The Szklary holtite is represented by three compositional varieties: (1) Ta-bearing (up to 14.66 wt.% Ta2O5), which forms homogeneous crystals and cores within zoned crystals; (2) Ti-bearing (up to 3.82 wt.% TiO2), found as small domains within the core; and (3) Nb-bearing (up to 5.30 wt.% Nb2O5,) forming the rims of zoned crystals. All three varieties show variable Sb+As content, reaching 19.18 wt.% Sb2O3 (0.87 Sb a.p.f.u.) and 3.30 wt.% As2O3 (0.22 As a.p.f.u.) in zoned Ta-bearing holtite, which constitutes the largest Sb+As content reported for the mineral. The zoning in holtite is a result of Ta-Nb fractionation in the parental pegmatite-forming melt together with contamination of the relatively thin Szklary dyke by Fe, Mg and Ti. Holtite and the As- and Sb-bearing dumortierite, which in places overgrows the youngest Nb-bearing zone, suggest the following crystallization sequence: Ta-bearing holtite → Ti-bearing holtite → Nb-bearing holtite → As- and Sb-bearing, (Ta,Nb,Ti)-poor dumortierite → As- and Sb-dominant, (Ta,Nb,Ti)-free dumortierite-like mineral (16.81 wt.% As2O3 and 10.23 wt.% Sb2O3) with (As+Sb) > Si. The last phase is potentially a new mineral species. Al6□☐(Sb,As)3O15, or Al5☐2B(Sb,As)3O12(OH)3, belonging to the dumortierite group. The Szklary holtite shows no evidence of clustering of compositions around ‘holtite I’ and ‘holtite II'. Instead, the substitutions of Si4+ by Sb3++As3+ at the Si/Sb sites and of Ta5+ by Nb5+ or Ti4+ at the Al(l) site suggest possible solid solutions between: (1) (Sb,As)-poor and (Sb,As)-rich holtite; (2) dumortierite and the unnamed (As+Sb)-dominant dumortierite-like mineral; and (3) Ti-bearing dumortierite and holtite. i.e. our data provide further evidence for miscibility between holtite and dumortierite, but leave open the question of defining the distinction between them. The Szklary holtite crystallized from the melt along with other primary Ta-Nb-(Ti) minerals such as columbite-(Mn), tantalite-(Mn), stibiotantalite and stibiocolumbite as the availability of Ta decreased. The origin of the parental melt can be related to anatexis in the adjacent Sowie Mountains complex, leading to widespread migmatization and metamorphic segregation in pelitic-psammitic sediments metamorphosed at ∼390—380 Ma.

An experimental study of cadmium substitution into AgXS2 phases (X = As, Bi, Sb) indicates significant amounts of cadmium can be incorporated in the structure by the mechanism 2Cd ⇌ Ag + X. The limit of substitution of Cd in the high-temperature polymorph of miargyrite, β-AgSbS2 is 6.2 at.%, whereas the low-temperature polymorph, α-AgSbS2, can accommodate at least 12 at.% cadmium. Substitution of Cd into the cubic β-AgSbS2 induces a small monoclinic distortion and the unit cell becomes pseudo-cubic. The α ⇌ β transition in Cd-substituted miargyrites is modified by the solute ions, with both a reduction of Tc and transition smearing evident. Similar effects are also recorded in Cd-substituted AgAsS2 and AgBiS2.

