1597
The Canadian Mineralogist
Vol. 40, pp. 1597-1608 (2002)

DESCRIPTION AND CRYSTAL STRUCTURE OF MANGANLOTHARMEYERITE,
Ca(Mn3+,䡺,Mg)2{AsO4,[AsO2(OH)2]}2(OH,H2O)2, FROM THE STARLERA Mn DEPOSIT,SWISS ALPS, AND A REDEFINITION OF LOTHARMEYERITEJOËL BRUGGER§
Department of Geology and Geophysics, Adelaide University, North Terrace, 5001 Adelaide,
South Australia and South Australian Museum, North Terrace, 5000 Adelaide, South Australia

SERGEY V. KRIVOVICHEV¶
Department of Crystallography, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg, Russia

UWE KOLITSCH
Institut für Mineralogie und Kristallographie, Universität Wien, Geozentrum, A-1090 Wien, Austria

NICOLAS MEISSER
Musée Géologique et Laboratoire des Rayons-X, Institut de Minéralogie et de Géochimie,
UNIL-BFSH2, CH-1015 Lausanne-Dorigny, Switzerland

MICHAEL ANDRUTInstitut für Mineralogie und Kristallographie, Universität Wien, Geozentrum, A-1090 Wien, Austria

STEFAN ANSERMET
Musée Géologique et Laboratoire des Rayons-X, Institut de Minéralogie et de Géochimie,
UNIL-BFSH2, CH-1015 Lausanne-Dorigny, Switzerland

PETER C. BURNS
Department of Civil Engineering and Geological Sciences, University of Notre Dame,
Notre Dame, Indiana 46556-5602, U.S.A.

ABSTRACTManganlotharmeyerite, Ca(Mn3+,䡺,Mg)2{AsO4,[AsO2(OH)2]}2(OH,H2O)2, is a new member of the tsumcorite group ofminerals, of general formula Me(1)Me(2)2(XO4)2(OH,H2O)2, in which Me(1) represents Pb2+, Ca2+, Na+ and Bi3+, Me(2) represents
Fe3+, Mn3+, Cu2+, Zn2+, Co2+, Ni2+, Al3+ and Mg2+, and X can be P5+, As5+, V5+ or S6+. Manganlotharmeyerite occurs withsailaufite, (Ca,Na,䡺)2Mn3O2(AsO4)2(CO3)•3H2O, tilasite and calcite in discordant veinlets within massive braunite ores at theStarlera Mn deposit in the Eastern Alps of Switzerland. Manganlotharmeyerite and the associated arsenates are the product of thelatest stage of As remobilization during retrograde Alpine metamorphism of Triassic carbonate-hosted, syngenetic exhalative
Mn-ores. Manganlotharmeyerite forms elongate platy crystals and aggregates up to 1 mm in length, but optically homogeneous
crystals do not exceed 100 m in length. The mineral has a Mohs hardness of about 3, with a Dcalc of 3.75(2) and a Dmeas of
3.77(2) g/cm3; it is brittle, with an irregular fracture and a distinct cleavage parallel to {001}. Manganlotharmeyerite is transparent
to translucent with an adamantine luster. It is brown-red to dark reddish orange in color, and has a light brown streak. The newmineral species is biaxial positive, with  1.785(5),  1.814(5) and  1.854(5), 2V(meas.) about 85°, 2V(calc.) 82°, dispersion
r < v weak. The average composition of the mineral, measured with an electron microprobe, is [wt%]: V2O5 0.67, As2O5 53.41,§¶

E-mail address: brugger.joel@saugov.sa.gov.au
Present address: Mineralogisch-Petrographisches Institut, Universität Kiel, Olshausenstrasse 40, D-24098 Kiel, Germany.

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THE CANADIAN MINERALOGISTMgO 3.95, Mn2O3 16.70, CaO 12.42, Fe2O3, 0.91, NiO 1.07, minor quantities (< 1 wt%) of Al2O3, SrO, Na2O, CoO, and ZnO,
H 2 O calc 8.84, sum 99.3, resulting in the empirical chemical formula (Ca 0.94Sr 0.01 Na 0.01 )(Mn 3+0.45 䡺 0.26Mg 0.20 Ni 0.03
Fe0.02Zn0.02Al0.01Co0.01)2(As0.98V0.02)2O10H4.16. The structural chemical formula of the mineral derived on the basis of the crystalstructure refinement is Ca(Mn3+0.59䡺0.24Mg2+0.17)2{(AsO4)0.76[AsO2(OH)2]0.24}2[(OH)0.59(H2O)0.41]2. Manganlotharmeyerite is
monoclinic, C2/m, a 9.043(1), b 6.2314(7), c 7.3889(9) Å,  116.392(2)°, V 372.99(9) Å3 and Z = 2. Single-crystal structurerefinement (R1 = 0.025) confirmed isotypy with the tsumcorite structure. The strongest ten lines in the X-ray powder-diffraction
pattern [d in Å (I)(hkl)] are: 4.93(80)(1̄10), 4.61(50)(111), 3.426(60)(2̄02), 3.182(100)(1̄12), 3.122(50)(020), 2.927(70)(201),
2.822(70)(02̄1), 2.718(80)(3̄11), 2.555(100)(2̄21,3̄12), 2.134(70)(202,221). Unit-cell parameters from the powder-diffraction
data are: a 9.074(5), b 6.239(3), c 7.406(4),  116.60(3)°. The nomenclature of members of the tsumcorite group with Me(1) = Ca
and X = As (lotharmeyerite subgroup) is based on the occupant of the Me(2) site. Manganlotharmeyerite represents the Mn3+dominant member of the group, and lotharmeyerite is redefined to represent the Zn-dominant member. The lotharmeyerite
subgroup now contains six phases: cabalzarite with Me(2) = Mg, ferrilotharmeyerite (Fe3+), cobaltlotharmeyerite (Co),nickellotharmeyerite (Ni), lotharmeyerite (Zn) and manganlotharmeyerite (Mn3+).
Keywords: manganlotharmeyerite, new mineral species, lotharmeyerite, structure refinement, tsumcorite group, Starlera Mn
deposit, Swiss Alps.

