A New Mineral Hanauerite, AgHgSI, and Common Crystal Chemical Features of Natural Mercury Sulphohalides

Igor V. Pekov; Natalia V. Zubkova; Sergey N. Britvin; Atali A. Agakhanov; Yury S. Polekhovsky; Dmitry Y. Pushcharovsky; Gerhard Möhn; Joy Desor; Günter Blass

doi:10.3390/cryst13081218

,

and

¹

Faculty of Geology, Moscow State University, Vorobievy Gory, 119991 Moscow, Russia

²

Institute of Earth Sciences, St. Petersburg State University, University Emb. 7/9, 199034 St. Petersburg, Russia

³

Nanomaterials Research Center, Kola Science Center, Russian Academy of Sciences, 184209 Apatity, Russia

⁴

Fersman Mineralogical Museum of the Russian Academy of Sciences, Leninsky Prospekt 18-2, 119071 Moscow, Russia

Crystals2023, 13(8), 1218;https://doi.org/10.3390/cryst13081218

This article belongs to the Special Issue Mineralogical Crystallography (3rd Edition)

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Abstract

A new mineral, hanauerite, ideally AgHgSI, was found in the oxidation zone of Ag- and Hg-bearing ores at two old, abandoned mines in Rhineland-Palatinate, Germany. In a holotype specimen originating from the Schöne Aussicht Mine, Dernbach, Westerwald, it is associated with plumbogummite–hinsdalite series of minerals and goethite. In cotype from the Friedrichssegen Mine, Bad Ems, it is associated with perroudite, goethite, and quartz. At both localities, hanauerite occurs as a prismatic crystal up to 0.15 mm long and up to 0.02 mm thick. The mineral is yellow, transparent, with an adamantine lustre. It is brittle, and cleavage was not observed. The calculated density values are 6.671 and 6.575 g cm⁻³ for holotype and cotype, respectively. The empirical formulae calculated (from electron microprobe data) based on the sum of all atoms = 4 apfu are Ag_0.95Hg_1.00S_1.01(I_0.83Br_0.19Cl_0.03)_Σ1.05 for holotype and Ag_0.97Hg_0.97S_1.05(I_0.76Br_0.25)_Σ1.01 for cotype. Hanauerite is orthorhombic, space group Pmma; the unit cell parameters (from single-crystal X-ray diffraction data; holotype/cotype) are: a = 9.932(2)/9.9256(8), b = 4.6219(19)/4.6209(2), c = 9.891(4)/9.9006(4) Å, V = 454.0(3)/454.19(5) Å³, and Z = 4. The crystal structure was studied on single crystals extracted from both holotype and cotype specimens; R1 = 0.0416 (holotype) and =0.0544 (cotype). In hanauerite, Hg²⁺ cations centre strongly distorted octahedra with two short Hg–S bonds (Hg and S atoms build “crankshaft-type” chains) and four strongly elongated Hg–I bonds. The Hg-centred octahedra are connected via common edges and faces to form corrugated layers; Ag⁺ cations are located between these layers. Hanauerite is named in honour of the German mineral collector Dr. Alfred Hanauer (1912–1988). The common crystal chemical features of mercury sulphohalide minerals are discussed.

Keywords:

hanauerite; new mineral; silver mercury sulphide iodide; mercury sulphohalide; crystal structure; oxidation zone of ore deposit; Schöne Aussicht Mine; Friedrichssegen Mine

