American Mineralogist, Volume 91, pages 21–28, 2006

First occurrence of iodine in natural sulfosalts: The case of mutnovskite, Pb2AsS3(I,Cl,Br),a new mineral from the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation
MICHAEL ZELENSKI,1 TONÿI BALIý-ŽUNIý,2 LUCA BINDI,3 ANNA GARAVELLI,4 EMIL MAKOVICKY,2
DANIELA PINTO,4 AND FILIPPO VURRO4,*
1

Institute of Volcanology, Russian Academy of Sciences, Bulvar Piipa 9, Petropavlovsk-Kamchatsky, 683006 Russia
2
Geological Institute, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark3
Museo di Storia Naturale, Sezione di Mineralogia, Università degli Studi di Firenze, Via La Pira, 4-I-50121 Firenze, Italy
4
Dipartimento Geomineralogico, Università degli Studi di Bari, Via E. Orabona 4, I-70125 Bari, Italy

ABSTRACT
Mutnovskite, ideally Pb2AsS3(I,Cl,Br), is a new mineral from the high-temperature fumaroles ofthe Mutnovsky volcano, Kamchatka Peninsula, Russian Federation. It occurs as microscopic rubycolored short-prismatic crystals up to 100 μm across, closely associated with halogen-sulfosalts of
Pb, Bi, and As, Cd-Pb-Bi sulfosalts, pyrite, anhydrite, and cristobalite. Mutnovskite is transparent inthin fragments with a dark-red to blue color. The crystals are soft and fragile. Cleavage and fracture
were not observed and the Mohs hardness is approximately 2. In reflected light mutnovskite is silvery
lead-grey in color with an iridescent tarnish. Pleochroism and anisotropy are not visible because of
the strong orange internal reflections, especially in immersion. Reflectance percentages measured in
air in the range 400–700 nm were tabulated. Reflectance percentages (Rmin and Rmax) for the four COM
wavelengths are 34.2, 34.6 (470 nm), 33.2, 33.5 (546 nm), 32.5, 32.7 (589 nm), and 31.4, 31.7 (650nm), respectively. A mean of four electron microprobe analyses gave Pb 62.0(3), As 11.0(4), Bi 0.6(1),S 14.4(2), Se 0.2(3), I 8.9(3), Cl 2.44(9), Br 1.1(7), Cu 0.03(2), Fe 0.01(1), total 100.7 wt%, corresponding, on the basis of a total of 7 atoms, to Pb1.99(As0.98Bi0.02)Σ1.00(S2.98Se0.02)Σ3.00(I0.47Cl0.46Br0.09)Σ1.02.
The nine strongest powder-diffraction lines [d in Å (I/I0) (hkl)] are: 4.69 (32) (002); 4.37 (67) (210);
3.34 (73) (020); 3.19 (100) (212); 2.715 (61) (022); 2.648 (66) (410); 2.539 (31) (213); 2.455 (29)(402); 1.894 (30) (232). Mutnovskite is orthorhombic, space group Pnma, with a = 11.543(1), b =6.6764(7), and c = 9.359(1) Å, V = 721.3(1) Å3, Z = 4. The crystal structure was solved and refined
to R = 4.14%. It consists of three independent cation positions: Pb1 and Pb2 have tricapped trigonal
prismatic coordinations with S and I atoms (completed with one As atom in the case of Pb2), while
As has threefold coordination with S atoms, which form the base of a trigonal pyramid with As at theapex. Pairs of Pb1-Pb2 prisms are connected in columns which extend along c. AsS3 coordinations
are isolated from each other. S atoms and half of the Pb atoms form wavy close-packed layers. Twokinds of channels parallel to b occur between the layers. The smaller channels host As atoms close
to the channel walls, with their lone-electron pairs occupying the median part, while the bigger ones
accommodate rows of alternating halogen and Pb atoms. The new mineral is named after the type
locality, the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation.
Keywords: Mutnovskite, chemical composition, new mineral, X-ray data, crystal struture, Kamchatka Peninsula, Mutnovsky volcano

INTRODUCTION
The new mineral described herein, mutnovskite,
Pb2AsS3(I,Cl,Br), is an unusual mineral species from hightemperature fumaroles at the Mutnovsky volcano (Kamchatka
Peninsula, Russian Federation), an interesting, and up to now
scarcely investigated source of rare sublimate minerals. Mutnovskite represents the first iodine-bearing sulfosalt occurrence
reported in nature. According to both the chemical composition
and X-ray powder data, the mineral has no analogues amongminerals or synthetic compounds. With the exception of the
halogen content, however, the chemical composition is close
to the recently approved mineral tsugaruite, Pb4As2S7 (Shimizu
et al. 1998).
* E-mail: f.vurro@geomin.uniba.it
0003-004X/06/0001–21$05.00/DOI: 10.2138/am.2006.1870

21

The name mutnovskite is for the type locality. The type material is housed in the mineralogical collection of the Museum“C.L. Garavelli”, Dipartimento Geomineralogico, Università
di Bari, under the catalogue number 7/nm (V28). The polishedsections used for both the quantitative reflectance and electronmicroprobe studies, as well as the crystal of mutnovskite used forthe structural study, are preserved at the Dipartimento Geomineralogico, Università di Bari. The mineral and mineral name havebeen approved by the IMA Commission on New Minerals andMineral Names (2004-032).

OCCURRENCE AND ASSOCIATED MINERALS
Mutnovskite was found among volcanic sublimates at the
Mutnovsky volcano, southern Kamchatka, Russia (52.35° N,
158.27° E) at a temperature of about 250 °C. It occurs as microscopic ruby to brownish-red euhedral crystals up to 100 μm

22

ZELENSKI ET AL.: MUTNOVSKITE, A NEW MINERAL FROM KAMCHATKA PENINSULA

across, directly deposited on the host rock (Fig. 1), as well as
on other Pb-Bi-As sulfosalts previously grown. The mutnovskite
crystals exhibit a short-prismatic morphology, sometimes tabular,
and are without inclusions or intergrowths with other minerals.
In the samples analyzed, mutnovskite is closely associated with
the Cd-bearing Pb-Bi sulfosalts, kudriavite, and Cd-cannizzarite,
but especially with needle-like crystals of less-characterized PbBi-As sulfosalts currently under study. Other minerals spatiallyassociated with mutnovskite are sulfohalides and halogen-sulfosalts of Pb, Bi, and As, pyrite, anhydrite, and cristobalite. A
complete description of the geological setting of the fumarole
deposit from which mutnovskite was collected is given by Zelenski and Bortnikova (2005).