SOMMAIRE
La manganlotharmeyerite, Ca(Mn3+,䡺,Mg)2{AsO4,[AsO2(OH)2]}2(OH,H2O)2, est un nouveau membre du groupe de latsumcorite, dont la formule générale est Me(1)Me(2)2(XO4)2(OH,H2O)2, dans laquelle Me(1) représente Pb2+, Ca2+, Na+ et Bi3+,
Me(2) représente Fe3+, Mn3+, Cu2+, Zn2+, Co2+, Ni2+, Al3+ et Mg2+, et X pourrait être P5+, As5+, V5+ ou S6+. On trouve la manganlotharmeyerite avec la sailaufite, (Ca,Na,䡺)2Mn3O2(AsO4)2(CO3)•3H2O, la tilasite et la calcite dans des veinules discordantes
d’un minerai de braunite massive du gisement de manganèse de Starlera, dans les Alpes orientales en Suisse. La
manganlotharmeyerite et les arsenates qui lui sont associés sont le produit du stade ultime de remobilisation de l’arsenic au coursde la rétrogression du minerai carbonaté syngénétique exhalatif, d’âge triassique, et métamorphisé lors de l’événement alpin. La
manganlotharmeyerite se présente en cristaux allongés en plaquettes et en aggrégats jusqu’à 1 mm de taille, mais les cristaux,
optiquement homogènes, ne dépassent pas 100 m. Sa dureté de Mohs est environ 3, la densité calculée, 3.75(2), et la densité
mesurée, 3.77(2) g/cm3; elle est cassante, avec une fracture irrégulière et un clivage distinct parallèle à {001}. La
manganlotharmeyerite est transparente à translucide, avec un éclat adamantin. Les cristaux sont brun-rouge à orange rougeâtre
foncé, et la rayure est brun pâle. Il s’agit d’un minéral biaxe positif, avec  1.785(5),  1.814(5) et  1.854(5), 2V(mes.) d’environ
85°, 2V(calc.) 82°, dispersion r < v, faible. La composition moyenne du minéral, mesurée avec une microsonde électronique, en% (poids), est: V2O5 0.67, As2O5 53.41, MgO 3.95, Mn2O3 16.70, CaO 12.42, Fe2O3, 0.91, NiO 1.07, avec des quantités mineures(< 1%) de Al2O3, SrO, Na2O, CoO, et ZnO, H2Ocalc 8.84, somme 99.3, ce qui mène à la formule empirique (Ca0.94Sr0.01Na0.01)(Mn3+0.45䡺0.26Mg0.20Ni0.03Fe0.02 Zn0.02Al0.01Co0.01)2(As0.98V0.02)2O10H4.16. La formule structurale, dérivée d’après les données
obtenues par affinement de la structure, est Ca(Mn3+0.59䡺0.24Mg2+0.17)2{(AsO4)0.76[AsO2(OH)2]0.24}2[(OH)0.59(H2O)0.41]2. La
manganlotharmeyerite est monoclinique, C2/m, a 9.043(1), b 6.2314(7), c 7.3889(9) Å,  116.392(2)°, V 372.99(9) Å3 et Z = 2.
L’affinement de la structure, effectué sur cristal unique (R1 = 0.025) confirme l’isotypisme avec la tsumcorite. Les dix raies lesplus intenses du spectre de diffraction (méthode des poudres) [d en Å (I)(hkl)] sont: 4.93(80)(1̄10), 4.61(50)(111), 3.426(60)(2̄02),
3.182(100)(1̄12), 3.122(50)(020), 2.927(70)(201), 2.822(70)(02̄1), 2.718(80)(3̄11), 2.555(100)(2̄21,3̄12), et 2.134(70)(202,221).
Les paramètres réticulaires calculés à partir du spectre de diffraction X sur poudre sont: a 9.074(5), b 6.239(3), c 7.406(4), 
116.60(3)°. La nomenclature des membres du groupe de la tsumcorite ayant Me(1) = Ca et X = As (sous-groupe de la
lotharmeyerite) est fondée sur l’occupant du site Me(2). La manganlotharmeyerite représente le membre du groupe à dominancede Mn3+, et la lotharmeyerite, ici redéfinie, en serait le membre à dominance de Zn. Le sous-groupe de la lotharmeyerite contientmaintenant six phases: cabalzarite avec Me(2) = Mg, ferrilotharmeyerite (Fe3+), cobaltlotharmeyerite (Co), nickellotharmeyerite(Ni), lotharmeyerite (Zn) et manganlotharmeyerite (Mn3+).
(Traduit par la Rédaction)
Mots-clés: manganlotharmeyerite, nouvelle espèce minérale, lotharmeyerite, affinement de la structure, groupe de la tsumcorite,
Starlera, gisement de manganèse, Alpes, Suisse.