1. Introduction

Natural mercury sulphohalides compose a specific—in terms of both geochemistry and crystal chemistry—family of minerals. They form in the oxidation zone of ore deposits containing primary Hg-bearing minerals, the most commonly found cinnabar- or/and Hg-enriched fahlore. Besides mercury, these minerals can effectively concentrate such scattered-in-nature elements as bromine and iodine. This family contains ten mineral species and can be subdivided to two sub-families. One of them consists of six minerals with the general formula Hg₃S₂Hal₂ (Hal = halogen: Cl, Br, I), namely three polymorphs of Hg₃S₂Cl₂ (corderoite [], lavrentievite [,], and kenhsuite []); dimorphous arzakite [,] and grechishchevite [,,], with the ideal end-member formula Hg₃S₂Br₂; and radtkeite Hg₃S₂ICl [,,]. The second sub-family contains four sulphohalide minerals with both Hg and Ag as metal cations: dimorphs of AgHgSCl (capgaronnite [] and iltisite []); perroudite, Ag₄Hg₅S₅(I,Br)₂Cl₂ [,,]; and a recently discovered hanauerite, AgHgSI, first described in the present paper. Hanauerite is related to capgaronnite and iltisite in stoichiometry, their chemical analogue being species-defining I instead of Cl; however, these three Ag–Hg sulphohalides strongly differ from each other in symmetry, unit cell dimensions, and powder X-ray diffraction patterns that reflect the structure differences.

The type specimens of hanauerite were collected from two old, abandoned mines located in Rhineland-Palatinate, Germany. The holotype specimen, for which electron microprobe analyses (EMPA), optical data, single-crystal and powder X-ray diffraction (XRD) data were obtained and crystal structure was determined, originates from the Schöne Aussicht Mine, Dernbach, Neuwied, Wied Iron Spar District, Westerwald. The locality of the cotype specimen, for which EMPA and single-crystal XRD data were obtained and crystal structure was determined, is the Friedrichssegen Mine, Frücht, Bad Ems District, Lahn valley.

The new mineral is named in honour of the prominent German mineral collector Dr. Alfred Hanauer (1912–1988). He was a pioneer in the collecting of micromounts in Germany and Central Europe in the early 1960s. Dr. Hanauer collected at the Schöne Aussicht Mine the specimens in which the mineral described here was first found.

Both the new mineral and its name have been approved by the IMA Commission on New Minerals, Nomenclature and Classification (IMA2018–045) []. The type specimens of hanauerite are deposited in the systematic collection of the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow, with the catalogue numbers 96264 (Schöne Aussicht Mine) and 96265 (Friedrichssegen Mine).

2. Materials and Methods

2.1. Occurrence, General Appearance, and Physical Properties

Hanauerite is a secondary, supergene mineral formed in the oxidation zone of the complex sulphide ores containing primary silver and mercury sulphide mineralization. At both localities, the new mineral occurs as isolated prismatic crystals, elongated along [010], up to 0.15 mm long and up to 0.02 mm thick in cavities of the oxidized ores. The crystal faces belonging to the {h0l} zone are major and the pinacoid {010} is the major form on terminations. At the Schöne Aussicht Mine, hanauerite is associated with plumbogummite–hinsdalite series minerals in cavities of goethite (limonite) aggregates (Figure 1 and Figure 2). At the Friedrichssegen Mine, hanauerite occurs in association with perroudite, goethite, and quartz.

Figure 1. Prismatic crystals of hanauerite on crusts consisting of sharp rhombohedral plumbogummite crystals. Schöne Aussicht Mine. SEM (SE) images.

Figure 2. Yellow prismatic crystals of hanauerite on goethite and aggregates of greenish-yellow rhombohedral plumbogummite crystals. Schöne Aussicht Mine. FOV width: (a)—1.2 mm, (b)—0.35 mm.

The general mineralogical data for the Schöne Aussicht Mine and the Friedrichssegen Mine are reported in [] and [], respectively.

Fresh hanauerite from both localities is yellow; however, like some other silver or mercury halides, it is photosensitive and darkens after exposure to strong light (especially under sunlight), becoming almost black. Hanauerite has an adamantine lustre; fresh crystals are transparent, whereas altered under light crystals are semi-transparent to almost opaque. The mineral is brittle, cleavage or parting was not observed, the fracture is uneven. The density values calculated using the empirical formulae are 6.671 and 6.575 g cm⁻³ for holotype and cotype, respectively. The difference is caused by different I:Br ratios (see below).