OPTICAL AND PHYSICAL PROPERTIES
Mutnovskite is transparent in thin fragments with a dark-red
to blue color. It has a cherry-red to orange streak and the luster
is resinous to submetallic.
In reflected light mutnovskite is silvery lead-gray in color
with an iridescent tarnish. Pleochroism and anisotropy are notvisible owing to the strong orange internal reflections, especiallyin immersion oil.
Reflectance measurements were performed in air by meansof a MPM-200 Zeiss microphotometer equipped with a MSP20 system processor on a Zeiss Axioplan ore microscope. The
filament temperature was approximately 3350 K. Readings weretaken for specimen and standard (SiC) maintained under thesame focus conditions. The diameter of the measuring area was
0.1 mm. Reflectance percentages for Rmin and Rmax in the range
400–700 nm in 20 nm increments are reported in Table 1. In
Figure 2 the reflectance percentages for mutnovskite together
with those measured by Shimizu et al. (1998) for tsugaruite,
Pb4As2S7, are plotted. The reflectance values for the two minerals
are almost identical, which shows the necessity of a chemical
analysis or diffraction study to distinguish between them.
The mutnovskite crystals are soft and fragile. Cleavage
and fracture were not observed and the Mohs hardness is approximately 2. The density could not be measured owing to thedearth of material and the small size of the crystals. The calcu-

lated density, obtained from the chemical formula and unit-cellparameters, is 6.177 g/cm3. Twinning was not observed in themorphological characteristics of crystals or in their optical properties. In addition, no indications of twinning were discovered
during the X-ray diffraction study.

CHEMICAL COMPOSITION
Four crystal fragments of mutnovskite were analyzed witha Jeol JXA-8600 electron microprobe at the Dipartimento di
Scienze della Terra, Università di Firenze. The operating conditions were: accelerating voltage 15 kV, beam current 20 nA;
standards (element, emission line, counting time for one spot
analysis): galena (PbMα, 20 s); marcasite (FeKα, 40 s; SKα,20 s); iodargyrite (ILα, 20 s); tugtupite (ClKα, 20 s); synthetic
GaAs (As second order Lα, 40 s); synthetic Bi2Se3 (BiMα, 40s; Se second order Lα, 40 s), covellite (CuKα, 40 s), pure Tl(TlMα, 40 s), and bromargyrite (Br second order Lα, 40 s). The
estimated analytical precision (in wt%) is: ± 0.60 for Pb, ± 0.50
for I; ± 0.30 for Bi, Cl, and Br; ± 0.20 for As and S; ± 0.10 for
Se; ± 0.05 for Fe, Cu, and Tl. The results of the analysis, theaverage chemical composition and the theoretical compositionin wt% of elements, are reported in Table 2. The valence balanceis rather good: deviations do not exceed about 2.9% in absolutevalue. Mutnovskite clearly contains minor Bi [up to 0.02 atoms
per formula unit (apfu)], Se (up to 0.11 apfu), and Br (up to
0.17 apfu) in addition to the major constituents Pb (1.94 to 2.01
apfu), As (0.94 to 1.01 apfu), S (2.93 to 3.01 apfu), Cl (0.44 to
TABLE 1. Reﬂectance measurements in air for mutnovskite
λ (nm)
Rmin (%)
Rmax (%)λ (nm)
Rmin (%)
Rmax (%)
400
39.2
44.1
560
32.9
33.1
420
38.6
39.4
580
32.7
32.8
440
36.5
37.6
589
32.5
32.7
460
35.3
36.2
600
32.2
32.5
470
34.2
34.6
620
31.9
32.1
480
33.9
34.2
640
31.7
31.9
500
33.7
34.0
650
31.4
31.7
520
33.6
33.8
660
31.2
31.4
540
33.4
33.6
680
30.9
31.0
546
33.2
33.5
700
30.7
30.8
Note: The four COM wavelengths at 470, 546, 589, and 650 are indicated in
bold.

46
44
42

R (%)

40
38
36
34
32
30
28
400

450

500

550

600

650

700

wavelength (nm)
FIGURE 1. Scanning electron photomicrograph of mutnovskite
crystals (BSE image). Needle-like crystals of Pb-Bi-As halogensulfosalts, which are currently under study, appear on the left.

F IGURE 2. Reflectivity curves for mutnovskite in air. Opensymbols refer to tsugaruite (Shimizu et al. 1998), filled symbols refer
to mutnovskite (this study). Circles and squares refer to Rmax and Rminvalues, respectively.

ZELENSKI ET AL.: MUTNOVSKITE, A NEW MINERAL FROM KAMCHATKA PENINSULA

23

TABLE 2. Chemical composition of mutnovskite (microprobe data, wt%) and empirical chemical formulas
No.
1
2
3
4
5
6
7
8

Pb
61.40
61.02
61.65
62.40
62.07
61.84
61.94
62.37

Fe
0.02
–
0.03
–
–
0.01
0.01

Cu
–
0.02
0.01
0.01
0.07
0.04
0.02
0.04

Bi
0.51
0.53
0.58
0.45
0.47
0.70
0.55
0.47

As
10.54
11.28
10.81
10.63
11.03
11.59
11.04
10.80

S
14.22
14.49
14.31
14.24
14.31
14.59
14.31
14.18

Se
0.70
0.55
0.38
1.33
–
–
0.33

Cl
2.62
2.41
2.45
2.44
2.63
2.53
2.48
2.31

I
9.06
9.04
8.86
8.90
8.32
8.72
8.69
9.39

Br
1.61
1.37
0.06
2.06
0.93
1.86
1.21
1.05

Total
99.98
100.8699.31
101.51101.16101.88100.28†100.95Val. %*
2.83
2.73
0.84
2.65
2.70
0.14
0.24
0.29

Average‡

61.95

0.01

0.03

0.58

11.06

14.35

0.22

2.44

8.92

1.05

100.61

1.50

Theoretical§
62.15
–
–
–
11.24
14.43
–
2.66
* Valence in % was calculated with formula : | [-(val+ ) – -(val– )] × 100/-(val– ) |.
† Includes 0.04 wt% Tl.
‡ Calculated from four selected analyses (No. 3, 6, 7, 8) with a good balance of valence (deviations less than 1.5%).
§ Calculated from the ideal formula : Pb2AsS3(I,Cl).