INTRODUCTION
The tsumcorite group of minerals is characterized by
the general formula Me(1)Me(2)2(XO4)2(OH,H2O)2,where the site Me(1) can contain Pb, Ca, Na and Bi,
Me(2) can contain Fe3+, Mn3+, Cu2+, Zn, Co, Ni, Al, andMg, and X can contain P5+, As5+, V5+ and S6+ (Krause etal. 1998, 2002, Brugger et al. 2000). In this paper, we

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describe the occurrence, the physical and chemical properties, and results of a crystal-structure refinement of a
Zn-free, Mn-rich tsumcorite-group mineral with Me(1)= Ca, Me(2) = Mn3+ (mainly), and X = As. This mineral
has been named manganlotharmeyerite, with the simplified chemical formula Ca(Mn 3+,䡺,Mg) 2{AsO 4,[AsO2(OH)2]}2(OH,H2O)2. The holotype specimen isdeposited at the Musée géologique cantonal, Lausanne,

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Switzerland (MGL #54000; cotype specimen MGL#54014). The name acknowledges the relation withlotharmeyerite, whose ideal chemical formula is redefined as Ca(Zn,Mn3+)2(AsO4)2(H2O,OH)2. The newmineral and the revision of lotharmeyerite have been
approved by the Commission on New Minerals andMineral Names (CNMMN) of the International Mineralogical Association (IMA 2001–026).

OCCURRENCE
The Val Ferrera Fe–Mn province
The Starlera Fe–Mn deposit belongs to a group ofsmall Fe–Mn–(Ba,V,As,Sb,Be,W,REE) deposits hosted
in Triassic platform carbonates belonging to the Middle
Penninic domain (Briançonnais) of the Eastern Swiss
Alps (Trümpy 1980). At Val Ferrera, these sedimentaryrocks have been segmented into four distinct tectonic
units during the Alpine orogeny (the Tambo, Suretta,
Starlera and Schams nappes; Baudin et al. 1995, Schmid
et al. 1997). Décollement and stacking of the nappes
predated the Tertiary Alpine metamorphism and thus,
all of these units and the related ore deposits underwent
a similar Tertiary metamorphic evolution, characterized
by an early, cryptic blueschist-facies metamorphism
followed by a pervasive event under greenschist-facies
conditions (D1; Schreurs 1995, Marquer et al. 1996,
Schmid et al. 1997). The age bracket 35–40 Ma is themost realistic estimate for the timing of the thermal peakduring D1 (Hurford et al. 1989). A later greenschist-facies metamorphism took place before the intrusion of
the Bergell granodiorite at 30.13 ± 0.17 Ma (vonBlanckenburg 1992), and is linked to a phase of rapid
decompression (Baudin & Marquer 1993). D3 produced
a fine crenulation in the most incompetent rocks, andthe last event (D4), occurring under brittle conditions,
was responsible for the formation of subvertical N–Sstriking faults.
The carbonate-hosted ores at Val Ferrera have acomplex Fe–Mn–(Ba,V,As,Sb,Be,W,REE) geochemical
association that arose mainly from their syngenetic
exhalative origin and their location above a granite-richcontinental basement (Brugger & Gieré 2000). The
complex ore mineralogy observed nowadays is a consequence of small-scale (m to dm) redistribution ofelements and recrystallization during the Alpine metamorphism (Brugger & Gieré 2000).
The Starlera deposit
The Starlera mine is located at an altitude of 2400 m
in Val Ferrera, Eastern Swiss Alps. The mine first produced Fe-ore from 1825 to 1845, and small-scale mining for asbestos took place around 1880. Following thediscovery of manganese at Starlera in 1917, the mine
became the only deposit of Val Ferrera to be exploited