2.2. Methods

Optical studies. The reflectance values for hanauerite were measured by means of the MSF-21 microspectrophotometer (LOMO, St. Petersburg, Russia) using the SiC standard (Zeiss, No. 545).

EMPA. For the determination of chemical composition, hanauerite crystals were embedded into epoxy resin, polished and coated with carbon film. Electron microprobe data were obtained by means of a JEOL Superprobe JCXA-733 instrument. Quantitative analyses were performed in wavelength-dispersive mode under accelerating voltage of 20 kV, beam current 10 nA and beam diameter 5 μm. The following standards were used: Ag₂Te (Ag), HgTe (Hg), ZnS (S), atacamite (Cl), TlBr (Br), and CuI (I). The contents of other elements with atomic numbers higher than carbon were below detection limits.

Powder XRD data were obtained using a Rigaku RAXIS Rapid II diffractometer (curved image plate, Debye-Scherrer geometry, r = 127.4 mm, CoKα, rotating anode with microfocus optics, 40 kV, 15 mA, exposure 15 min). Data conversion was performed by means of osc2xrd programme [].

Single-crystal XRD studies were carried out using a Bruker Kappa APEX DUO diffractometer for the holotype specimen and using an Xcalibur S diffractometer for the cotype specimen of hanauerite. Both diffractometers are equipped with CCD detectors, and MoKα radiation was used in both cases. The crystal structures were solved via direct methods. Data collection and structure refinement details are summarized and discussed below, in Section 3.3.

Attempts to measure the micro-indentation hardness value were unsuccessful because hanauerite crystals are tiny and brittle (and not embedded in a rock matrix) that causes the cracking during the indentation of the Vickers diamond pyramid. Density could not be measured because crystals are too small for volumetric methods and because of the lack of heavy liquids of necessary density.

3. Results

3.1. Optical Data

Under the microscope in reflected light, the holotype hanauerite is grey, and pleochroism was not observed. Bi-reflectance is very weak, ΔR = 1.1% (589 nm). Anisotropism is weak. Internal reflections were not observed. The reflectance values are given in Table 1.

Table 1. The reflectance data of hanauerite from the Schöne Aussicht Mine.

3.2. Chemical Composition

The chemical composition of hanauerite in wt.% is given in Table 2.

Table 2. Chemical composition of hanauerite.

The empirical formulae calculated on the sum of all atoms = 4 apfu are:

holotype (Schöne Aussicht Mine): Ag_0.95Hg_1.00S_1.01(I_0.83Br_0.19Cl_0.03)_Σ1.05;
cotype (Friedrichssegen Mine): Ag_0.97Hg_0.97S_1.05(I_0.76Br_0.25)_Σ1.01.

The simplified formula of hanauerite can be written as AgHgS(I,Br). The idealized, end-member formula AgHgSI requires Ag 23.08, Hg 42.91, S 6.86, I 27.15; total 100 wt%.

3.3. X-ray Crystallography and Crystal Structure Determination

Powder XRD data of the holotype hanauerite are given in Table 3. The orthorhombic unit cell parameters calculated from the powder data are: a = 9.931(2), b = 4.622(1), c = 9.909(3) Å, and V = 454.8(3) Å³. The calculations of intensities (I_calc in Table 3) were performed using a standard STOE WinXPOW programme.

Table 3. Powder X-ray diffraction data (d in Å) of hanauerite from the Schöne Aussicht Mine.

The crystal structure was studied on single crystals for both holotype and cotype specimens of hanauerite. The structures were solved in the frame of the orthorhombic space group Pmma via direct methods and refined with the use of SHELX software package [] and to R = 0.0416 on the basis of 607 independent reflections with I > 2σ(I) (holotype) and to R = 0.0544 on the basis of 635 independent reflections with I > 2σ(I) (cotype). Crystal data and details on data collection and structure refinement are given in Table 4, coordinates and equivalent thermal displacement parameters of atoms in Table 5, and selected interatomic distances in Table 6. Crystallographic information files (CIFs) are available as Supplementary Materials.

