by hydrogen bonds only. Despite the loose connection, the(NH4)+ group is ordered and forms clearly defined hydrogen bonds. The N atom of the (NH4)+
cation has a tetrahedral environment: H―N―H and O···N···O are 101.14(11) to 115.24(8)°.
The bond lengths N―Hn (0.81(3) and 0.90(5) Å), Oh―Hh (0.65(7) Å), and Ow―Hw (0.84(7)Å) are in the range expected for X-ray data. The hydrogen bonds are close to linearity(N/O―H···O = 169(4) / 176(4)°). The hydrogen bond lengths in general are relative longemphasising the loose connection of the [Fe(OH)(SO3)2]2- chains: N―Hn···O is 2.803(4) to
2.958 Å, Oh―Hh···Ow and Ow―Hw···O2 are 2.747(6) and 3.104(4) Å, respectively. The
atomic arrangement accords with the needle-like shape of the crystals: the crystals areelongated parallel to [001], i.e., the direction of the [Fe(OH)(SO3)2]2- chains.
Two further phases were found at the same locality: (NH4)9Fe3+(SO3)6 is metastable;−(NH4)2Fe2+(SO3)2 crystallizes trigonal, R 3m, a = 5.3879(8) Å, c = 19.980(4) Å, V = 502.3 Å3.

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TWO NEW POLYMORPHS IN THE POOL OF (Li,Sc)-PYROXENE STRUCTURES
Ende, M.1, Kunit, R.1, Redhammer, G.J.2, Miletich, R.1
1

Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
2
Fachbereich Materialforschung und Physik, Universität Salzburg,
Jakob-Haringer-Strasse 2a, 5020 Salzburg, Austria
e-mail: martin.ende@univie.ac.at

Pyroxenes are among the most abundant minerals in the upper mantle. Knowledge of their highpressure behavior is of particular interest, since phase transitions of pyroxenes are discussed as
being responsible for discontinuities in seismic wave propagation (e.g. WOODLAND, 1998).
As the compression behavior of pyroxenes does not follow the bulk modulus – unit cell volume
relationship for isostructural compounds proposed by ANDERSON & ANDERSON (1970) for
isostructural compounds, but strongly depends on chemical compositions (e.g. ENDE et al.,2020), systematic studies seem inevitable to predict their high-pressure behavior. Germanateanalogue phases have already been in the focus early, as the larger Ge atoms were supposed toprovide easier access to equivalent high-pressure phases.
In this context in-situ compression studies were conducted on synthetic crystals of αLiScGe2O6 (LSG) orthopyroxenes using Raman spectroscopy as well as single-crystal X-ray
diffraction. The purpose of this study is to understand the stability criteria from a structural
perspective, any polymorphism, and the mechanisms of the underlying transitions in nonambient pressure conditions.
In compression studies below 10 GPa on LSG crystals an orthopyroxene- (OEn-Pbca) to postorthopyroxene (pOEn-P21/c) transition has been discovered and found to be the second exampleof this type of transformation (ENDE et al., 2020). However, by a further increase in pressure
for the α-phase two more phase transitions were observed between 9.9 and 10.4 GPa as well
as around 14 GPa. The first transition was an expected transition from a monoclinic lowclinoenstatite (LCEn-P21/c) to a monoclinic high-pressure clinoenstatite (HP-CEn-C2/c) not
known for LSG before. Nevertheless, the second transition, visible with Raman spectroscopy
and single crystal X-ray diffraction, follows the first transition with only ~ 4 GPa pressure
increase and therewith considerably lower pressure as expected. While a structure
determination of the first modification was successful using in-situ diffraction data the structureof the second new phase could not be determined reliably even after a quenching from high-P
conditions. However, a twinned and still monoclinic new high-pressure clinoenstatite unit cell
was found most probably preserving the C2/c space group.
WOODLAND, A.B. (1998): Geophys. Res. Lett., 25, 1241-1244.
ANDERSON, D.L., ANDERSON, O.L. (1970): J. Geophys. Res., 75, 3494-3500.
ENDE, M., MEUSBURGER, J.M., ZEUG, M., SCHEIDL, K.S., REDHAMMER, G.J., MILETICH, R. (2020):
Inorg. Chem., 59, 17981-17991.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

SOLID SOLUTION BETWEEN THE TOURMALINE END-MEMBERS
ALUMINO-OXY-ROSSMANITE AND OXY-FOITITE FROM A PEGMATITE IN
HIGH-GRADE METAMORPHIC ROCKS
Ertl, A.1
Institut für Mineralogie und Kristallographie, University of Vienna, Althanstrasse 14, 1090 Vienna, Austria
e-mail: andreas.ertl@a1.net

1

Recently, a new tourmaline was described that represents the most Al-rich end-member
composition (ERTL et al., 2021). Alumino-oxy-rossmanite, ideally Al3Al6(Si5AlO18)(BO3)3(OH)3O, is an Al-rich oxy-tourmaline from a small pegmatitic body embedded in high-grade
metamorphic rocks (amphibolite, biotite-rich paragneiss). This new pink coloured tourmaline
was found in a Moldanubian pegmatite (of the Drosendorf Unit) that occurred in a large
quarry near the village of Eibenstein an der Thaya, Waidhofen an der Thaya district, Lower
Austria. Because of the low mode of associated mica (muscovite), ERTL et al. (2021)
assumed that the silica melt, which formed this pegmatite, crystallized under relatively dry
conditions, in agreement with the observation that alumino-oxy-rossmanite contains a lower
amount of OH than most other tourmalines. These authors also concluded that the significant
content of tetrahedrally-coordinated Al reflects the relatively high-temperature conditions(~700 °C) inferred for crystallization of this pegmatitic rock. From the same pegmatitic bodya dark green Al- and Fe-rich tourmaline was described by ERTL et al. (2004). Based on new
Mössbauer interpretations, this tourmaline does not have any tetrahedrally-coordinated Fe3+ incontrast to that publication. The amount of Fe3+ instead occurs at an octahedral site that is
tetrahedrally distorted. Hence, the recalculated formula of the dark green tourmaline is(Na0.52 0.47Ca0.01)(Al1.49Fe2+0.83Mn2+0.40Fe3+0.10Li0.05Mg0.03Ti4+0.03Mn3+0.02 0.05)(Al5.90Mg0.10)(BO3)3[Si5.73Al0.27O18](OH)3[O0.55(OH)0.31F0.14]. Considering this formula, the components ofthe dark green tourmaline are 27 mol% alumino-oxy-rossmanite, 16 mol% oxy-foitite, 15mol% schorl, 11 mol% fluor-tsilaisite, 6 mol% dutrowite, 4 mol% foitite, 3 mol% bosiite, 3mol% oxy-dravite, 2 mol% fluor-elbaite, 2 mol% tsilaisite, and 1 mol% fluor-liddicoatite. The
sum of these components is 90 mol%. Hence this sample is a complex intergrowth of different
endmembers, mainly of the alumino-oxy-rossmanite – oxy-foitite – schorl solid solution.
Oxy-foitite, also described from high-grade metamorphic rocks (migmatitic gneisses) by
BOSI et al. (2017) fits therefore well into the paragenesis with alumino-oxy-rossmanite.
This work was supported by the Austrian Science Fund (FWF) project no. P 31049-N29.
BOSI, F., SKOGBY, H., HÅLENIUS, U. (2017): Europ. J. Mineral., 29, 889-896.
ERTL, A., HUGHES, J.M., PROWATKE, S., LUDWIG, T., LENGAUER, C.L., MEYER, H.-P., GIESTER, G.,
KOLITSCH, U., PRAYER, A. (2021): Amer. Mineral., 106 (accepted).
ERTL, A., PERTLIK, F., DYAR, M.D., PROWATKE, S., HUGHES, J.M., LUDWIG, T., BERNHARDT, H.-J.
(2004): Canad. Mineral., 42, 1057-1063.

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PETROLOGY AND GEOCHEMISTRY OF TRACHYANDESITES AND
RHYOLITES FROM BAD GLEICHENBERG, STYRIAN BASIN
Fehleisen, A.1, Hauzenberger, C.A.1, Skrzypek, E.1, Gallhofer, D.1
University of Graz, Universitätsplatz 3, 8010 Graz, Austria
e-mail: anna.fehleisen@edu.uni-graz.at

1

The volcanic formation of Bad Gleichenberg, localized in the eastern region of the Styrian
Basin, is one of the less well studied magmatic formations in the Pannonian Basin System.
This occurrence, which nowadays forms the Gleichenberg and Bschaidkogel, presents
trachyandesites and rhyolites with a calc-alkaline to shoshonitic affinity. A Middle Miocene
crystallization age (13 ± 1 Ma) has been determined by K/Ar dating (BALOGH et al., 1990),
and is clearly different from the Pliocene alkaline basaltic magmatic formation thatcharacterizes the Styrian Basin. Samples collected from different areas around Bad
Gleichenberg were investigated by petrological, mineral chemical and geochemical methods,
which allowed to obtain novel information about this volcanic formation. The
trachyandesites, which represent the majority of the volcanic rocks, follow a typical magmaticdifferentiation trend with SiO2 varying from 57 to 62 wt%. CaO, FeO and MgO decrease withincreasing SiO2, while Al2O3, K2O, Na2O and P2O5 increase with increasing SiO2. Rhyolites
occur in subordinate amounts with SiO2 contents >71 wt%. Hydrous minerals such as biotite
and apatite are commonly found in both magmatic series. The F content is high in biotite andapatite with values up to 2 and 3 wt%, respectively. TiO2 contents in biotite can be as high as
8 wt%.
Idiomorphic zircons are commonly found in all samples, some with abundant apatite
inclusions and visible zircon cores. LA-MC-ICPMS U-Pb zircon dating yielded homogeneous
crystallization ages of ~14 Ma for both volcanic rock types. The analyzed zircon cores
resulted in exactly the same age as the rims and the homogeneous zircons. The Gleichenberg
volcanism and its geochemical characteristics are related to the simultaneous occurring
extension and compression in the Styrian/Pannonian Basin caused by the collision of the
Adriatic plate with Europe and a subsequent slab retreat. The Gleichenberg formation belongs
to a group of related volcanic outcrops in the Western Pannonian Basin System such as theBalatonmária and Bükkalja Volcanic Fields in Hungary.
BALOGH, K., HARALD, L., PÉCSKAY, Z., RAVASZ, CS., SOLTI, G. (1990): MÁFÍ Évi Jel. 1988-ról, 451468.

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U/Pb AGES OF DETRITAL ZIRCONS OF DIFFERENT METASEDIMENTARYCOMPLEXES OF THE KORALPE-WÖLZ NAPPE SYSTEM (EASTERN ALPS) NEW EVIDENCES OF VARYING PROVENANCE AND PROTOLITH AGESBY LA-ICPMS ANALYSESFrank, N.1, Hauzenberger, C.A.1, Skrzypek, E.1, Schuster, R.2, Gallhofer, D.1,
He, D.3, Kurz, W.1
University of Graz, Graz, NAWI Graz Geocenter, Universitätsplatz 2, 8010 Graz, Austria
Department of Hard Rock Geology, Geologcial Survey of Austria, Neulinggasse 38, 1030 Vienna, Austria
3State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University,
Xian, No.229, North Taibai Road, Xi'an City, Shaanxi Province, Chinae-mail: nils.frank@edu.uni-graz.at
1

2

The Koralpe-Wölz nappe system, as part of the Austroalpine nappe complex, belongs to the
crystalline basement of the Eastern Alps and is composed of different metasedimentarycomplexes with mono-, bi-, or polymetamorphic history (SCHMID et al., 2004; HABLER &THÖNI, 2001; THÖNI & MILLER, 2009). Very little is known about the protoliths of theKoralpe-Wölz nappe system, while the metamorphic conditions for several metamorphic eventsare very well constrained. This nappe system experienced high grade Eo-Alpine metamorphism
during or after Alpine nappe stacking. The different complexes were also affected by Permian
high-temperature – low-pressure metamorphism.
Based on U/Pb data of detrital zircons from different metasedimentary complexes, we can givean overview about maximum ages of sediment deposition.
Zircon age spectra of sampled metasediments of three different complexes indicate postVariscan sedimentation with maximum ages of ~300 Ma (Koralpe / Saualpe), ~330 Ma(Rappold) and ~360 Ma (Millstatt). Zircon ages of the Radenthein complex indicate postCadomian sedimentation. The main peaks for zircons of the Koralpe and Saualpe complex show
Ordovician and Carboniferous ages. Two samples from Saualpe (Koralpe Complex) havemetamorphic rims or crystals and show main zircon age peaks at ~275 Ma which agrees wellwith the metamorphic “Permian event” (THÖNI et al., 2008). The age spectra for the Rappold,
Millstatt, and Radenthein complexes are dominated by Cadomian zircons. Dominating
Cadomian zircon ages are detectable at one micaschist sample of the Pohorje massif (Koralpe)
as well. One micaschist sample from Saualpe and one micaschist sample from the Pohorje
massif (Koralpe) are dominated by zircons with an age of around 90 Ma, recording the EoAlpine high-grade metamorphic event.
HABLER, G., THÖNI, M. (2001): J. Metamorphic Geol., 19, 679–697.
SCHMID, S.M., FÜGENSCHUH, B., KISSLING, E., SCHUSTER, R. (2004): Eclogae geol. Helv., 97, 93–117.
THÖNI, M., MILLER, C. (2009): Chem. Geol., 260, 20–36.

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THE EFFECT OF FLUORINE ON REACTION RIM GROWTH DYNAMICS IN THE
TERNARY CaO-MgO-SiO2 SYSTEM
Franke, M.G.1, Joachim-Mrosko, B.1
1

Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52f, 6020 Innsbruck, Austria
e-mail: Mees.Franke@uibk.ac.at

Metamorphic corona and reaction rim structures are examples of a net-transfer reaction, where
pre-existing mineral phases react to new phases. Growth of these metamorphic structuresindicates a change in physical parameters such as pressure and temperature, a change in thechemical composition of the system and/or the presence of volatiles. In particular the effect ofvolatile components on net-transfer reactions remains is, however, poorly understood. In orderto accurately model metamorphic and metasomatic processes and test the potential of natural
reaction rims to be used as "geofluidometers”, a quantification of the effect of volatiles onreaction-rim growth dynamics is necessary.
In this study, we investigate the effect of fluorine on reaction rim growth dynamics in the
ternary CaO-MgO-SiO2 system. A series of piston cylinder experiments was conducted at P-T
conditions of 1000 °C and 1.5 GPa. In each experiment, reaction rims were grown for 20
minutes between a natural wollastonite crystal and MgO powder matrix with the addition of 0
to 10 wt% fluorine. Electron microprobe analyses and Raman spectroscopy were used toanalyse the crystalline phases present in the reaction rim.
In the fluorine free system, we produced a monomineralic rim sequence of wo | mer | di | fo |per, complying with phase stabilities at water saturated conditions. As soon as 0.1 wt% fluorine
was introduced into the system, humite group minerals (HGMs) and monticellite werestabilized resulting in the multilayer rim sequence wo | mer | mtc | fo + HGMs | per. In
experiments with fluorine concentrations >1 wt%, palisades of diopside and cuspidine appear
where cuspidine represents the major fluorine sink. Our data show that the addition of fluorine
stabilises the fluorine bearing phases cuspidine and HGMs to higher temperatures. Furthermore,
results of this study reveal a positive correlation between overall rim thickness and fluorine
content. Reaction rim widths increased from 12.50 (146) to 105.49 (185) m in fluorine free
and 10 wt% F experiments respectively.
Our results illustrate the significance of fluorine during net-transfer reactions, where its
presence has a strong effect on [I] the overall rim thickness, which increases by 10-fold if 10
wt% F is added to the water saturated system, [II] phase stabilities, where fluorine bearing
minerals such as humite group minerals and cuspidine are stabilised, [III] the relative mobilitiesof the individual components, and as a consequence [IV] the internal rim microstructure. Thesefindings have important implications for reaction rims to be utilized as a potential“geofluidometer” and may allow us to unravel the chemical composition of metasomatic fluids.

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MAGMATIC AND SEDIMENTARY EVOLUTION OF THE NORIC NAPPES(GREYWACKE ZONE) – THE VARISCAN SLOPING CONTINENTAL MARGIN
Fritz, H.1, Nievoll, J.2, Gallhofer, D.1, Hauzenberger, C.A.1, Gritsch, B.1, Pfatschbacher, M.1,
Krenn, K.1, Karner-Rühl, K.1
University of Graz, Heinrichstrasse 26 and Universitätsplatz 2, 8010 Graz, Austria
2
Gumpendorfer Straße 83–85/2/48, 1060 Vienna, Austria
e-mail: harald.fritz@uni-graz.at

1

Detailed mapping of monotonous (boring) magmatic and sedimentary suites within the Eastern
Greywacke Zone allow distinction of four different nappes within the Noric-Tirolic nappe
assembly. These are from tectonic bottom to top the Hocheck-, Rossegg-, Steinbach-, andAschbach nappes. The lowermost Hocheck nappe rests tectonically on slivers of Silbersberg
and Veitsch nappes. U/Pb dating of about 600 zircons of magmatic members and of detrital
zircons derived from sandstones enable correlation of units across individual nappes.
Retrodeformation of the nappe assembly together with definition of different sedimentary facies
realms allow a reconstruction of the Ordovician to lower Devonian paleogeography. Highlightsof the study include: (1) Magmatism of Blasseneck porphyry type initiated already by c. 480
Ma and continued until c. 445 Ma; all magmatics are calc-alkaline and range from andesite torhyolite. This documents magmatic pulses from the end of the Ceneric Orogeny to the openingof the Rheic Ocean. (2) Massive, up to 1000 meter thick porphyries within the Hocheck- andRossegg Nappes correlate timely with thin layers of tuffs and sills within the Steinbach Nappe.
This suggests originally large distances between these nappes and consequently large tectonic
transport during Variscan and/or Alpine times. (3) Detrital zircons allow dating of thesandstones within Steinbach- and Aschbach-nappes that range from lower Ordovician to upper
Silurian. Sandstones incorporated increasingly lithic components of the collapsing passive
continental Gondwana margin. (4) Age correlation together with retrodeformation anddefinition of facies domains allow reconstruction of this continental margin. The Rad Formation
within Hocheck- and Rossegg-nappes is defined, from macrofossils, as shallow marine domain
whereas the Stocker Formation of the Steinbach Nappe is, from sedimentary structures, definedas continental slope. The Sommerauer Formation of the Aschbach Nappe contains turbidite
interpreted as channel or lobe sediments on the ocean floor.

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COUPLED DISSOLUTION AND CRYSTALLIZATION KINETICS OF
AMORPHOUS AND CRYSTALLINE CALCIUM CARBONATE INAQUATIC MEDIA
Galan, I.1, Purgstaller, B.1, Grengg, C.1, Müller, B.2, Dietzel, M.1
Institute of Applied Geosciences, Graz University of Technology, Rechbauerstraße 12, 8010 Graz, Austria
2Institute of Analytical Chemistry and Food Chemistry, Graz University of Technology,
Stremayrgasse 9, 8010 Graz, Austria
e-mail: igalangarcia@tugraz.at

1

The transformation behaviour of amorphous (ACC) and crystalline calcium carbonate (e.g.
vaterite) in aquatic media at high solid/liquid ratio can lead to the formation of so-called‘calcium carbonate cements’, where reaction kinetics are still less explored. In the present study
the dissolution and precipitation processes in the ACC-vaterite-H2O system were monitored bymeans of in-situ optical pH sensors and Raman spectroscopy. In addition, solids and liquids
were sampled and classically analysed at specific experimental run times. The experimental
data were complemented with thermodynamic modelling. The influence of Mg2+ ions on thereaction kinetics was assessed in parallel experiments where a 30 mM MgCl2 solution insteadof pure water was used. Vaterite - in the presence of ACC - leads to significantly more cohesive
matrixes than aragonite and calcite, which is attributed to the differences in morphology,
surface area and dissolution kinetics. The dissolution of vaterite is accompanied by a pH rise
and takes place in two stages: (i) immediately after the conversion of ACC to vaterite and (ii)after a period of ~48 hours. In the presence of Mg the formation of vaterite is inhibited and only
one dissolution stage, corresponding mostly to the initially added vaterite, is observed after ~30
h. Mg is mostly incorporated into the final calcite and the Mg-containing experiment constantconditions are reached after ~90 h, about 10 hours earlier than using pure H2O. Time-resolved
in-situ technique for pH and solid analyses are suitable and promising tools to further tailor new
calcium carbonate based binders.

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GEOCHEMICAL AND GEOCHRONOLOGICAL CHARACTERIZATION OFZIRCON MEGACRYSTS FROM KAWISIGAMUWA CARBONATITE, SRI LANKA
Gallhofer, D.1, Skrzypek, E.1, Fernando, G.W.A.R. 2, Hauzenberger, C.A.1
University of Graz, Graz, Universitätsplatz 2, 8010, Graz, Austria
The Open University of Sri Lanka, PO Box 21, Nugegoda, Sri Lankae-mail: daniela.gallhofer@uni-graz.at
1

2

Since in-situ dating methods consume large amounts of matrix-matched reference materials,
suitable materials are highly sought-after. Ideally, reference materials should have a large
volume and be isotopically homogeneous. Here, we present zircon megacrysts from the
Kawisigamuwa carbonatite, Sri Lanka, which fulfil these criteria. In this study, we firstcharacterize the crystallinity and composition of the zircon megacrysts. We then present U-Pb
isotopic data collected with laser ablation-inductively coupled plasma mass spectrometry(LA-ICPMS) and test the influence of various instrumental settings, primary referencematerials, and chemical composition on U-Pb dates.
The Sri Lankan zircon megacrysts have low and variable trace element contents
corresponding to zones with distinct cathodoluminescence emission (CL-zones) and are well
crystallised (FWHM <5 cm-1). The increasingly darker CL-zones reflect an increase of REE,
Th, U, and, to some degree, P, while Hf concentration is inversely correlated with CLbrightness and also seems to be grain-dependant. Very dark CL bands have total REE
abundances of more than 100 µg/g, which are associated with high Th/U ratios (2.6-3), low P
and Hf contents. Some moderately CL-bright zones are highly enriched in P (>120 µg/g) andshow only moderate REE and Hf contents. Phosphorus, REEs, and Al are likely
accommodated in the crystal lattice by xenotime-type and berlinite-type substitutions.
We determined U-Pb ages for four zircon megacrysts. The single zircon dates range from480-540 Ma. Data show that smaller spot diameters (15 µm, 25 µm) yield a larger scatter ofsingle data, with some of them being markedly younger. Data determined with 35 µm spot
size show little variation and commonly overlap within error. The concordant zircon analyses
yield a weighted mean 206Pb/238U age of 529.3 ± 0.4 Ma (internal 2 SE, n = 304/318, MSWD
= 3), which is regarded as the best estimate of the (minimum) crystallization age of the zircon
megacrysts from the carbonatitic magma.
Our results indicate that the Sri Lankan zircons are probably less suitable as a secondaryreference material for LA-ICPMS analysis of trace elements. However, due to their isotopic
homogeneity the zircons can be used as secondary reference material for U-Pb dating when an
additional TIMS reference age is established.

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REACTION OF MgO WITH CARBOXYLIC ACID
Gerger, S.1, Baldermann, A.1, Dietzel, M.1
1

Institute of Applied Geosciences, Graz University of Technology, NAWI Graz Geocenter,
Rechbauerstraße 12, 8010 Graz, Austria
e-mail: sabrina.gerger@tugraz.at

The chemical reaction mechanisms during cast stone formation and in particular the reaction of
periclase (MgO) with organic acids are still poorly understood. Therefore, experimental
investigations on the reaction of MgO-organo-H2O castables inferred by type and compositionof low temperature MgO_l together with dead-burned MgO_d with citric, malic or acetic acids
were carried out. The mineralogy, microstructure and the reactivity of the educts and theprecipitates were assessed by XRD, FTIR spectroscopy, sound velocity analyses and scanningelectron microscopy. The overall hardening behavior of the reaction product within the MgOcarboxylic acid-H2O system is strongly influenced by the type and spatial distribution of the
distinct acid reacting with the MgO_l. Best hardening performance was observed with citricand malic acid due to the formation of interconnecting Mg-Hcitrate and Mg-malate precipitates,
whereas Mg-acetate binding was spatially restricted. Impurities of MgO_d, such as the minerals
merwinite [Ca3Mg(SiO4)2], magnesioferrite [MgFe3+2O4] or larnite [Ca2(SiO4)], lead toenhanced hardening by the formation of Ca-Fe-Mg-organo precipitates. Ongoing studies help
to better understand the coupled dissolution and precipitation phenomena within the MgOcarboxylic acid-H2O system. In particular, the stability constants of distinct aqueous complexes
and solid phases have to be considered and assessed to develop a conceptual model of thereaction mechanisms and pathways, which are responsible for the hardening process.

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ATOM PROBE TOMOGRAPHY OF GEOLOGIC MATERIALS
Gopon, P.1,2, Hofer, C.3, Douglas, J.1,4, Moody, M.2, Melcher, F.1
Ls. für Geologie und Lagerstättenlehre, Montanuniversität Leoben, Peter-Tunner Straβe, 8770 Leoben, Austria
2Dept. of Materials, University of Oxford, Parks Road, OX1 3PH, Oxford, UK
3
Ls. für Stahldesign, Montanuniversität Leoben, Roseggerstrasse, 8770 Leoben, Austria
4Dept. of Materials, Imperial College London, Royal School of Mines: Exhibition Road, SW7 2AZ, London, UK
1

As geologists we are often focused on large scale questions, however many of the answers tothese questions lie not in describing regional structures but in the proper interpretations of small
scale observations. The emerging field of nano-geochemistry has been important in deepening
our understanding of a range of geological processes. From a new understanding of the U/Pb
system to ore body formation, many of these findings have been elucidated with the aid of therelatively new technique of atom probe tomography (APT; VALLEY et al., 2015; Gopon et al.,2019). APT is a destructive technique that evaporates a sample one atom at a time, in order todigitally reconstruct it (Figure 1). The resultant dataset contains the location and chemical, andisotopic, identity of nearly every atom of the sample in three dimensions to near atomic scale
resolution (Figure 1). These datasets are a treasure trove of major, minor, and isotopic chemical
information that provides us with an unrivaled view into a materials inner workings.
This talk will introduce the audience to the new technique of APT, challenges of APT, as wellas its application or potential application to a select number of geologic systems; namely cosmochemistry, ore geology, and diffusion studies. We will also introduce the cutting edge new APT
capability at the University of Leoben, and our current and future research.