9.52

–

100.00

Empirical chemical formulas of selected analyses (based on 7 apfu):
3.
Pb2.00(As0.97Bi0.02Y0.99(S3.01Se0.05)Y3.06(I0.47Cl0.47Br0.01)Y0.95
6.
Pb1.96(As1.01Bi0.02Y1.03S2.99(I0.45Cl0.47Br0.15)Y1.07
7.
Pb2.00(As0.98Bi0.02Y1.00S2.98(I0.46Cl0.47Br0.10)Y1.03
8.
Pb2.01(As0.96Bi0.02Y1.00(S2.96Se0.03)Y2.99(I0.50Cl0.44Br0.09)Y1.03
Average empirical formulaPb1.99(As0.98Bi0.02Y1.00(S2.98Se0.02)Y3.00(I0.47Cl0.46Br0.09)Y1.02

0.49 apfu), and I (0.43 to 0.49 apfu). Traces of Fe, Cu, and Tl
were also detected. With a total of 7 apfu, as determined fromthe crystal structure solution, the empirical chemical formulas
for the best four determinations (balance of valence less than
1.5% in absolute value) were calculated and are reported in Table
2. The resulting average empirical formula for mutnovskite isPb1.99(As0.98Bi0.02)Σ=1.00(S2.98Se0.02)Σ=3.00(I0.47Cl0.46Br0.09)Σ=1.02, very
close to the ideal Pb2AsS3(I,Cl,Br).

X-RAY DIFFRACTION STUDY
X-ray powder diffraction
The X-ray powder pattern for the holotype (Table 3) was obtained using a 57.3
mm Debye-Sherrer camera (FeKα). Indexing of the reflections was performed on
the basis of the structure refinement, taking into account the calculated intensities.
The following orthorhombic unit-cell parameters were obtained by least squares
refinement: a = 11.544(4), b = 6.669(2), and c = 9.365(4) Å.

Structural determination and refinement
A small crystal fragment (34 × 54 × 72 μm) was selected for X-ray single-crystal
diffraction study. The X-ray data were collected using a Bruker AXS four-circle
diffractometer equipped with a CCD SMART1000 area detector and flat graphite
monochromator using MoKα radiation from a fine-focus sealed X-ray tube (Table
4). SMART (Bruker AXS 1998) software was used to determine the orientation of
the crystal lattice and for data collection; SAINT Plus (Bruker AXS 1997a) wasused to integrate intensities and for Lorentz-polarization correction and calculationof the final unit-cell parameters. For the empirical absorption correction (ellipsoid
approximation) the program XPREP from SHELXTL package (Bruker AXS 1997b)
was used. The Rint factor after the empirical absorption correction was 6.92% compared to 12.47% before the absorption correction. The minimum and maximum
X-ray transmission factors were 0.00901 and 0.04252, respectively.
Systematic absences (0kl: k + l = 2n; hk0: h = 2n; h00: h = 2n; 0k0: k = 2n;00l: l = 2n) were consistent with space groups Pn21a and Pnma. Statistical tests
on the distribution of |E| values strongly indicated the presence of an inversion
center, thus suggesting the choice of space group Pnma.
The crystal structure of mutnovskite was solved by direct methods using the
program SHELXS-97 (Sheldrick 1997a) and the subsequent structure refinement
proceeded by means of the full-matrix least-squares program SHELXL-97 (Sheldrick 1997b). Neutral scattering factors for Pb, As, I, Cl, and S were taken fromthe International Tables for X-ray Crystallography (Ibers and Hamilton 1974). The
solution revealed three cation sites. The As1 position was defined on the basis of
its threefold coordination and bond lengths, which were characteristic for As3+ in

TABLE 3. X-ray powder-diﬀraction data for mutnovskite
I/Io
5
7
7
32
67
12
12
73
100
10
19
61
66
31
29
26
5
22
22
16
19
30
11
15
15
13
10
8
11
18
13
9
15
5
6
7
17
15
6
10

d(obs)
5.770
5.440
4.930
4.690
4.370
3.970
3.620
3.340
3.190
2.890
2.763
2.715
2.648
2.539
2.455
2.294
2.234
2.180
2.123
1.976
1.914
1.894
1.849
1.814
1.780
1.760
1.730
1.715
1.666
1.634
1.621
1.589
1.572
1.505
1.474
1.455
1.425
1.395
1.380
1.335

d(calc)
5.772
5.433
4.914
4.682
4.365
3.956
3.636
3.335
3.193
2.886
2.746
2.716
2.649
2.539
2.457
2.294
2.236
2.182
2.125
1.978
1.916
1.897
1.849
1.814
1.780
1.761
1.728
1.715
1.667
1.633
1.622
1.591
1.571
1.507
1.474
1.454
1.425
1.395
1.380
1.333

h
2
0
2
0
2
2
2
0
2
4
2
0
4
2
4
1
1
4
4
4
3
2
6
6
3
4
2
3
0
3
5
6
0
1
5
3
7
8
4
5

k
0
1
0
0
1
1
0
2
1
0
0
2
1
1
0
0
2
2
2
2
1
3
1
1
3
3
3
2
4
1
2
1
4
1
2
4
1
1
4
2

l
0
1
1
2
0
1
2
0
2
0
3
2
0
3
2
4
3
0
1
2
4
2
0
1
2
0
3
4
0
5
3
3
2
6
4
2
3
1
2
5

sulfosalts. One anion site (X) showed an electron density higher than that of sulfur.
This site was refined as a mixed (I,Cl) position giving occupancies of 0.52 for I and0.48 for Cl. This corresponds to a mean number of electrons of 35.7, which is inexcellent agreement with the value obtained from the chemical data (35.9). Br was
not considered at the X site because of a very low content of this element relative
to the accuracy of the method. However, as the refinement suggested that I and Cl24