Table 4. Crystal data, data collection information, and structure refinement details of hanauerite.

Table 5. Coordinates and equivalent displacement parameters (U_eq, in Å²) of atoms, site multiplicities (Q), and site occupancy factors (s.o.f.) of hanauerite. Data for the sample from the Friedrichssegen Mine are given in the first line of each row and data for the sample from the Schöne Aussicht Mine in the second line of each row.

Table 6. Selected interatomic distances (Å) in the structure of hanauerite.

4. Discussion

4.1. Crystal Structure of Hanauerite

The crystal structure of hanauerite (Figure 3) is very close to those known for its synthetic analogue AgHgSI and isostructural compounds CuHgSeBr and AgHgSBr [], as well as HT phases CuHgSCl [] and CuHgSBr []. These synthetic compounds crystallize in the same orthorhombic space group Pmma and are close to hanauerite in unit cell dimensions. Two crystallographically non-equivalent Hg sites are present in the structure of hanauerite (as well as in the abovementioned synthetic compounds) and each Hg²⁺ cation forms covalent bonds with two sulphur atoms. The parameters of these bonds are as follows: distances 2.366(5) Å for both Hg sites and S–Hg–S angles 171.2° for Hg(1) and 180.0° for Hg(2) (cotype) and Hg(1)–S 2.372(4) Å and Hg(2)–S 2.363(4) Å and S–Hg–S angles 171.1° for Hg(1) and 180.0° for Hg(2) (holotype). Hg and S atoms form “crankshaft-type” chains along the a axis (Figure 4). The coordination environment of Hg atoms is complemented by elongated Hg–I bonds (Table 6). Thus, distorted Hg-centred octahedra are formed (Figure 5). Both I(1) and I(2) sites are iodine-dominant; the refined I:Br ratios are I_0.54Br_0.46 for the I(1) site and I_0.97Br_0.03 for the I(2) site (cotype) and I_0.57Br_0.43 for the I(1) site and I_0.94Br_0.06 for the I(2) site (holotype; minor Cl impurity was ignored during the refinement), both resulting in the total I:Br ratio of 3:1 that is in good agreement with electron microprobe data (Table 2). Hg(2)-centred octahedra share I(1)–I(1) edges to form the (001) layers, while Hg(1)-centred octahedra share I(1)–I(2) common edges to form the chains running along [010]. The chains are connected with the corrugated octahedral layers via common faces of octahedra from both sides of each layer (Figure 6). Ag⁺ cations are located between the octahedral layers in hanauerite. Unlike synthetic compounds AgHgSI and AgHgSBr [], the Ag site in both structurally studied samples of hanauerite is split into two subsites labelled as Ag’ and Ag” (Table 5). The Ag’–Ag” distance is 0.52 Å in the cotype and 0.70 Å in the holotype sample. Their occupancy factors are approximately equal (the refinement presented s.o.f. values of 0.49 for both sites; thus, they were fixed at 0.5 for each) in cotype, while in holotype, the Ag’ site is 74% occupied and Ag” is 26% occupied (Table 5). The location of the Ag’ site in hanauerite is very close to that of the non-split Ag site in synthetic AgHgSI and AgHgSBr. In all these sulphohalides, this position is coordinated by two S atoms and two halogen atoms, thus centring the distorted tetrahedron. The Ag”-centred polyhedron in hanauerite has two short distances Ag”–S, one longer Ag”–I distance, and two strongly elongated Ag”–I distances (Table 6). Coordination environments of Ag sites in hanauerite are shown in Figure 7.

Figure 3. The crystal structure of hanauerite. The unit cell is outlined.

Figure 4. “Crankshaft-type” Hg–S chains in the structure of hanauerite. The unit cell is outlined.

Figure 5. Coordination environments of Hg(1) (a) and Hg(2) (b) sites in the structure of hanauerite. The distances (in Å) for the holotype sample are given in square brackets and for the cotype sample without brackets.