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for Mn, producing 145 tonnes of Mn ore between 1918
and 1920.
The Starlera deposit is characterized by a complicated paleogeographic and structural position. The
present thickness of the ore (up to 12 m) is due to deposition in a trough and to doubling of the series throughisoclinal folding (Brugger & Gieré 2000). Breccias witha matrix rich in asbestiform magnesioriebeckite areabundant and characteristic of the Starlera deposit. Compared to other deposits of the province, the Mn-ores arecharacterized by relatively low Si-contents and high Ascontents. Braunite is the main ore-mineral, whereas theMn-silicates rhodonite and spessartite are absent. Numerous discordant veins of roméite [(Ca,Fe,Mn,Na)2(Sb,Ti)2O6(O,OH,F)], tilasite [CaMgAsO4F], calcite ±aegirine, phlogopite, fluorite and tripuhyite up to 30 cm
in thickness cut the ore (Brugger & Gieré 1999). Greenish tilasite is also the main constituent of some concordant bands and lenses (up to 3  0.5 cm in size) in somehematite – carbonate – quartz ores. Furthermore, a complex association of Ti, As, Sb, Be, Ba (±REE, W, Sr)
minerals has been described by Brugger & Gieré (1999)
from quartz-rich, pink, muscovite – aegirine – albite
schists interbedded with the Fe–Mn ores. Aligned in themain S1 schistosity are strontian barite, As-poor fluorapatite, Sb-free rutile, and possibly Ce-rich roméite andSb-bearing pyrophanite [MnTiO3]. A later paragenesis,
overgrowing S1, contains As-rich fluorapatite, REE-richroméite, bergslagite [CaBeAsO4(OH)], Sb-rich rutile,
Sb-bearing pyrophanite, and Sb–As-bearing titanite, as
well as aegirine porphyroblasts. Arsenic-rich fluorapatite, bergslagite, stibian rutile, and stibian pyrophanite
occur in fractures within titanite crystals.
Appearance and association of manganlotharmeyerite
Manganlotharmeyerite has been discovered in small(cm to dm), late (D4?), open fissures inside massive
braunite ore. Manganlotharmeyerite forms elongate
platy crystals and aggregates up to 1 mm in length.
These aggregates and crystals are mostly translucent.
Clear, optically homogeneous grains usually do notshow crystal faces, and their size does not exceed 100
m. Subparallel intergrowths are common (Fig. 1).
Manganlotharmeyerite is associated with calcite, tilasite,and sailaufite, (Ca,Na,䡺)2Mn3O2(AsO4)2(CO3)•3H2O,
a new species discovered in the Sailauf rhyolite quarry,
Spessart, Germany (Wildner et al., in press); the natureof the latter mineral was confirmed by a single-crystal
structure refinement. The sailaufite from Starlera forms
thin platy brown crystals grouped in rosettes up to 1 mm
in diameter.
Manganlotharmeyerite and sailaufite represent thelatest stage of the retrograde remobilization of As in theStarlera ores. In this way, the formation of these minerals may be compared to that of fianelite [Mn2V(V,As)
O7•2H2O] found in a nearby lens of V-rich ore (Brugger& Berlepsch 1996).

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THE CANADIAN MINERALOGISTPHYSICAL AND OPTICAL PROPERTIES
Manganlotharmeyerite is brown-red to dark reddish
orange, with an adamantine luster. The streak is lightbrown, and the Mohs hardness is about 3. The mineralis brittle, with an irregular fracture and a distinct cleavage parallel to {001}. The density of the mineral wasmeasured using a test tube in which a density gradientis created using the Tl formate – Tl malonate – water
system (Clerici solution). The solution at the level ofthe crystal has been sampled using a fine chromatography syringe, and its density deduced from its index ofrefraction. The measured density is 3.77(2) g/cm3. This
compares well to a calculated density of 3.75(2) g/cm3
obtained using the average formula in Table 1, a cellvolume of 372.99 Å3 and Z = 2. The uncertainty for the
calculated density arises from the compositional range
listed in Table 1.
Manganlotharmeyerite is biaxial positive, with 
1.785(5),  1.814(5) and  1.854(5) (white light); 2Vcalc
82.4°, 2Vmeas about 85°, dispersion r < v, weak. Using
the average chemical analytical data, the calculated density and the mean index of refraction, the compatibility
index according to the Gladstone–Dale relationship is–0.037 (excellent; Mandarino 1981). The orientation of
the optical indicatrix is unknown.

CHEMICAL COMPOSITION
The chemical composition of manganlotharmeyeriteand of a crystal of lotharmeyerite from the type locality
in Mexico (South Australian Museum specimen G26280)
have been established using a Cameca SX–50 electron
microprobe (Table 1). High sums for lotharmeyerite are
due to the small size of the analyzed grains, and thenecessity to work with a highly focused beam. Empirical formulae were derived from the electron-microprobe
analyses on the basis of full occupancy of the tetrahedral sites, i.e., As + V = 2. The number of hydrogenatoms per formula unit (apfu) was calculated to obtain atotal of 10 atoms of oxygen. For manganlotharmeyerite,
it was further assumed that one [AsO2 (OH)2]– groupreplaces an [AsO4]3– group for each Me(2) vacancy (seebelow). The resulting empirical formula for manganlotharmeyerite is: (Ca0.94Sr0.01Na0.01)(Mn3+0.45䡺0.26Mg0.20
Ni0.03Fe0.02Zn0.02Al0.01Co0.01)2 (As0.98V0.02)2O10H4.16. A
detailed discussion of the crystal-chemical formula ofmanganlotharmeyerite is given in the Crystal Structure
section.

Mangan lotharmeyerite, Starlera
FIG. 1.

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Scanning electron micrograph of subparallel crystals of manganlotharmeyerite.

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MANGANLOTHARMEYERITE, A NEW SPECIES FROM THE STARLERA DEPOSIT, SWITZERLANDRAMAN AND IR SPECTROSCOPY
Raman spectra of single crystals of manganlotharmeyerite were recorded in the spectral range from 100
to 4000 cm–1, using excitation with an argon laser (488
nm line) and a Renishaw M1000 Raman system (spectral resolution 2 cm–1). A typical spectrum (Fig. 2)
clearly shows the presence of strong hydrogen bonding(broad bump of medium intensity centered around 3000
cm–1 in the O–H stretching vibrational region). Thisband agrees with the results from the structure determination, indicative of strong hydrogen bonds, with O...O
distances of 2.59(2) and 2.62(2) Å (see below). In some
spectra, a very small broad bump at roughly 1630–1570
cm–1 was recognizable; we assigned it to H–O–H bending, indicating the presence of molecular H2O.