Figure 1. Generalized APT workflow, example from metallic inclusions in Apollo 16 lunar dust. a) BSE image
showing sub-micrometer phases of Fe-Si; b) region chosen for a site specific liftout; c) APT specimen prior to thefinal annular milling step; d); APT specimen after the final annular milling, ready to be put into the atom probe;e) generalized geometry of an APT experiment, the needle shaped sample (from d) on the left; f) reconstruction of
the APT needle shaped specimen after the experiment, note that only Si, Cr, and P are shown for clarity.

GOPON, P., DOUGLAS, J.O., AUGER, M.A., HANSEN, L., WADE, J., CLINE, J.S., ROBB, L.J., MOODY,
M.P. (2019): Econ. Geol., 114, 1123–1133.
VALLEY, J.W., REINHARD, D.A., CAVOSIE, A.J., USHIKUBO, T., LAWRENCE, D.F., LARSON, D.J.,
KELLY, T.F., SNOEYENBOS, D.R., STRICKLAND, A. (2015): Presidential Address. Amer. Miner.,
100, 1355–1377.

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EOARCHEAN SUBDUCTION-LIKE MAGMATISM
RECORDED IN 3750 MA MAFIC–ULTRAMAFIC ROCKS OF THE
UKALIQ SUPRACRUSTAL BELT (QUÉBEC)
Grocolas, T.1,2, Bouilhol, P.1, Caro, G.1, Mojzsis, S.J.3,4,5
Université de Lorraine, CNRS, CRPG, 15 rue Notre Dame des Pauvres BP 20,54500 Vandœuvre les Nancy, France
2
Institute of Earth Sciences, University of Lausanne, Géopolis, 1015 Lausanne, Switzerland
3
Origins Research Institute, Research Centre for Astronomy and Earth Sciences,15-17 Konkoly Thege Miklós Road, 1121 Budapest, Hungary
4
Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
5Department of Geological Sciences, University of Colorado, 2200 Colorado Avenue, Boulder,
Colorado 80309-0399, USAe-mail: stephen.james.mojzsis@univie.ac.at
1

Our understanding of the nature of crustal formation in the Eoarchean is limited by the scarcity
and poor preservation of the oldest rocks, and variable and imperfect preservation of protolithmagmatic signatures. These limitations hamper our ability to place quantitative constraints onthermomechanical models (e.g., the stagnant-lid and the active-lid models; FISCHER &GERYA, 2016a, 2016b) for early crustal genesis and hence on the operative geodynamic
regimes at that time. The ca. 3.75 Ga Ukaliq supracrustal enclave (northern Québec; CARO etal., 2017) is composed of diverse serpentinized ultramafic rocks and amphibolitized mafic
schists. The protoliths of the ultramafic rocks are cumulative dunites, olivine-pyroxenites andhornblendites and the mafic amphibolites are basalts to basaltic andesites. Based on major andtrace element mineral chemistry and geothermometry, we show the partial preservation of
cumulative pyroxenes and amphiboles. Two suites of lavas–cumulates are inferred with a TiO2rich, flat rare-earth element pattern-bearing, clinopyroxene-dominated, tholeiitic suite, and a
TiO2-poor, U-shaped rare earth element pattern-bearing, orthopyroxene-dominated, boninitelike suite. Coupled with 142Nd isotopic measurements (CARO et al., 2017) and melt modeling,
we explored two liquid lines of descent: (i) a water-undersaturated, adiabatic decompressionrelated, tholeiitic sequence fractionating olivine, clinopyroxene, amphibole, and plagioclase;and (ii) a boninite-like suite documenting the evolution of an initially primitive, flux meltingassociated basaltic to andesitic melt at ~0.5 GPa and containing >4 wt% H2O throughfractionation of olivine, orthopyroxene, and amphibole. The large amounts of water required toform near-liquidus amphibole as well as the negative 142Nd anomalies in boninitic lavas suggestthat a deep fluid carrying the 142Nd anomaly played a role in the genesis of the boninitic melts.
The simplest way to explain such differentiation sequences and geochemical signatures is thefoundering of a Hadean crust in a similar way as modern-style subduction triggering adiabatic
decompression generating the tholeiitic melts followed by flux melting producing the 142Nd
anomaly-bearing boninitic melts.
CARO, G., MORINO, P., MOJZSIS, S.J., CATES, N.L., BLEEKER, W. (2017): Earth Planet. Sci. Lett., 457, 2337.
FISCHER, R., GERYA, T. (2016a,b): J. Geodyn., 100, 198-214; Gondwana Res., 37, 53-70.

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A U/Pb ZIRCON STUDY ON THE SCHLADMING NAPPE AND ITSIMPLICATIONS FOR THE PRE-ALPINE EVOLUTION OF THE AUSTROALPINEBASEMENT
Haas, I.1, Kurz, W.1, Gallhofer, D.1, Hauzenberger, C.A.1
1

University of Graz, NAWI Graz Geocenter - Institute of Earth Sciences, Heinrichstraße 26, Graz, 8010, Austria
e-mail: isabella.haas@uni-graz.at

The Schladming Nappe of the Eastern Alps is part of the Silvretta-Seckau Nappe system and is
widely built up by pre-Alpine crystalline basement rocks. It consists mainly of paragneisses
intruded by subsequently overprinted granites and granodiorites, which are further overlain by
a sedimentary cover (quartzite and meta-conglomerate, e.g. Rannach Formation).
Lacking precise geochronological data, the meta-granitoids have so far been assumed to beconnected to widely distributed magmatic intrusions related to the Variscan orogeny. To gain
insight into the timing of the magmatic emplacement, as well as the tectono-metamorphic
history of the Schladming nappe, U-Pb zircon ages were determined by LA-MC-ICPMS. The
acquired ages of the meta-granitoids hint at two intrusive events for the main part of the
Schladming Nappe: (1) a Cambrian event with zircon 206Pb/238U mean ages between 494±2 Ma
and 498±3 Ma and (2) an Upper Devonian event with zircon mean ages between 353±2 Ma and371±2 Ma correlating with early Variscan magmatism. Interestingly, an additional Permianaged intrusion event was found in the SE part of the research area with zircon mean ages
between 262±2 Ma and 264±2 Ma. According to the available geological maps these intrusives
are part of the Schladming Nappe. However, due to the unclear tectonic contact to the adjacentmetapelites of the Wölz Nappe system the actual tectonic position remains debated.
The geochemical data confirms a peraluminous character for all meta-granitoids. The older
group has consistently higher SiO2 values while the Upper Devonian age group has moderate
SiO2 contents but higher amounts of MgO, FeO, and Al2O3 as well as Sr and Ba. Additionally,
the samples of the Devonian age group can be divided into subgroups, one group reflecting
negative Eu-anomalies (EuN/Eu* = 0.44-0.69) and the other lacking pronounced Eu-anomalies(EuN/Eu* = 0.82-1.08). The Permian group clearly differs geochemically through partly higher
abundance of K2O, and otherwise shows similarities to the Cambrian age group. While
characteristics of the Upper Devonian samples hint at a magmatic arc origin, the oldest andyoungest group seem to be linked to a more complex formation.

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THE COLLECTIONS OF THE ARCHIVE OF THE HISTORY OF GEOLOGYAT THE UNIVERSITY OF VIENNA:
ORGANIZING AND DIGITIZING OF GEOLOGICAL HERITAGE
Hamilton, M.1, Nagl, P.2
1

Archiv der Geschichte der Geologie, Institute of Geology, University of Vienna, Althanstraße 14, 1090 Vienna,
Austria2
Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
e-mail: Margret.Hamilton@univie.ac.at

The collections of the Geological Institute go back to the initiative of the former head of theGeological Institute Alexander Tollmann (1928-2007). He collected documents from the1970s at the former institute and transferred them into a separate depot when relocating of theinstitute in 1995 to the present Geozentrum in the 9th district of Vienna, Althanstraße 14. He
arranged and labelled a number of documents.
Many documents of the institute were collected and preserved in various files during themanagement period of Alexander Tollmann including also his personal records. Thus, there
are documents about new acquisitions of the institute and also books about excursions.
Partial, but also entire legacies of various geoscientists, were collected in colorful boxes. Aninteresting part of Eduard Suess’s (1831-1914) legacy, the first professor of the Geological
Institute, contains a lot of handwritten records. Alexander Tollmann sorted and described asmall number and put them into files.
Likewise, part sorted or unsorted legacies were obtained from well-known geoscientists, such
as Martha Cornelius-Furlani (1886-1974) and her husband Peter Cornelius (1888-1950). An
extensive legacy by Walter Medwenitsch (1927-1992) was found in colorful boxes in an
extremely chaotic state. As a side note: there is a beautiful collection of beer mats and evencollectors magazines. This gives an indication for the preference of Medwenitsch for beers.
A geological map of the Eastern Alps painted by Leopold Kober (1883-1970) had been
restored. Kober named it “Tektonogramm”, dated in 1937.
There is also a hammer-collection, hammers of geologists and mineralogists from former
times to nowadays given to the Geological Archive.
A large collection of slides with geological content from the legacy of Alexander Tollmannhas been preserved. Similarly, many slides of Walter Medwenitsch existed in a disorderly
state. In the legacy of Tollmann and Medwenitsch there are a series of photos of geoscientists.
These are already sorted and digitized.
A collection of about 1000 pieces of black and white glass photo plates, in excellent
condition, are also put into order and digitized. An extensive collection of hammers datingback to the time of Eduard Suess has already been brought into shape.
At the request of the current head of the institute, Prof. Mag. Dr. Bernhard Grasemann, theauthor took up the task of organizing, systematizing, digitizing, and making accessible thisextensive collection in modern archive boxes to the interested audience, professors, andstudents alike.

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DER EINFLUSS VON ALTERUNGSPROZESSEN AUF DIE RHEOLOGISCHENEIGENSCHAFTEN UND CHEMISCHE ZUSAMMENSETZUNG
KOHLENSTOFFHALTIGER TONE
Hassler, J.1, Knodt, R.1, Piribauer, C.1, Diedel, R.2, Häußer, S.2
1

Forschungsinstitut für Anorganische Werkstoffe – Glas | Keramik (FGK), Heinrich-Meister-Straße 2,56203 Höhr-Grenzhausen, Germany
2
Stephan Schmidt KG, Bahnhofstraße 92, 65599 Dornburg, Germany
e-mail: jannis.hassler@fgk-keramik.de

Im Rahmen eines öffentlich geförderten Projektes wird das Alterungsverhalten
kohlenstoffhaltiger, keramischer Tone untersucht und die Einflussgröße eines industriell
verwendeten Additivs zur Kontrolle von Alterungsprozessen ermittelt. Alterungsprozesse in
Tonen führen zu einer Veränderung der chemischen und mineralogischen Zusammensetzung
der Tone und so zu (je nach entstehendem Produkt positiven oder negativen) Änderungen derkeramischen Verarbeitungseigenschaften. So konnte im Rahmen vorheriger Arbeiten gezeigt
werden, dass Huminsäuren, welche selbst Produkte von Oxidations- und Zersetzungsprozessenorganischer Materie und somit natürliche Bestandteile von Tonen sind, sich positiv auf die
keramischen Verarbeitungseigenschaften auswirken (PIRIBAUER et al., 2020).
Zur Ermittlung der Veränderungen über die Zeit wurde ein kohlenhaltiger Haldenton über einen
Zeitraum von 6 Monaten parallel an Luftatmosphäre sowie in einer Klimakammer unter stetiger
Atmosphäre zur Alterung gelagert und periodisch auf rheologische Eigenschaften (Viskosität,
Trockenbiegefestigkeit (TBF)) und chemische-mineralogische Zusammensetzung (eluierbare
Ionen, Leitfähigkeit, Gehalte an C, N und S) untersucht. Zur Erfassung des Einflusses industriell
genutzter Additive zur Kontrolle von Alterungsprozessen wurden mit BaCO3 versetzte Proben
analog eingelagert und analysiert. In den mit Additiv versetzten Tonproben ist über den
Versuchszeitraum eine stetige Abnahme an eluierbarem Barium so lange zu beobachten, bis die
Elementkonzentration im Eluat zum Messzeitpunkt 12 Wochen unterhalb der Nachweisgrenze
fällt. In allen untersuchten Proben ist ein Anstieg an löslichem Sulfat über den
Versuchszeitraum nachzuweisen, welcher in den Proben ohne zugegebenes Additiv im direkten
Vergleich verstärkt und beschleunigt nachweisbar ist. In allen Tonproben sind in Korrelation
zu den löslichen Sulfatgehalten verstärkte Löslichkeiten an Ca- und Mg-Kationen zu
beobachten. Die mit BaCO3 versetzten Haldentone verzeichnen in der ersten Hälfte desVersuchszeitraums eluierbare Konzentrationen an Fe- und Al-Ionen, welche unstetig mit der
Versuchsdauer abnehmen, bis sie zum Zeitpunkt t = 8 Wochen unterhalb der Nachweisgrenze
fallen. Veränderungen an Gehalten von Gesamtschwefel, Stickstoff und Kohlenstoff in den
Proben sind über den Versuchszeitraum nicht erkennbar.
Die Haldentone ohne zugegebenes Additiv verzeichnen in Korrelation mit den zunehmenden
eluierbaren Anteilen an Sulfat und Erdalkalielementen eine Zunahme der Viskosität. Eine
Zunahme der TBF ist in keiner der untersuchten Proben über den Versuchszeitraum zu
beobachten.
PIRIBAUER, C. (2020): Ceramic Forum Internat., 97, E36-E42.

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HIGH PRESSURE BEHAVIOUR OF
PEARCEITE-POLYBASITE GROUP MINERALS
Hejny, C.1, Wierer, A.1, Venturi, A.1
1

University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria
e-mail: clivia.hejny@unibk.ac.at

Pearceite-polybasite group minerals (PPGM), [(Ag,Cu)6(As,Sb)2S7][Ag9CuS4], are intriguingmaterials with Ag+ fast ion conduction character that have attracted a lot of interest in the recent
years. The notation of the chemical formula reflects the fact, that PPGM are composed of two
different layers: layer A with general composition [(Ag,Cu)6(As,Sb)2S7]2- and layer B withgeneral composition [Ag9CuS4]2+, whereat layer B is the place where the ionic conductivity
takes places (BINDI et al., 2007). The root-name pearceite is given to minerals where As isdominant over Sb and the root-name polybasite for Sb-dominant phases. In addition, a suffix is
attached to the root-name to give crystallographic information on the superstructure variant.
Trigonal polytypes with lattice parameters a  7.5, c  12.0 Å are given the hyphenated italic
suffix -Tac, trigonal polytypes with lattice parameters a  15.0, c  12.0 Å have -T2ac andmonoclinic polytypes with a  26.0, b  15.0 c  24.0 Å,   90° have -M2a2b2c as suffix.
Depending on the exact chemical composition and disorder of the Ag and Cu atoms within the
crystal structure a number of different crystal structures and their temperature-induced phasetransitions are known (e.g. BINDI et al., 2006).
In order to test the possibility to use pressure as a switch for superconductivity, i.e. to induce
phase transitions from the ionic conduction form to an ordered or partially ordered
superstructure form with Ag ions “frozen-up” into fixed atomic positions, in-situ single-crystal
diffraction experiments of PPGM have been performed in the diamond anvil cell.
A crystal fragment of pearceite-Tac, Ag13.3Cu3.8As1.5Sb0.4S11, a = 7.3510(6), c = 11.892(1) Å,V = 556.5(1) Å3, P3̅ m1, from the Clara Mine, Oberwolfbach, Schwarzwald, Germany, shows
strong diffuse diffraction features parallel to c* at ambient conditions that are characteristic forthe high temperature fast ion conduction form. On P increase the appearance of additionalreflections at h/2 and k/2 reveals a phase transition to the T2ac superstructure between 0.1 and
1.2 GPa (1.2 GPa: a = 7.3137(5), c = 11.723(4) Å, V = 542.8(2) Å3). Diffuse maxima condense
within the originally uniform diffuse diffraction features. Furthermore, a number of sharp
satellite reflections appear at 1.2 GPa and move between 1.2 and 2.6 GPa (2.6 GPa: a =7.2723(4), c = 11.530(3) Å, V = 528.1(1) Å3). These features are in accordance with the
explanation of a composite modulated structure model for the PPGM superstructures(WITHERS et al., 2008). A crystal of polybasite-T2ac, Ag15.0Cu1.7Sb1.8As0.2S11, a =15.1006(5), c = 11.9329(4) Å, V = 2356.5(1) Å3, P321 (Husky Mine, Elsa, Yukon Territory,
Canada) transforms to the M2a2b2 superstructure variant, a = 14.785(5), b = 22.643(9), c =25.48(2) Å,  = 89.94(5),  = 90.69(5),  = 89.98(3), V = 8531(9) Å3 between 3.5 and 5.4 GPa.
BINDI, L., EVAIN, M., PRADEL, A., ALBERT, S., MENCHETTI (2006): Phys. Chem. Miner., 33, 677-690.
BINDI, L., EVAIN, M., SPRY, P.G., MENCHETTI, S. (2007): Amer. Miner., 92, 918-925.
WITHERS, R.L., NORÉN, L., WELBERRY, T.R., BINDI, L., EVAIN, M., MENCHETTI, S. (2008): Solid State
Ionics, 179, 2080-2089.

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THERMODYNAMICS OF ALKALI FELDSPAR SOLID-SOLUTIONS DERIVED
FROM PARTITIONING EXPERIMENTS
Heuser, D.1, Ingegneri, F.1, Lengauer, C.L.2, Petrishcheva, E.1, Abart, R.1
1
Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
Institute of Mineralogy and Crystallography, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
e-mail: david.heuser@univie.ac.at2

Alkali feldspars form a solid-solution between the NaAlSi3O8 (albite) and the KAlSi3O8 (Kfeldspar) end-members with complete miscibility at temperatures above about 600 °C and a
miscibility gap at lower temperatures. Accordingly, alkali feldspar of intermediate
composition usually exsolves during slow cooling producing a lamellar intergrowth of more
Na-rich and more K-rich alkali feldspar, a microstructure referred to as perthite. The lamellarintergrowth is usually coherent. The strain energy associated with coherent lamellarintergrowth counteracts exsolution. As a consequence, the solvus for coherent exsolution is
located at lower temperatures than the “strain free solvus”. Despite being a widespread
phenomenon, the quantification of exsolution in alkali feldspar remains challenging due to thechemical and structural variability of alkali feldspars and the complex interplay between nonideal thermodynamic mixing properties and elastic stress and strain in coherent intergrowth.
In this study, four natural gem-quality alkali feldspars including Madagascar Orthoclase (XK =0.95, where XK is the K site fraction on the alkali sublattice), Volkesfeld Sanidine (XK =0.85), Zillertal Adular (XK = 0.85) and Zinggenstock Adular (XK = 0.90) were used forpartitioning experiments. Powder XRD revealed monoclinic (C2/m) symmetry for
Madagascar Orthoclase and Volkesfeld Sanidine, which both have highly disordered Al-Si,
and triclinic (C1) symmetry for Zillertal and Zinggenstock Adular, which both have ordered
Al-Si. All four feldspars have very low Ca contents (Ca p.f.u. <0.001), Madagascar orthoclase
has an appreciable Fe content (Fe p.f.u. = 0.045), the other three feldspars contain some Ba(Ba p.f.u. = 0.013 (Volkesfeld), 0.015 (Zillertal), 0.010 (Zinggenstock), 0.001 (Madagascar).
The Na-K partitioning between the feldspars and a KCl-NaCl salt melt was determined
experimentally at 800 °C, 900 °C and 1000 °C. The partitioning curves were used todetermine the parameters for an asymmetric Margules-type binary mixing model including
their temperature dependence. The obtained Margules parameters were used for calculating
the partitioning curves and the coherent and strain free solvi, where the strain energy due tocoherent intergrowth was taken from ROBIN (1974).
Comparison of the measured and the calculated partitioning curves reveals that the models
systematically underestimate the thermodynamic non-ideality of the solid-solution, especiallyat low temperatures. The triclinic Zillertal Adular exhibits the most non-ideal Na-K
partitioning, and the calculated partitioning curves show the strongest deviation from theexperimentally observed curves followed in both aspects by the triclinic Zinggenstock Adular.
This suggests increasing deviation of the thermodynamic model from the observed relations
with increasing degree of non-ideality in the element partitioning. We infer that differences in
Al-Si ordering and in the concentrations of minor elements such Ca, Ba, and Fe havesubstantial influence on the thermodynamics of the solid-solution.
ROBIN, P.-Y.F. (1974): Am. Mineral., 59, 1299–1318.

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PETROLOGICAL CONSTRAINTS ON THE EVOLUTION OF THE
ECCENTRIC CONES MONTE MALETTO, MONTE FRUMENTO,
AND MONTE NUOVO – MT. ETNA
Hofbauer, B.1, Ntaflos, T.1, Abart, R.1, Giacomoni, P.P.2, Coltorti, M.2, Ferlito, C.3
University of Vienna, Althanstraße 14, 1090 Vienna, Austria
2
University of Ferrara, Via Saragat 1, 44122 Ferrara, Italy
3
University of Catania, Piazza Università, 2, 95131 Catania, Italye-mail: babsi.ho@live.at
1

Mt. Etna is one of the most pronounced features of the eastern coastline of Sicily, Italy, lying
in a complex geodynamic setting; it is situated on the Gela-Catania Foredeep structural
domain which lies on the front of the Apenninic-Maghrebian Chain. The volcano covers an
area of about 1418 km2 and rises approximately 3350 metres above sea level with frequent
eruptions from the summit craters. The eruptive activity has been divided according to its age
into 6 stages: (1) Tholeiitic Stage active between 600-320 ka ago, (2) Timpe Stage between
220 to 110 ka ago, (3) Ancient Alkaline Volcanism (AAC) between 110 to 65 ka ago, (4) the
Ellittico Stage was active between 57 to 15 ka ago, (5) the Mongibello Stage from 15 ka ago
until 1971, and (6) the now active “post-1971 Stage” (CASETTA et al., 2020).
Besides the three summit craters there is a plethora of monogenetic cones, referred to as“eccentric cones” all around the edifice of the volcano. We studied three eccentric cones(Monte Maletto, Monte Nuovo, and Monte Frumento) and the 2001 eruption on the south
flank of the volcano using mineral and whole rock chemistry. The overall prevalent texture istrachytic and the lavas are trachybasalts with Mg# varying in Monte Maletto between 56-58,
in Monte Nuovo between 52-53, and in Monte Frumento between 43-46.
The olivine phenocrysts occur as: (1) diffusive rim/normal zoning (Fo core 57.6-87.5, rim 5682.8), (2) skeletal (Fo core 68.3, rim 57.8-82.1), and (3) inverse zoning (Fo core 69.3-75, rim
70.2-81.4). The Ni content is generally low (NiO  0.16 wt%) and correlates positively with
the Mg# whereas the CaO content ranges between 0.16 and 0.58 wt% and decreases withincreasing Fo content. The most MgO-rich olivine with a Fo of 87.5 was found in Monte
Maletto with a core NiO content of 0.16 wt% and CaO content of 0.24 wt% indicating amagmatic origin. The most evolved lavas with Fo = 63.9-69.4 are those of Monte Frumento.
Olivine from both, the 2001 eruption and Monte Nuovo show a characteristic inverse zoning.
Clinopyroxene exhibit complex zonation patterns of which four can be distinguished: (1)normal zoning with Fe-rich rim, (2) sieve textured core, (3) oscillatory zoning of FeO, MgO,
and Al2O3, and (4) hourglass zoning. Clinopyroxene from all sample locations plot in thediopside field of the quadrilateral diagram and only a few clinopyroxenes, most notably fromMonte Maletto, are plotting in the augite field, albeit only just so. The overall composition of
the clinopyroxene ranges between Wo42.2En31.1Fs7.7 and Wo49.8En47.1Fs20.8.
The preliminary results suggest that the lavas of the 2001 eruption and Monte Nuovo
experienced magma mixing. Furthermore, Monte Maletto lavas represent the most primitive
and Monte Frumento the most evolved magma.
CASETTA, F., GIACOMONI, P. P., FERLITO, C., BONADIMAN, C., COLTORTI, M. (2020): Int. Geol.
Rev., 62, 338-359.