Figure 6. Octahedral layer built by edge-sharing Hg(2)-octahedra (central part) and chains of Hg(1) octahedra in the structure of hanauerite (for better clarity Hg(1)- and Hg(2)-centred octahedra are illustrated in different colours).

Figure 7. Coordination environments of Ag’ (a) and Ag” (b) sites in the structure of hanauerite. The distances (in Å) for the holotype specimen are given in square brackets and for the cotype specimen without brackets.

4.2. Common Crystal Chemical Features of Natural Mercury Sulphohalides

In minerals, the octahedral coordination of Hg²⁺ by sulphur and halogen atoms was reported for capgaronnite [], perroudite [], and the synthetic analogues of corderoite [] and radtkeite [,]. Distorted Hg²⁺-centred octahedra with two short Hg–S bonds and four elongated Hg–Hal (Hal = Cl, Br, I) were found in the synthetic analogue of grechishchevite [,]. Pervukhina et al. [,] reported a distorted octahedral coordination of Hg atoms in structures of two polymorphic modifications of Hg₃S₂Cl_2–_xBr_x(x ≈ 0.5) obtained during the attempts to synthesize an analogue of lavrentievite and in two polymorphic modifications of Hg₃S₂Br_2–_xCl_x(x ≈ 0.5) obtained during the attempts to synthesize an analogue of arzakite. In the structure of capgaronnite, HgS₂(Cl,Br)₄ octahedra form (010) straight layers connected by the pairs of Ag-centred tetrahedra, whereas in perroudite, face-sharing Hg²⁺ octahedra form triple chains that are further linked by double chains of Hg-centred octahedra to the framework. In both hanauerite and capgaronnite, Hg–S chains are planar but essentially different in topology: the zigzag chain is reported for capgaronnite, and the “crankshaft-type” chain for hanauerite and structurally close and related synthetic compounds. At the same time, in perroudite, these chains are helical as well as cinnabar in shape. Structural relationships of perroudite with capgaronnite, corderoite, cinnabar, and synthetic HgCuSCl, β-Hg₃S₂Br₂, and Hg₃S₂I₃ are discussed in [] and references therein.

5. Conclusions

This paper is devoted to the new mineral hanauerite, ideally AgHgSI, the first natural mercury-bearing sulphohalide in which iodine is the only species-defining halogen. It is an analogue in the formulae for capgaronnite and iltisite, both ideally AgHgSCl; however, they are significantly different in terms of structure and, in general, hanauerite has no structural analogues among minerals.

Hanauerite possesses the same main crystal chemical features as typical for mercury sulphohalides. The cations Hg²⁺ occupy strongly distorted octahedra with two short Hg–S bonds (Hg and S atoms build “crankshaft-type” chains) and four strongly elongated Hg–I bonds. The Hg-centred octahedra are connected via common edges and faces to form corrugated layers. Such linkage is also characteristic for other compounds with layered or framework structures built by Hg-centred octahedra.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/cryst13081218/s1, The crystallographic information files (CIF) are in Supplementary Files.

Author Contributions

Conceptualization, I.V.P., N.V.Z. and S.N.B.; methodology, N.V.Z., S.N.B., I.V.P. and D.Y.P.; investigation, I.V.P., N.V.Z., S.N.B., A.A.A. and Y.S.P.; writing—original draft preparation, I.V.P. and N.V.Z.; writing—review and editing, I.V.P., N.V.Z., S.N.B. and D.Y.P.; mineral collection and providing samples, G.M., J.D. and G.B. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Not applicable.

Acknowledgments

The research has been carried out using facilities of XRD Research Centre of St. Petersburg State University in part of XRD studies of holotype hanauerite. We are grateful to reviewers for useful comments.

Conflicts of Interest

The authors declare no conflict of interest.

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Figure 1. Prismatic crystals of hanauerite on crusts consisting of sharp rhombohedral plumbogummite crystals. Schöne Aussicht Mine. SEM (SE) images.