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The bands at 880, 830 (broad), 475 + 426 and 344 +365 cm–1 are assigned to the normal vibrations 3, 1, 4
and 2, respectively, of the AsO4 group. In the free arsenate ion with Td symmetry, these Raman-active vibrations occur at 878, 837, 463 and 349 cm–1 (e.g.,
Griffith 1970). The observed splitting and broadeningof the majority of bands are the result of two effects:
firstly, the reduction of the local site-symmetry of the
AsO4 group, and secondly, the substitution of Mn, Mg
and vacancies at the Me(2) site resulting in considerably different local crystal-fields. The band at 765 cm–1
consequently may be attributed to locally different 1
vibrations. The remaining bands below 600 cm–1 are
attributed to vibrations involving the Mn and Mg cations, and lattice vibrations.
Single-crystal infrared spectra of small irregular
crystal fragments were recorded in the range between
4000 and 650 cm–1 using a Bruker IFS 66v/S FTIR spectrometer with attached microscope. These spectra also
showed the broad, strong bump in the spectral region
from 2500 to 3500 cm–1, with a maximum at around2980 cm–1 (O–H stretch). A distinct, slightly broadened
peak at about 1630 cm–1 confirms the presence of molecular H2O inferred from the results of the crystal-structure analysis. Owing to very strong absorption below
1200 cm –1 , the crystals become opaque at thesewavenumbers. Choosing very thin grains did not resultin sufficient lowering of the absorption or any otherimprovement of the generally poor spectra.
Monoclinic tsumcorite-group minerals can containup to 3 H apfu located around the O(1) atom, in whichcase the hydrogen-bonding scheme results in an [H3O2]–
group (see Effenberger et al. 2000 for a review):
O(4)…H–O(1)–H…O(1)–H–O(4)O(4)…H–O(1)…H–O(1)–H–O(4)In the case of tsumcorite-group minerals that contain 4
H apfu, the hydrogen bonds rearrange, with the development of hydrogen bonds involving the O(3) atoms ofoxygen. The ordering of the hydrogen bonds is indicatedby weak superstructure reflections in X-ray patterns, andresults in a triclinic superstructure in the members of
the “helmutwinklerite group” (Effenberger et al. 2000).
Broad to very broad IR and Raman absorption bands inthe spectral region from 2500 to 3500 cm–1 are typicalfor tsumcorite-group minerals containing either a mixture of H2O and OH, or only OH (Brugger et al. 2000,
Krause et al. 1998, 2001a). Among existing tsumcoritegroup minerals, only those containing two H2O molecules per formula unit and no OH groups (i.e., of
helmutwinklerite type) do not show such a broad band,
but instead sharp bands between 3500 and 3800 cm–1,
which provide evidence for relatively weak hydrogenbonds (Krause et al. 1998, Effenberger et al. 2000). IR
and Raman spectroscopy, therefore, indicates that longrange ordering of H-bonds, such as that found in

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THE CANADIAN MINERALOGIST

FIG. 2. Unpolarized Raman spectrum of manganlotharmeyerite crystal with randomorientation.

helmutwinklerite-group minerals, does not occur inmanganlotharmeyerite. This result also agrees with theoccupancy of the O(1) site by nearly equal amounts ofOH and H2O derived from the results of the chemical
analysis (Table 1) and the crystal-structure refinement(see below).

CRYSTAL STRUCTURE
Data collection
A crystal of manganlotharmeyerite with approximate
dimensions 0.08  0.06  0.03 mm was selected andmounted on a Bruker PLATFORM goniometer equippedwith a 1K SMART CCD detector with a crystal-to-detector distance of 5 cm. The data were collected using
MoK X-radiation and frame widths of 0.3° in , with45 s used to acquire each frame. More than a hemisphereof three-dimensional data was collected. The unit-celldimensions were refined on the basis of 628 reflections
using least-squares techniques (Table 2). The data werereduced and corrected for Lorentz, polarization, andbackground effects using the Bruker program SAINT.
A semi-empirical absorption-correction based upon theintensities of equivalent reflections was done by modeling the crystal as an ellipsoid, and reduced Rint of 457
intense reflections [>10 (I)] from 4.7 to 2.7%.
Structure refinement
Scattering curves for neutral atoms, together withanomalous dispersion corrections, were taken from In-

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ternational Tables for X-Ray Crystallography, Vol. IV(Ibers & Hamilton 1974). The Bruker SHELXTL Version 5.1 set of programs was used for refinement of thecrystal structure on the basis of F2. The starting model
used the atom coordinates given for the monoclinic
members of the tsumcorite-group minerals by Krause
et al. (1998). Refinement of all atom-position parameters, allowing for anisotropic displacement of all atoms, and the inclusion of a weighting scheme of thestructure factors, resulted in a final agreement index(R1) of 2.5%, calculated for the 387 unique observedreflections (|Fo| > 4 F), and a goodness-of-fit (S) of