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THE SPODUMENE PEGMATITES IN DEFEREGGEN (EASTERN TYROL)
Horvat, C.1, Mali, H.1
Chair of Geology and Economic Geology MUL, Peter-Tunner-Straße 5, 8700 Leoben, Austria
e-mail: christian.horvat@unileoben.ac.at

1

In the eastern part of the Defereggen valley pegmatites of Permian age (SCHUSTER et al.,2001) occur in the Petzeck-Rotenkogel Complex and the Michelbach Complex of theKoralpe-Wölz and Drauzug-Gurktal Nappe System, respectively. In addition to simple
pegmatites, spodumene pegmatites crop out in the area of Poling, Ratzell, Glanzalm, and a
newly discovered one at Großer Zunig mountain (HORVAT, 2021). Representing the highly
fractionated part of the pegmatite forming melt, spodumene pegmatites are important inunderstanding the genesis of the Permian pegmatites (KNOLL et al., 2018). Furthermore, arising economic interest in Li makes spodumene pegmatites a promising target for
exploration.
The spodumene pegmatites north and south of the Defereggen valley form predominately
concordant dykes in the range of a few meters in thickness and can be followed over several
tens of meters at the surface. The Li-pegmatites are mainly composed of quartz, K-feldspar,
plagioclase, muscovite, spodumene, tourmaline, and garnet. The sharp contact to the host rockis often characterized by garnet and tourmalinisation. Accessory minerals detected in heavy
mineral concentrates and thin sections include apatite, cassiterite, columbite group minerals,
monazite group minerals, microlite group minerals, rutile, strüverite, uraninite, native
bismuth, an undefined bismuth phosphate mineral, xenotime group minerals, and zircon.
Zircon and the columbite group minerals follow a general fractionation trend where Hf and Ta
are enriched with respect to Zr and Nb, respectively. Columbite-(Fe) is the main columbitegroup mineral.
Whole rock analyses of 8 spodumene pegmatite samples yield up to 2.28 % Li2O with anaverage grade of 1.12 % Li2O and 88 ppm Nb and 122 ppm Ta. Certain zones of spodumene
pegmatites contain up to 50 vol% of spodumene.
LA-ICP-MS and SEM-EDS measurements were performed on 112 muscovites from a total of
74 simple and spodumene pegmatite occurrences. High trace element contents of Li, Rb, Nb,
Sn, Cs, Ta, and Tl in muscovite from spodumene pegmatites point to a high fractionation.
However, some muscovites from simple pegmatites in the area also contain significant traceelements, making it likely that certain spodumene pegmatites are “hidden” among the simple
pegmatites and additional ones are yet to be discovered in the area.
HORVAT, C (2021): Masterarbeit, Montanuniversität Leoben.
KNOLL, T., SCHUSTER, R., HUET, B., MALI, H., ONUK, P., HORSCHINEGG, M., ERTL, A., GIESTER G.
(2018): The Canad. Miner., 56, 489–528.
SCHUSTER, R., SCHARBERT, S., ABART, R., FRANK, W. (2001b): Mitt. Ges. Geol. Bergbaustudenten inÖsterr., 45, 111–141.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

LITHIUM PEGMATITE OF ANATECTIC ORIGIN:
A PETROLOGICAL AND GEOCHEMICAL MODEL
Huet, B.1, Knoll, T.2, Schuster, R.1, Mali, H.3
Fachabteilung Kristallingeologie, Geologische Bundesanstalt, Neulinggasse 38, 1030 Wien, Austria
Fachabteilung Rohstoffgeologie, Geologische Bundesanstalt, Neulinggasse 38, 1030 Wien, Austria
3
Department Angewandte Geowissenschaften und Geophysik, Montanuniversität Leoben,Peter-Tunner-Straße 5, 8700 Leoben, Austria
e-mail: benjamin.huet@geologie.ac.at1

2

Albite-spodumene pegmatite deposits are a valuable source of Li and other rare elements. They
are considered to be the product of extreme crystal fractionation of melts or fluids deriving fromlarge fertile granite intrusions. In contrast, none of the ~80 albite-spodumene pegmatite
occurrences in the Austroalpine Unit Pegmatite Province (Eastern Alps) are associated with alarge fertile granite. Instead, albite-spodumene pegmatite is found at the upper structural levelof lithostratigraphic complexes where migmatitic metapelite occurs at the base. Additionally, it
is accompanied by simple pegmatite, evolved pegmatite, and relatively small inhomogeneous
leucogranite bodies, all Permian in age. Geochronology, metamorphic petrology, field
relationships, and geochemistry all converge to the same conclusion: simple pegmatite,
leucogranite, evolved pegmatite, and albite-spodumene are products of anatectic melts derived
from Al-rich metapelite, at different stages of crystal fractionation. Bulk rock and LA ICP-MS
analyses suggest that the source of Li would reside in the Al-rich metapelite (120 ppm Li inaverage) with staurolite as dominant Li-carrier (up to 2900 ppm Li).
The aim of this contribution is to test if melting of a metapelite could be the origin of albitespodumene pegmatite. The modelling approach consists in three steps. (1) The proportion ofsolid phases and melt during prograde melting of an Al-rich metapelite is modelled bythermodynamic forward modelling. The considered P-T conditions of melting (6-7 kbar and<750 °C) are dictated by the Permian metamorphic record in the lithostratigraphic complexes
hosting pegmatite. (2) The Li distribution between solid phases and melt is calculated using themodelled phase proportions and Li-partitioning coefficient derived from LA ICP-MS analyses.
Different partitioning models are considered in order to account for the different melting
scenarios. (3) Crystal fractionation is modelled with mass-balance.
Using conservative parameters and realistic hypotheses, we show that ~7 to ~20 vol% melt
containing 200 to 1000 ppm Li can escape the migmatite in case melting is associated withdestabilization of staurolite. Subsequent crystal fractionation of the melt with a fractionation
degree comprised between 81 and 99% enriches the residual melts to 5,000-10,000 ppm Li.
This range corresponds to the Li saturation in felsic melts necessary for crystallizing
spodumene. Our model therefore shows that direct transfer of Li from destabilizing staurolite
to anatectic melt when a Li-Al-rich metapelite melts for the first time followed by crystal
fractionation of the anatectic melt is a realistic genetic process for the formation of the albitespodumene pegmatites of the Austroalpine Unit Pegmatite Province.

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Al INCORPORATION AND DIFFUSION IN NATURAL RUTILE:
A GEOTHERMOMETER?
Joachim-Mrosko, B.1, Konzett, J.1, Ludwig, T.2, Libowitzky, E.3, Stalder, R.1
1
University of Innsbruck, Institute of Mineralogy and Petrography, Innrain 52, 6020 Innsbruck, Austria
Heidelberg University, Institute of Earth Sciences, Im Neuenheimer Feld 236, 69120 Heidelberg, Germany
3
University of Vienna, Institute of Mineralogy and Crystallography, Althanstraße 14, 1090 Vienna, Austria
e-mail: bastian.joachim@uibk.ac.at

2

Rutile is one of the most important accessory minerals in igneous and medium- to ultrahighpressure metamorphic rocks and is often used as geothermobarometer and geothermometer.
This study aims to experimentally investigate the incorporation mechanism and diffusivity of
Al and H in natural rutile, thus bridging the gap between elaborate diffusion studies in defined
simplified synthetic and complex natural systems.
High-P-T experiments were performed at pressures ranging from 1 bar to 7 GPa, and attemperatures between 1223 and 1373 K. The samples contained natural rutiles extracted froman eclogite that were embedded in a natural metapelitic host rock at fixed µ(Al2O3) with ∆fO2
buffered to CCO. Based on diffusion profiles of the respective elements in rutile that wereanalyzed using EPMA and SIMS, the following Arrhenius relations were determined within
the experimental temperature range of this study:
𝑚𝑚2−659 ± 20⁡𝑘𝑘𝑘𝑘𝑚𝑚𝑚𝑚𝑚𝑚 −1
𝑟𝑟𝑟𝑟( ) = 3.75 × 1011 exp⁡ (⁡)
𝐷𝐷𝐴𝐴𝐴𝐴𝑠𝑠
𝑅𝑅𝑅𝑅

𝑚𝑚2−820 ± 33⁡𝑘𝑘𝑘𝑘𝑚𝑚𝑚𝑚𝑚𝑚 −1)
𝐷𝐷𝐻𝐻𝑟𝑟𝑟𝑟 ( ) = 3.08 × 1017 exp⁡ (𝑠𝑠
𝑅𝑅𝑅𝑅

EPMA analyses further reveal a complex distribution of oxygen defects at the scale of the
diffusion profiles. FTIR analyses indicate that the incorporation of hydrogen is not related tometal impurities. Based on these results, we suggest a complex combination of mechanisms to
explain the incorporation of Al and H in natural rutile and its high-pressure polymorphs. This
includes (i) the incorporation of Al3+ in octahedrally coordinated Ti-sites charge balanced by
the formation of oxygen vacancies and (ii) the incorporation of oxygen in interstitial positions
charge balanced by hydrogen interstitials.
Al-diffusivities in natural rutile determined in this study are about 8 to 9 orders of magnitude
faster than Al-diffusivities in synthetic rutile determined by CHERNIAK & WATSON(2019). Available literature data on the Al content of natural rutiles (e.g., MEINHOLD, 2010)
indicate a strong tendency of Al to be returned to coexisting silicates through diffusion in thewake of retrogressive re-equilibration, thus supporting the assumption that Al diffusivities inrutile and its TiO2-polymorphs in natural systems are comparatively fast. As a consequence,
results of this study question the applicability of the Al-in-rutile geothermobarometer innatural systems.
CHERNIAK, D.J., WATSON, E.B. (2019): Amer. Mineral., 104, 1638-1649.
MEINHOLD, G. (2010): Earth Sci. Rev., 102, 1-28.

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POLYTYPISM AND ALLOTWINNING IN SFCA-III:KILLING TWO BIRDS WITH ONE STONE
Kahlenberg, V.1, Krüger, H.1, Goettgens, V.S.1
Institute of Mineralogy and Petrography, Innsbruck University, Innrain 52, 6020 Innsbruck, Austria
e-mail: volker.kahlenberg@uibk.ac.at1

Silico-Ferrites of Calcium and Aluminum compounds (so-called SFCA’s) are major
constituents of iron-ore sinters. Concerning their chemical compositions, different types of
SFCA compounds can be distinguished. They represent complex solid solutions
corresponding to the general formula M14+6nO20+8n, where M = Si, Fe, Al, Ca and Mg. The
two most frequently observed representatives in industrial sinters are named SFCA (n = 0 or
M14O20) and SFCA-I (n = 1 or M20O28).
A part of the system CaO-SiO2-Al2O3-Fe2O3-MgO which is of relevance to iron-ore sinteringhas been studied in detail. For a bulk composition corresponding to 10.45 wt.-% CaO, 5.49
wt.-% MgO, 69.15 wt.-% Fe2O3, 13.37 wt.-% Al2O3, and 1.55 wt.-% SiO2 synthesis runs havebeen performed in air in the range between 1100 and 1300 °C. Products have beencharacterized using reflected-light microscopy, electron-microprobe analysis and diffraction
techniques. At 1250 °C, an almost phase pure material with composition
Ca2.99Mg2.67Fe3+14.58Fe2+0.77Al4.56Si0.43O36 has been obtained. The novel compound
corresponds to the first Si-containing representative of the abovementioned polysomatic series
with n = 2 and is denoted as SFCA-III.
Single-crystal diffraction investigations using synchrotron radiation at the X06DA beamlineof the Swiss Light Source revealed that the chemically homogenous sample contained both a
triclinic and monoclinic polytype. Basic crystallographic data are as follows: triclinic form: a= 10.3279(2) Å, b =10.4340(2) Å, c = 14.3794(2) Å,  = 93.4888(12)°,  = 107.3209(14)°,–and  = 109.6626(14)°, V = 1370.49(5) Å3, Z = 2, space group P1; monoclinic form: a =10.3277(2) Å, b = 27.0134(4) Å, c = 10.4344(2) Å,  = 109.668(2)°, V = 2741.22(9) Å3, Z =4, space group P21/n.
Structure determination of both modifications was successful using diffraction data from thesame allotwinned crystal. A description of the observed polytypism within the framework of
OD-theory is presented. Triclinic and monoclinic SFCA-III actually correspond to the two
possible maximum degree of order structures based on OD-layers containing three spinel (S)and one pyroxene (P) modules (<S3P>). The existence of SFCA-III in industrial iron-ore
sinters has yet to be confirmed. Polytypism, however, is likely to occur in other SFCAmembers (SFCA, SFCA-I) relevant to sintering as well, but has so far been neglected in thecharacterization of industrial samples. Our results shed light on this phenomenon and may
therefore be also helpful for better interpretation of the powder diffraction patterns that areused for phase analysis of iron-ore sinters.

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STRUCTURAL SYSTEMATICS OF SFCA-I TYPE SOLID SOLUTIONSIN THE SYSTEM CaO–Fe2O3–FeO–Al2O3
Kahlenberg, V.1, Krüger, H.1, Tribus, M.1
Institute of Mineralogy and Petrography, Innrain 52, 6020 Innsbruck, Austria
e-mail: volker.kahlenberg@uibk.ac.at

1

The present investigation provides - for the first time - a detailed crystallographic analysis on
the impact of chemical variations on a compound that is of relevance for the field of appliedmineralogy related to the technologically important process of iron-ore sintering.
Effects of Fe ↔ Al substitution on triclinic SFCA-I-type compounds with general formula
A40O56 (A: Ca, Al, Fe3+, Fe2+) have been studied using single-crystal X-ray diffraction.
Crystals of sufficient quality and size were synthesized in the temperature range between
1200 and 1300 °C. Six samples with Al/FeTot-ratios of 0.127, 0.173, 0.216, 0.310, 0.349, and
0.459, respectively, have been structurally characterized. SFCA-I can be described with amodular approach involving the stacking sequence <PSS> of “P” and “S” modules that can be
imagined as being cut from the well-known pyroxene (P) and spinel (S) structure-types.
Furthermore, SFCA-I is related to the sapphirine supergroup of minerals.
Within the present solid-solution series the contents in calcium show only minor variations (≈6.7 a.p.f.u.). The twenty crystallographically independent tetrahedrally (T) and octahedrally(M) coordinated cation sites exhibit considerable differences concerning the Al-uptake.
Indeed, Al is preferentially incorporated into the tetrahedra belonging to the single-chainslocated in the pyroxene-modules. Ferrous iron, on the other hand, is restricted to one of the Tpositions within the spinel-blocks. Most structural aspects, from unit-cell parameters and cellvolumes to site occupancies, tetrahedral chain kinking as well as polyhedral distortions aredefined by linear or nearly linear trends when plotted against the Al/FeTot-ratio.
Analysis of the <T-O> and <M-O> distances showed a complex interplay between the
different coordination polyhedra resulting in a contrasting behaviour of these values withpositive or negative change rates as a function of composition.
Evaluation of the average chemical strain tensor derived from the sets of lattice parameters forthe two limiting compositions of the series indicated that the major contraction withincreasing Al-content is perpendicular to the pyroxene- and spinel-modules. Furthermore, thepyroxene-module seems to be more effected when compared with the spinel-block.
There is evidence that the SFCA-I type solid-solution series is limited on both the Al- and Ferich sides.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

STRUCTURE AND CHEMISTRY OF AEROSOL JET PRINTED GRAPHENE AND
CARBON NANOTUBES
Kaindl, R.1, Gupta, T.2, Blümel, A.3, Pei, S.4, Hou, P.4, Du, J.4, Liu, C.4, Patter, P.3,
Popovic, K.3, Dergez, D.5, Elibol, K.2, Liu, J.6, Eder, D.2, Kieslinger, D.5, Ren, W.4,
Waldhauser, W.1, Bayer, B.C.2
JOANNEUM RESEARCH – MATERIALS, Institute for Surface Technology and Photonics,
Leobner Straße 94, 8712 Niklasdorf, Austria
2
Vienna University of Technology, Getreidemarkt 9/165, 1060 Vienna, Austria
3
JOANNEUM RESEARCH – MATERIALS, Institute for Surface Technology and Photonics,
Franz-Pichler-Straße 30, 8160 Weiz, Austria
4Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China
5ZKW Elektronik GmbH, Samuel-Morse-Straße 18, 2700 Wiener Neustadt, Austria
6
Chalmers University of Technology, Department of Microtechnology and Nanoscience,
Kemivägen 9, Se 412 96 C, Sweden
e-mail: reinhard.kaindl@joanneum.at
1

Nanocarbon materials like graphene and carbon nanotubes (CNTs) are promising materials fora number of applications like thermal and electrical interconnects in opto- and high-speed
electronics. The direct writing via additive manufacturing technology of aerosol jet printing
enables low-cost fabrication, for example by integration into high-throughput roll-to-roll
printing processes, rapid customization and prototyping and deposition of several layers on topof each other (PANDHI et al., 2018; ROTHER, 2019).
In this work, the micro- and nano-structure and chemistry of nanocarbon layers on flat silicon
and glass and rough aluminium oxide surfaces, printed from inks by aerosol jet, were
investigated by light- and scanning electron microscopy, energy-dispersive X-ray spectroscopy,
atomic force microscopy, Raman spectroscopy, X-ray diffraction and high-resolution brightfield transmission electron microscopy.
Orientation, arrangement and structural quality of the graphene and CNT aggregates in theprinted layers strongly depends upon substrate, ink composition and printing parameter. The
investigations demonstrate possible routes to applications mentioned before, on not only flat
polished silicon wafers, glass and polymer foils but also on more realistic substrates like rough,surface oxidized aluminium blocks.
PANDHI, T., KREIT, E., AGA, R., FUJIMOTO, K., SHARBATI, M.T., KHADEMI, S., CHANG, A.N., XIONG,
F., KOEHNE, J., HECKMAN, E.M., ESTRADA, D. (2018): Sci. Rep., 8, 10842.
ROTHER, M. (2019): Dissertation, Heidelberg University, Germany, 236pp.

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SYNTHESIS AND CRYSTAL STRUCTURE OF THALLIUMPHARMACOSIDERITE
Karasalihović, T.1 Karanović, Lj.2, Đorđević, T.1
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
2
Laboratory of Crystallography, Faculty of Mining and Geology, Đušina 7, 11000 Belgrade, Serbia
e-mail: tamara.djordjevic@univie.ac.at1

Thalliumpharmacosiderite (TPS), TlFe4[(AsO4)3(OH)4]·4H2O (RUMSEY et al., 2014) is asecondary mineral belonging to the pharmacosiderite-group, adopting general formulaAFe4[(OH)4(AsO4)3]·nH2O (A = Na+, K+, Ba2+ or H3O+). It is a very important sink of botharsenic and thallium in As- and Tl-rich environments.
Single-crystals of TPS, Tl2.5Fe4[(AsO4)3(OH)4](OH)1.5·3H2O, have been obtained under mildhydrothermal conditions (Tmax = 170 °C) and were characterized using single-crystal X-ray
diffraction (SXRD), infrared, and Raman spectroscopy. TPS crystallizes in the form ofyellowish orange, slightly elongated cubes up to 60 µm in size (Fig. 1a) together with scorodite,
FeAsO4·2H2O, and/or amorphous arsenic bearing iron oxo-hydroxides (FOH). Ferric iron salts(nitrates and chlorides) and thallium(I) sulfates and/or carbonates led to the precipitation of TPS
in the relatively broad pH range from 2-6.

Figure 1. (a) single crystals of TPS; (b) crystal structure of TPS along [001].

TPS is cubic, space group P 4 3m with a = 7.9645(1) Å, V = 505.214(19) Å3, Z = 1. Its crystal
structure was solved from the SXRD data and refined to R1 = 0.0156 for 318 reflections with
I > 2(I). The structure consists of a heteropolyhedral 3D open framework of thepharmacosiderite-type (ZEMANN, 1948) with large channels occupied by 12-coordinatedthallium atoms, hydroxyl groups, and water molecules. Besides not fully occupied special 3d(Tl1A) site, TPS contains one additional 6g (Tl1B) site (Fig. 1b), which is split in twosymmetrically equivalent positions close to the Tl1A [Tl1A–Tl1B = 0.461(3) Å], with less thanhalf-occupancy each. Tl is coordinated by eight oxygens from AsO4 groups and by four
statistically distributed O atoms, ¾ from water molecule O4A or O4B and ¼ from hydroxyl
group. Oxygen atom (O5) from hydroxyl group, whose presence is required to maintain charge
neutrality, were found in special half-occupied 1b position. The discrete hydroxyl group O5H
is statistically distributed and bonded to O4 by hydrogen bonding interactions.
RUMSEY, M.S., MILLS, S.J., SPRATT, J., HAY, D.G., FARBER, G. (2014): Mineral. Mag., 78, 549–558.
ZEMANN, J. (1948): Tschermaks Mineral. Petrogr. Mitt. 1, 1.

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METAMORPHIC EVOLUTION AND GEOCHRONOLOGY OF
VARISCAN REMNANTS IN THE EASTERN ALPS:THE CRYSTALLINE "SCHOLLEN" IN THE GRAUWACKENZONE
Karner-Rühl, K.1, Hauzenberger, C.A.1, Skrzypek, E.1, Fritz, H.1
University of Graz, Universitätsplatz 2, 8010 Graz, Austria
e-mail: kevin.karner-ruehl@edu.uni-graz.at

1

The Eastern Greywacke Zone is composed of three Alpine nappes. From bottom to top these
are the Veitsch nappe (Early Carboniferous to Permian molasse), the Silbersberg nappe with
the Kaintaleck metamorphic complex and Permian phyllites as cover, and the Noric nappe(Late Ordovician shelf sediments and Permian cover). All units experienced early Alpine
metamorphism within the lower greenschist facies which resulted in the formation of ductile
shear zones and the appearance of the Kaintaleck Complex as lens-shaped bodies of 10-100 m
thickness within the Eastern Greywacke Zone. This work tries to determine the P-T-t path of
the Kaintaleck Complex by U/Pb dating and application of geothermobarometric andpetrological techniques. Based on whole rock geochemistry, amphibolites and garnetamphibolites of the Prieselbauer unit and the Frauenberg unit in the area of Bruck/Mur and
Kapfenberg, represent tholeiitic basalts with a MORB affinity. The garnet-amphibolites show
distinct plagioclase-epidote-rich symplectitic coronas, which are indicative of decompression
from possibly eclogite-facies metamorphic conditions. In addition to amphibolites, micaschists and gneisses are exposed in the area, which leads to a classification of the Kaintaleck
crystalline unit into mafic and felsic units. The mafic units represent a former ocean, thePaleotethys, whereas the felsic units may derive from a former continental margin. By
investigating these units, a geochronological sequence of metamorphic events within the
Kaintaleck Complex can be determined.

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THE EXCEPTIONAL ICE NUCLEATION ACTIVITY OF ALKALI FELDSPAR IN
AIRBORNE MINERAL DUST
Kiselev, A.1, Keinert, A.1, Gaedeke, T.1, Leisner, T.1,2, Sutter, C.3, Petrishcheva, E.3,
Abart, R.3
Karlsruhe Institute of Technology, Karlsruhe, Germany, 76128 Karlsruhe, Germany
Universität Heidelberg, Heidelberg, Germany, Im Neuenheimer Feld 229, 69120 Heidelberg, Germany
3
University of Vienna, Althanstraße 14, 1090 Vienna, Austria
e-mail: rainer.abart@univie.ac.at
1

2

Due to its ubiquitous presence in the Earth’s crust, feldspar is an important constituent of
airborne mineral dust, where desert dust and volcanic ash are the main contributors. Solidaerosol particles play an important role in the nucleation and growth of ice. The presence of ice
particles in the atmosphere has a strong influence on a variety of processes such as radiative
heat transfer, precipitation and absorption of trace gases. Some alkali feldspars stand out fromother solid aerosol particles due to their particularly high ice nucleation (IN) activity. Thisphenomenon has been ascribed to structural similarities of the ice (101̅ 0) prism planes and the(100) planes of alkali feldspar. In this study, this hypothesis is tested by investigating the IN
activity of alkali feldspar with a high fraction of surfaces oriented sub-parallel to (100), whichwere produced by chemically induced fracturing. To this end, K-rich, gem quality alkali
feldspar was subjected to cation exchange with an NaCl-KCl salt melt at 850 °C to shift its
composition towards the Na-rich side. The associated anisotropic contraction of the crystal
lattice produced a system of parallel cracks with close to (100) orientation. Grain mounts of thecation exchanged alkali feldspars were used for droplet freezing assay experiments, which
confirmed an increase of the overall density of ice nucleating active sites (INAS) with respect
to the untreated feldspar corroborating the view that the particularly high IN activity of somealkali felspars is due to preferential nucleation of ice on (100) surfaces of the feldspar.
Annealing at 550 °C subsequent to primary cation exchange further enhanced the INAS density
and lead to IN activity at exceptionally high temperatures. In nature, parting planes with similar
orientation as the chemically induced cracks may be generated in lamellar microstructures
resulting from the exsolution of initially homogeneous alkali feldspar, a widespread
phenomenon in alkali feldspar known as perthite formation. Perthitic alkali feldspars indeed
show the highest IN activity. We tentatively ascribe this phenomenon to the preferential
exposure of feldspar crystal surfaces oriented sub-parallel to (100).