Figure 2. Yellow prismatic crystals of hanauerite on goethite and aggregates of greenish-yellow rhombohedral plumbogummite crystals. Schöne Aussicht Mine. FOV width: (a)—1.2 mm, (b)—0.35 mm.

Figure 3. The crystal structure of hanauerite. The unit cell is outlined.

Figure 4. “Crankshaft-type” Hg–S chains in the structure of hanauerite. The unit cell is outlined.

Figure 5. Coordination environments of Hg(1) (a) and Hg(2) (b) sites in the structure of hanauerite. The distances (in Å) for the holotype sample are given in square brackets and for the cotype sample without brackets.

Figure 6. Octahedral layer built by edge-sharing Hg(2)-octahedra (central part) and chains of Hg(1) octahedra in the structure of hanauerite (for better clarity Hg(1)- and Hg(2)-centred octahedra are illustrated in different colours).

Figure 7. Coordination environments of Ag’ (a) and Ag” (b) sites in the structure of hanauerite. The distances (in Å) for the holotype specimen are given in square brackets and for the cotype specimen without brackets.

Table 1. The reflectance data of hanauerite from the Schöne Aussicht Mine.

λ, nm	R₁, %	R₂, %	λ, nm	R₁, %	R₂, %
400	14.3	13.1	560	11.6	10.5
420	13.9	12.8	580	11.3	10.2
440	13.5	12.4	589	11.2	10.1
460	13.2	12.1	600	11.1	10.0
470	13.1	11.9	620	10.9	9.8
480	12.9	11.8	640	10.7	9.6
500	12.6	11.4	650	10.6	9.5
520	12.2	11.1	660	10.5	9.4
540	11.9	10.8	680	10.3	9.2
546	11.8	10.7	700	10.1	9.1

The values for wavenumbers (λ) recommended by the IMA Commission on Ore Microscopy (COM) are given in bold type.

Table 2. Chemical composition of hanauerite.

Sample	Holotype (Schöne Aussicht Mine)		Cotype (Friedrichssegen Mine)
Constituent	Wt.% *	Range	Wt.% *	Range
Ag	22.42	21.83–23.22	23.26	22.84–23.61
Hg	43.94	43.02–44.52	43.05	42.74–43.30
S	7.12	6.92–7.34	7.42	7.17–7.76
Cl	0.20	0.12–0.24	-	-
Br	3.26	2.69–4.22	4.41	3.92–5.24
I	23.23	21.12–24.04	21.39	20.41–22.04
Total	100.17		99.53

* Averaged for five spot analyses for holotype and three spot analyses for cotype; dash means that the Cl content is below detection limit.

Table 3. Powder X-ray diffraction data (d in Å) of hanauerite from the Schöne Aussicht Mine.