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***

*** O(1) = (OH)0.59(H2O)0.41

cies at the Me(2) site lower the local symmetry ofmanganlotharmeyerite to triclinic. We were unable toindex the diffraction pattern using a large triclinic cell
(as suggested by Effenberger et al. 2000), and wereunable to account for the streaking in the refinement.
Description of the structure
The structure of manganlotharmeyerite is identicalto that of other tsumcorite-group minerals (Fig. 3a). The
Me(2) 6 octahedra ( : O2–, OH–, H2O) share transedges, resulting in chains that extend along the b axis.
These chains are linked by sharing corners with AsO4
tetrahedra, resulting in sheets of composition Me(2)(AsO4)(OH,H2O) that are parallel to (001) (Fig. 3b). The
topology of the sheet is identical to that in natrochalcite,
NaCu2(SO4)2(H3O2) (Hawthorne et al. 2000). Its graphical representation (octahedra shown by black vertices,
tetrahedra, by white vertices; links indicate the numberof O atoms shared between adjacent polyhedra) isshown in Figure 3c. Ca2+ cations are located between
the sheets; they provide linkage between the sheets
along the a axis.
The Me(1) site

0.890. The final atom parameters are listed in Table 3,
selected interatomic distances are in Table 4, and thebond-valence analysis is given in Table 5. Observed andcalculated structure-factors are available from the Depository of Unpublished Data, CISTI, National Research Council, Ottawa, Ontario K1A 0S2, Canada.
Notes on symmetry
The CCD camera detected weak streaking in areasof the diffraction pattern, consistent with presence of
local domains in the structure. It is possible that vacan-

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The Me(1) site is coordinated by eight anions withan average Me(1)–O bond length of 2.55 Å. Refinementof the site-scattering factor indicated that this position
is fully occupied by Ca, in good agreement with thechemical data and the bond-valence sum of 1.88 vu (valence units; Brown & Altermatt 1985).
The Me(2) site
The Me(2) site is octahedrally coordinated by six
ligands. Bond-valence sums, calculated with the parameters for Mn3+ and Mn2+ (Brown & Altermatt 1985) are
2.82 and 3.11 vu, respectively, consistent with occupancy by Mn3+. The Jahn–Teller distortion of the Me(2)octahedral coordination (Burns et al. 1994, Foley et al.

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1604

THE CANADIAN MINERALOGIST1997) (Table 4) is also consistent with occupancy by
Mn3+. Occupancy refinement for the Me(2) site using
scattering factors for Mn and Mg, and allowing for vacancy, lead to Mn3+0.59Mg2+0.17䡺 0.24, which corresponds to an average scattering power of ~19.2 e. The
Me(2) occupancy derived from the structure determination is very close to that obtained from the electron-microprobe data (Table 1).
The O(1) site
In minerals of the tsumcorite group, the O(1) site is
occupied by OH or H2O groups (or both). The O(1) atom
is bonded to two Me(2) cations. According to Krause etal. (1998), exclusive occupancy of the Me(2) site withtrivalent cations causes the O(1) sites to be fully occupied by hydroxyl groups, whereas exclusive occupancyof the Me(2) site with divalent cations causes a complete occupation of the O(1) sites by H2O molecules.
The latter is also valid in the case where the Me(2) site
is vacant. In the case of manganlotharmeyerite, the refined occupancy of the Me(2) site is Me3+0.59Me2+0.17
䡺0.24. Taking into account the points of Krause et al.
(1998), the occupancy of the O(1) site in manganlotharmeyerite is (OH)0.59(H2O)0.41.
The AsO4 group
The AsO4 group in monoclinic members of thetsumcorite group (space group C2/m) contains three
crystallographic types of O atoms. The O(4) atom isstrongly bonded to As [As–O(4) = 1.655(4) Å] and to
Ca [Ca–O(4) = 2.417(4) Å]. Its bond-valence sum isa1.65 vu, which corresponds to the full occupancy of theO(4) site by O atoms, and its additional bond-valence
requirements are met by hydrogen bonding [O(4)…O(1)= 2.59(2) Å]. The O(2) atom forms a slightly lengthened bond to As [As–O(2) = 1.712(4) Å], two shortbonds to Me(2) [Me(2)–O(2) = 2.116(3) Å] and one
weak bond to Ca [Ca–O(2) = 2.909(4) Å]. Where theMe(2) site is occupied by Mn3+, the bond-valence sum
incident upon the O(2) site is 2.08 vu (Table 5). However, where the Me(2) site is vacant, the O(2) bond-valence sum is 1.32 vu, which is consistent with a hydroxyl
group. Thus, the occupancy of the O(2) site inmanganlotharmeyerite is O0.76(OH)0.24. The O(3) atom
is bonded to As [2  As–O(3) = 1.694(3) Å], Ca [Ca–O(3) = 2.437(3) Å] and Me(2) [Me(2)–O(3) = 2.020(3)Å]. If the Me(2) site is occupied by Mn3+, the bond-valence sum for the O(3) site is 2.00 vu (Table 5). If theMe(2) site is vacant, the bond-valence sum for the O(3)site is 1.50 vu, which suggests a hydroxyl group. The
As is bonded to two O(3) atoms, and it is unlikely thatboth of these positions are occupied by OH. Rather, wesuggest that the local symmetry of the AsO4 group islowered where the Me(2) site is vacant, and the O(3)site is split into two sites, O(3a) and O(3b), one of whichis occupied by O and another one by OH. In summary,a vacancy at the Me(2) site results in lowering of thelocal symmetry and replacement of an AsO43– group by
an [AsO2(OH)2]– group. For manganlotharmeyerite, thisresults in the replacement of the AsO43– group by{(AsO4)0.76[AsO2(OH)2]0.24}2.52–.

b
z
y

x

AsO4

c
Ca
Me(2)O6

FIG. 3.