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MICROSTRUCTURE AND ORIENTATION RELATIONSHIPS OF A GARNET
HOST CRYSTAL AND RUTILE INCLUSIONS IN A PEGMATITE FROM THE
MOLDANUBIAN ZONE (BOHEMIAN MASSIF, AT)
Kohn, V.1, Griffiths, T.1, Abart, R.1, Habler, G.1
University of Vienna, Vienna, Austria, Althanstraße 14, 1090 Vienna, Austria
e-mail: victoria.kohn@univie.ac.at

1

An 8 mm sized euhedral spessartine-almandine garnet from a pegmatite in the Moldanubian
Gföhl Unit (Bohemian Massif, AT) hosts numerous rutile inclusions. The internal
microstructure of garnet is characterized by distinct inclusion and colour zoning: in the optical
microscope (OM) a yellowish to brownish coloured garnet core with equant nano- and µmsized inclusions is observed. The core is rimmed by two colourless, c. 1 mm wide garnet
growth zones predominantly parallel to a Grt{110} facet. The main focus of our study is theinner rim. It bares regularly spaced, rutile needles with a total of seven different shapepreferred orientations (SPO).
Crystallographic orientation relationships (CORs) between garnet and rutile are known to becomplex. In the literature, a total of 11 different CORs have been described from garnet-rutile
host-inclusion-systems (GRIFFITHS et al., 2020, and references therein). Based on Electron
Backscatter Diffraction (EBSD) data, the vast majority of the inclusions in the innercolourless garnet growth zone belong to one of three COR groups: Two of those groups arelinked to the Grt<111> directions: with either the rutile c-axis or a rutile <103> direction
parallel to Grt<111>. The third COR group has the c-axis of rutile parallel to a Grt<100>direction.
Combining the EBSD dataset with OM observations unmasks a correlation between the rutile
needle elongation directions in the garnet host crystal and their COR: out of the sevenobserved SPOs, a set of 4 SPOs exclusively reflect the two COR groups associated with
Grt<111>. The 3 remaining SPOs exclusively pertain to the COR group connected toGrt<100>. This interrelation suggests that the crystallographic and shape preferred orientationof rutile needles is governed by the garnet host crystal and potentially gives insight toformation mechanisms.
In addition, the abundance of rutile inclusions having a particular COR varies between
microstructurally different garnet zones as follows: in the coloured garnet core, the majorityof needles have Grt<111> || Rt<103>. Whereas, in the colourless inner rim Grt<111> || Rt<001> needles are predominant.
Representing work in progress, the new findings in pegmatite garnet contribute to theidentification of petrogenetic parameters that influence the development of particular
microstructures and textures in the garnet host-rutile inclusion system.
Funding by the Austrian Science Fund (FWF): I4285-N37 is acknowledged.
GRIFFITHS, T.A., HABLER, G., ABART, R. (2020): Amer. J. Sci., 320, 753-789.

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REVISION OF THE CRYSTAL STRUCTURE OF RHABDOPHANE-(Ce)Kolitsch, U.1,2
Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum, Burgring 7, 1010 Wien, Austria
2Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
e-mail: uwe.kolitsch@nhm-wien.ac.at

1

The crystal structure of rhabdophane, ideally CePO4·H2O according to the current
nomenclature, was first reported by MOONEY (1950) using synthetic material (powder
precipitate from aqueous solution). On the basis of powder X-ray diffraction data and a trialand-error approach, she determined a hexagonal atomic arrangement, with the unit-cellparameters a = 7.07(2) and c = 19.06(5) Å, and the space group P6222 (no R-value given).
However, she cautioned „The final assignment of the space-group symmetry must follow rather
than precede the structure determination.” In fact, an earlier study by her had suggested spacegroup P3121 (MOONEY 1948), and a subsequent study, in which the structure of the Bi
analogue was determined from Weissenberg data, led to the formula BiPO4·0.5H2O, spacegroup P3121 (MOONEY-SLATER 1962) and the following conclusion: “In any case, the true
space-group symmetry of CePO4 and of the other hexagonal rare-earth phosphates remains aquestion for further inquiry.“ MOONEY (1948, 1950) also noted the presence of zeolitic waterin the channels of the structure „[XPO4 (0-0.5H2O)]“ which „is probably necessary to stabilize
the structure.” However, the idealised formula CePO4·H2O is given in the subsequentmineralogical literature (including the IMA list of approved minerals), while inorganicchemical literature generally uses the formula CePO4·0.5H2O.
No modern study of the structure of natural rhabdophane-(Ce) or isostructural members of therhabdophane group was ever published. The author has reinvestigated the atomic arrangementof rhabdophane-(Ce) using small but sharp, hexagonal, colourless prisms of a Nd- and La-richspecimen from the Clara mine, Black Forest, Germany. The structure solution, based on singlecrystal intensity data (MoKα; 293 K) showed the correct space group to be P3121 [Flack x
parameter: 0.01(4)], with a = 7.037(1), c = 6.429(1) Å, V = 275.71(7) Å3; R(F) = 1.68%. SEMEDS analyses of both crystals and crystal fragments adjacent to the studied crystal showed only
minor variations of the chemical composition. Refinement of the O(H2O) site occupancy gave
0.62(2). The bulk structural formula is ~(Ce0.41Nd0.22La0.16Ca0.06Sm0.05Pr0.05Eu0.02Gd0.01Sr0.01U0.01)(P0.94S0.04As0.2)O4·0.62(2)H2O. Rhabdophane-(Ce) is therefore isostructural with its Bi
analogue for which a modern multi-technique study gave the formula BiPO4·0.67H2O(ROMERO et al., 1994). The asymmetric unit of the Clara mine crystal contains one metal, one
semimetal and three O sites. Bond lengths of the nine-coordinate (Ce,REE) site range between
2.430(2) and 2.636(3) Å (average: 2.158 Å). The (P,S,As) site shows a bond-length range
between 1.524(2) and 1.532(2) Å, with an average of 1.528 Å.
MOONEY, R.C.L. (1948): J. Chem. Phys., 16, 1003.
MOONEY, R.C.L. (1950): Acta Crystallogr., 3, 337-340.
MOONEY-SLATER, R.C.L. (1962): Z. Kristallogr., 117, 371-385.
ROMERO, B., BRUQUE, S., ARANDA, M.A.G., IGLESIAS, J.E. (1994): Inorg. Chem., 33, 1869-1874.

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MITT.ÖSTERR.MINER.GES. 167 (2021)(Ag4.38Cu2.62)7.00AsS5: A NEW SILVER-COPPER SULPHOSALTFROM THE BOU AZZER MINING DISTRICT, MOROCCO
Kolitsch, U.1,2, Topa, D.1
1

Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum, Burgring 7, 1010 Wien, Austria
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
e-mail: uwe.kolitsch@nhm-wien.ac.at

2

We have characterised a new silver-copper sulphosalt species from Vein no. 53 (‘Filon 53’),
Aït Ahmane (Bou Azzer mining district), Zagora Province, Drâa-Tafilalet Region, Morocco,
by quantitative electron-microprobe data, a single-crystal structure determination, andreflected-light studies. The new mineral, of which only one specimen is presently known toexist, forms black, elongate pseudo-orthorhombic prisms (up to 0.5 mm in length) with astrong metallic lustre. The crystals show wedge-shaped crystal terminations (similar tolöllingite), strong mosaic growth and are arranged in sprays in a void in a white carbonate(probably calcite). The new mineral is intimately associated with tiny dark red, six-sided
platelets of earlier crystallised cupropearceite with the empirical formulaAg11.39Cu4.67As1.97S10.96 (microprobe data). The black prisms were briefly described, alongwith preliminary SEM-EDS data, as “UK26 - cupropearceite?” in a collectors’ journal(FAVREAU & BARRAL, 2019).
The solution of the structure (R = 7.6%) from single-crystal XRD data (MoKα; 293 K)
unambiguously indicated space group P21/n (no. 14), with a = 7.175(1), b = 13.411(3), c =10.048(2) Å,  = 91.49(3)°, V = 966.5(3) Å3 (Z = 4), with the refined chemical formula(Ag4.38Cu2.62)7.00AsS5, i.e. an Ag:Cu ratio of 1.67. The microprobe data, which were obtained
from a spray at the edge of the void, show a lower Ag:Cu ratio (1.48; range: 1.41-1.54). They
confirm the complete absence of Sb. Optically, the polished crystals are homogeneous, withno indication of twin lamellae or other anomalies. The associated cupropearceite has adistinctly higher Ag:Cu ratio (2.44).
The asymmetric unit contains seven metal sites, one As site and four S sites. The metal sites
comprise three Ag sites, one mixed (Ag0.91(4)Cu0.09) site, one Cu site and two (Cu,Ag) sites
with occupancies (Cu0.89(3)Ag0.11) and (Cu0.65(3)Ag0.35). The formula is charge-balanced and no
As–As or distinct metal–metal bonds exist. Ag–S bond lengths range between 2.45 and 2.80
Å, while the Cu–S and (Cu,Ag)–S bond lengths show a range between 2.21 and 2.55 Å. The
As–S bonds are between 2.23 and 2.26 Å long. The atomic arrangement can be described as a
3D framework composed of metal-Sn (n = 2-4) polyhedra and AsS3 pyramids.
Comparisons will be drawn with chemically related species.
We thank Jean-Pierre Barral for providing the specimen (via Philippe Roth) for analysis.
FAVREAU, G., BARRAL, J.-P. (2019): Le Cahier des Micromonteurs, 145, 3-129 (in French).

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REVISIONS OF THE CRYSTAL STRUCTURES OF
MATILDITE, AgBiS2, aND CHRISTITE, TlHgAsS3
Kolitsch, U.1,2, Topa, D.1, Giester, G.2
1

Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum, Burgring 7, 1010 Wien, Austria
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
e-mail: uwe.kolitsch@nhm-wien.ac.at2

Results of a crystal-structure determination of matildite (low-temperature form of AgBiS2) werefirst reported by GELLER & WERNICK (1959) using synthetic material. On the basis of
powder X-ray diffraction data (PXRD) and a comparison with “isostructural” AgBiSe2 (studied
by both single-crystal and PXRD, and using some assumptions), they determined the “most–probable space group” to be P 3m1, with a = 4.07(2), c = 19.06(5) Å (no R-value given). No
detailed study of the structure of natural matildite was ever published. However, for crystals
from Canada, HARRIS & THORPE (1969) postulated a doubled a axis, with a = 8.12; c =19.02 Å, whereas SHIMIZU et al. (1998) gave a = 4.0670, c = 18.996 Å for a slightly Sebearing sample from Japan. We have reinvestigated the atomic arrangement of matildite using
well-crystallised material from the Clara mine, Black Forest, Germany (grey, distorted acicular
to bladed crystals with a strong metallic lustre). The structure solution, based on single-crystal
intensity data (MoKα; 293 K) showed the correct space group to be P3121 [Flack x parameter:
0.017(11)], with a = 4.0675(3), c = 18.9570(13) Å, V = 271.62(3) Å3; R(F) = 1.48%.
Quantitative electron-microprobe data showed the crystals to have a stoichiometric, nearly purecomposition, with only trace amounts of Pb present. The asymmetric unit contains one Ag, one
Bi, and one S site. Bond lengths are: Ag–S = 2.5263(6) (2), 2.8541(7) (2) Å; Bi–S =2.6660(6) (2), 2.8543(7) (2), 3.0386(7) (2) Å. The crystal structure is much more distorted
than that of the incorrect model from the 1950s.
The crystal structure of synthetic christite, TlHgAsS3, was first reported by BROWN and
DICKSON (1976). They gave space group P21/n, with a = 6.113(1), b = 16.188(4), c = 6.111(1)Å,  = 96.71(2)°; R(F) = 4.4%. No structural study of natural material was ever published.
Because the reported unit cell looked suspicious (a ~ c), we have reinvestigated christite using
well-developed crystals from the Jiepaiyu Mine, Shimen deposit, China. Quantitative electron
microprobe analysis confirmed the material to be chemically pure. The atomic arrangement wasredetermined from single-crystal intensity data (MoKα; 293 K). It was found to unambiguously
have space group Cmca, with a = 8.080(5), b = 9.123(6), c = 16.190(9); R(F) = 6.5%. The
higher symmetry is also confirmed by a critical analysis of the literature model with thesoftware PLATON, which clearly indicated space group Cmca. The crystal faces can all beindexed with simple forms: {010}, {011} and {111}. The asymmetric unit contains one Tl, one
Hg, one As, and two S sites (instead of three S sites in the literature model).
BROWN, K.L. & DICKSON, F.W. (1976): Z. Kristallogr., 144, 367-376.
HARRIS, D.C., THORPE, R.I. (1969): Canad. Mineral., 9, 655-662.
GELLER, S., WERNICK, J. H. (1959): Acta Crystallogr., 12, 46-54.
SHIMIZU, M., KATO, A., MATSUYAMA, F. (1998): Resource Geol., 48, 117-124.

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ANATECTIC ORIGIN OF PERMIAN PEGMATITES OF THE EASTERN ALPS –EVIDENCE FROM FLUID INCLUSIONS
Krenn, K.1, Husar, M.1, Mikulics, A.1
1

Insitute of Earth Sciences Nawi Graz, University of Graz, Heinrichstrasse 26, 8010 Graz, Austria
e-mail: kurt.krenn@uni-graz.at

Fluid inclusions (FIs) and associated solids in host minerals garnet, tourmaline, spodumene,
and beryl from five large pegmatite field areas with Permian origin (Radegund, Kor-Saualpe,
Millstatt, Polinik, and Bretstein-Lachtal), all located in the Koralpe-Wölz high-pressure nappe
system of the Eastern Alps, have been investigated. Although pegmatites suffered intense
Eoalpine high-pressure metamorphic overprint during the Cretaceous period, most of thestudied samples originate from rock sections with well-preserved Permian magmatic textures.
Pegmatite minerals are proposed as having been crystallized under incipient anatectic
conditions of their surrounding host rock lithologies and comprise primary FIs with acomplex CO2±N2±CH4-H2O-NaCl-CaCl2±MgCl2 chemistry. However, the presence of partly
exsolved fluids during garnet crystallization in the Kor-Saualpe enables a distinction into two
fluid assemblages: assemblage A, defined by coevally entrapped CO2-N2 and H2O-NaClCaCl2±MgCl2 FIs, and assemblage B, characterized by FIs of CO2±N2±CH4-H2O-NaClCaCl2±MgCl2 chemistry. This suggests a different fluid evolution history in the Kor-Saualpe
pegmatites compared to the other pegmatite fields. In the Koralpe, two separately evolved
fluids (CO2-N2 and H2O) entrapped in magmatic garnet domains and experienced subsequent
mixing at the solvus. This mixed fluid dominated during tourmaline and spodumene
crystallization and entrapped as assemblage B in the form of primary inclusions (cf. KRENN
et al., 2021a). At Radegund, Millstatt, Polinik, and Bretstein-Lachtal, fluid assemblage B was
the dominant fluid during crystallization of the pegmatite host minerals garnet, tourmaline,
and spodumene. Additionally, beryl-hosted FIs from pegmatites of the Polinik pegmatite field
consist of assemblage B and can be compared to FIs from beryl host of the Texel pegmatitefield in the westernmost areas of the Eastern Alps (KRENN et al., 2021b). Minimum
conditions for pegmatite crystallization in the Polinik pegmatite field of ca. 6.3–7.3 kbar in
garnet and 5.1–5.9 kbar in beryl as well as 4.5–5.5 kbar in tourmaline of the Kor-Saualpe at
650–750 °C have been constrained by primary FIs that have not been affected by postentrapment modifications. It is therefore proposed that magmatic/metamorphic fluid
interaction dominated during Permian pegmatite formation in a high-grade metamorphic
environment: a low-saline aqueous fluid as magmatic constituent mixed with a CO2-N2-richfluid that formed as result of partial anatexis with the surrounding host rocks. As potential
source for N, mica minerals of the metapelite host are proposed (cf. KRENN et al., 2021b).
The dominance of N in almost all CO2-bearing FIs of the studied host minerals of thepegmatite field areas provides further evidence for an anatectic origin of the pegmatites of theAustroalpine basement of the Eastern Alps.
KRENN, K., HUSAR, M., MIKULICS, A. (2021a): Minerals, 11, 638, 1-22.
KRENN, K., KONZETT, J., STALDER, R. (2021b): Canad. Mineral., in press.

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FEASIBILITY STUDY ON THE INVESTIGATION OF FORMERPOLYCHROME PAINTING ON THE “ROMAN STONES FROM HERNALS”
Krickl, R.1, Steigberger, E.2
1

Forschungsinstitut Dr. Robert Krickl, Al. Groß G. 42, 2345 Brunn/Geb. / Amundsenstr. 3, 1140 Vienna, Austria
2
Bundesdenkmalamt, Abteilung für Archäologie, Kartäuserplatz 1, 3001 Mauerbach, Austria
e-mail: mail@r-krickl.com

In 2003, remarkable Roman stone artefacts were excavated during construction activities in the
17th district of Vienna and thereafter given the name “Römersteine aus Hernals” (“Romanstones from Hernals”). Classified as one of the most important Roman stone finds in the last
decades in Austria, they were archaeologically investigated, restored, and put on display by theFederal Monuments Authority Austria in Mauerbach Charterhouse (cf. BLESL et al., 2012).
In the course of a feasibility study on the application of noninvasive methods (mainly
multispectral imaging in combination with X-ray fluorescence analysis and Raman
spectroscopy) in museal environments, the Roman funerary monuments where now
investigated on remnants of former polychrome decoration. Aside from visible traces of ironoxide, green earth and carbon black pigments, multispectral imaging could reveal the hitherto
unknown presence of abundant Egyptian blue in form of dustsized particles not perceptible by
the naked eye (cf. Fig. 1). A very precise localisation was achieved by using the new CoRL
technique (KRICKL, 2019), thus indicating different usage of this blue pigment: not only as
background colour alluding to the sky, but also for depicting metal objects and colourful
clothing and, last but not least, as contouring agent for accentuating shadows and plasticity.
With few and manageable limitations, the new multispectral methods proved very well suitedfor the investigation of large stone artefacts in museums, promising new information onmaterials used in ancient artwork.

Figure 1. Visible (left), infrared luminescence (middle) and CoRL (right) image of a side element of a Roman
funerary aedicula displayed in Mauerbach Charterhouse, depicting a male servant. White areas in the latter two
images indicate the presence of Egyptian blue pigment.
BLESL, C., HEBERT, B., MARIUS, M. (2012): Wiederhergestellt 02 – Römersteine aus Hernals. Mediterrane
Bilder in >Barbarengräbern<. Bundesdenkmalamt, Wien.
KRICKL, R. (2019): Mitt. Österr. Miner. Ges., 165, 54.

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THE CRYSTAL STRUCTURE OF THE NEW MINERAL DEVILLIERSITECa4Ca2Fe3+10O4[(Fe3+10Si2)O36]
Krüger, B.1, Krüger H.1, Galuskina, I.O.2, Galuskin, E.L.2, Vapnik, Ye.3
University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria
Faculty of Earth Sciences, University of Silesia, Będzińska 60, 41-200 Sosnowiec, Poland
3
Ben-Gurion University of the Negev, POB 653, Beer-Sheva 84105, Israele-mail: biljana.krueger@uibk.ac.at
1

2

The crystal structure of the new mineral (IMA 2020-073) devilliersite,
Ca4Ca2Fe3+10O4[(Fe3+10Si2)O36], was solved from single-crystal synchrotron data PSI (SLS).
Devilliersite, as well as khesinite, Ca4Mg2Fe3+10O4 [(Fe3+10Si2)O36] (GALUSKINA et al.,2017), is a VIFe3+-analog of dorrite, Ca4Mg2Fe3+10O4[(Al10Si2)O36] (COSCA et al., 1988) andsynthetic SFCA (Silico-Ferrite of Calcium and Aluminium) (KAHLENBERG et al., 2019).
The structural formula of minerals of the dorrite–khesinite series can be written as
VII(A12A22)Σ4VI(M1M2M32M42M52M62M72)Σ12O4[(T12T22T32T42T52T62)Σ12O36], where A are
seven coordinated sites, M are octahedral sites and T are tetrahedral sites (Figure 1). In the
structure of devilliersite all of the A-sites are fully occupied by calcium. Further excess of Ca,
additional 0.68 atoms, has to be expected at the largest octahedral site M5. The remaining
scattering power at the M5 site is explained by Mg. The octahedral M1, M2, M3, M4, and M6
sites are dominated by Fe3+, their scattering power was modelled with Fe and Mg, andconverged for all sites to ~93% Fe. The M7 is a Ti-rich site. Scattering power indicates that theT4 site in devilliersite is fully occupied by Si. Occupancy of all other tetrahedral sites wasrefined as Al vs Fe.
The refined chemical formula is VIICa4VI(Ca1.36Mg1.33Fe9.07Ti0.24)Σ12O4IV(Al3.24Fe6.76Si2)Σ12O36.

Figure 1. The devilliersite structure, projection on (100): Fe-dominant polyhedra (M1, M2, M3, M4, M6, M7octahedra and T2, T3, T5, and T6 tetrahedra are in red. In blue are 6+1 coordinated pure Ca-polyhedra (A1 and A2polyhedra). The octahedra M5, predominantly occupied by Ca (68%) is in light blue colour. Pure Si tetrahedra T4
are in yellow. Al-dominant tetrahedra T1 have orange colour.
GALUSKINA, I.O., GALUSKIN, E.V., PAKHOMOVA, A.S., WIDMER, R., ARMBRUSTER, T., KRÜGER,B., GREW, E.S., VAPNIK, Y.E., DZIERAZANOWSKI, P., MURASHKO, M. (2017). Eur. J. Miner., 29, 101–
116.
COSCA, M.A., ROUSE, R.R., ESSENE, E.J. (1988). Amer. Miner,, 73, 1440-1448.

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A DEDICATED ELECTRON DIFFRACTOMETER FOR SOLVINGCRYSTALLOGRAPHIC CHALLENGES IN MINERALOGY
Lanza, A.E.1, Hovestreydt, E.1, Santiso-Quinones, G.1, Steinfeld, G.1, Mugnaioli, E.2,
Gemmi, M.2
ELDICO Scientific AG, 5234 Villigen, Switzerland
Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia,
piazza S. Silvestro 12, 56127 Pisa, Italye-mail: lanza@eldico.ch
12

While several methods based on Electron Diffraction (ED) are applied in mineralogy since theinvention of electron microscopy, the recent development of 3D ED methods has caused a
breakthrough into many different fields of science, for the structural determination of microand nanocrystalline samples (GEMMI et al., 2019).
Both in natural and synthetic minerals, the structural characterization can be hampered by a toosmall crystal size, limited sample quantity, presence of spurious phases and by complicatedfeatures such as twinning and intergrowth occurring at the submicrometric scales. 3D ED allows
to collect complete diffraction datasets from individual nanocrystalline domains, and thus tosolve and refine their unknown crystal structures, overcoming the above-mentioned
complications (MUGNAIOLI & GEMMI, 2018).
Here we present some examples of mineralogic challenges solved with 3D ED (LANZA et al.,2019; MUGNAIOLI et al., 2020a; MUGNAIOLI et al., 2020b). These complex
microcrystalline minerals, showing incommensurate modulations, microtwinning and complex
structural rearrangements, all showcase the potential of an electron diffractometer. Our device,developed and optimized exclusively for 3D ED, allows a time-effective, automated andstandardized experimental workflow along with user-friendly operability and seamless
interaction with the widespread crystallographic software.

GEMMI, M., MUGNAIOLI, E., GORELIK, T.E., KOLB, U., PALATINUS, L., BOULLAY, P., HOVMÖLLER,
S., ABRAHAMS, J.P. (2019): ACS Cent. Sci., 5, 1315-1329.
LANZA, A.E., GEMMI, M., BINDI, L., MUGNAIOLI, E., PAAR, W.H. (2019). Acta Crystal., B75, 711-716.
MUGNAIOLI, E., BONACCORSI, E., LANZA, A.E., ELKAIM, E., DIEZ-GOMEZ, V., SOBRADOS, I.,
GEMMI, M., GREGORKIEWITZ, M. (2020a): IUCrJ, 7, 1070-1083.
MUGNAIOLI, E., GEMMI, M. (2018): Z. Kristallogr. – Cryst. Mater., 233, 163-178.
MUGNAIOLI, E., LANZA, A.E., BORTOLOZZI, G., RIGHI, L., MERLINI, M., CAPPELLO, V., MARINI, L.,
ATHANASSIOU, A., GEMMI, M. (2020b): ACS Cent. Sci., 6, 1578-1586.

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DIACHRONOUS METAMORPHISM OF CORDIERITE BEARING ASSEMBLAGESFROM THE WANNI COMPLEX – SRI LANKA
Lechner, N.1, Hauzenberger, C.A.1, Skrzypek, E.1, Masten, M.1, Sorger, D.1,
Fernando, G.W.A.R.2
1
University of Graz, Universitätsplatz 2, 8010, Graz, Austria
The Open University of Sri Lanka, PO Box 21, Nugegoda, Sri Lankae-mail: nikolaus.lechner@uni-graz.at

2

The Sri Lankan basement is subdivided into the Highland Complex (HC), Wanni Complex(WC), and Vijayan Complex (VC) mainly based on Nd-model ages from MILISENDA et al.
(1988, 1994) and underwent amphibolite to granulite facies metamorphism during the PanAfrican orogeny ~ 600 - 500 Ma ago. While the boundary between VC and HC is well known
due to differences in metamorphic grade and a thrust/shear contact, the boundary between the
WC and HC is still matter of discussion. The HC probably represents a deeper crustal level
than the WC which is overprinted by up to UHT conditions in the central HC (SAJEEV et al.,2010). Parts of the WC may have also experienced UHT conditions but clear evidence is still
missing. For this study cordierite bearing garnet-biotite gneisses were collected from the
WC/HC boundary area from south-western Sri Lanka. This rock type occurs less frequently
compared to the dominant meta-granitoides, garnet-sillimanite gneisses, charnockitic gneisses
and basic granulites/amphibolites and are regarded as an own unit. Symplectitic cordierite andbiotite growth around garnet indicates decompression by the reaction Melt + Grt + Qtz + Sil =Crd + Sp + Bt. Based on mineral assemblages, textures and EPMA mineral analyses, P-T
conditions of 850 ± 50 °C and 6 ± 1 kbar are proposed during metamorphism of the cordierite
bearing unit. Recently, WANNIARACHCHI & AKASAKA (2016) and HIRAYAMA et al.
(2020) reported metamorphic ages of ~530-540 Ma determined by in-situ monazite and zircon
U-Pb dating, respectively. Here, we report additional in-situ EPMA Th-U-Pb monazite ages
based on the textural position of the monazite grains: (1) monazite inclusions in garnet yield aweighted mean age of 572 ± 2 Ma, which is interpreted to represent the age of main
metamorphism in the HC, which was documented by SAJEEV et al. (2010) with a similar
result of 569 ± 5 Ma. They found a metamorphic overprint at approximately 550 Ma (zircon
and monazite rims) which is probably also present here, but not well constrained. (2)Monazites in the matrix cluster around 565 ± 3 Ma and 534 ± 2 Ma. The older age is close to
the age found in monazites enclosed in garnet and thus represents the age of metamorphism in
the HC, while the younger age represents the timing of cordierite formation and the LP/HT
metamorphic event seen in southwestern Sri Lanka.
MILISENDA, C. C., LIEW, T. C., HOFMANN, A. W., KRONER, A. (1988): J. Geol., 96, 608–615.
MILISENDA, C. C., LIEW, T. C., HOFMANN, A. W., KÖHLER, H. (1994): Precambrian Res., 66, 95–110.
SAJEEV, K., WILLIAMS, I. S., OSANAI, Y. (2010): Geology, 38, 971–974.
WANNIARACHCHI, D. N. S., AKASAKA, M. (2016): J. Mineral. Petrol. Sci., 111, 351–362.
HIRAYAMA, E., TSUNOGAE, T., MALAVIARACHCHI, S. P. K., TAKAMURA, Y., DHARMAPRIYA, P.
L., TSUTSUMI, Y. (2020): Geol. J., 55, 6147–6168.