I_obs	d_obs	I_calc *	d_calc **	h k l
20	9.88	16	9.891	001
15	6.99	11	7.008	101
3	4.932	0.5, 0.5	4.966, 4.945	200, 002
13	4.439	14	4.438	201
32	4.185	27	4.187	011
58	3.857	56	3.858	111
11	3.377	6, 3	3.383, 3.377	210, 012
16	3.300	10	3.297	003
22	3.201	21	3.201	211
20	3.138	22, 4	3.139, 3.129	301, 103
100	2.793	100	2.792	212
3	2.685	1	2.684	013
10	2.594	12	2.591	113
30	2.477	18, 24	2.483, 2.473	400, 004
10	2.332	7	2.336	303
22	2.312	30	2.311	020
6	2.217	3, 1	2.219, 2.214	402, 204
6	2.189	1, 4, 1	2.195, 2.187, 2.181	121, 410, 014
7	2.133	4, 3	2.136, 2.130	411, 114
5	2.050	3	2.050	221
13	1.999	11, 6	2.000, 1.996	412, 214
2	1.950	0.5, 0.5	1.948, 1.940	501, 105
4	1.895	4	1.892	023
6	1.862	8, 1	1.861, 1.859	321, 123
5	1.824	3, 3	1.823, 1.819	413, 015
4	1.791	6, 4	1.795, 1.789	511, 115
5	1.771	1, 4	1.770, 1.768	322, 223
8	1.754	9	1.752	404
6	1.708	4	1.708	215
12	1.692	10, 13	1.692, 1.688	420, 024
5	1.643	4, 4	1.643, 1.638	323, 414
3	1.598	2, 0.5, 2	1.601, 1.599, 1.597	422, 224, 513
2	1.557	2, 1	1.558, 1.553	610, 016
2	1.503	1, 3	1.505, 1.505	423, 131
6	1.484	5, 7	1.486, 1.482	612, 216
3	1.468	1, 1	1.468, 1.467	514, 415
1	1.440	1	1.438	225
5	1.411	10, 0.5	1.410, 1.409	232, 613
4	1.400	0.5, 0.5, 8	1.402, 1.399, 1.396	505, 107, 424
1	1.383	1	1.382	133
2	1.373	0.5, 0.5, 1	1.376, 1.373, 1.370	604, 406, 523
1	1.343	1, 1, 1	1.346, 1.344, 1.341	620, 711, 515
2	1.319	2, 2	1.318, 1.316	614, 416
1	1.297	0.5, 0.5, 0.5	1.299, 1.298, 1.296	622, 431, 134
2	1.266	2, 1	1.266, 1.265	432, 234
2	1.244	1, 1	1.244, 1.242	326, 800
2	1.216	0.5, 1	1.217, 1.215	433, 035
2	1.208	2, 1, 0.5	1.208, 1.206, 1.206	531, 135, 027

* For the calculated pattern, only reflections with intensities ≥ 0.5 are given; **, the unit cell parameters calculated from single-crystal data. The strongest reflections are marked in bold type.

Table 4. Crystal data, data collection information, and structure refinement details of hanauerite.

Locality	Friedrichssegen Mine	Schöne Aussicht Mine
Formula, from structure refinement	AgHgS(I_0.75Br_0.25)
Formula weight	455.67
Temperature, K	293(2)
Radiation and wavelength, Å	MoKα; 0.71073
Crystal system, space group, Z	Orthrhombic, Pmma, 4
Unit cell dimensions, Å/°	a = 9.9276(8)	a = 9.932(4)
	b = 4.6209(2)	b = 4.6219(19)
	c = 9.9006(4)	c = 9.891(4)
V, Å³	454.19(5)	454.0(3)
Absorption coefficient μ, mm⁻¹	45.61	45.63
F₀₀₀	766
Crystal size, mm	0.02 × 0.02 × 0.05	0.01 × 0.01 × 0.15
Diffractometer	Xcalibur S CCD	Bruker Kappa APEX DUO CCD
θ range for data collection, °/Collection mode	2.91–28.22/full sphere
Index ranges	−13 ≤ h ≤ 13, −6 ≤ k ≤ 6, −13 ≤ l ≤ 13	−11 ≤ h ≤ 13, −6 ≤ k ≤ 6, −13 ≤ l ≤ 13
Reflections collected	7457	4037
Independent reflections	667 (R_int = 0.0654)	666 (R_int = 0.0992)
Independent reflections with I > 2σ(I)	635	607
Data reduction	CrysAlisPro, Agilent Technologies, v. 1.171.37.35 []	Bruker APEX-2 []
Absorption correction	Gaussian	Multi-scan
Structure solution	direct methods
Refinement method	full-matrix least-squares on F²
Number of refined parameters	37	35
Final R indices (I > 2σ(I))	R1 = 0.0544, wR2 = 0.0984	R1 = 0.0416, wR2 = 0.1040
R indices (all data)	R1 = 0.0586, wR2 = 0.0995	R1 = 0.0469, wR2 = 0.1068
GoF	1.447	1.142
Largest diff. peak and hole, e/Å³	3.01 and −2.28	2.15 and −2.61

Table 5. Coordinates and equivalent displacement parameters (U_eq, in Å²) of atoms, site multiplicities (Q), and site occupancy factors (s.o.f.) of hanauerite. Data for the sample from the Friedrichssegen Mine are given in the first line of each row and data for the sample from the Schöne Aussicht Mine in the second line of each row.