The determination of the crystal structure of benleonardite (P3m1; R = 0.0321 for 1250 reflections and 102 parameters; refined formula Ag15.00Cu1.00Sb1.58As0.42S7.03Te3.97) obtained using data from a gem-quality, untwinned crystal recovered from the type material, revealed that benleonardite exhibits the structure observed for minerals of the pearceite-polybasite group. The structure consists of the stacking of [Ag6(Sb,As)2S6Te]2– A and [Ag9Cu(S,Te)2Te2]2+B layer modules in which (Sb, As) forms isolated SbS3 pyramids typically occurring in sulfosalts; Cu links two (S,Te) atoms with linear coordination, and Ag occupies sites with coordination geometries ranging from quasi-linear to almost triangular. The silver ions are found in the B layer module along two-dimensional diffusion paths and their electron densities are evidenced by means of a combination of a Gram-Charlier development of the atom displacement factors and a split model. In the structure, two S positions are completely replaced by Te (i.e. Te3 and Te4) and one is half occupied [S1: S0.514(9)Te0.486], whereas S2 is completely filled by sulfur. This distribution reflects the crystal-chemical environments of the different cations. On the basis of information gained from this characterization, the crystal-chemical formula of benleonardite was revised according to the structural results, yielding Ag15Cu(Sb,As)2S7Te4 (Z = 1) instead of Ag8(Sb,As)Te2S3(Z = 2) as previously reported. Thus, the mineral must be considered a member of the pearceite-polybasite group. A recalculation of the chemical data listed in the scientific literature for benleonardite according to the structural results obtained here leads to excellent agreement.

Eckerite, ideally Ag2CuAsS3, is a new mineral from the Lengenbach quarry in the Binn Valley, Valais, Switzerland. It occurs as very rare euhedral crystals up to 300 μm across associated with realgar, sinnerite, hatchite, trechmannite and yellow, fibrous smithite. In thick section eckerite is opaque with a metallic lustre and shows a dark orange-red streak. It is brittle; the Vickers hardness (VHN25) is 70 kg/mm2 (range: 64–78) (Mohs hardness of ∼2½–3). In reflected light, eckerite is moderately bireflectant and weakly pleochroic from light grey to a slightly bluish grey. Internal reflections are absent. Under crossed nicols, it is weakly anisotropic with greyish to light blue rotation tints. Reflectance percentages for Rmin and Rmax are 27.6, 31.7 (471.1 nm), 22.8, 26.1 (548.3 nm), 21.5, 24.5 (586.6 nm) and 19.4, 22.3 (652.3 nm), respectively.

Eckerite is monoclinic, space group C2/c, with a = 11.8643(3), b = 6.2338(1), c = 16.6785(4) Å, β = 110.842(3)°, V = 1152.81(5) Å3, Z = 8. The crystal structure [R1 = 0.0769 for 1606 reflections with Fo > 4σ(Fo)] is topologically identical to that of xanthoconite and pyrostilpnite. In the structure, AsS3 pyramids are joined by AgS3 triangles to form double sheets parallel to (001); the sheets are linked by Cu(Ag) atoms in a quasi-tetrahedral coordination. Among the three metals sites, Ag2 is dominated by Cu. The mean metal–S distances reflect well the Ag ↔ Cu substitution occurring at this site.

The eight strongest powder X-ray diffraction lines [d in Å (I/I0) (hkl)] are: 3.336 (70) (312); 2.941 (100) (314,114); 2.776 (80) (400,206); 2.677 (40) (312); 2.134 (50) (421); 2.084 (40) (208,206); 2.076 (40) (420); 1.738 (40) (228,226). A mean of five electron microprobe analyses gave Ag 52.08(16), Cu 11.18(9), Pb 0.04(1), Sb 0.29(3), As 15.28(11), S 20.73(13), total 99.60 wt.%, corresponding, on the basis of a total of 7 atoms per formula unit, to Ag2.24Cu0.82As0.94Sb0.01S2.99. The new mineral has been approved by the International Mineralogical Association Commission on New Minerals, Nomenclature and Classification (2014–063) and named for Markus Ecker, a well known mineral expert on the Lengenbach minerals for more than 25 years.