ZELENSKI ET AL.: MUTNOVSKITE, A NEW MINERAL FROM KAMCHATKA PENINSULA

occupy the same site in the structure, it is most probable that a significant amount of
Br can also enter, or even dominate at this site. As shown by the chemical analysis,
the mutnovskite samples contain only low amounts of Br, but this is evidently due
to the chemistry of the environment, and not to structural limitations. All attempts
to refine the occupancy of the Pb sites (Pb + As), the As site (As + Bi), and the
S sites (S + Se) produced values consistent with pure Pb, As, and S respectively.
Attempts to refine the coordinates of I and Cl in the X site independently from eachother resulted in an unstable refinement, and were abandoned.
The final refinement was performed with anisotropic temperature factors for
all the atoms. The refinement of the crystal structure of mutnovskite converged to
R = 4.14% for 753 observed reflections [Fo > 4σ(Fo)] and R = 5.63% for all 976
independent reflections.
Inspection of the difference Fourier map revealed maximum positive andnegative peaks of 2.04 and 3.23 e–/Å3, respectively. Crystal data, as well as details
about data collection and refinement, are summarized in Table 4. Fractional atomic
coordinates and anisotropic-displacement parameters are shown in Table 5. Table
61 lists the observed and calculated structure factors, while selected bond distances
and angles are shown in Table 7.
As the atomic displacement ellipsoid of Pb2 was more anisotropic than forother structural sites (elongated along [010]), and the sum of valences for this site
was significantly lower than the expected value of 2 (see Table 8), a refinement with
Pb2 moved out of the symmetry plane was attempted (split-Pb2 site). The displacement factor had to be kept isotropic in this case to avoid large correlation factors.

TABLE 4.

Crystal data and summary of parameters describing datacollection and reﬁnement for mutnovskite

Empirical chemical
formulaCrystal size (mm)Cell setting, space
group
a, b, c (Å)
V (Å3)Z
Dx (g/cm3)
Radiation
Temperature
Detector to sample
distance
Active detection-area
Resolution
Number of frames
Rotation width per frame
Measuring time
Maximum covered 2eUnique reﬂections
Reﬂections I > 2mI
Rint before absorption
correction
Rint after absorption
correction
Rm
Range of h, k, l

Crystal data
Pb1.99(As0.98Bi0.02)Y1.00(S2.98Se0.02)Y3.00(I0.47Cl0.46Br0.09)Y1.02
0.034 × 0.054 × 0.072
Orthorhombic, Pnma
11.543(1), 6.6764(7), 9.359(1)721.3(1)4
6.177
Data collection
MoK_ (graphite monochromator)
293 K
4 cm
6.25 × 6.25 cm2
512 × 512 pixels
2800
0.2°
60 s
56.58° (d = 0.75 Å)
976
753
0.12470.0692
0.042–15 ) h ) 15, –8 ) k ) 8, –12 ) l ) 11

DESCRIPTION OF THE CRYSTAL STRUCTURE
In the crystal structure of mutnovskite (Fig. 3) the Pb atoms
occupy two independent sites: Pb1 and Pb2. The coordinations ofboth Pb1 and Pb2 have the form of a distorted tricapped trigonal
prism, if the closest As atom is included in the coordination of
Pb2. Pb1 is coordinated by 6 S atoms (2.76–3.64 Å) and 3 I(Cl)atoms (3.35–3.57 Å), Pb2 by 6 S (2.91–3.45 Å) and 2 I(Cl)atoms (3.05–3.45 Å). One “missing” vertex in the Pb2 prism is
occupied by an As atom (Pb-As distance of 3.35 Å). Such short
Pb-As distances in crystal structures are not unusual. In the two
representatives from the apatite group, finnemanite (Effenberger
and Pertlik 1979) and mimetite (Dai et al. 1991), distances of 3.27
and 3.37 Å respectively are encountered. In sulfosalts, distancesof 3.37 Å are found in, e.g., wallisite (Takeuchi et al. 1968), anddufrenoysite (Marumo and Nowacki 1967).
Pb1-Pb2 prisms are paired on bases made up of two S andone I(Cl) atom, and these pairs connect in columns by sharing
an S-S edge with the other base for positions with As atoms. The
columns extend along c and are laterally connected through PbS bonds in layers parallel (100). The As atoms are in threefold
coordination with S atoms (As-S = 2.24–2.25 Å) occupying the
top of a trigonal pyramid with 3 S making a base. AsS3 coordinations are isolated from each other. The characteristics of the
As coordination polyhedra as well as those of the Pb atoms areillustrated in Table 8.
As mentioned above, the crystal structure has a layered
character with layers parallel to (100). The median plane of thelayers coincides with the n-glide planes. The backbone of eachlayer is formed by straight [010] rows of S1 atoms with an S1-S1
intrarow separation of 1/2 b (Figs. 4a and 4b). Attached to themon both sides of a layer are the Pb1-X and Pb2-S2 rows. The Pb1
atoms are backed by S2 atoms from the other side of the layer,
1

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Reﬁnement
R [Fo > 4m(Fo)]R (all data)wR (on Fo2)wR (all data)
Goof
Number of leastsquares parameters

The results showed splitting of the Pb2 site with a distance of 0.38 Å between thetwo possible positions on the two sides of the mirror plane. At the same time the
R factors were worse than for the non-split refinement (R1 = 4.89%), and the sumof the valences for the site did not improve significantly (1.77). It is interesting tonote that, if the bonding between Pb2 and the neighboring As atom is included in
the valence calculation, the sum for the Pb2 valence would be 1.91 (not-split) and1.95 (split) respectively. As described later, the As atom completes the coordination of Pb2 as the “missing vertex” of the trigonal prism, and this can explain thelower sum of valences if it is excluded. Because no significant improvement in thereliability factors or the crystal-chemical parameters is obtained with the “splitrefinement” and no evidence for the movement of Pb2 out of the mirror plane could
be obtained, the results of the former refinement were accepted as final.