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CONTRIBUTIONS TO THE CRYSTAL STRUCTURE OF GUÉRINITE FROM THE
LAVRION MINING DISTRICT, GREECE
Liebhart, I.1, Rieck, B.1, Giester, G.1
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
e-mail: gerald.giester@univie.ac.at

1

Guérinite was first described from samples originating from Schneeberg, Saxony and Richelsdorf, Hessia as Ca5H2(AsO4)4·9H2O (NEFEDOV, 1961). The crystal structure was solved onsynthetic material only by single-crystal diffraction methods (CATTI & FERRARIS, 1974) inspace group P21/n with a = 17.63(1), b = 6.734(3), c = 23.47(2) Å, β = 90.6(1)°. However,these authors discussed several models, favouring a disordered one with two additional,
partially occupied calcium sites, leading to the formula Ca5(HAsO4)2(AsO4)2·9H2O.
Recently, during sampling of an arsenic-rich area of the Mine No. 145 at the Lavrion Mining
District, Greece, a large number of secondary Ca and Mg arsenates were found. Among them,some specimens were tentatively identified as guérinite. However, the Ca/As-ratio of EMPAstudies did not fit well with published formulas in the literature. The crystals being wellformed (Fig. 1) and of adequate quality enticed the authors to try a full-fledged crystal
structure determination of the new material.
Based on single-crystal X-ray data, collected at 200 K, the structure was refined in spacegroup P21/n with a = 17.631 (2), b = 6.731(1), c = 23.388(3) Å, β = 90.69(1)° to R1 = 0.051
and the hydrogen–bond system established. The true formula of guérinite turned out to be
Ca6(HAsO4)3(AsO4)2·10½H2O. It further showed up that there is obviously no type specimen
still in existence. The authors therefore propose that guérinite be redefined according to thepresent results, that the specimen used for our study be termed neotype specimen and the type
locality be the Mine No. 145 in the Plaka area of the Lavrion Mining District.

Figure 1. Guérinite, associated with white, needle-like rauenthalite (lower left) and deformed pharmacolite(right) on calcite matrix that is partially covered by tiny marcasite crystals (mainly left of guérinite).
NEFEDOV, E.I. (1961): Mat. All-Union Sci. Res. Geol. Inst., 45, 113-115.
CATTI, M., FERRARIS, G. (1974): Acta Crystallogr., B30, 1789-1794.

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ON A NOVEL PHASE IN THE SYSTEMS K2O–CaO–SiO2 —SOLVING A 90 YEARS OLD RIDDLE
Liu H., Hildebrandt E., Krammer H., Kahlenberg V., Krüger H., Schottenberger H.
University of Innsbruck, Institute of Mineralogy and Petrography, Innrain 52, A-6020 Innsbruck, Austria
e-mail: volker.kahlenberg@uibk.ac.at

When it comes to the re-use of residual materials such as different types of ashes and slags
occurring in industrial combustion, gasification, pyrolysis, and metallurgical processes, thesystem K2O-CaO-SiO2 is of great interest and importance. Revealing the complete picture of
all ternary phases as well as detailed crystal structure information on all compounds in thesystem is of essence for both identification of the phases in technical products and related
thermodynamic assessments. In the course of an ongoing research project, we found evidence
for the existence of the so-called 2:1:6 phase (K4CaSi6O15) and finally proved its presence as astable material at ambient conditions.
Actually, a compound with composition K4CaSi6O15 was first mentioned by MOREY et al.
(1930). However, limited by the available analytical tools in the 1930’s, the chemical formula
was estimated from the initial weight fractions of the educts, i.e. no chemical analysis of the
product has been performed. Furthermore, the only other characterization method of the crystals
was the determination of their optical properties including measurements of the refractive
indices. Though optical features of the crystals served to establish hypotheses concerning the
crystal system, neither detailed powder/single-crystal diffraction nor spectroscopic data havebeen collected.
In the present study, polycrystalline K4CaSi6O15 was prepared from (i) solid-state reactions
between stoichiometric mixtures of the corresponding oxides/carbonates and (ii) combustion
solution synthesis using K- and Ca-nitrates, tetraethyl orthosilicate (TEOS), and glycine (fuelcomponent) as starting reagents. The compound was characterized by powder X-ray diffraction.
Differential thermal analysis indicated that K4CaSi6O15 melts congruently at about 956 °C. On
cooling down from the liquid state, a distinct glass-forming tendency was observed. Singlecrystals suitable for further structural investigations were obtained from sinter experiments justbelow the melting point. Basic crystallographic data are as follows: monoclinic symmetry,space group Pc, a = 6.9299(2) Å, b = 27.3496(9) Å, c = 12.2187(4) Å,  = 93.744(3)°, V =2310.86(13) Å3, Z = 3. The crystal structure of K4CaSi6O15 belongs to the group of interrupted
framework silicates with exclusively Q3-units. The tetrahedral network is the first inorganic
representative of the so-called eth-type (O'KEEFFE et al., 2008) which has been previously
observed in metal organic frameworks or molecular structures only. Charge compensation in
the structure is achieved by incorporation of potassium and calcium cations, which arecoordinated by five to nine oxygen ligands.
MOREY G.W., KRACEK F.C., BOWEN N.L. (1930): J. Soc. Glass Technol., 14, 149-187.
O'KEEFFE M., PESKOV M.A., RAMSDEN S.J., YAGHI O.M. (2008): Acc. Chem. Res., 41, 1782-1789.

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GEOCHRONOLOGY AND HIGH-GRADE METAMORPHISM OF THE
WANNI COMPLEX, SRI LANKA
Masten, M.1, Hauzenberger, C.A.1, Lechner, N.1, Skrzypek, E.1, Gallhofer, D.1,
Fernando, G.W.A.R.2
University of Graz, Universitätsplatz 2, 8010 Graz, Austria
The Open University of Sri Lanka, PO Box 21, Nugegoda, Sri Lankae-mail: marcel.masten@edu.uni-graz.at
1

2

The assembly of Gondwana in the Neoproterozoic/Early Paleozoic resulted in a number oflarge-scale orogenic systems. Sri Lanka is located in a central position of the supercontinentand is usually associated with the Mozambique Belt in Eastern Africa, Madagascar andAntarctica. The main geological units of Sri Lanka comprise the (1) Vijayan Complex, which
is separated from the (2) Highland Complex by a thrust contact and the (3) Wanni Complex.
The boundary between the Wanni and the Highland Complex is poorly defined and a matterof debate. Differences in isotopic model ages were used to separate both units (KITANO etal., 2018; MILISENDA et al., 1994). Here, we report new zircon U-Pb ages defining theemplacement age of the igneous precursor rocks as well as the metamorphic overprint. In
addition, a detailed petrological study reveals the UHT nature of at least some Wanni
metamorphic rocks.
Large areas of the Wanni Complex are covered by migmatitic orthogneisses with occurrencesof “arrested” charnockites or displaying potassium metasomatism (COORAY, 1994;
KRÖNER et al., 2003). However, charnockitic gneisses, mafic granulites and garnet bearing
gneisses and, in the southwestern part, cordierite bearing gneisses and metapelites are
frequently found and can be used for constraining the P-T-t history of this complex. P-T
conditions of the Wanni Complex obtained from garnet bearing rocks place the metamorphic
overprint clearly into the granulite facies and partly into the UHT field with T = 800-1000 °C
at 7-9 kbar.
Zircon U/Pb ages obtained from felsic hornblende-biotite gneisses and charnockitic gneissesfrom different locations of the Wanni Complex show igneous protolith ages of 960-990 Ma.
In one sample newly grown metamorphic zircons revealed Cambrian ages that cluster around
530 Ma.
COORAY, P.G. (1994): Precambrian Res., 66, 3–18.
KITANO, I., OSANAI, Y., NAKANO, N., ADACHI, T., FITZSIMONS, I.C.W. (2018): J. Asian Earth Sci.,
156, 122–44.
KRÖNER, A., KEHELPANNALA, K.V.W., HEGNER, E. 2003. “Ca” Journal of Asian Earth Sciences 22,
279–300.
MILISENDA, C.C., LIEW, T.C., HOFMANN, A.W., KÖHLER, H. (1994): Precambrian Res., 66, 95–110.

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CESIUM-ORDERING AND HIGH-PRESSURE BEHAVIOUR IN
CESIUM-STUFFED BERYL-TYPE JOHNKOIVULAITE
Milos, S.1, Ende, M.1, Gatta, G.D.2, Palke, A.C.3, Miletich, R.1
1
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstrasse 14, 1090 Vienna, Austria
Dipartimento di Scienze Della Terra, Università Degli Studi di Milano, Via Botticelli 23, 20133, Milano, Italy
3
Gemological Institute of America, Inc., The Robert Mouawad Campus, 5345 Armada Drive,
Carlsbad, CA 92008, USAe-mail: sofija.milos@univie.ac.at

2

The newly discovered beryl-type mineral johnkoivulaite (CsBe2BMg2Si6O18, space group
P6/mmc, PALKE et al., 2021) has a discrete structural site for Cs, in some way similar to therelated structure of rhombohedral pezzottaite (Cs(Be2Li)Al2Si6O18; LAURS et al., 2003; ENDE
et al., 2021). A striking difference between the two structures is the distinguishable heterovalent
substitution (1/3 B3+ versus 1/3 Li+ on the T1 site, and Mg2+ versus Al3+ on the M site) within
the [T1[4]3M[6]2Si6O18] framework. Despite the different charge distribution within theframework, there is a comparable stoichiometry of one Cs-atom per formula unit. Nevertheless,the overall symmetry is different, and it raises the question of whether the different charge
distribution within the framework has a consequence on the extra-framework Cs ordering andif the high-pressure properties of johnkoivulaite are identical or different compared to thosereported for pezzottaite (ENDE et al., 2021).
In this context first in-situ compression studies were conducted on a natural single crystal
sample originating from the gem deposit of Mogok, Myanmar, using Raman spectroscopy andsingle-crystal X-ray diffraction. The purpose of this study is to understand the stability criteria
from a structural perspective, any polymorphism, and the mechanisms of the underlying
transitions in non-ambient pressure conditions. In Raman spectra at ambient conditions
johnkoivulaite crystals exhibit no characteristic Raman band in the low-frequency range
between 50 and 200 cm-1 Raman shift. Such a vibrational band was found for pezzottaite around
111 cm-1 and was attributed to Cs-O vibrations (e.g. ENDE et al., 2021). However, at elevatedpressure a massive band with its tentative maximum below 50 cm-1 shifts from below the lower
detection limit (50 cm-1) to higher frequencies within the detectable spectral range. At 6 GPa
two new Raman bands evolve at 80 cm-1 and 120 cm-1, which indicates a change in Cs-O
bonding and related coordination of the Cs site, most likely accompanied by a least local
symmetry lowering related to changes in the Cs ordering. First results of X-ray diffraction
measurements will be presented to shed light on these potential pressure-induced changes, ascompared to the high-pressure behaviour of the related pezzottaite structure.
PALKE, A.C., HENLING, L.M., Ma, C., ROSSMAN, G.R., SUN, Z., RENFRO, N., KAMPF, A.R., THU, K.,
MYO, N., WONGRAWANG, P., WEERAMONKHONLERT, V. (2021): Amer. Mineral., in press
LAURS, B.M., SKIP SIMMONS, W.B., ROSSMAN, G.R., QUINN, E.P., MCCLURE, S.F., PERETTI, A.,
ARMBRUSTER, T., HAWTHORNE, F.C., FALSTER, A.U., GÜNTHER, D., COOPER, M.A.,
GROBETY, B. (2003): Gems Gemol., 39, 284–301.
ENDE, M., GATTA, D.G., LOTTI, P., GRANDTNER, A., MILETICH, R. (2021): J. Solid State Chem., 293,
121841, 1-11.

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MINERALOGICAL ALTERATIONS OF GEOPOLYMERS DOPED WITH METALSUNDER AGGRESSIVE LAB AND SEWER CONDITIONS
Mittermayr, F.1, Ukrainczyk, N.2, Gluth, G. J.G. 3, Koraimann, G.4, Dietzel, M.5, Grengg, C.5
Institute of Technology and Testing of Building Materials, Graz University of Technology,
Inffeldgasse 24, 8010 Graz, Austria
2Institute of Construction and Building Materials, Technical University of Darmstadt,
Franziska-Braun-Strasse 3, 64 287 Darmstadt, Germany
3
Division 7.4 Technology of Construction Materials, Bundesanstalt für Materialforschung und -prüfung (BAM),
Unter den Eichen 87, 12205 Berlin, Germany
4
Institute of Molecular Biosciences, University of Graz, Humboldstraße 50, 8010 Graz, Austria
5Institute of Applied Geosciences, Graz University of Technology, Rechbauerstraße 12, 8010 Graz, Austria
e-mail: f.mittermayr@tugraz.at
1

Highly aggressive environmental conditions in wastewater infrastructure can lead to a fast
rate of deterioration of concrete sewers. This degradation process is associated with complex
biological activities referred to as microbial induced acid corrosion (MIAC). Damage related
to MIAC is still an unresolved global challenge with high economic and social relevance.
Currently used construction materials in sewers do not withstand long-term requirements, thus
raising the demand for more durable alternatives. Options in this context comprise highly
durable new materials such as geopolymers and/or reduce or totally inhibit relevant microbes
from colonizing concrete surfaces in order to avoid in-situ biogenic sulfuric acid production.
In this study we report results and highlight mineralogical and chemical alteration processes
from lab test, where samples were immersed in sulfuric acid (pHstat = 2) and from an on-site
testing campaign. After exposure to lab and field conditions geopolymer mortars doped with
Cu and Zn metal ions in different concentrations were compared to geopolymer mortars
without metal additions, calcium aluminate cement-based mortars and ordinary Portland
cement-based mortars. Metal-containing geopolymers performed significantly worse
compared to un-doped ones in sulfuric acid tests in the lab. In contrast, geopolymers withsmall amounts of CuSO4 additions (~0.1 wt.% Cu per binder) exhibited a much better
performance in the field, compared to un-doped materials, due to multiple effects on the
microorganisms.

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NATURAL ROCKS AS IN-HOUSE CONTROL SAMPLESFOR GEOCHEMICAL ANALYSIS
Nagl, P.1, Mader, D.1
Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
e-mail: peter.nagl@univie.ac.at

1

All analytical methods are subject to errors, therefore it has to be an analyst's goal tominimize them. Those quality control measurements are not only time consuming but cancause considerable costs by the use of different certified rock reference materials, e.g. forchecking repeatability, reproducibility or determining the correctness (deviation from true
value). This can be done also by “in-house control samples“.
The idea of the present study at the Department of Lithospheric Research of the University of
Vienna was to have samples of different rock types available for the geochemical analysis formonitoring analytical processes and also for teaching purposes.
First three different rock types (acid, basic and ultramafic) were selected from Austrian
localities where samples were collected in larger amounts. Later the suite was expanded bydifferent carbonates and a quarzite and finally with a silty sediment.
After crushing and homogenization, the samples were split using riffle and rotary sample
splitters. Sample preparation and analysis using wavelength dispersive X-ray fluorescenceanalysis (WDXRF) and integrated neutron activation analysis (INAA) was done according to
NAGL & MADER (2019) and MADER & KOEBERL (2009). Very good comparability wasapproved by randomly selected subsamples.
Comparison of the results of WDXRF and INAA showed, that both types of analysis cancomplement each other in geochemical whole rock analysis; for a lot of elements bothmethods show (sometimes very) good accordance.
The whole suite of those eight different in-house control sample types is covering most kindsof rocks investigated at the Department of Lithospheric Research. Those 8 samples can beused for monitoring the processes following the laboratories' SOP and they can be used also
for teaching and research purposes.
The analysis using WDXRF is flexible, comparatively quick (especially for major elements),
and precise. For some other (trace) elements, preference should be given to the more suitablemeasurement method, but always with regard to availability and the necessity of a certain
method and the cost/benefit ratio.
MADER, D.,KOEBERL, C. (2009): Appl. Rad. Isotopes, 67, 2100–2103.
NAGL, P., MADER, D. (2019): SAAGAS 27, abstracts, 48.

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GEOCHEMISTRY AND ZIRCON U-Pb GEOCHRONOLOGY OF LATE MESOZOIC
IGNEOUS ROCKS FROM SW VIETNAM – SE CAMBODIA
Nong, A.1 , Gallhofer, D.1, Skrzypek, E.1, Hauzenberger, C.A.1
University of Graz, Graz, Austria, Universitätsplatz 2, 8010 Graz, Austria
e-mail: christoph.hauzenberger@uni-graz.at

1Late Mesozoic volcanic and plutonic rocks are predominantly found in the Dalat zone of southern
Vietnam, but smaller volumes also occur in southwesternmost Vietnam and southeastern Cambodia
comprising mainly basalt and basaltic-andesite to dacite, and diorite, granodiorite and granite.
These igneous rock suites indicate several pulses of magmatism during the late stages of a longlived convergent margin, where the Paleo-Pacific plate subducted beneath the eastern margin of
Asia. The age of the plutonic suites (monzogabbro, monzodiorite, diorite, syenite, granodiorite andgranite) is constrained by LA-MC-ICPMS U-Pb zircon dating with 107 to 91 Ma. The associatedvolcanic suite displays U-Pb zircon ages of 105–95 Ma. Mineral and whole-rock chemistry of
volcanic and plutonic rocks is characterized by a calc-alkaline affinity for samples in the Dalat zone
and high-K calc-alkaline to shoshonitic affinity for rocks in SW-Vietnam – SE-Cambodia. Mineralcharacteristics and variation diagrams of selected elements suggest that fractional crystallization
dominated during magma differentiation.
A younger magmatic suite (83–75 Ma) is found within the intrusive rocks displaying A-typecharacteristics. These plutonic bodies comprise fine-grained biotite granites, which are partly
fluorite bearing and coarse-grained two-mica granites which are characterized by high contents of
HFSEs. Geochemical signatures of these young igneous rocks indicate an extensional tectonic
setting, possibly related to basaltic injection/asthenospheric upwelling. This additional heat input isrequired for partial melting of a dry residual crustal source which resulted from the extraction of
subduction-related granitoids at the earlier stage. Geochemical and geochronological results clearly
demonstrate that the Late Mesozoic magmatism in southern Indochina can be related to two
significant tectonic stages in Indochina and adjacent areas: (1) the Paleo-Pacific subduction (110–90
Ma) and (2) the transitional phase leading to the opening of the East Vietnam Sea/South China Sea(90–75 Ma).

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OLIVINE CRYSTAL CHEMISTRY REVEALS THE POSSIBLE TRIGGERING OF
THE 2002-2003 Mt. ETNA FLANK ERUPTION
Ntaflos, T.1, Abart, R.1, Ferlito, C.2, Giacomoni, P.P.3, Casetta, F.1, Coltorti, M.3,
Hauzenberger, C.A.4
Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
2
Department of Biological, Environmental and Geological Sciences, University of Catania,
Piazza Universitá 2, 95131 Catania, Italy
3
Department of Physics and Earth Sciences, University of Ferrara, Via Saragat 1, 44122 Ferrara, Italy
4
University of Graz, Universitätsplatz 3, 8010 Graz, Austria
e-mail: theodoros.ntaflos@univie.ac.at
1

Mount Etna is a stratovolcano with a complex plumbing system. Besides the 3 central summit
craters, there are fissure eruptions as well as a large number of eccentric cinder cones locatedon the flanks around the volcano. We studied the 2002-2003 effusive fissure eruption at 2750
m a.s.l. in the NE flank of the volcano. The rocks are trachybasalts, which were collected
directly from the fissure and represent the very last effusive lavas of this eruption. The texture
is porphyritic and the mineralogical assemblage is dominated by clinopyroxene phenocrysts
with olivine and Fe-Ti oxide inclusions and complex zoning, followed by olivine andplagioclase, which frequently shows cores with sieve texture. The groundmass consists ofclinopyroxene, olivine, plagioclase, Ti-Fe oxides and variable amounts of glass.
The whole rock Mg# is about 52, the alkali content (Na2O+K2O) is close to 5.3 wt%, and the
REE abundances (La/Yb)N = 20 are lower than those of the typical Mongibello lavas. High
precision EPMA analyses of olivine phenocrysts have shown simultaneous occurrence of
normal and complex inverse zoning. According to the detailed elemental profiles based on
major, minor and trace elements, olivine is divided into three groups: group A with normal
zoning, group B with inverse zoning, and group C overgrowth on existing olivine with normal
and inverse zoning. The rim to rim compositional profiles in olivine grains of the group A
show a remarkably wide plateau with Mg# = 80-83 and Ni = 1000-1700 ppm and a narrow,up to 50 microns wide rim where the Mg# drops to 75-73 and the Ni content to 420 ppm. The
olivine from group B is characterized by inverse zoning and has, like group A olivine, a wide
compositional plateau but rims with variable thickness. The Mg# at the plateau varysystematically from grain to grain between 69 and 74, whereas the up to 100 microns wide
rims show a bell-shaped profile with maximum Mg# between 77 and 79 which, at the veryrim in contact with matrix, drops to values similar to those in the corresponding plateau. The
Ni-contents at the plateau vary from 100 to 380 ppm and correlate positively with thecorresponding Mg#. In the rim, the Ni content increases steeply ranging from 100 to 800 ppm
and decreases at the very margin in contact with the matrix to the level of the plateau
concentrations. The olivine from group C shows a compositional profile similar to the group
A normal zoning and an overgrowth of 50 microns wide rim with a bell shaped Mg# profile,which decreases from 73 in the core to 68 in the rim. It is evident that an ascending magma,
which experienced en-route fractional crystallization, mixed with a more mafic magma
responsible for the inverse olivine zoning prior to the eruption at relatively shallow depths.
The estimated time of the diffusive Fe-Mg exchange between the mafic magma and olivine isvery short and ranges from a few days to 100 days. Apparently, the magma mixing is
associated with the triggering of the 2002-2003 flank eruption.

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SYNCHROTRON RADIATION MICROTOMOGRAPHIC ANALYSIS
OF A SYNTHETIC TRACHYBASALT:INSIGHTS INTO TITANOMAGNETITE NUCLEATION MECHANISMS
Peres, S.1, Griffiths, A.T.1, Colle, F.2, Iannini Lelarge, S.2, Mancini, L.3, Masotta, M.2,
Pontesilli, A.4
University of Vienna, Vienna, Althanstrasse 14,1090 Vienna, Austria
2
University of Pisa, Via Santa Maria 53, 56126 Pisa, Italy
3
Elettra-Sincrotrone Trieste S.C.p.A., S.S. 14, 34149 Basovizza, Trieste, Italy
4
Instituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Roma, Italye-mail: stefano.peres@univie.ac.at1

Titanomagnetite (Tmt) and Clinopyroxene (Cpx) commonly form clusters in mafic magmas.
Studying the mechanisms of active crystal clustering and the formation conditions of clusters
offers important insights into the nature and evolution of volcanic plumbing systems and crystal
mushes. 2D images are not sufficient to capture the geometry and true degree of clustering
between two phases. To overcome this, we present a phase-contrast synchrotron X-ray
microtomographic analysis of Tmt-Cpx clusters in a synthetic trachybasalt sample with 2 wt%
H2O added. The sample is one of a series of isothermal time series experiments, produced in a
Quick Press piston-cylinder apparatus at 4 kbar. After 30 minutes of superheating at 1300 °C
the sample was cooled to 1150 °C and held for 30 minutes before quenching.
3D X-ray imaging reveals a vertical gradient in crystallinity and in the size of the mineral phases
caused by an intrinsic temperature (and thus undercooling) gradient in the experimental
apparatus (temperature decreases of approximately 30 °C from bottom to top of the capsule).
At the cold end of the capsule, the crystallinity is maximum. The crystal phases are small
dendritic Cpx grains (between 100 µm to 300 µm in size) and small anhedral Tmt grains (1 µm
to 25 µm in diameter). In the central portion of the sample, the crystallinity is lower but theoverall size of Cpx (> 500 µm) and Tmt (skeletal, 80 µm to 150 µm in diameter) increases. The
shape of the crystals is less dendritic/anhedral, respectively. In the hot end of the capsule (where
the temperature is controlled by the thermocouple), the sample is dominated by glass, and onlyisolated skeletal Tmt grains crystallized.
Cpx and Tmt grains are clustered together whenever both crystal phases are present. Althoughlarge skeletal Tmt grains are more abundant in the central portion while small anhedral Tmt
grains dominate the cold end of the sample, the occurrence of the two Tmt morphologies
overlaps, and both can be found in contact with the same Cpx grain. The coexistence of two
different Tmt grain morphologies and sizes implies two different nucleation mechanisms. Largeskeletal Tmt in the bottom (hotter) and central portion of the sample likely crystallized byhomogeneous nucleation and probably predated the crystallization of Cpx grains. Smaller,
anhedral Tmt crystals, which decorate dendrites in the central to upper (cooler) portion of thesample, probably crystallized by heterogeneous nucleation on already crystallized Cpx grains.
In future, EBSD analysis on the sample will assess if crystallographic orientation relationships
between Tmt and Cpx in clusters differ depending on Tmt morphology and inferred nucleation
mechanism.