Site	x	y	z	U_eq	Q	s.o.f.
Hg(1)	0.25	0.5	0.75709(13)	0.0392(3)	2	1
Hg(1)	0.25	0.5	0.75732(10)	0.0413(3)	2	1
Hg(2)	0.0	0.5	0.5	0.0402(4)	2	1
Hg(2)	0.0	0.5	0.5	0.0421(3)	2	1
Ag’	0.0914(17)	0.0	0.2230(14)	0.059(3)	4	Ag_0.50 Ag_0.744(11)
Ag’	0.0827(5)	0.0	0.2196(5)	0.0651(12) *	4	Ag_0.50 Ag_0.744(11)
Ag”	0.0521(17)	0.0	0.1885(16)	0.088(5)	4	Ag_0.50 Ag_0.256(11)
Ag”	0.0388(14)	0.0	0.1644(15)	0.0651(12) *	4	Ag_0.50 Ag_0.256(11)
I(1)	0.25	0.0	0.4769(2)	0.0303(7)	2	I_0.54(2)Br_0.46(2) I_0.57(2)Br_0.43(2) **
I(1)	0.25	0.0	0.47676(17)	0.0324(6)	2	I_0.54(2)Br_0.46(2) I_0.57(2)Br_0.43(2) **
I(2)	0.25	0.0	0.98976(17)	0.0336(6)	2	I_0.97(3)Br_0.03(3) I_0.94(2)Br_0.06(2) **
I(2)	0.25	0.0	0.99018(13)	0.0349(5)	2	I_0.97(3)Br_0.03(3) I_0.94(2)Br_0.06(2) **
S	0.4876(5)	0.5	0.7387(5)	0.0297(10)	4	1
S	0.4881(4)	0.5	0.7386(4)	0.0285(7)	4	1

* Displacement parameters were restricted to be equal. ** Minor Cl impurity (see Table 1) was ignored during the refinement.

Table 6. Selected interatomic distances (Å) in the structure of hanauerite.

Friedrichssegen Mine		Schöne Aussicht Mine
Hg(1)–S	2.366(5) × 2	Hg(1)–S	2.372(4) × 2
–I(2)	3.2626(14) × 2	–I(2)	3.2627(15) × 2
–I(1)	3.6102(19) × 2	–I(1)	3.6113(19) × 2
Hg(2)–S	2.366(5) × 2	Hg(2)–S	2.363(4) × 2
–I(1)	3.3986(2) × 4	–I(1)	3.3998(10) × 4
Ag’–S	2.558(8) × 2	Ag’–S	2.529(2) × 2
–I(2)	2.795(17)	–I(2)	2.813(3)
–I(1)	2.966(12)	–I(1)	3.038(7)
Ag”–S	2.504(8) × 2	Ag”–S	2.552(5) × 2
–I(2)	2.780(19)	–I(2)	2.715(10)
–I(1)	3.466(14)	–I(1)	3.734(14)
–I(2)	3.479(14)	–I(2)	3.250(17)

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A New Mineral Hanauerite, AgHgSI, and Common Crystal Chemical Features of Natural Mercury Sulphohalides

Abstract

1. Introduction

2. Materials and Methods

2.1. Occurrence, General Appearance, and Physical Properties

2.2. Methods

3. Results

3.1. Optical Data

3.2. Chemical Composition

3.3. X-ray Crystallography and Crystal Structure Determination

4. Discussion

4.1. Crystal Structure of Hanauerite

4.2. Common Crystal Chemical Features of Natural Mercury Sulphohalides

5. Conclusions

Supplementary Materials

Author Contributions

Funding

Data Availability Statement

Acknowledgments

Conflicts of Interest

References

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