0.04140.05630.0891
0.0922
1.25
41

TABLE 5. Fractional atomic coordinates and anisotropic displacement parameters (Å) for the crystal structure of mutnovskite
Site
Pb1
Pb2
As
X
S1
S2

x
0.37509(6)0.17188(7)0.9213(1)0.9544(1)0.2969(3)0.5985(4)

y
1/4
3/4
3/4
3/4
0.9998(4)1/4z0.19184(8)0.21713(9)0.0355(2)0.4017(2)0.4194(4)0.2968(5)U110.0342(4)0.0363(4)0.0199(7)0.0283(9)0.037(2)0.024(2)U220.0539(5)0.0817(6)0.0358(9)0.046(1)0.026(1)0.066(3)U33
0.0347(4)0.0355(5)0.0246(9)0.028(1)0.030(2)0.022(2)

U23
0
0
0
0
0.001(1)0U13–0.0073(3)–0.0052(3)–0.0013(6)–0.0017(7)–0.001(1)–0.004(2)

U12
0
0
0
0
0.002(1)0Ueq0.0409(2)0.0512(3)0.0268(4)0.0342(6)0.0310(6)0.038(1)ZELENSKI ET AL.: MUTNOVSKITE, A NEW MINERAL FROM KAMCHATKA PENINSULA

25

TABLE 7. Selected interatomic distances (Å) and angles (°) for mutnovskite
PB1
S2
S1
S1
S2
X
X
X
S1
S1

S2
2.760( 5)4.028( 5)4.028( 5)5.838( 7)3.749( 5)4.166( 3)4.166( 3)
6.007( 6)6.007( 6)S1
91.7( 1)2.853( 3)3.341( 4)3.483( 5)5.875( 4)3.887( 4)6.117( 3)5.849( 5)4.803( 5)S1
91.7( 1)71.7( 1)2.853( 3)3.483( 5)5.875( 4)6.117( 3)3.887( 4)4.803( 5)5.849( 5)S2
157.2( 1)
70.1( 1)70.1( 1)
3.194( 5)5.882( 5)5.383( 4)5.383( 4)3.361( 5)3.361( 5)CN: 9X
74.9( 1)
142.2( 1)
142.2( 1)
127.8( 1)
3.354( 2)
3.955( 1)
3.955( 1)
4.294( 4)4.294( 4)X
81.2( 1)73.5( 1)144.2( 1)
105.3( 1)
69.6( 0)3.570( 1)
6.676( 1)
6.023( 3)3.743( 4)X
81.2( 1)144.2( 1)
73.5( 1)105.3( 1)
69.6( 0)138.5( 1)
3.570( 1)
3.743( 4)6.023( 3)S1
139.4( 1)
128.3( 1)
94.7( 1)58.5( 1)75.7( 1)113.4( 1)
62.6( 1)
3.636( 4)3.336( 4)S1
2.906( 3)3.336( 4)4.294( 4)5.849( 5)4.803( 5)3.887( 4)5.865( 4)3.483( 5)S1
70.0( 1)2.906( 3)4.294( 4)4.803( 5)5.849( 5)3.887( 4)3.483( 5)5.865( 4)X
92.3( 1)92.3( 1)
3.047( 2)5.603( 4)5.603( 4)6.431( 2)
4.166( 3)4.166( 3)S1
142.5( 1)102.0( 1)
125.0( 1)
3.269( 4)3.341( 4)3.743( 4)3.361( 5)5.796( 4)CN: 8S1
102.0( 1)
142.5( 1)
125.0( 1)61.5( 1)
3.269( 4)3.743( 4)5.796( 4)3.361( 5)X
74.9( 1)74.9( 1)
164.3( 1)
67.7( 1)67.7( 1)3.445( 2)5.383( 4)5.383( 4)S2
134.6( 1)65.9( 1)79.6( 1)60.0( 1)
119.3( 1)
102.7( 1)
3.446( 1)
6.676( 1)S2
65.9( 1)134.6( 1)79.6( 1)
119.3( 1)60.0( 1)102.7( 1)
151.2( 1)
3.446( 1)

PB2
S1
S1
X
S1
S1
X
S2
S2

S1
139.4( 1)
94.7( 1)
128.3( 1)
58.5( 1)75.7( 1)62.6( 1)113.4( 1)
54.6( 1)
3.636( 4)

AS

CN: 3
S1
S1
S2
S1
2.241( 3)
96.2( 2)97.0( 1)
S1
3.336( 4)2.241( 3)97.0( 1)
S2
3.361( 5)3.361( 5)2.245( 5)Note: The values in diagonals (bold) are the central atom-ligand distances; the bond angles are given in the upper-right triangle and the ligand-ligand distances
are given in the lower left.

TABLE 8. Coordination parameters* for the cation sites of mutnovskite
Site
Coordination
<d>
d min
d max
Vs
ECCL
SPHL
Vp
p
valencePb1
6S+3X
3.3(4)
2.760(5)3.336(4)142.935
0.16450.947967.1(1)0.0381
2.07
Pb2
6S+2X
3.2(2)
2.906(3)3.446(1)140.0640.07900.945850.2(1)0.1731
1.73
As
3S
2.243(3)2.241(3)2.245(5)30.37
0.58521––
3.15
Notes: <d> = average bond distance, Vs = volume of the circumscribed sphere, ECCL = linear eccentricity of the coordination, SPHL = linear sphericity of the coordination, Vp = volume of the coordination polyhedron, p = volume distortion.
* The polyhedron parameters for atomic coordinations are deﬁned by Balić-Žunić and Makovicky (1996) and Makovicky and Balić-Žunić (1998). All calculations
were done using IVTON (Balić-Žunić and Vicković 1996).