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DIFFUSION OF CHROMIUM INTO PERICLASE: AN ELECTRON PROBE
MICROANALYZER AND PHOTOLUMINESCENE SPECTROSCOPY STUDY
Pesek, P.R.1,2, Abart, R.2, Nasdala, L.1
University of Vienna, Institut für Mineralogie und Kristallographie, Althanstraße 14, 1090 Vienna, Austria
2
University of Vienna, Department für Lithosphärenforschung, Althanstraße 14, 1090 Vienna, Austria
e-mail: patrick.pesek@univie.ac.at

1

The diffusion of chromium in periclase (MgO) was investigated experimentally. To this end,
cubic periclase single crystals with polished (100) faces were either coated with, or embeddedin, a fine powder of magnesiochromite (MgCrO4), which served as the Cr source. The samples
were annealed at temperatures in the range 1500–1600 °C for 16–96 h under either oxidizing(in air) or reducing (under argon using a graphite crucible) conditions. The annealed samples
were investigated with optical and scanning electron microscopy, electron-probe microanalysis
and photoluminescence spectroscopy. Depending on the experimental conditions, Cr contents
in the range <0.005-0.32 apfu were attained in MgO. Precipitates of magnesiochromite and of
metallic Cr were formed under oxidizing and reducing conditions, respectively. For all
experiments where the diffusion source was applied as a thin coating, the diffusion profiles
show a local maximum of the Cr concentration at a depth of several tens of micrometers below
the samples surface. This profile shape is not consistent with the diffusion behavior ofchromium under constant boundary conditions and is explained by the successive
decomposition of the magnesiochromite (RUTMAN et al., 1968; LEE & SATA, 1978;
CHAKRABORTY et al., 2005) and subsequent loss of Cr from the sample surface via the gas
phase. The diffusion profiles analyzed in an embedded periclase annealed under oxidizing
conditions show inwardly decreasing Cr concentrations, with profiles being approximately
linear. This geometry is explained by an increase in the diffusion coefficient with increasing Cr
concentration. A diffusion model, in which a linear relationship between the diffusion
coefficient and the concentration of chromium was assumed, fits the measurement datareasonably well. Photoluminescence spectroscopy revealed that the luminescent Cr3+ is present
in different local environments, which is indicated by the shift in relative intensities of one
broad- and several narrow-band emissions. The narrow bands tend to increase at low Cr
concentrations. The broad band increases at higher Cr-concentrations, which was also observed
by CASTELLI & FORSTER (1975). A correlation between the Cr content and the broad-band
Cr3+ luminescence emission shows a linear increase in the emission with Cr concentration. The
emission is saturated at ~1.5 wt% Cr and suppressed by self-quenching at higher Cr
concentrations. However, even at higher Cr contents, the concentration of Cr is correlated
linearly with the Cr-related light absorption observed in transmission mode.
CASTELLI, F., FORSTER, L.S. (1975): Phys. Rev. B, 11, 920-928.
CHAKRABORTY, D., RANGANATHAN, S., SINHA, S.N. (2005): Metall. Mater. Transactions B, 36, 437-444.
RUTMAN, D.S., SHCHENETNIKOVA, I.L., KELAREVA, E.I., SEMENOV, G.A. (1968): Refractories, 9, 648652.
LEE, H.L., SATA, T. (1978): Yogyo-Kyokai-Shi, 86(989), 34-40.

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THE YOUNGEST PSEUDOTACHYLYTE GENERATION AT THE BASE OF THE
SILVRETTA NAPPE AND THE UPPER PLATE DEFORMATION
Pittarello, L.1, Levi N.2, Wegner W.1, Stehlik H.3
1
Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria
University of Vienna, Department of Geology, Althanstraße 14, 1090 Vienna, Austria and
NiMBUC Geoscience OG, Degengasse 41/5, 1160 Vienna, Austria
3
Ing. Harald Stehlik, Hagedornweg 2, 1220 Vienna, Austria
e-mail: lidia.pittarello@nhm-wien.ac.at

2

The seminal work by KOCH & MASCH (1992) presented and investigated the mutual
relationship between pseudotachylytes and (ultra)mylonites formed in amphibolites andgneisses at the base of the Silvretta Nappe, Austroalpine Unit (Eastern Alps). As supported byradiometric dating (THÖNI, 1988), KOCH & MASCH (1992) proposed that these structures
cyclically formed during the Eoalpine phase (mid Cretaceous), likely in extensional regime,
when the Silvretta Nappe was decoupled from its lithospheric roots. The study of new samples
collected in the Jamtal, Tyrol (Austria) allowed the discovery of a further step in the
deformation history at the base of the Silvretta Nappe. Detailed petrographic investigations
revealed the presence of a generation of pseudotachylytes overprinting the previously described
pseudotachylytes and mylonites. Compared to the previously described pseudotachylytes, thesehave not been further deformed under viscous-plastic conditions or epidotized, and have been
perfectly preserved, suggesting a more recent and possibly shallower formation. This
deformation event might be related to the final subduction of the Penninic Unit in the Paleogene,as also supported by anomalous young ages obtained by dating (THÖNI, 1988) that were notpreviously considered. The formation of pseudotachylytes in the upper plate in a shallow
subduction setting at the base of the Silvretta Nappe recalls the network of pseudotachylytes
observed in the Dent Blanche Austroalpine Unit in the Western Alps, also representing thehanging wall of a subduction zone in the Paleogene (MENANT et al., 2018). These authors
refer the possible occurrence of multiple shallow earthquakes in mid-crustal environment in theupper plate due to the presence of asperities, such as rigid bodies, “scratching” the base of theupper plate in the subduction zone. In the case of the Silvretta Nappe, such asperities could
have been represented by the fragments of the Briançonnais microcontinent within the
subducting Penninic Unit. Our work provides further constraints to the tectonic history of the
Silvretta Nappe, where the deformation mostly localized along its base over a long time,through several cycles of pseudotachylyte formation, and supports the understanding of brittle
deformation localization in the upper plate in subduction environments.
KOCH, N., MASCH, L. (1992): Tectonophysics, 204, 289-306.
MENANT, A., ANGIBOUST, S., MONIÉ, P., ONCKEN, O., GUIGNERD, J.-M. (2018): Earth Planet. Sci.
Letters, 487, 84-93.
THÖNI, M. (1988): Jb. Geol. Bundesanstalt, 131, 169-201.

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ON THE STRONTIUM INCORPRATION INTO BREDIGITE –THE SOLID SOLUTION SERIES Ca7-xSrxMg[SiO4]4
Salzmann, M.F.G.1, Prosser, L.1, Kahlenberg, V.1
Institute of Mineralogy and Petrography, Innsbruck University, Innrain 52, 6020 Innsbruck, Austria
e-mail: volker.kahlenberg@uibk.ac.at1

Bredigite (idealized chemical composition Ca7Mg[SiO4]4) is a rare mineral that has been
described from different petrological settings related to pyrometamorphism (GRAPES, 2011).
It has been observed, for example, in contact-metamorphized rocks or in altered carbonatesilicate xenoliths within volcanites based on siliceous limestone-dolomite protoliths.
Furthermore, small bredigite grains were repeatedly found in rocks belonging to the famous
Hatrurim Complex (Jordan) consisting of products of combustion metamorphism(KAHLENBERG et al., 2019). Apart from being a mineralogical curiosity, bredigite is also ofinterest for the field of material science and has been intensively studied as a host for rareearth elements for synthesis of new photoluminescent compounds. In addition, research on
bredigite included areas as diverse as bioactive ceramics, steelmaking slags or chemical
stabilizing of radioactive waste.
So far, only limited information on the cation substitutions in bredigite is available.
MOSELEY & GLASSER (1982) found evidence that Ba and Sr can replace Ca. However, nodetailed structural investigations have been performed. In the course of an ongoing research
project on the cation substitutions in bredigite-type compounds we investigated the potential
solid-solution series Ca7-xSrxMg[SiO4]4 (x = 0,1,…,7). Samples were prepared by solid-state
reactions using pressed pellets prepared from stoichiometric mixtures of the respectiveoxides/carbonates. The kinetics of the sintering reactions performed in the range between
1275 and 1325 °C was rather sluggish and, therefore, each mix had to be reground andreturned to the furnace for at least two times. Progress of the reactions was monitored using
PXRD. From the final sinter pellets of each composition crystals of sufficient size and quality
could be extracted for single-crystal diffraction experiments. Evolution of the lattice
parameters as well as crystal structure analysis proved the existence of a bredigite-type solid
solution series in the samples up to x = 4. Studies on the Sr/Ca distributions among the six
potential cation sites revealed a clear preference of strontium for specific positions.
GRAPES, R. (2011): Pyrometamorphism. 2nd ed. Springer, Heidelberg, Dordrecht, London, New York.
KAHLENBERG, V., GALUSKINA, I., KRÜGER, B., PAULUHN, A., GALUSKIN, E. (2019): Miner. Petrol.,113, 261-272.
MOSELEY, D., GLASSER, F.P. (1982): J. Mater. Sci., 17, 2736-2740.

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PETROGENESIS AND ECONOMIC SIGNIFICANCE OF THE ABU DABBAB
Sn, Ta-BEARING GRANITES FROM THE NORTH ARABIAN-NUBIAN SHIELD
Sami, M.1,4, Abd El Monsef, M.2, Toksoy-Köksal, F.3, Ntaflos, T.4, Abart, R.4,
Abdelfadil, K.M.5
Geology Department, Faculty of Science, Minia University, Shalaby Land, Main road, 61519 El-Minia, Egypt
2
Geology Department, Faculty of Science, Tanta University, El-Giesh Street, 31111 Tanta, Egypt
3
Department of Geological Engineering, Middle East Technical University, Üniversiteler Mahallesi,
Dumlupınar Bulvarı 1/6-133, 06800 Çankaya/Ankara, Turkey
4
Department of Lithospheric Research, University of Vienna, Althanstraße 14, UZAII, 1090 Vienna, Austria
5
Geology Department, Faculty of Science, Sohag University, Nasser City Street, 82524 Sohag, Egypt
e-mail: mabrouk.hassan@mu.edu.eg

1

The Abu Dabbab pluton, which is located in the Central Eastern Desert of Egypt, is one of themost promising Sn, Ta-bearing Neoproterozoic granites in the north Arabian Nubian Shield(ANS). The Abu Dabbab granites are still being explored with their petrogenesis andrelationship to Sn, Nb, and Ta mineralization. Mineral chemistry, whole-rock geochemical, andSr-Nd isotopic data are reported, to constrain their petrogenesis, geodynamic evolution, andeconomic significance. Geochemically, the Abu Dabbab albite granites are weakly to mildlyperaluminous with high SiO2, alkalis, Nb, Ta, Sn, F, and Ga/Al, but low MgO, CaO, and P2O5
contents. They have tetrad-type REE patterns (TE1-3 = 1.8-2.5), strong negative Eu anomalies
and extreme depletion in Ba, Sr, P, and Ti, which are characteristics of highly fractionated Atype granites. The isotopic data display positive εNd(t) values (+1.11 to +8.32) and tDM2 (0.681.13 Ga), suggesting a juvenile magma source of Neoproterozoic age similar to other granitic
plutons in the ANS. The granites were formed by partial melting of crustal materials followedby an extensive fractional crystallization and were subsequently affected by late- to postmagmatic fluids during their magmatic evolution. The crystallization of cassiterite andcolumbite-tantalite may have occurred due to localized saturation and crystallization withintrapped intercumulus melt. The granites were formed during the transition from late to post
collisional magmatism in the ANS. They are probably related to lithospheric delamination andslab breakoff, which lead to upwelling of asthenospheric magma that provided a continuous
flow of volatile-rich fluids and enhanced the fertility of the crustal magma. The strong Ta andSn enrichments in the granites could be a consequence of crystal melt fractionation and fluid
saturation that made the mineralized Abu Dabbab granites of valuable economic significancewith promising tonnage of Sn and Ta reserve.

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MINERALOGY AND GEOCHEMISTRY OF THE MICROGRANULAR ENCLAVESHOSTED BY HIGHLY EVOLVED GRANITES FROM THE
CENTRAL EASTERN DESERT OF EGYPTSami, M.1,2, Ntaflos, T.2, Abart, R.2, Farahat, E.S.1, Fathy. D.1
1
2

Geology Department, Faculty of Science, Minia University, Shalaby Land, Main road, 61519 El-Minia, Egypt
Department of Lithospheric Research, University of Vienna, Althanstrasse 14, UZAII, 1090 Vienna, Austria
e-mail: mabrouk.hassan@mu.edu.eg

The genesis of enclaves hosted by highly evolved granites is still a point of dispute,particularly the relative contributions of crustal and mantle sources to the formation of thesegranites. To address this issue, we report mineralogical and geochemical data for enclaves
hosted by fluorite bearing highly fractionated granites from the Central Eastern Desert of
Egypt. The majority of the enclaves are circular in shape and have sharp contacts to the hostrock. The enclaves have an intermediate silica composition and may be classified as
monzodiorite. They consist of biotite, hornblende, plagioclase, quartz, K-felspar, and fluorite
as the main mineral phases. Titanite, ilmenite, rutile, and zircon are present as accessory
phases. The plagioclases range in composition from oligoclase to labradorite, while biotite
and hornblende are classified as Mg-rich minerals. Geochemically, the monzodiorite enclaves
have a calc-alkaline and metaluminous character. They contain significant quantities of large
ion lithophile elements like Rb and K but are deficient in high field strength elements like Nb,
Ta, P, Ti, and U. The studied enclaves are probably formed by partial melting of ametabasaltic to metatontalitic magmatic source. The enclaves represent trapped blebs ofintermediate parental magma mixed with felsic melts during their magmatic evolution.

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AGE DATING AND GEOCHEMISTRY OF INTRUSIVE IGNEOUS ROCKS IN
BOKEO AND LUONG NAMTHA PROVINCES, LAO PDR
Santitharangkun, S.1,2, Hauzenberger, C.A.1, Gallhofer, D.1, Phajuy, B.2
1Karl-Franzens-University Graz, Universitätsplatz 2, 8010 Graz, Austria
Chiang Mai University, 239 Huay Kaew Road, 50200, Chiang Mai, Thailande-mail: srett.santitharangkun@gmail.com

2

The igneous rocks from the Bokeo and Luong Namtha provinces, northwestern Lao PDR are
important for constraining the tectonic evolution Indochina and the closure of the PaleoTethys ocean. The investigated area belongs to the Sukhothai zone which is also known as
Eastern Granitoid Belt in Thailand and is linked to the Lancangjiang zone in southwestern
China. The intrusive rocks in the study area can be separated into two main groups based ongeochemical composition: (1) gabbro to diorite group and (2) granitoid group.
(1) The gabbro-diorite group can be further divided into three subgroups: (I) gabbro dike, (II)gabbro, and (III) diorite suites. The mineral assemblage of the gabbro dike suite is plagioclase+ clinopyroxene + opaque mineral. The geochemical characteristics of the gabbro dike suite
represent a magma derived from a depleted continental lithospheric mantle with contamination from subduction components. The typical mineral assemblage of the gabbro and diorite
suites is plagioclase + clinopyroxene + hornblende ± orthopyroxene ± quartz ± biotite +opaque mineral ± apatite and represent melts derived from a subduction setting. The gabbro
pluton and diorite suite yielded a zircon U–Pb age of 232.2 ± 3.1 Ma.
(2) The granitoid group can be classified as (I) alkaline-rich granitoid (potassium feldspar
rich-granitoid suite), (II) alkaline-poor granitoid (potassium feldspar poor granitoid suite), and(III) cordierite bearing granitoid suite. The alkaline-rich granitoid sample from Bokeo andLuong Namtha provinces yields a zircon U–Pb age of 231.0 ± 3.1 Ma. The samples contained
the mineral assemblage quartz + plagioclase + K-feldspar + biotite ± opaque mineral ± apatite± zircon ± allanite. Most of the alkaline-rich granitoid samples display a well developed negative Eu anomaly which indicates plagioclase crystal fractionation. The primitive mantle normalized diagram proved Nb and Ta negative anomalies. The gabbro and diorite suites represent melts derived from a subduction setting. The alkaline-poor granitoid suite yielded a zircon U–Pb age of 250.8 ± 3.4 Ma, implying that these rocks were generated in a magmatic arc
system during the Early Triassic. The alkaline-poor granitoid suite does not display a negative
Eu anomaly suggesting no plagioclase crystal fractionation. The cordierite bearing granitoid
suite yielded a zircon U–Pb age of 244.4 ± 3.2 Ma. The cordierite bearing granitoid suite displays a narrow range in CaO/Na2O and a high LaN/YbN ratio.
The petrological, geochemical, and geochronological results of this study suggest that thealkaline-poor and cordierite bearing granitoid suite rocks from Bokeo and Luong Namtha
provinces represent mainly a volcanic arc setting during the Early Triassic. The gabbro, diorite, and alkaline-rich granitoid suites may be related to a post-collision event following theclosure of the Paleo-Tethys during Late Triassic.

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H2O-FLUXED MELTING OF ECLOGITE DURING EXHUMATION: AN EXAMPLEFROM THE ECLOGITE TYPE-LOCALITY, EASTERN ALPS (AUSTRIA)
Schorn, S.1, Hartnady, M.I.H.2, Diener, J.F.A.3, Clark, C.2, Harris, C.3
NAWI Graz Geocenter, University of Graz, Universitätsplatz 2, 8010 Graz, Austria
2
School of Earth and Planetary Sciences, Curtin University, Perth, WA, Australia
3
Department of Geological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
e-mail: simon.schorn@uni-graz.at
1

Epidote eclogites embedded in paragneisses from the Austrian Eastern Alps host rare,
decimetre- to metre-sized planar pegmatitic segregations (`pegmatoids') that consist of ahornblende–plagioclase–epidote–titanite–quartz assemblage. The pegmatoids cut the primaryeclogite foliation at a high angle, show abrupt terminations and exhibit numerous microtexturesindicating the former presence of melt, whereas the surrounding eclogites and paragneisses lackevidence for dehydration melting. We interpret the pegmatoids as crystallised hydrous melts ofintermediate composition derived from a nearby eclogitic source, similar to the eclogite hostrock. The host eclogite preserves high-pressure assemblages of garnet–omphacite–epidote–quartz–rutile ± phengite that yield peak P–T estimates of 21 ± 2 kbar and 700 ± 20 °C calculated
via pseudosection modelling and Zr-in-rutile thermometry. Subsequent near-isothermal
decompression occurred in a closed system under fluid-absent conditions that favoured thepreservation of garnet–omphacite assemblages in eclogites. Thermodynamic modelling of themetapelitic country rock indicates that the paragneisses remained fluid-absent during early
exhumation, but became fluid-saturated at mid-crustal conditions of 7.5–9 kbar and 680–
690 °C. We suggest that, as the metapelites dehydrated, minor aqueous fluid was released andinfiltrated the enclosed eclogites along discordant fractures that formed in response tounloading, further facilitated by steep gradients in µH2O between the fluid-saturated pelitic
country rock and fluid-absent eclogite lenses. Eclogite distal from fluid sources/pathways
experienced limited retrogression, whereas localised re-equilibration and H2O-fluxed melting
is inferred for eclogite affected by extensive fluid infiltration. Zr-in-titanite thermometry on
crystals from pegmatoids yields a crystallisation temperature of 697 ± 10 °C at 8.5 ± 1.5 kbar,
similar to retrograde conditions recorded by the regionally dominant metapelites. Oxygen- andhydrogen isotopic data for eclogite, pegmatoids and paragneiss are consistent with hydrous
fluid transfer from paragneisses to eclogites and a low fluid/rock ratio. We suggest that, atconditions that preclude dehydration-melting, even small-scale melting of eclogite requires
addition of fluid from a suitable near-field source.

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AUTOMATED IDENTIFICATION AND EVALUATION OF MINERALS BY
SEM-EDS: MAPS MINERALOGY – THE SIMPLE TOOL FOR COMPLEX ROCKS
Schwarzmüller, S.1, Phifer, D.1, Goergen, E.1
Thermo Fisher Scientific, Zwaanstraat 31G/H, Building TR, 5651 CA Eindhoven, The Netherlands
e-mail: stefan.schwarzmueller@thermofisher.com

1

Automated mineralogy with SEM-EDS has a long-standing history within Thermo Fisher
Scientific (legacy FEI). QEMSCAN and the Mineral Liberation Analyzer (MLA) have beenused for decades in commercial and scientific applications like mineral exploration andprocessing, petrology, environmental sciences, archaeology and so on (REID et al., 1984;
GOTTLIEB et al., 2000). MAPS MINERALOGY builds on this knowledge in automatedmineralogy by providing a higher degree of automation and less manual work to QC the results:
Decoupling the backscattered image from EDS enables a submicron SEM image resolution andguarantees preservation of textural details even at coarse EDS resolution. In case several
minerals are present within the interaction volume (Figure 1), the “Mixel” technology permits
accurate multi-phase mineral ID as well as the quantitative proportions of those phases. The“Mixel” thereby allows deployment of automated mineralogy even on fine-grained orcomplicated mineral textures and at grain boundaries - areas where other technologies fail toprovide accurate results. Minerals are assigned from a database with greater than 4000 entries
on an improved classification approach to any rock type with no need for a priori knowledge.
Users can even modify and create their own solid solutions based on the full database of theend members’ chemistry. The mineral coloring scheme in Maps Mineralogy is dynamic andrepresentative of chemical variance within a mineral. Figure 1 displays a mineral map where
the blue phase is dolomite. Variance in the blue shades reflect the amount of Fe distributed in
the phase. This makes quick inspection of relative chemical zoning fast and aids targeting
additional chemical analysis in other systems (e.g. EPMA). Finally, Maps mineralogy also
provides accurate Bulk compositional data that is equivalent to XRF data.
Figure 1. Left: Interaction volume from a
mixture of dolomite,smectite and quartz as
well as mixed and unmixed (individual contributions) EDS spectra.
Right: Point of dataacquisition (orange) andassignment of colors
and opacity according
to database and predefined solid solutions.

REID, A.F., GOTTLIEB, P., MACDONALD, K.J., MILLER, P.R. (1984): In PARK, W.C., HAUSEN, D.M.,
HAGNI, R.D. (eds): Appl. Miner. (Warrendale, PA: TMS), 191-204.
GOTTLIEB, P., WILKIE, G., SUTHERLAND, D., HO-TUN, E., SUTHERS, S., PERERA, K., JENKINS, B.,
SPENCER, S., BUTCHER, A., RAYNER J. (2000): JOM, 52, 24-25.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

MANTLE ROCKS IN CONTINENTAL COLLISIONAL OROGENS
Sizova, E.1, Hauzenberger, C.1, Gerya, T.2,3, Fritz, H.1, Faryad, S.W.4
Institute of Earth Sciences, University of Graz, Universitätsplaz 2/2.Stock, 8010 Graz, Austria
2Institute of Geophysics, ETH-Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland
3
Geology Department, Moscow State University, 119199 Moscow, Russia
4
Institute of Petrology and Structural Geology, Charles University, Albertov 6, 12843 Prague 2, Czech Republic
e-mail: elena.sizova@uni-graz.at
1

During the last decades the rising interest for ultrahigh-pressure crustal rocks in the collisional
orogens has led the geologists to the detailed investigation of the associated ultramafic rocks,
which could be valuable for the reconstruction of the tectonothermal conditions duringcontinental collision. The most intriguing of these rocks are garnet peridotites which arecommon in the continental collision orogens. Garnet peridotites are typically polymetamorphic
rocks appearing as relics (meters to kilometres bodies) within lower-grade ultramafic host rocks(gneisses or granulites) and have concordant to discordant contacts with those (MEDARIS,
1999). The garnet peridotites vary dramatically even within the individual tectonic orogens andpropose distinct metamorphic evolution based on their P–T–t paths. The main two groups ofthese rocks are crustal and mantle peridotites, where the first group represents ultramafic blocks
emplaced into the crust prior to subduction event. Based on a series of 2D petrological–
thermomechanical numerical experiments we investigated the fate of mantle peridotites
incorporated into the subducted continental crust at different continental collision scenarios.
We reconstructed the evolution of both crustal and mantle peridotites involved into collision.
In the final collisional orogens in the experiments we determined 18 distinct groups of theperidotites based on their P–T–t paths: 12 groups of peridotites from the overriding plate
lithospheric mantle and the asthenospheric mantle below, 3 groups of peridotites from thecrustal ultramafic blocks (initially emplaced into the later subducting continental crust), and 3groups among the peridotites from the lithospheric mantle of the subducting plate. The
associated crustal material does not necessarily show the same metamorphic evolution showing
higher or lower peak metamorphic conditions, meeting with the peridotite markers in most cases
during exhumation stage. The determined P–T–t paths for the peridotites cover most of themetamorphic conditions proposed for the natural peridotites from the continental collisional
orogens all over the world including those coming from the extreme large depths from the
mantle.
MEDARIS, L.G. (1999): Internat. Geol. Rev., 41, 799-815.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

RAMAN SPECTROSCOPIC STUDY OF CARBONACEOUS MATERIAL
AFFECTED BY CONTACT AND REGIONAL METAMORPHIC EVENTS(RYOKE BELT, SW JAPAN)
Skrzypek, E.1,2
Department of Geology and Mineralogy, Graduate School of Science, Kyoto University,
Kitashirakawa-Oiwakecho, Sakyo-ku, 606-8502 Kyoto, Japan
2
Institute of Earth Sciences, NAWI Graz Geozentrum, Petrology and Geochemistry, University of Graz,
Universitätsplatz 2, 8010 Graz, Austria
e-mail: etienne.skrzypek@uni-graz.at
1

The first- and second-order Raman spectra of carbonaceous material (CM) are explored inmetamorphic rocks affected by successive contact and regional metamorphic events (W partof the Ryoke belt, Iwakuni-Yanai area, SW Japan). The area exposes metasedimentary rocks
that underwent contact metamorphism before and after the main regional tectonometamorphic event (DP1). First-order spectra document a decreasing peak area ratio R2 andan increasing temperature TCM towards the south and the surrounding granitoids. Domains
with intermediate (535–600 °C) TCM values match the extent of the pre-DP1 contact aureole
but also image a so far unrecognized post-DP1 aureole. The axial part of the belt, likely
unaffected by granite intrusions, preserves southward increasing TCM from 425 to 660 °C,
which is compatible with the regional low-Pressure/high-Temperature gradient described in
the area. Second-order spectra show a single S1 band that splits into two peaks (S1- and S1+)
whose frequency difference ΔS1 increases stepwise towards the south. The spatial distributionof ΔS1 follows that of the E–W trending regional metamorphic zones.
The splitting of S1 indicates a transition from two-dimensional to three-dimensional CM andoccurs at ~500 °C, which seems to be common to all metamorphic belts worldwide. Despite
regional metamorphism, CM was also able to record the post-DP1 contact overprint. A
discrepancy between first- and second-order Raman parameters suggests that they partly
record the influence of different factors; R2 gives an account of thermal events, particularly
those related to localized contact metamorphism, whereas ΔS1 potentially yields information
on regional variations in heating duration and pressure. This demonstrates the potential of thefull Raman spectrum of CM for deciphering the complex thermal history of orogenic systems.