Crystal structure of manganlotharmeyerite (a); Me(2)(AsO4)(OH,H2O) sheet (b) and its graphical representation (c).

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MANGANLOTHARMEYERITE, A NEW SPECIES FROM THE STARLERA DEPOSIT, SWITZERLAND

The protonation of the XO4 group (X = As, P, V, S)
in tsumcorite-group minerals was discussed in detail by
Krause et al. (1998). These authors focused their attention on the O(2) site and pointed out that it cannot be
occupied by OH in all the structures they studied because: (1) the O(2) atom is in fourfold coordination, andtherefore its bond-valence requirements are satisfied; (2)protonated anion groups show a decrease of the OH–X–
O angles (Baur 1974), whereas in the tsumcorite-groupminerals studied by Krause et al. (1998), the only decreased angles are O(2)–X–O(4) (102.4–107.4°),
whereas the other O(2)–X–O angles are larger than
108.9°. However, these observations are not applicableto manganlotharmeyerite owing to the presence of vacancies at the Me(2) site. Where Me(2) is vacant, both
the O(2) and O(3) atoms become 2-coordinated with theAs–O(2) bond lengthened, and the geometry of the
AsO2(OH)2 group is different from that of the AsO3(OH) group. The latter was demonstrated for theAs(2)O2(OH)2 group in the structure of Ca(H2AsO4)2,
which was determined by Ferraris et al. (1972) using
neutron diffraction. The As(2)–OH bond lengths are
1.695 and 1.732 Å, whereas the As(2)–O bond lengths
are 1.652 and 1.677 Å. The OH–As–O angles vary from100.4 to 114.1°. In manganlotharmeyerite, the OH–As–
O angles vary from 102.2 to 112.0°. However, taking
into account our hypothesis about the lowering of symmetry and the splitting of the O(3) position, the observed
bond-lengths and angles are average values of those in
the real structure.
The existence of vacancies in the Me(2) position is a
key feature that distinguishes lotharmeyerite from othermembers of the tsumcorite group. We suggest that thepresence of vacancies results in the protonation of some
AsO4 groups, and in the rearrangement of the system ofhydrogen bonds.
Structural formula and charge-balance mechanism
On the basis of our crystal-structure analysis, thestructural formula for manganlotharmeyerite is
C a ( M e 3+0.59䡺 0.24M e 2+0.17) 2{ ( A s O 4) 0.76[ A s O 2(OH)2]0.24}2((OH)0.59(H2O)0.41)2. The charge-balancemechanism responsible for the incorporation of vacancies at the Me(2) site is described by:

1. CaMn3+2[AsO4]2(OH)2

3. CaMg2+2[AsO4]2(H2O)2

17%

The simplified formula is Ca(Mn3+,䡺,Mg)2{AsO4,[AsO2(OH)2]}2(OH,H2O)2.

X-RAY POWDER-DIFFRACTION STUDYThe X-ray powder-diffraction pattern of manganlotharmeyerite, obtained using a 114.6 mm Gandolfi
camera and Mn-filtered FeK radiation, is given in
Table 6. The powder pattern is similar to that of othermonoclinic members of the tsumcorite group. The intensities were estimated visually. Weak reflections at
5.46 Å (Iobs=10), 3.361(30), 2.999(5), and 2.354(5)could not be indexed, and were omitted. The strongest
ten lines in the X-ray powder-diffraction pattern [d in Å(I)(hkl)] are: 4.93(80)(110), 4.61(50)(1̄11), 3.426(60)( 2̄02), 3.182 (100)( 1̄12), 3.122(50)(020) 2.927(70)(201), 2.822(70)(021), 2.718(80) ( 3̄11), 2.555(100)(2̄21,3̄12), 2.134(70)(202,221). The unit-cell parametersof manganlotharmeyerite were obtained by least-squares
refinement of the powder-diffraction data (program
UnitCell: Holland & Redfern 1997): a 9.074(5) Å, b
6.239(3) Å, c 7.406(4) Å,  116.60(3)°. The theoreticald-values and intensities listed in Table 6 were calculated
for the formula Ca(Mn0.45Mg0.20Ni0.06䡺0.29)2As2O10
with the program CrystalDiffract of D.C. Palmer(www.crystalmaker. com).

DISCUSSION
Nomenclature of the lotharmeyerite subgroup
The cation composition of the Me(2) site is the main
guide for the naming of the minerals of the lotharmeyerite subgroup. The lotharmeyerite subgroup

The divalent Me(2) cations are accommodated via thecoupled substitution:{Me3+ + (OH)–}– → {Me2+ + H2O}–
Consequently, the composition of the manganlotharmeyerite specimen from Starlera can be expressedin terms of three theoretical end-members:

1605

59%

2. Ca䡺2[(AsO2(OH)2)]2(H2O)2 24%{Me3+ + AsO43– + (OH)–}– →{䡺 + AsO2(OH)2– + H2O}–

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THE CANADIAN MINERALOGIST

contains monoclinic tsumcorite-group minerals with
Me(1) = Ca and X = As. Lotharmeyerite was originallydescribed from the oxidation zone of the Ojuela mine,
Mapimi, Mexico as red crystals with the formula
CaZnMn3+(AsO4)2(OH)•2H2O (Dunn 1983). Its chemical formula was revised to CaZnMn(AsO3OH)2(OH)3
by Kampf et al. (1984). On the basis of a crystal-structure refinement of the Fe3+ analogue of lotharmeyerite(ferrilotharmeyerite), Krause et al. (1998) revised thechemical formula for lotharmeyerite to Ca(Mn3+,Zn)2(AsO4)2(OH,H2O)2. Because the available chemicalcomposition of lotharmeyerite and ferrilotharmeyerite
showed a small range, with (Fe+Mn) : Zn values close
to 1, Krause et al. (1998) followed the IMA guidelines
for the nomenclature of solid solutions (Nickel 1992),
and did not define different names for the Mn3+ and Zn2+
end-members.
Manganlotharmeyerite clearly has a Me(2)-site occupancy very different from the lotharmeyerite from theZntype locality (Fig. 4, Table 1). Thus, according to Krause
et al. (1998), and in accordance with the IMA rules, a
new name is warranted for manganlotharmeyerite. In
cabalzarite, another recently described mineral of thelotharmeyerite subgroup, the Me(2) site is occupied
mainly by Mg2+ and Al3+, with the Mg:Al ratio scattered about 1 (Fig. 4; Brugger et al. 2000). In the absence of clearly Mg- or Al-dominant crystals, only one
name was given, and by convention it was decided todefine cabalzarite as the Mg end-member. There is noevidence for ordering of cations at the Me(2) site in
lotharmeyerite, manganlotharmeyerite, and cabalzarite.
Such Me2+–Me3+ ordering results in a symmetry reduction in “gartrellite-type” tsumcorite-group minerals,
hence justifying a new name for intermediate compositions (Effenberger et al. 2000). As the new mineral from
Starlera is relatively Mn-rich (Fig. 4), we define
manganlotharmeyerite to represent the Mn3+-dominant
end-member of the lotharmeyerite subgroup.

Lotharmeyerite &manganlotharmeyerite

Occupancy of
the M2 site
[Atom%]
Lotharmeyerite
ManganlotharCabalzarite meyerite

Mg

Cabalzarite Manganlotharmeyerite

Starlera (this study)
Mapimi
Dunn (1983)
Kampf et al. (1984)
This study

Cabalzarite
Falotta
Brugger et al. (2000)

Mn

UnnamedendmemberAl
FIG . 4. New proposed nomenclature for Ca-dominant tsumcorite-group minerals(lotharmeyerite subgroup) with Mn3+, Mg2+, Zn2+ and Al3+ at the Me(2) site.

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MANGANLOTHARMEYERITE, A NEW SPECIES FROM THE STARLERA DEPOSIT, SWITZERLAND

The type specimen of lotharmeyerite was reported
to contain more Zn than Mn (Dunn 1983). Our analyses
on a sample from the same locality also show Zn > Mn
(Table 1). Consequently, we redefine lotharmeyerite torepresent the Zn-dominant member, Ca(Zn,Mn3+)2(AsO4)2(H2O,OH)2. Note that the “lotharmeyerite”
sample studied by Kampf et al. (1984) contains more
Mn than Zn, and should be named manganlotharmeyerite according to the new nomenclature. The consequences of the updated nomenclature for the namingof published occurrences of lotharmeyerite andferrilotharmeyerite are summarized in Table 7.
There are now six phases in the lotharmeyerite subgroup: Me(2) = Mg (cabalzarite, Brugger et al. 2000),Zn (lotharmeyerite, Dunn 1983, and this paper), Mn3+
(manganlotharmeyerite, this paper), Fe 3+ (ferrilotharmeyerite, Ansell et al. 1992, Krause et al. 1998),
Co (cobaltlotharmeyerite, Krause et al. 1999), and Ni(nickellotharmeyerite, Krause et al. 2001a). Manganlotharmeyerite is the first tsumcorite-group mineral witha significant amount of Me(2) vacancies. The crystalstructure refinement indicates that the investigatedcrystal from Starlera contains 24% of the Ca䡺2[(AsO2(OH)2)]2(H2O)2 end-member.
Occurrence of tsumcorite-group minerals
The great majority of the tsumcorite-group minerals
are found in the oxidation zone of polymetallic ore deposits; however, two recently described species, cabalzarite Ca(Mg,Al,Fe)2(AsO4)2(H2O,OH)2 (Brugger et al.
2000) and krettnichite, PbMn3+2(VO4)2(OH)2 (Brugger
et al. 2001), occur in association with Fe–Mn ores.
Cabalzarite is a product of the remobilization of arsenic
during retrograde metamorphism (in the zeolite facies)
in syngenetic exhalative ores. In contrast, krettnichite isa primary hydrothermal mineral crystallizing late in theparagenetic sequence in a vein of manganite. Hence,cabalzarite and manganlotharmeyerite share a very similar geological origin. This similarity is reflected in the
crystal chemistry of both minerals. The Me(1) and X

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1607

sites have almost identical occupancy, and the Me(2)sites both contain significant amounts of Mn, Mg and
Al (Fig. 4).

ACKNOWLEDGEMENTS
We thank J.A. Mandarino, E. Sokolova, I.V. Pekov
and W. Krause for helpful reviews, and R.F. Martin for
helping us to integrate this large amount of informationand for his own review.

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Received March 11, 2002, revised manuscript accepted
November 11, 2002.

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