while the Pb2 atoms are in the same way backed by X atoms, inaccordance with the n-glide symmetry of the layer. In this way
the Pb atoms reside in a half-cavity formed by 5S +2X (Pb1)or 6S+1X (Pb2). Arsenic atoms “ride” on each S2 atom and are
additionally bonded to the two nearest S1 atoms.
The centers of symmetry and 21 axes (parallel to b) are situated between the layers. These are mutually attached in such a
way that the Pb1-X rows from one layer face the Pb2-S2 rows
from the adjacent one, mutually displaced so that Pb atoms fromone layer face S and X atoms from the other (Fig. 4c). The rowsof As atoms from one layer face As rows from the adjacent one,but due to the mutual 1/2 b displacement the As lone-electron
pairs point into empty interspaces between the As atoms of theadjacent layer. The coordination of Pb1 is completed to CN9by the bonds made to S2 and X from the neighboring layer,
whilst Pb2 forms only one additional bond (to X) and faces thelone-electron pair of As from the adjacent layer. Although there
is no short interlayer As-S bond, the structure does not have awell-expressed layer character due to the fact that the shortest
Pb-S and Pb-X bonds are interlayer bonds.
The superposition of layers brings together the two Pb1X rows from adjacent layers, which are surrounded from all
sides by the framework of S and Pb2 atoms (Fig. 5). The latter

framework consists of wavy closed-packed layers parallel to(100). Due to the wavy character of these layers the two types ofchannels running parallel to [010] are formed in the interlayers.
In the smaller ones As atoms bonded to S atoms make up thewalls of the channel, with the lone-electron pairs of As pointing
inside the channel. The bigger ones each host two Pb1-X rows,
as shown in Figure 5.

DISCUSSION
Mutnovskite is the first example of a multi-component sulfosalt where halogens (I, Cl, Br) act as essential constituents
together with sulfur, lead, and arsenic. The presence of Cl iswell known among natural halogen-bearing sulfosalts (ardaite,
Pb10Sb6S17Cl4 = Breskovska et al. 1982; dadsonite, Pb23Sb25S60Cl= Moëlo 1979; pillaite, Pb9Sb10S23ClO0.5 = Orlandi et al. 2001;
pellouxite, (Cu,Ag)2Pb21Sb23S55ClO = Orlandi et al. 2004; vurroite, Pb20Sn2(Bi,As)22S54Cl6 = Garavelli et al. 2005). Less usualis the presence of minor Br substituting for Cl, which has only
been reported in the recently approved halogen-sulfosalt vurroite (Garavelli et al. 2005). The most interesting feature is thepresence of iodine in mutnovskite. The occurrence of I together
with Cl and Br is quite common among mercury halogen-sulfidesof the corderoite-arzakite and capgaronnite-perroudite groups

26

ZELENSKI ET AL.: MUTNOVSKITE, A NEW MINERAL FROM KAMCHATKA PENINSULAFIGURE 3. The crystal structure of mutnovskite
projected on (010). Blue circles: Pb atoms; redcircles: As atoms; light blue circles: X sites(I,Cl,Br); yellow circles: S atoms. The unit cell
is displaced by –1/2a, –1/2b, –1/2c. Dark dashedlines: limits of layers parallel to (100); red dashedlines: connection from Pb2 to As, which forms
the “missing” vertex of the prism. A column of
Pb1 and Pb2 trigonal prism is shaded on the lefthand side.

FIGURE 4. The (100) layers in the structure of mutnovskite. The anions are expanded to show the packing. Light blue: X sites (I,Cl,Br); orange:
S1 atoms; yellow: S2 atoms; dark-blue: Pb atoms; red: As atoms. (a) A view parallel to b; (b) a layer projected on the (100) plane; (c) a superpositionof the Pb, As, X, and S2 atoms from the adjacent layer.

(Strunz and Nickel 2001), but certainly it is original among sulfosalts. The presence of iodine in mutnovskite makes this newmineral the first representative of a new mineralogical class: theI-bearing sulfosalts.
According to both the chemical composition and X-ray
powder data, the mineral has no analogues among minerals orsynthetic compounds. With the exception of the halogen content,

the chemical composition of mutnovskite is close to the mineral
tsugaruite, Pb4As2S7 (Shimizu et al. 1998). Compositionally, thesubstitution 2(I,Cl,Br) → S in tsugaruite would give the formulaof mutnovskite Pb2AsS3(I,Cl,Br). The strong compositional
similarity between the two minerals explains the resemblancein reflectance values and some other physical properties.
In the depositional environment, mutnovskite can be assumed

ZELENSKI ET AL.: MUTNOVSKITE, A NEW MINERAL FROM KAMCHATKA PENINSULA

27

FIGURE 5. The [010] channels in the crystal structure of mutnovskite. Light blue: X sites (I,Cl,Br); yellow: S atoms; dark-blue: Pb atoms; red:
As atoms. (a) Pb1- X rows and columns of S atoms along [010]; (b) a view along the channels showing the smaller channels which accommodate
the lone-electron pairs of As, and the larger ones which host the halogen and Pb1 atoms inside the framework of the wavy close-packed layers of
S and Pb2 atoms.

to form according to the reaction: 2AsS + 4PbS + ½O2 + 2HX→ 2Pb2AsS3X + H2O, with X = I, Cl, Br. This is confirmed by
the presence of PbS and As-I-S compounds among sublimates
deposited on the inner walls of silica tubes inserted in high-temperature fumarole vents at the Mutnovsky volcano (Zelenski and
Bortnikova 2005). The presence of halogens in fluids discharging
from fumaroles, as well as their role in the transport of the metals
and in the deposition of sulfosalt minerals, has been amply discussed in the literature (Quisefit et al. 1989; Symonds et al. 1987,
1992; Symonds and Reed 1993; Garavelli et al. 1997; Cheynet etal. 2000). In fluids discharging from active volcanoes Cl and Br
are the most abundant halogens whilst iodine is rarely found. In
volcanic gases from the Mutnovsky volcano the halogen concentrations range as follows: Cl 2800–4800 ppm, Br 3.7–6.00 ppm,
and I 0.35–1.7 ppm (Zelenski and Bortnikova 2005). In fumarole
environments, especially Cl, but also Br, generally play the double
role of carrier for the metals and catalyst in the reactions involving
sulfosalts. The use of iodide as a catalyst and as a transport medium
during synthesis experiments in the laboratory is well known. Several sulfo-iodides with bismuth and some other metals have beenobtained from such syntheses as, e.g., (Pb1–x,Bix)Bi2Cu2Cu2–xS5I2(Ohmasa and Mariolacos 1974), Cu4–x Pb1–xBi2+xS5I2 (Mariolacos
2004), Cu0.507(5)Pb8.73(9)Sb8.15(8)I1.6S20.0(2) (Kryukova et al. 2005), andCu3Bi2S3I3 (Baliþ-Žuniþ et al. 2005). The presence of iodine inmutnovskite suggests that this element, in addition to chlorine andbromine, could play a significant role in the transport of metals andin the condensation processes of sulfosalts in natural environmentswith a high partial-pressure of halogens.
Mutnovskite contains traces of Se (up to 1.33 wt%); thepresence of this element is ascribed to the high Se content of
the fluids discharging from the fumarole vents and it is a common feature of sulfosalts deposited in contemporary epithermal
deposits connected to active volcanoes (Borodaev et al. 1998;
Vurro et al. 1999; Borodaev et al. 2000, 2001, 2003; Garavelli
et al. 2005).