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THE ROLE OF ADDITIVES AND HUMIDITY ON THE TRANSFORMATION OF
AMORPHOUS CALCIUM CARBONATE –MINERALOGICAL AND MICROSTRUCTURAL EVOLUTION
Spirk, T.C.1, Goetschl, K.E.1, Dietzel, M.1
Institute of Applied Geosciences, Graz University of Technology, Rechbauerstraße 12, 8010 Graz, Austria
e-mail: tina.spirk@student.tugraz.at

1

Amorphous calcium carbonate (ACC) is one of the seven CaCO3∙nH2O (0 ≤ n ≤ 6) solids anddue to its high solubility, high specific surface area and porosity of vast interest for thedevelopment of advanced materials. The mechanisms and individual pathways of
microstructural porosity development during ACC transformation exposed to different
humidity-levels have not been sufficiently understood yet.
Therefore, the transformation of four ACC-types, either pure or synthesized with the additionof activated carbon, magnesium chloride or xanthan, was investigated at two distinct humidity
levels. The pure and additive containing ACC standard material was stamped into a pellet andexposed to 45 % and 74 % relative humidity (RH) over a period of 28 days.
The addition of xanthan induced a reduction of the vaterite content, activated carbon resulted
in an extreme low vaterite content and the presence of Mg2+ ions completely inhibited theformation of vaterite. Furthermore, this study highlights that elevated RH favours initial vaterite
formation and causes an increase of the mean pore size of the final crystalline product by afactor up to 6.
The findings on porosity evolution during the transformation of ACC can be used to tailor andimprove ACC and highly porous CaCO3 (micro-nano) material designs and syntheses forpharmaceutical and industrial applications.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

EFFECT OF SUCROSE AND SEED CRYSTALS ON
THAUMASITE AND ETTRINGITE (co)-PRECIPITATION
Steindl, F. R.1,2, Baldermann, A.1, Galan, I.1, Mittermayr, F.2, Letofsky-Papst I.3, Dietzel, M.1
Institute of Applied Geosciences, Graz University of Technology, Rechbauerstraße 12, 8010 Graz, Austria
2Institute of Technology and Testing of Building Materials, Graz University of Technology,
Inffeldgasse 24, 8010 Graz, Austria
3Institute of Electron Microscopy and Nanoanalysis and Center for Electron Microscopy,Graz University of Technology, NAWI Graz, Steyrergasse 17, 8010 Graz, Austria
e-mail: florian.steindl@tugraz.at

1

A particular form of sulfate attack on concrete is the formation of thaumasite, which can cause
the destruction of the cement matrix. The influence of ettringite seed crystals on thaumasite
formation and the effect of sucrose on the incorporation of Si and carbonate into ettringite were
investigated in precipitation experiments using a synthesis protocol adapted from BLANCOVARELA et al. (2012). The precipitation reactions were monitored regarding the chemicalcomposition, pH, and electrical conductivity of the solutions. The precipitates were examinedby infrared spectroscopy, powder X-ray diffraction, and scanning and transmission electron
microscopy. The results provide indications for the incorporation of Si and/or carbonate into
the ettringite structure during precipitation (Fig. 1). Furthermore, the presence of ettringite seed
crystals strongly enhanced thaumasite formation, with seeded experiments yielding significant
amounts of precipitate within only 7 days, whereas control experiments without seeds yielded
no precipitate within 56 days. The presence of sucrose did not only influence the incorporationof Si and/or carbonate into ettringite, but strongly controlled the crystal morphology of
ettringite, causing a shift from acicular crystals to watermelon-shaped balls (Fig. 2). The results
provide interesting implications for the formation paths and environmental controls ofthaumasite and/or ettringite-thaumasite solid solutions in cementitious materials.
0.000

initial CO32-/SO42-

0.010

0.020

0.030

0.040

0.050

11.23
21.48
parameter ano sucrosewith sucrose
parameter cno sucrosewith sucrose

a (Å)

11.22

11.21

with sucrose

21.46

c (Å)

no sucrose

21.44
21.42

0.00

0.05

0.10

initial Si/Al

0.15

21.40

Figure 1. Change of ettringite lattice parameters withincreasing Si(OH)4 and CO32- concentrations in theinitial solution.

Figure 2. Precipitate of ettringite synthesis after 14days of reaction, showing “watermelon ettringite”.

BLANCO-VARELA, M.T., CARMONA-QUIROGA, P.M., SÁEZ DEL BOSQUE, I.F., MARTÍNEZRAMÍREZ, S. (2012): Cem. Concr. Res., 42, 994-1000.

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AN UPDATE ON SECONDARY THALLIUM MINERALS
Steinfeld, A.1, Đorđević, T.1, Kolitsch, U.2,1, Nagl, P.3, Tasev, G.4, Serafimovski, T.4,
Boev, I.4, Boev, B.4
1
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum, Burgring 7, 1010 Wien, Austria
3
Department of Lithospheric Research, Universität Wien, Althanstraße 14, 1090 Wien, Austria
4
Department of Mineral Deposits, University “Goce Delčev”-Štip, Goce Delčev 89, 2000 Štip, North Macedonia
e-mail: tamara.djordjevic@univie.ac.at
2

In order to gain more knowledge on the environmental behaviour of thallium in As- and Tlextreme environments, we have chosen the abandoned As–Sb–Tl–Au Allchar deposit (North
Macedonia) with unique mineral composition and high thallium grades of the ore. We used Xray fluorescence analysis (XRFA), powder X-ray diffraction (PXRD), scanning electron
microscopy with energy-dispersive spectroscopy (SEM-EDS) and Raman spectroscopy todetermine the retention of thallium in secondary minerals of the especially Tl-rich Crven Dollocality in the northern section of the Allchar deposit.
XRFA showed that the mean concentrations of Tl and As in soils adjacent to dumps are 3 g/kg
and 59 g/kg, respectively, but can locally, in realgar-rich dumps, rise to extreme values of 11
g/kg for Tl and 166 g/kg for As.
PXRD studies showed that the various solid waste samples are comprised mostly of carbonates(dolomite and calcite), gypsum, quartz, muscovite, kaolinite-group minerals followed byorpiment, realgar, pyrite, marcasite, lorándite (TlAsS2), and various iron and calcium arsenates.
Using SEM-EDS and Raman spectroscopy on polished sections, we took a closer look at thesecondary minerals formed in the carbonate-buffered environments (pH = 7-8). Besides
common arseniosiderite, Ca2Fe33+(AsO4)3O2·3H2O, talmessite, Ca2Mg(AsO4)2·2H2O, minor
thalliumpharmacosiderite, TlFe4[(AsO4)3(OH)4]·4H2O, Tl3+-bearing scorodite (up to 1.7 at.%),Fe3+AsO4·2H2O, and rare Ca-Mn arsenates, we proved the existence of small (up 100 µm)
aggregates of at least five previously unknown secondary thallium phases at the present stageof our studies:
1) Tl–M2+–arsenates with approximate Tl:M:As ratios of (i) ~3:1:1 (Mg- or Ca-dominant with
Mg  Ca); (ii) 2:1:1 (mainly Mg- oder Mn-dominant); (iii) 1:1:1 (mainly Ca- or Mg-dominant,with major, but variable Fe); (iv) 1:3:2 (strongly Mn-dominant, with apparent Si(?) content).
All these arsenates show slightly to distinctly variable ratios of the M2+ cations within individual
aggregates.
2) Cryptomelane-type Tl-bearing Mn oxides (3.1 to 3.8 at.% Tl), probably closely related tothalliomelane, Tl(Mn4+7.5Cu2+0.5)O16.
This study provides further evidence of thallium uptake by newly found thallium secondary
phases in carbonate-buffered, near-neutral As- and Tl-rich environments and indicates the needfor further studies on Tl speciation in As- and Tl-extreme environments.
This work was supported by the Austrian Science Fund (FWF) [grant number P 30900-N28 to T. Đorđević].

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GEOCHRONOLOGIE, GEOCHEMIE UND PETROLOGIE EINES TOPASFÜHRENDEN ORTHOGNEISES INNERHALB DER „MONOTONENSERIE“ (OSTRONG EINHEIT, NÖ)
Stockinger, V.1, Göd, R.1, Grasemann, B.1, Linner, M.2, Klötzli, U.1, Abart, R.1, Slama, J.3
Universität Wien, Althanstraße 14, 1090 Wien, Österreich
Geologische Bundesanstalt, Neulinggasse 38, 1030 Wien, Österreich
3
Institute of Geology of the Czech Academy of Sciences,
Rozvojová 269, 165 00 Prag 6-Lysolaje, Tschechische Republik
e-mail: verena.stockinger@univie.ac.at1

2

In den 80er-Jahren wurden weite Teile des österreichischen Anteiles an der Böhmischen
Masse in Hinblick auf das Auftreten von Rohstoffen prospektiert (GÖD, 1988), wobei eine
spurenhafte Topas-Führung in Gerinnen, die den Ostabhang des Ostrongs entwässern,
entdeckt wurde. Die in der gegenständlichen Arbeit untersuchten Orthogneise der Monotonen
Serie (Ostrong Einheit, Niederösterreich) wurden als die Quelle dieser Topase nachgewiesen,
indem mittels RAMAN-Spektroskopie Topase aus Schwermineralkonzentraten aus den
Orthogneisen bestimmt werden konnten. Nach derzeitigem Wissensstand ist dies das einzige
Vorkommen Topas-führender Orthogneise innerhalb des gesamten Moldanubikums.
Detaillierte geochemische Untersuchungen der Haupt- und Spurenelemente dieser Gesteine
mittels RFA, ICP-MS und Ionenchromatographie ergaben eine Einstufung als Meta-graniteoder-rhyolithe mit einem hohen Differenzierungsgrad. Sie besitzen einen hohen SiO2-Gehalt
von 72,8 - 77,3 Gew.%, außerdem ist ein hoher Fluor-Gehalt von bis zu 2760 ppm indikativ
und zudem besitzen sie einheitlich einen peraluminösen Charakter. Insgesamt zeigen sichgeochemische Ähnlichkeiten einerseits zum Blanik-Gneis (Ostrong Einheit) und andererseits
zum Gföhl-Gneis. Die untersuchten Gesteine weisen eine tektonische Überprägung auf undzeigen eine schwache bis gut ausgeprägte Foliation, sowie stellenweise Verfaltungen. Proben,
die in der Nähe der tektonischen Grenze der Ostrong zur Drosendorf Einheit genommen
wurden, zeigen eine stärkere scherende Deformation mit ausgeprägter mylonitischer Foliationund Streckungslineation. Das Gestein führt durchgehend Sillimanit und jene Proben nahedieser tektonischen Grenze auch Disthen. Untersuchungen der Mineralchemie mittels
Elektronenstrahlmikrosonde zeigen zonierte Plagioklase mit einer Albit-Komponente vonetwa 87 – 99 Mol%, die gegen den Korn-Rand zunimmt. In den Proben nahe der tektonischen
Grenze der Ostrong zur Drosendorf Einheit tritt Almandin-dominierter Granat auf, der keine
Zonierung zeigt und als einphasig charakterisierbar ist. Um das bisher noch unbekannte Alterder untersuchten Orthogneise zu bestimmen, wurde die U-Pb Datierungsmethode an Zirkonen
angewandt und dadurch das erste absolute minimale Alter der „Monotonen Serie“ bestimmt.
Die Methodik ergab die Alter von 475,3 ± 0,5 Ma, 474,8 ± 1,3 Ma und 473,5 ± 0,8 Ma. Der
kurzprismatische Habitus der untersuchten Zirkone deutet darüber hinaus auf eine plutonische
und nicht vulkanische Herkunft der Orthogneise hin. Die in dieser Arbeit erzielten Ergebnisse
können zum Verständnis der paläogeographischen Position, des tektonischen Aufbaues undder Entwickelung des Moldanubikums beitragen.
GÖD, R. (1988): Zusammenfassende Übersicht über ausgeführte Erzprospektionsvorhaben, dabei eingesetzte
Methoden sowie Hoffnungsgebiete im Kristallin der Böhmischen Masse; unveröffentl. Bericht, GBA
Projektcode N-C-006a/87.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

AGE DATING OF DETRITAL ZIRCON AND PETROLOGY OF THE
ENNSTAL PHYLLITE ZONE (EASTERN ALPS)
Stumpf, S.1, Skrzypek, E.1, Stüwe, K.1
University of Graz, Universitätsplatz 2, 8010 Graz, Austria
e-mail: sebastian.stumpf@edu.uni-graz.at

1

The Ennstal Phyllite Zone is a west-east striking zone paralleling the Enns valley east of
Schladming in the Eastern Alps. The affiliation of this area to either the micaschist units of
the Koralpe-Wölz nappe system to its south or to the Greywacke Zone to its north is still
unclear. In fact, due to the similarities with the phyllites of the Greywacke Zone to the northand the low-grade micaschists in the south, no clear boundary between these units isobservable. In order to clear this debate, we present the first U/Pb age dating results and PTcalculations for the Ennstal Phyllite Zone. Samples were taken along multiple north – south
striking valleys which transect the Ennstal Phyllite Zone and the northernmost part of the
Wölz-Complex. All the samples consist of low-grade metapelite. Detrital zircon grains from
pelitic (EA09) and psammitic (SP02) samples in the Ennstal Phyllite Zone were analyzed bylaser ablation-inductively coupled plasma- mass spectrometry. In both samples the youngest
zircon population yielded dates around 625 Ma, with smaller peaks at ~1000, 2000, 2200 and
between 2500 Ma and 2950 Ma. Raman thermometry on carbonaceous material andthermodynamic modelling for garnet-bearing samples in the Ennstal Phyllite Zone and WölzComplex do not show any significant difference in peak metamorphic temperature. Bygathering the first age and PT data for this area, the correlation of the Ennstal Phyllite Zone
with either the Wölz-Complex or the Greywacke Zone can be discussed.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

CURVED GROWTH OF CLINOPYROXENE DENDRITESIN A BASALTIC ROCK-PSEUDOFULGURITE
Sutter, C.1, Habler, G.1, Abart, R.1, Griffiths, T.1, Ferrière, L.2
1

Department of Lithospheric Research, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
2
Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria
e-mail: christoph.sutter@univie.ac.at

Fulgurites are tubular structures generated from rock or soil by lightning strike. They arecomprised of vesicular glass and relic as well as newly formed crystals. Pseudofulgurites are
similar structures produced by anthropogenic electrical discharge events. During such events,
energies of up to 30 MJ are transferred in a fraction of a second, and peak temperatures of
105 K are attained at heating rates of several thousand K per second (PASEK & PASEK,2018). Typically, the target material melts and partially evaporates during such flash heating.
Subsequently, the material cools very rapidly leading to solidification as glass and to
crystallization under extreme undercooling. This results in mineral growth at conditions far
from equilibrium, which may lead to peculiar phenomena such as dendritic and curved crystal
growth. We studied a pseudofulgurite (24 x 15 x 5 mm³) from Maharashtra, India, which wasformed in a Deccan Trapp basalt as a result of an anthropogenic high-voltage discharge. The
pseudofulgurite has a homogeneous glass matrix of basaltic composition with relics ofplagioclase and quartz (partially converted into cristobalite), as well as newly grownclinopyroxene (CPx) with dendritic morphology. Both straight and curved CPx dendrites
grew on plagioclase needles, which in turn grew epitaxially on plagioclase relics. The
dendrites feature several hierarchical levels of branches and side branches. The main branches
grow in the CPx [100] or CPx [001] direction and the first level side branches extend in (001).
In the curved dendrites the CPx crystal lattice rotates about [010], while the [100] or [001]growth direction of the main branch is maintained. The lattice rotation is clockwise, whenlooking down the positive b axis. The twisted dendrite has a length up to 100 µm, the rotationis >180° with a radius of 20 µm. This corresponds to an average rotation of almost 2° per µm.
Similarly curved growth of CPx dendrites was observed experimentally (HAMMER et al.,2010) and in more recent hitherto unpublished crystallization experiments. We hypothesizethat the curved growth is related to the peculiar situation encountered during far fromequilibrium crystal growth in a melt. Thereby the morphology of a growing crystal isdetermined by (i) diffusive heat and mass transport in the melt, which favors dendritic growth,and (ii) the tendency of the crystal to reduce interfacial energy, which suppresses dendritic
morphology. The general tendency of dendrites to propagate towards the most pronounced
compositional and thermal gradients would lead to dendritic growth with maximum
morphological symmetry. This is, however, not compatible with the monoclinic structure of
CPx. The curved growth probably reflects the compromise between growth along
crystallographically preferred growth directions and dendrite growth with maximum
morphological symmetry.

HAMMER, J.E., SHARP, T.G., WESSEL, P. (2010): Geology, 38, 367-370.
PASEK, M.A., PASEK, V.D. (2018): Miner. Petrol., 112, 185–198.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

THE ‘LOUKASTEINE’ FROM THE MORAVIAN KARST – RADIAL CALCITECONCRETIONS FORMED IN A PLASTIC GEL-LIKE CLAY MEDIUM
Talla, D.1, Zwicker, J.1, Peckmann, J.2, Nagl, P.3, Filek, T.4, Losos, Z.5
Department of Mineralogy and Crystallography, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
2Institute for Geology, Center for Earth System Science and Sustainability, University of Hamburg,
20146 Hamburg, Germany
3
Department of Geosciences, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
4
Department of Palaeontology, University of Vienna, Althanstraße 14, 1090 Vienna, Austria
5Department of Geological Sciences, University of Brno, Kotlářská 2, 61137 Brno, Czech Republic
e-mail: dominik.talla@univie.ac.at

1

The so-called ‘Loukasteine’ are sedimentary carbonate concretions with radial internal
structure occurring in red to whitish sandy clays of the lower Cretaceous Rudice strata in theMoravian karst, Czech Republic. The concretions exhibit disc-shaped morphologies, centred
within and aligned parallel to pale sandier strata, with concretion ‘caps’ reaching into
surrounding red kaoline clay; the latter apparently having acted as hydraulic seals (cf. SELLÉZMARTÍNEZ, 1996). As commonly observed for carbonate concretions, the host sediment,
consisting of quartz, kaolinite and muscovite, is cemented by the calcite matrix of theconcretions. Most concretions reveal a core without radial structure and well-preserved beddingof the host sediment, indicating pervasive growth due to lower supersaturation of pore fluids
during the initial stages of concretion formation. The radial overgrowth, disrupting the original
bedding of the host sediment, supposably reflects an increase in carbonate supersaturation andcrystallization pressure, forcing the parent sediment outwards, analogous to the formation
conditions of similar concretions at Kettle Point, Canada (WINDER, 1974). Here, the increaseof fluid supersaturation even led to the development of calcite crystals on the surface of someconcretions. An increase in fluid supersaturation with respect to calcite is also suggested by thesystematic increase in carbonate content from the core to the rim of the concretions (45 - 85
wt.%, respectively).
Growth experiments in agar gels of varying strength using CaCl2 and Na2CO3 asreagents led to the successful reproduction of radial calcite sphaerolites. Sphaerolites formed
both during the initial stages of the reaction and at the end of the experiments, whensupersaturation was low enough, with calcite crystals precipitating at high supersaturation.
It is a rare case to find carbonate concretions in such a soft host rock. This circumstanceenabled a detailed study of external concretion topologies, even preserving fine striations due
to slight variation in stiffness of the surrounding plastic material. The ‘Loukasteine’ represent
a mineralogical peculiarity in the Moravian karst. Carbon and oxygen stable isotope analyses
are currently underway to elucidate their potential biogenic origin.
SELLÉS-MARTÍNEZ, J. (1996): Earth-Sci. Rev., 41, 177-210.
WINDER, C.G. (1974): University of Western Ontario Faculty of Science Bulletin, 2, 13.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

GEOTHERMOBAROMETRIE DER VARISZISCHEN EKLOGITEAUS DEM ÖTZTALKOMPLEX
Tropper, P.1, Hackhofer, E.1
1

Institut für Mineralogie und Petrographie, Universität Innsbruck, Innrain 52, 6020 Innsbruck, Österreiche-mail: peter.tropper@uibk.ac.at

Diese Untersuchung beschäftigt sich mit der Geothermobarometrie, sowie mit dermineralchemischen Charakterisierung von variszischen Eklogiten im Ötztal-Stubai-Kristallin,
aus den Lokalitäten Flauerlinger Alm bei Flauerling in der Nähe von Telfs, Längenfeld imÖtztal und Verpeiltal östlich von Feichten im Kaunertal. Die geothermobarometrischen
Untersuchungen wurden mittels Granat-Klinopyroxen-Geothermometrie und Thermocalc
v.3.21 Average P-T Methode durchgeführt.
Die Eklogite an der Flauerlinger Alm sind durch die Paragenese von Granat + Omphazit +Amphibol + Quarz + Rutil + Klinozoisit + Symplektit charakterisiert. Dabei repräsentieren die
Symplektite die retrograden Umwandlungen von Omphazit zu Albit, Diopsid und Amphibol.
Die Eklogite aus Längenfeld sind charakterisiert durch die Paragenese von Granat + Omphazit+ Amphibol + Quarz + Klinozoisit + Kyanit + Symplektit. Die Eklogite aus Verpeil sindcharakterisiert durch die Paragenese Granat + Omphazit + Amphibol + Rutil + Quarz +Klinozoisit + Symplektit. Auch hier erkennt man wieder, dass die Omphazite und auch die
Amphibole als Einschlüsse in großen Granatkörnern vorkommen. Die Matrix ist bei diesen
Eklogiten völlig symplektitisiert, mit einzeln vorkommenden Omphaziten.
Im Durchschnitt haben die Granate eine Zusammensetzung von etwa 50 % Almandin, 25%
Pyrop und 25 % Grossular, die Omphazite bestehen zu etwa gleichen Teilen aus Jadeit undDiopsid-Hedenbergit, mit einer z.T relativ hohen Ägirin-Komponente (Flauerlinger Alm). Bei
den Amphiboleinschlüssen in Granat handelt es sich um Taramite, Katophorite, Pargasite (bzw.
Ferro-Pargasite) und Sadanagaite. Die retrograd gebildeten Amphibole sind ausschließlich
Pargasite. Die Ergebnisse der Granat-Klinopyroxen-Geothermometrie ergaben Werte von 654± 37 °C, 597 ± 47 °C und 642 ± 62 °C, jeweils für Flauerling, Verpeil und Längenfeld. Unter
der Annahme dass a(H2O) = 1 ergaben sich für die Average P-T Berechnungen mittlere P-T
Bedingungen von 639 ± 32 °C, 21.3 ± 1.9 kbar für Flauerling, 638 ± 28 °C, 23.2 ± 1.6 kbar für
Längenfeld und 665 ± 24 °C, 19.3 ± 1.3 kbar für Verpeil. Da die P-a(H2O) Berechnungenergaben dass a(H2O) signifikant von 1 abweicht, stellen diese P-T Bedingungen ein oberes
Limit dar.
Betrachtet man die mineralchemischen Daten und die P-T Ergebnisse so kann man vermuten
dass die Längenfelder Eklogite im Vergleich zu den Eklogiten von Verpeil tiefere
Krustenanteile darstellen. Die Eklogite der Flauerlinger Alm liegen hingegen isoliert vor, wobei
keine näheren tektonischen Beziehungen zu den beiden anderen Eklogitvorkommen hergestellt
werden können. Allenfalls könnten sie auch im Zuge der eoalpinen Orogenese nach Nordentransportiert worden sein.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