In the depositional environment, mutnovskite occurs commonly interspersed with needle-like crystals of less characterized
Pb-Bi-As sulfosalts and occasionally with the Cd-bearing Pb-Bi
sulfosalts kudriavite and Cd-cannizzarite.
The sequence of deposition observed in all the samples
analyzed (greenockite-kudriavite and Cd-cannizzarite-Pb-Bi-As
sulfosalts-mutnovskite) suggests a strong relationship between
temperature and sulfosalts deposition at the Mutnovsky volcano.
At high temperature (480 °C) the most abundant sulfosalt isgreenockite, while mutnovskite occurs at quite a low temperature(250 °C). The Cd-bearing sulfosalts kudriavite and Cd-cannizzarite and Pb-Bi-As sulfosalts occur at intermediate temperature
values. This evidence is in contrast with the condition of deposition observed in the actual epithermal deposit of the La Fossa
crater of Vulcano, Aeolian Islands, Italy (Garavelli et al. 2005;
Borodaev et al. 2003). This latter deposit is characterized by asulfosalt assemblage which is very similar to that occurring at
the Mutnovsky volcano, but no relevant paragenetic sequenceof deposition could be observed. The discrepancy between thetwo fumarole deposits could be explained with a more stablechemical composition, temperature, and flux rate of the fumarole
fluids discharging from the Mutnovsky volcano with respect tothe fluids emitted from Vulcano fumaroles, the latter which havebeen found to change instantaneously (Borodaev et al. 2003).

ACKNOWLEDGMENTS
The authors thank Y. Moëlo and a second anonymous referee for their helpfulcomments which improved the quality of the paper. We are indebted also to Associate Editor S. Quartieri, for her work. We thank A. Mokhov (IGEM, Moscow,
Russian Federation) for assistance with the SEM investigations, A. Tsepin (IGEM,
Moscow, Russian Federation), and F. Olmi (CNR, Istituto di Geoscienze e Georisorse, sezione di Firenze) for their assistance with the electron microprobe work.
Y. Soejima (Kyushu University, Japan) is gratefully acknowledged for his help
with the reflectance measurements. This research was performed with financial
support from MIUR (Ministero dell·Istruzione, dell·Università e Ricerca, Italy),
CoFin 2003, project “Mineralogical and crystal-chemical investigations on lead,bismuth, and arsenic sulfosalts, and secondary metal minerals,” and from the Danish
Research Council of Natural Science, project number 21.03.05.19.

28

ZELENSKI ET AL.: MUTNOVSKITE, A NEW MINERAL FROM KAMCHATKA PENINSULAREFERENCES CITEDBaliþ-Žuniþ, T. and Makovicky, E. (1996) Determination of the centroid or “the best
centre” of a coordination polyhedron. Acta Crystallographica, B52, 78–81.
Baliþ-Žuniþ, T. and Vickoviþ, I. (1996) IVTON— Program for the calculation ofgeometrical aspects of crystal structures and some crystal chemical applications. Journal of Applied Crystallography, 29, 305–306.
Baliþ-Žuniþ, T., Mariolacos, K., and Makovicky, E. (2005) Crystal structureof a synthetic halogen-sulfosalt, Cu3Bi2S3I3. Acta Crystallographica, B61,
239–245.
Borodaev, Y.S., Garavelli, A., Kuzmina, O.V., Mozgova, N.N., Organova, N.I.,
Trubkin, N.V., and Vurro, F. (1998) Rare sulfosalts from Vulcano, Aeolian
Islands, Italy. I. Se-bearing kirkiite, Pb10(Bi,As)6(S,Se)19. Canadian Mineralogist, 36, 1105–1114.
Borodaev, Y.S., Garavelli, A., Garbarino, C., Grillo, S.M., Mozgova, N.N., Organova, N.I., Trubkin, N.V., and Vurro, F. (2000) Rare sulfosalts from Vulcano,Aelian Islands, Italy. III. Wittite and Cannizzarite. Canadian Mineralogist,38, 23–34.
Borodaev, Y.S., Garavelli, A., Garbarino, C., Grillo, S.M., Mozgova, N.N., Uspenskaya, T.Y., and Vurro, F. (2001) Rare sulfosalts from Vulcano, Aeolian Islands,
Italy. IV. Lillianite. Canadian Mineralogist, 39, 1383–1396.
Borodaev, Y.S., Garavelli, A., Garbarino, C., Grillo, S.M., Mozgova, N.N., Paar
W.H., Topa, D., and Vurro, F. (2003) Rare sulfosalts from Vulcano, Aeolian Islands, Italy. V. Selenian Heyrovskýite. Canadian Mineralogist, 41, 429–440.
Breskovska, V.V., Mozgova, N.N., Bortnikov, N.S., Gorshov, A.I., and Tsepin,
A.I. (1982) Ardaite—a new lead-antimony chlorosulphosalt. Mineralogical
Magazine, 46, 357–361.
Bruker AXS (1997a) SAINT Plus, Version 6.02/NT—Bruker Analytical X-ray
Systems, Inc. Madison, Wisconsin 53719, U.S.A.
——— (1997b) SHELXTL, Version 5.1. — Bruker Analytical X-ray Systems,
Inc. Madison, Wisconsin 53719, U.S.A.
——— (1998) SMART, Version 5.1. — Bruker Analytical X-ray Systems, Inc.
Madison, Wisconsin 53719, U.S.A.
Cheynet, B., Dall·Aglio, M., Garavelli, A., Grasso, M.F., and Vurro, F. (2000)
Trace elements from fumaroles at Vulcano Island (Italy): rates of transport
and a thermochemical model. Journal of Volcanology and Geothermal Research, 95, 273–283.
Dai, Y.-S., Hughes, J.M., and Moore, P.B. (1991) The crystal structures of mimetiteand clinomimetite, Pb5(AsO4)3Cl. Canadian Mineralogist, 29, 369–376.
Effenberger, H. and Pertlik, F. (1979) Die Kristalstruktur des Finnemanits,
Pb 5Cl(AsO 3) 3 mit einem Vergleich zum Strukturtyp des Chlorapatits,
Ca5Cl(PO4)3. Tschermaks Mineralogische und Petrographische Mitteilungen,26, 95–107.
Garavelli, A., Laviano, R., and Vurro, F. (1997) Sublimate deposition from hydrothermal fluids at the Fossa crater—Vulcano, Italy. European Journal of
Mineralogy, 9, 423–432.
Garavelli, A., Mozgova, N.N., Orlandi, P., Bonaccorsi, E., Pinto, D., Moelo,Y., and Borodaev, Y. (2005) Rare sulfosalts from Vulcano, Aeolian Islands,
Italy. VI. Vurroite, Pb20Sn2(Bi,As)22S54Cl6, a new mineral species. Canadian
Mineralogist, 43, 703–711.
Ibers, J.A. and Hamilton, W.C., Eds. (1974) International Tables for X-ray Crystallography, vol. IV, 366 p. Kynock, Dordrecht, The Netherlands.
Kryukova, G N., Heuer, M., Wagner, G., Doering, T., and Bente, K. (2005)
Synthetic Cu0.507(5)Pb8.73(9)Sb8.15(8)I1.6S20.0(2) nanowires. Journal of Solid State
Chemistry, 178, 376–381.
Makovicky, E. and Baliþ-Žuniþ, T. (1998): New measure of distortion for coordination polyhedra. Acta Crystallographica, B54, 766–773.