LOOKING INSIDE EARLY BRONZE AGE SMELTING REMAINS
USING MICRO-COMPUTERTOMOGRAPHY
Tropper, P.1, Kronenberg, L.1, Piccolruaz, M.1, Degenhart, G.2, Angerer, T. 1, Keil, J.3
Institut für Mineralogie und Petrographie, Universität Innsbruck, Innrain 52, 6020 Innsbruck, Österreich
Department Radiologie, Medizinische Universität Innsbruck, Anichstraße 35, 6020 Innsbruck, Österreich
3
Institut für Archäologie, Universität Innsbruck, Langer Weg 11, 6020 Innsbruck, Österreiche-mail: peter.tropper@uibk.ac.at12This project deals with the mineralogical and micro-computertomographic (µ-CT) investigationof Early Bronze Age metallurgical remains (slag-tempered ceramics, slag-adherent crucible
fragment) from the Buchberg site near Wiesing in the Lower Inn Valley. This archaeologicalsite represents one of the earliest Cu-smelting sites in the Tyrol. The samples were investigatedusing thin-section microscopy, micro-X-ray fluorescence (XRF) as well as electron-probe
microanalysis (EPMA) and two fragments were also investigated using µ-CT-analyses.
Surprisingly the mineralogical results of the slag-tempered ceramic fragments yield two
different sorts of copper such as Cu-Sb-As and Cu-Fe. Also, cassiterite was discovered in a slag
temper fragment – until now the use of cassiterite was thought to have begun later as well.
In the crucible sample three different areas were observed based on mineralogical and chemical
data: The first area (A) is unmelted and consists mainly of clay minerals and different tempering
components. The second area (B) was melted and thus consists of a glass matrix and again
temper components. The third area (C) represents the slag crust and consists mainly of highdensity metals, clinopyroxenes and a glass matrix. XRF reveals an increase in Cu, As, P, andSb and a decrease in Si from area A (core of the crucible fragment) to area C (slagged rim of
the fragment).
The investigations using µ-CT allow the 3-D spatial distribution of high-density particles in theslag temper of the ceramic (Cu-Sb-As- and Cu-Fe-droplets) and crucible (Fe-Sb-Cu-Zn-O
phases) fragments. Based upon these data it was possible to calculate the metal and the porecontent of the slag crust. These data can then be used for further calculations regarding theefficiency of the Cu-smelting process.
Finally, the results clearly show that the Early Bronze Age ceramics were slag tempered andthe slag fragments show that ore minerals used for copper smelting were mostly fahlore-groupminerals. The occurrence of cassiterite in one of these Early Bronze Age slag fragments is still
puzzling. Moreover, the results show that different additives were used in the Cu-smelting
process such as slags, dolomite, quartz, and possibly bone material.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

RUTILE PETROCHRONOLOGY AND GEOTHERMOBAROMETRY OF
EO-ARCHAEAN METASEDIMENTS FROMNORTHERN QUEBEC (NUVVUAGITTUQ AND UKALIQ SUPRACRUSTAL BELTS)

Tropper, P.1, Mojzsis, S.J.2, Schmitt, A.K.3
Institute of Mineralogy and Petrography, University of Innsbruck, Innrain 52, 6020 Innsbruck, Austria
Department of Geological Sciences, University of Colorado, UCB 399, Boulder, CO 80309-0399, USA
3
Institute of Geosciences, Heidelberg University, Im Neuenheimer Feld 236, 69120 Heidelberg, Germany
e-mail: peter.tropper@uibk.ac.at
1

2

The world’s oldest rocks of demonstrable volcano-sedimentary origin comprise the Archean“supracrustal belts”, in which they occur as variably deformed enclaves within ancient
metamorphosed granite-granitoid gneiss terranes. The Inukjuak Domain in northern Québec ispart of the Archean Minto Block in the northwestern Superior Province of Canada. Eoarchean(ca. 3800-3780 Ma) rocks of the Nuvvuagittuq supracrustal belt (NSB) and the Ukaliq
supracrustal belt (USB) are the best known of numerous supracrustal enclaves within thisdomain. An Eoarchean metamorphic episode has been deduced from zircon depth-profiles,
recorded at 3.62 Ga. A Neoarchean event was discerned based on dating of metamorphic zircon,
garnet rutile and monazite and yielded 207Pb/206Pb and Sm/Nd ages ranging from 2.8 Ga to 2.5
Ga. The aim of this study was to provide geothermobarometric constraint on this Neoarchean
metamorphic event in the NSB and USB by applying multi-equilibrium geothermobarometry(average PT approach), pseudosection modelling (DOMINO-Theriak) and Zr-in-rutile
geothermometry. Two samples are quartz-biotite schists with the mineral assemblage garnet +biotite + muscovite + rutile + quartz ± plagioclase ± staurolite ± kyanite. All samples show
extensive retrogression under greenschist-facies metamorphic conditions. The average PT
calculations (H2O-free calculations only) yielded P-T conditions of 590 ± 95 °C and 0.5 ± 0.1
GPa and 610 ± 70 °C and 0.56 ± 0.2 GPa. Pseudosection modelling yielded similar P-T
conditions based on the occurrence of garnet + cordierite + biotite. Zr-in-rutile geothermometry
yielded 600 ± 30 °C.
From the USB, only one sample, a quartzite interpreted as a quartz-pebble metaconglomerate
could be used. The main mineral assemblage is anthophyllite + muscovite + quartz + rutile +zircon. Owing to the pervasive greenschist-facies retrogression of the sample, it was notpossible to constrain P-T conditions using phase equilibrium calculations; however, the Zr-inrutile geothermometer provides a tight constraint on T. Zr contents of rutile range from 407
ppm to 914 ppm and yielded T of 660-730 °C at an assumed pressure of 0.6 GPa. Ion
microprobe U-Pb dating of rutile from this sample yielded ages of 2500-2600 Ma, whichcorrelate well with the youngest zircon ages from this sample, consistent with the lower closure
T for Zr diffusion in rutile (<600 °C).
The rutile U-Pb ages combined with geothermobarometry show that Neoarchean
metamorphism reached upper amphibolite-facies conditions (580-670 °C) in these supracrustal
rocks in the northwestern Superior Province of Canada in accordance with previous T estimatesand U-Pb zircon ages.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

MINERALOGICAL AND GEOCHEMICAL CHARACTERIZATION OF THE
MAJOR WASTE DUMP OF THE FORMER As-Sb-Cr MINE AT
LOJANE, NORTH MACEDONIA
Uiblein, S.1, Đorđević, T.1, Kolitsch, U.2,1, Nagl, P.3, Drahota, P.4, Mihaljevič, M.4,
Tasev, G.5, Serafimovski, T.5
Institut für Mineralogie und Kristallographie, Universität Wien, Althanstraße 14, 1090 Wien, Austria
Mineralogisch-Petrographische Abteilung, Naturhistorisches Museum, Burgring 7, 1010 Wien, Austria
3
Department of Lithospheric Research, Universität Wien, Althanstraße 14, 1090 Wien, Austria
4
Faculty of Science, Charles University, Albertov 6, 128 43 Prague 2, Czech Republic
5
Department of Mineral Deposits, University “Goce Delčev”-Štip, Goce Delčev 89, 2000 Štip, North Macedonia
e-mail: stefan.uiblein@gmail.com
1

2

The As-Sb-Cr mine near Lojane, North Macedonia operated from 1923 to 1979. Despite highconcentration of toxic pollutants (As, Sb, Ni), the mine wastes were abandoned without taking
any precautions. We present results of the mineralogical and geochemical investigations of avertical profile (1.50 m) in the center of the major waste dump, located adjacent to a creek.
Along the sampled profile (six samples extracted at every 20 cm), the total chemicalcomposition (XRF analyses) is relatively constant for Cr (1771-2915 ppm) and Ni (1718-2959ppm). For As (10127-48524 ppm) and Sb (4660-12380 ppm), the variations are considerablylarger. They are mainly dependent on the amount of the major ore minerals (realgar, stibnite)in the samples. For As, Sb, and Ni, the total concentration correlates with changing samplinglevel and is lowest in the sample taken next to the surface.
The mineralogy is dominated by quartz, carbonates (dolomite, magnesite), serpentine minerals(lizardite), and layer silicates. The main primary minerals are realgar, stibnite, and Mg-rich
chromite. Minor greigite, pyrite, vaesite, violarite, and gersdorffite have also been confirmed.
The pH values of the mine waste samples are neutral (6.5-7.7) due to the carbonate bufferingthat is slowing down the weathering of the sulfides. Chemical extractions in 1 M HCl showedthat 20-90 % of As, 10-30 % of Sb, 40-60 % of Ni, and <5 % of Cr was recovered fromsecondary mineral phases. Mobile fractions were significantly lower (<1.6 % of Sb, <0.8 % of
As, <0.4 % of Ni, and <0.002 % of Cr) showing that Cr is almost immobile.
SEM-EDX measurements and Raman spectroscopy showed that the most abundant secondary
phases are various arsenates, Fe-oxides, Fe-oxy-hydroxides (FOH), and roméite-group
antimonates (RGA). Most of them are fine-grained, more or less poorly crystalline, andinhomogeneous. The FOH contain significant amounts of As (up to 11 at.%), Sb (up to 1.5at.%), and Ni (up to 1.2 at.%). The major arsenate is scorodite followed by hörnesite andannabergite. The RGA are sinks of Sb (up to 19 at.%) and As (up to 7 at.%).
The mildly oxidizing and temporarily wet conditions under neutral pH indicate that slow
weathering of the sulphide phases will continue. Under the present conditions, the confirmed
secondary minerals are not ultimate sinks. In particular, As and to a lesser extent Ni and Sb
could be re-released into the environment. Therefore, the leaching of contaminants into thegroundwater will remain of the highest concern in the future.
This work was supported by the Austrian Science Fund (FWF) [grant number P 30900-N28 to T. Đorđević].

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REVEALING THE MINERALOGICAL REASONS FOR DIFFERENCES IN THE
LEACHING BEHAVIOUR OF ELECTRIC ARC FURNACE SLAGS
Vollprecht, D.1, Neuhold, S.1, Sammer, T.1, Sorger, C.2, Gronen, L.3, Sokol, A.3,
Algermissen, D.3, Schintlmeister, A.4, Raith, J.G.1
Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austria
Stahl- und Walzwerk Marienhütte GmbH, Südbahnstraße 11, 8020 Graz, Austria
3
FEhS-Institut für Baustoffforschung e.V., Bliersheimer Straße 62, 47229 Duisburg, Germany
4
University of Vienna, Althanstraße 14, 1090 Vienna, Austria
e-mail: daniel.vollprecht@unileoben.ac.at
1

2

The mineralogy and leachability of electric arc furnace (EAF) slags has been studied in the lastyears (NEUHOLD et al., 2019). For a specific EAF slag it has been demonstrated that theleaching of vanadium can be significantly decreased by increasing the SiO2/FeO ratio by liquidslag treatment which has been explained by the formation of melilite at the expense of wuestite
and the subsequent hydration of melilite yielding adsorption sites for vanadium released fromits primary spinel host phase (NEUHOLD et al., 2020, SAMMER et al., 2019). However,
several research questions such as the mineralogical bonding of fluorine and molybdenum aswell as the transferability of the findings regarding mineralogical composition and vanadiumleachability could not be answered yet. Therefore, within this study (MiLeSlag 2.0, FFG Bridge,
871269) two novel findings are presented:(1) NanoSIMS was applied to identify the mineralogical bonding of fluorine andmolybdenum and succeeded in proving the bonding of the former element to spinels
and wuestite but failed in case of the latter due to several mass interferences.
(2) 20 EAF slag samples which were identified as outliers with respect to the total orleachable contents of chromium, vanadium, molybdenum, or fluorine, were investigatedin detail with respect to their chemical (XRF, ICP-MS, IC after pyrohydrolytic digestion
for fluorine) and mineralogical (XRD) composition. The chemical composition ofpresent mineral phases (EPMA) and the pH-dependent leaching (EN 14429, ICP-MS &IC) were investigated to understand the elemental distribution. Based on this dataset themechanisms controlling the leaching were modelled using LeachXSTM/Orchestra.
No consistent correlation between distinct chemical or mineralogical features and theleachability of a specific chemical element could be found, i.e. the previously observed inverse
correlation between SiO2/FeO ratio and vanadium leaching seems not to be generally valid.
Despite this fact, increasing the SiO2/FeO ratio in the liquid slag still had the desired effects ofdecreasing the leachability of four different EAF slags not only of vanadium, but also of
molybdenum and fluorine, although the reasons for this are not yet completely understood.
NEUHOLD, S., VAN ZOMEREN, A., DIJKSTRA, J., VAN DER SLOOT, H., DRISSEN, P., ALGERMISSEN,
D., MUDERSBACH, D., SCHÜLER, S., GRIESSACHER, T., RAITH, J., POMBERGER, R., VOLLPRECHT,
D. (2019): Minerals, 9, 525, 1-19.
NEUHOLD, S., ALGERMISSEN, D., DRISSEN, P., ADAMCZYK, B., PRESOLY, P., SEDLAZECK, K.P.,
SCHENK, J., RAITH, J., POMBERGER, R., VOLLPRECHT, D. (2020): Applied Sci., 10, 2549, 1-17.
SAMMER, T., NEUHOLD, S., VOLLPRECHT, D. (2019): Mitt. Österr. Miner. Ges., 65, 78.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

DIE MÖGLICHKEITEN VON MIKRO-COMPUTERTOMOGRAPHIE (-CT)
AN KORRODIERTEN EISENNÄGELN
Wagner, S.1, Degenhart, G.2, Tropper, P.1, Töchterle, U.3
Institut für Mineralogie und Petrographie, Universität Innsbruck, Innrain 52, 6020 Innsbruck, Österreich
Department Radiologie, Medizinische Universität Innsbruck, Anichstraße 35, 6020 Innsbruck, Österreich
3
Institut für Archäologie, Universität Innsbruck, Langer Weg 11, 6020 Innsbruck, Österreiche-mail: simon.wagner@student.uibk.ac.at1
2

Eines der größten Probleme der Konservierung- und Restaurierungswissenschaften in derArchäologie stellt der Korrosionsprozess von Eisenobjekten dar. Ausgelöst wird dieser Prozess
unter anderem durch den Wechsel der Umweltbedingungen sobald das Objekt von Archäologen
freigelegt wird. Durch Redoxprozesse bildet sich an der Metalloberfläche aus dem elementaren
Eisen zweiwertiges (Fe2+) und dreiwertiges Eisen (Fe3+). Zum besseren Verständnis derProzesse wurde mittels Computertomographie die räumliche Verteilung der einzelnen
Korrosionsprodukte genauer untersucht. Das bildgebende Verfahren der Computertomographie
zählt eigentlich zu einer der wichtigsten radiologischen Diagnosemethoden in der Medizin. Es
handelt sich dabei um tomographische Röntgentechnik wobei der Röntgenstrahl durch eine
Sammellinse zu einem dünnen Fächer geformt, beim Eintritt in ein Material abgeschwächt undanschließend mithilfe von Detektoren erfasst wird. Mittels geeigneter Computersoftware kanndiese Schwächung bildgebend mit unterschiedlichen Grauwerten verarbeitet und dargestellt
werden. Die μ-Computertomographie wurde am vivaCT 40 der Firma Scanco Medical AG
durchgeführt. Mit einer Auflösung von 10,5 - 76 μm können damit relativ feine Strukturen
aufgelöst und bildlich dargestellt werden. Die computertomographischen Untersuchungenwurden an einem archäologischen Nagel durchgeführt, der in Frischhaltefolie eingewickelt undsamt umgebendem Erdreich geborgen wurde. Dadurch sollte es auch möglich sein die gesamte
Abfolge der unterschiedlichen Korrosionsschichten beobachten zu können und dadurch einmöglichst vollständiges Korrosionsbild daraus zu generieren. Mittels festgelegter
Dichteintervalle ist es möglich, eine räumliche Verteilung des jeweiligen Dichtebereichs zu
generieren und dadurch die räumliche Anordnung der unterschiedlichen Korrosionsbereiche zu
visualisieren. Es konnten vier markante Korrosionsbereiche innerhalb des Nagels identifiziert
werden, die auch mittels Elektronenstrahlmikrosondenanalysen verifiziert werden konnten:• Reliktisches Eisen: Überreste des ursprünglichen Nagels, die nur noch skelettartig
ausgebildet sind. Dieser Bereich entspricht dabei dem „metallic substrate“.
• Hochdichte Korrosionsprodukte (Magnetit, Maghemit): Teile dieses Dichtebereichsfindet sich an der Stelle des ehemaligen Nagels, teilweise aber auch über dessen
ehemalige Oberfläche hinausgreifend (= dense product layer).
• Niedrigdichte Korrosionsprodukte: Dort treten vor allem Korrosionsprodukte (Fehydroxide) auf, die eine deutlich niedrigere Dichte aufweisen. - Eine bereits beginnende
Vermischung mit dem umgebenden Boden kann ebenfalls beobachtet werden.
• Anhaftendes Bodenmaterial: Dieser Bereich ist durch die geringsten Dichten
gekennzeichnet und besteht größtenteils aus Bodenpartikeln (Muskovit, Feldspat, Quarz).
Sowohl die niedrigdichten Korrosionsprodukte und das anhaftende Bodenmaterial
entsprechen dem sog. „transformed medium“.

155MITT.ÖSTERR.MINER.GES. 167 (2021)

POLYPHASE Co-Cu MINERALIZATION IN THE KUNENE REGION, NAMIBIA
Wallner, D.1, Bertrandsson Erlandsson, V.1, Bernegger, S. 1, Raith, J.G.1, Rantitsch, G.1,
Melcher, F.1, Ellmies, R.2
1

Montanuniversität Leoben, Leoben, Peter Tunner Straße 5, 8700 Leoben, Austria
2
Gecko Namibia, Einstein 10, 8912 Swakopmund, Namibia
e-mail: daniela.wallner@unileoben.ac.at

Cobalt is a critical metal that is crucial for the future energy transition. Almost two-thirds of the
global production (REICHL & SCHATZ, 2021) come from politically unstable countries(DRC, Zambia) in central Africa. Recently discovered sediment-hosted Co-Cu mineralizationin the Dolostone Ore Formation (DOF) in the Kunene region, northern Namibia, may become
an attractive alternative to these countries. The DOF is hosted within the Neoproterozoic
Ombombo Subgroup of the Kaoko Belt in northern Namibia (MILLER, 2008). It has been
traced for approximately 30 km in EW direction and dips ca. 60 °N with <1 m to 14 m
thickness. The main lithologies are low-grade metamorphosed sediments including pelites,
marls and carbonate rocks. The most abundant ore minerals are pyrite, pyrrhotite, chalcopyrite,
sphalerite, galena, members of the linnaeite-siegenite series, and cobaltite.
The ore minerals can be found in several mineralization styles: (1) irregular to clustereddisseminations, (2) nodules and concretions, (3) synmetamorphic mineralization withinpressure shadows, (4) veinlet-hosted mineralization of different generations, and (5) "DOF
events", which are distinctive ductile and/or brittle structures showing a complex zoned texture.
These mineralization styles can be assigned to four mineralization stages mainly related to theDamaran orogeny (560-550 Ma): Stage I) early stage with framboidal pyrite, Stage IIa) Co-FeZn-Pb stage with pyrite, pyrrhotite, members of the linnaeite-siegenite series (linnaeite),
sphalerite, chalcopyrite, and galena, Stage IIb) Cu-Zn-Fe stage with pyrite, pyrrhotite, cobaltite,
linnaeite, sphalerite, and chalcopyrite, Stage III) Cu-Pb-Zn stage with chalcopyrite, galena,
sphalerite, and linnaeite, and Stage IV) late stage with jaipurite, members of the linnaeiteviolarite series, covellite, pyrite, and magnetite.
Preliminary LA-ICP-MS analyses of sphalerite and chalcopyrite support these paragenetic
observations by indicating distinct differences in trace element geochemistry. Sphalerite andchalcopyrite from veins and pressure shadows are significantly enriched in elements such as
Ni, Se (and Cd in sphalerite), whilst being depleted in Co, compared to sphalerite andchalcopyrite from the other mineralization styles. Pyrite geochemistry show more complex
variations; strongly supporting a multi-stage mineralization model for the DOF.
Raman spectroscopy of carbonaceous material (LÜNSDORF et al., 2017) indicate a formation
temperature of 345±32 °C. This overlaps with the regional metamorphic temperature but may
indicate either a slightly lower temperature overprint or a higher stress regime in the DOF
horizon compared to the surrounding host rock.
LÜNSDORF, N. K., DUNKL, I., SCHMIDT, B. C., RANTITSCH, G., von EYNATTEN, H. (2017): Geostand.
Geoanal. Res., 41, 593-612.
MILLER, R. McG. (2008): Geol. Surv., 2nd ed. Windhoek, Namibia.
REICHL, C., SCHATZ, M. (2021): Federal Ministry of Agriculture, Regions and Tourism, 36, Vienna, Austria.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

EVALUATION OF GREEN SCALING INHIBITORS BY
THERMODYNAMIC RATE MODELING
Wedenig, M.1, Boch, R.1,2, Leis, A.3, Wagner, H.4, Dietzel, M.1
Institute of Applied Geosciences, Graz University of Technology, Rechbauerstrasse 12, 8010 Graz, Austria
2
Geoconsult ZT GmbH, Wissenspark Salzburg Urstein, Urstein Süd 13, 5412 Puch bei Hallein, Austria
3
JR-AquaConSol GmbH, Steyrergasse 21, 8010 Graz, Austria
4
ÖBB-Infrastruktur-AG, Streckenmanagement & Anlagenentwicklung, Fachbereich Bautechnik & Tunnelbau,
Europaplatz 2, 8020 Graz, Austria
e-mail: michael.wedenig@tugraz.at
1

Green technologies are on the rise and not stopping at the gate of tunnel construction sites. So
called “green inhibitors” (GI) are eco-friendly, biodegradable organic molecules, which are
already applied in many technical fields (oil/gas-industry, industrial and potable water
treatment, …) for scaling reduction (mainly CaCO3 precipitation) and increasingly used indrainage systems of motor- and railway tunnels. Although, GI’s are known to significantly
decrease mineral precipitation out of an aqueous solution, their individual inhibition effects areless explored. Therefore, we investigated the functionality and efficiency of aspartic, maleic
and acrylic GI products at dosages from 0.5 to 10 mg L-1, using a newly developed rapid andcompact test procedure. The GI performance is quantified by combining existing
thermodynamic rate models for CO2-flux and CaCO3-precipitation. The results showed that (i)the GI performance is independent of the CO2 degassing rates, (ii) the supersaturation of calcite
reaches an upper limit approaching the solubility of amorphous calcium carbonate, and (iii)average efficiencies of 70% up to 100%, and (iv) a delay of crystal nucleation of 3 to 6 times –compared to the control test (no inhibitor) – are observed. Our results also reveal new insights
into preferential CaCO3 polymorph formation: aspartate is suggested to modulate calcite
crystallites by serving as a template for predominant vaterite growth. The rate-model aided test
procedure provides a compact and rapid tool to assess and quantify GI performances against
CaCO3-scaling to be properly selected and individually tuned.

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MITT.ÖSTERR.MINER.GES. 167 (2021)

HIGH-PRESSURE PHASE TRANSITION OF KIESERITE-TYPE CoSO4·H2O
AND COMPARATIVE COMPRESSION PROPERTIES OF ISOTYPICCOMPOUNDS MeSO4·H2O (Me2+ = Mg, Fe, Ni)
Wildner, M.1, Ende, M.1, Meusburger, J.1,2, Kunit, R.1, Matzinger, P.1, Talla, D.1, Miletich, R.1
1

Universität Wien, Institut für Mineralogie und Kristallographie, Althanstraße 14, 1090 Wien, Austria
2
Camborne School of Mines, University of Exeter, Penryn TR10 9FE, Cornwall, UKe-mail:. manfred.wildner@univie.ac.at

The kieserite-type compound CoSO4⋅H2O has been investigated under hydrostatic pressures
up to 10.1 GPa in a diamond anvil cell using single-crystal X-ray diffraction and Raman spectroscopy. The monoclinic α-phase (space group C2/c, Fig. 1a) undergoes a second-orderferroelastic phase transition at Pc = 2.40(3) GPa to a triclinic β-phase (s.g. P 1 , Fig. 1b).
Lattice elasticities derived from fitting third-order Birch-Murnaghan equations of state to theunit-cell volume data yield V0 = 354.20(6) Å3, K0 = 53.0(1.7) GPa, K’ = 5.7(1.8) for the
α-phase and V0 = 355.9(8) Å3, K0 = 45.2(2.6) GPa, K’ = 6.6(6) for the β-phase.
The most obvious structural feature of the β-phase, and thus a possible driving mechanism of
the phase transition, is a partial rearrangement in the hydrogen bonding system (Fig. 1a,b).
However, a comparative analysis including the kieserite-type representatives of Mg, Fe andNi investigated under pressure to date (MEUSBURGER et al., 2019, 2020; ENDE et al.,2020) suggests that the loss of the point symmetry 2 at the otherwise rather rigid SO4
tetrahedron, allowing symmetrically unrestricted tetrahedral rotations and edge tiltings in the
β-phase, could be the actual driving mechanism of the phase transition (Fig. 1b).

Figure 1. Fragments of the structures of (a) α-CoSO4·H2O (at 10-4 GPa) and (b) β-CoSO4·H2O (at 4.9 GPa). In(b) the direction of tetrahedral rotations and the sense of edge tiltings relative to the α-phase are indicated.
MEUSBURGER, J.M., ENDE, M., TALLA., D., WILDNER, M., MILETICH, R. (2019): J. Sol. State Chem.,
277, 240-252.
MEUSBURGER, J.M., ENDE, M., MATZINGER, P., TALLA., D., MILETICH, R., WILDNER, M. (2020):
Icarus, 336, 113459.
ENDE, M., KIRKKALA, T., LOITZENBAUER, M., TALLA., D., WILDNER, M., MILETICH, R. (2020):
Inorg. Chem., 59, 6255-6266.

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