Mariolacos, K. (2004) Single crystal synthesis of higher-order sulfohalogenides inthe temperature gradient: Bi19S27Br3, Bi2Cu3S4Br, Pb1–xBi2+xCu4–xS5I2. Material
Research Bulletin, 39, 591–598.
Marumo, F. and Nowacki, W. (1967) The crystal structure of dufrenoysite,
Pb16As16S40. Zeitschrift für Kristallographie, 124, 409–419.
Moëlo, Y. (1979) Quaternary compounds in the system Pb-Sb-S-Cl: dadsonite andsynthetic phases. Canadian Mineralogist, 17, 595–600.
Ohmasa, M. and Mariolacos, K. (1974) The crystal structure of (Pb1–x,Bix)Bi2Cu2Cu2–
xS5I2 (x = 0.88). Acta Crystallographica, B30, 2640–2643.
Orlandi, P., Moëlo, Y., Meerschaut, A., and Palvadeau, P. (2001) Lead-antimony
sulfosalts from Tuscany (Italy). III. Pillaite, Pb9Sb10S23ClO0.5, a new Pb-Sb
chloro-sulfosalt, from Buca della Vena mine. European Journal of Mineralogy, 13, 605–610.
Orlandi, P., Moëlo, Y., Meerschaut, A., Palvadeau, P., and Léone, P. (2004) Leadantimony sulfosalts from Tuscany (Italy). VI. Pellouxite, ∼ (Cu,Ag)2Pb21Sb23
S55ClO, a new oxy-chloro-sulfosalt, from Buca della Vena mine, Apuan Alps.
European Journal of Mineralogy, 16, 839–844.
Quisefit, J.P., Toutain, J.P., Bergametti, G., Javoy, M., Cheynet, B., and Person,
A. (1989) Evolution versus cooling of gaseous volcanic emissions from
Momotombo Volcano, Nicaragua: Thermochemical model and observations.
Geochimica and Cosmochimica Acta, 53, 2591–2608.
Sheldrick, G.F. (1997a) SHELXS-97. A program for automatic solution of crystal
structures. University of Göttingen, Germany.
——— (1997b) SHELXL-97. A program for crystal structure refinement. University of Göttingen, Germany.
Shimizu, M., Miyawaki, R., Kato, A., Matsubara, S., Matsuyama, F., and Kiyota, K.
(1998) Tsugaruite, Pb4As2S7, a new mineral species from the Yunosawa mine,
Aomori Prefecture, Japan. Mineralogical Magazine, 62, 793–799.
Strunz, H. and Nickel, E.H. (2001) Strunz Mineralogical Tables. ChemicalStructural Mineral Classification System, 9th ed., 870 p. Schweizerbart Edit.,
Stuttgart, Germany.
Symonds, R.B. and Reed, M.H. (1993) Calculation of multicomponent chemical
equilibria in gas-solid-liquid systems: calculation methods, thermochemical
data and applications to studies of high-temperature volcanic gases with examples from Mount St. Helens. American Journal of Science, 293, 758–864.
Symonds, R.B., Rose, W.I., Reed, M.H., Lichte, F.E., and Finnegan, D.L. (1987)
Volatilization, transport and sublimation of metallic and non-metallic elements
in high- temperature gases at Merapi Volcano, Indonesia. Geochimica et Cosmochimica Acta, 51, 2083–2101.
Symonds, R.B., Reed, M.H., and Rose, W.I. (1992) Origin, speciation and fluxesof trace-element gases at Augustine volcano, Alaska: Insights into magma
degassing and fumarolic processes. Geochimica et Cosmochimica Acta, 56,
633–657.
Takeuchi, Y., Ohmasa, M., and Nowacki, W. (1968) The crystal structure of wallisite, PbTlCuAs2S5, the Cu-analoge of hatchite, PbTlAgAs2S5. Zeitschrift fürKristallographie, 127, 349–365.
Vurro, F., Garavelli, A., Garbarino, C., Moëlo, Y., and Borodaev, Y.S. (1999) Raresulfosalts from Vulcano, Aeolian Islands, Italy. II. Mozgovaite PbBi4(S,Se)7, a
new mineral species. Canadian Mineralogist, 37, 1499–1506.
Zelenski, M.E. and Bortnikova, S. (2005) Sublimate speciation at Mutnovsky
volcano, Kamchatka. European Journal of Mineralogy, 17, 107–118.

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