Yellow needles of 'iodolaurionite', Pb(OH)I, and a novel compound Pb2O(OH)I, have been prepared by hydrothermal reactions of PbO and PbI2 at 170°C. The crystal structure of 'iodolaurionite', Pb(OH)I (orthorhombic, Pnma, a = 7.8244(8), b = 4.2107(4), c = 10.4724(10) Å, V = 345.03(6) Å3, Z = 4) has been refined to R1 = 0.041 for 129 independent observed reflections. The structure is based on the OHPb3 triangles sharing common edges to produce single [OHPb]+ chains extending along the b axis and parallel to the ab plane. The three-dimensional integrity of the structure is provided by the Pb–I bonds and the O–H···I hydrogen bonding. The structure is isotypic with that of laurionite, Pb(OH)Cl. The crystal structure of Pb2O(OH)I (monoclinic, C2/m, a = 13.711(3), b = 4.0975(10), c = 9.584(2) Å, β = 110.64(1)°, V = 503.9(2) Å3, Z = 4), has been solved by direct methods and refined to R1 = 0.053 for 586 independent observed reflections. In the structure of Pb2O(OH)I, O(1)Pb4 tetrahedra link together by sharing edges and corners to form [OPb2]2+ chains similar to those observed in sidpietersite. The O(2) atoms belong to hydroxyl groups attached to both sides of the chains to produce novel [O(OH)Pb2]+ 1D units. The [O(OH)Pb2]+ units are extended parallel to the b axis and lie within the bc plane. The [O(OH)Pb2]+ units are linked together via hydrogen bonding in the (100) plane and by weak Pb–I bonds in the [100] direction. The [O(OH)Pb2]+ bands can be obtained from the [OPb] layer of OPb4 tetrahedra present in the structure of tetragonal PbO (litharge). The continuous [OPb] layer has to be broken into [O2Pb2] bands containing 3- and 4-coordinated O atoms in the 1:1 ratio with subsequent protonation of the 3-coordinated O sites. Relations of Pb(OH)I and Pb2O(OH)I to known Pb hydroxy- and oxyhalides are described briefly.

This work presents a geochemical study conducted on the abandoned Tinoca Copper mine (southeast Portugal) to evaluate the potential hazard in surrounding areas particularly the effect on the Abrilongo River Dam which receivesthe acid waters from the mine watershed. The characterization of the area was performed over a period of 3 y and involved the study of waters, sediments and mine wastes. A sequential extraction methodology was conducted on the sediments and mine wastes and five elements were selected (Cu, Fe, Zn, Cd and Pb). The statistical and spatial analysis allowed the inference of the affinities between the chemical elements and specific mineralogical phases and to characterize chemical behaviour such as mobility and bioavailability. The results show that the distance to the source (mine-waste deposit), the point of zero charge, and the dynamics of the system are factors that control the behaviour of the elementss tudied. The acid drainage is characterized by an average pH of 2.5 and concentrationsof copper 20 timesgreater than the legal limit for irrigation waters.

The crystal structure of veenite is reported for the first time from a sample from the type locality of Madoc (Ontario, Canada). It has been solved and refined by X-ray single-crystal diffraction on the basis of 4973 observed reflections (with Fo > 4σ(Fo)) with a final R1 = 0.0396. Veenite is monoclinic P21, with unit-cell parameters a = 8.429(2), b = 26.069(5), c = 8.962(2) Å, β = 117.447(2)o. The bulk veenite composition is Ag0.15Pb16.029Sb8.836As6.99S39.95 (for Z = 1) corresponding to N = 4.09 (Me8NS8N + 8, theoretical value is 4.0), with the percentage of the Ag-(As,Sb) substituted end-member only equal to 3.51 mol.%, i.e., a nearly pure Pb-Sb-As sulfosalt. The crystal structure is typical for the N = 4 sartorite homologue, with zig-zag walls of trigonal coordination prisms of Pb which separate slabs of diagonally oriented double-layers populated by Sb and As with partial Pb substitution. Orientation of three-membered crankshaft chains formed by strong (As,Sb) – S bonds on the two surfaces of double-layers differs substantially from that in dufrénoysite, which is a pure Pb-As (N = 4) sulfosalt.

In the Artikutza area, near the contact with the southern Aya granite, skarns containing hedenbergite, grandite, epidote, quartz, calcite, actinolite, idocrase and magnetite occur and have been found to contain ilvaite layers. This is the second reported occurrence of ilvaite in Spain; spectral reflectances, colour values. Vickers hardness numbers and chemical composition are given. The monomineralic ilvaite lens intercalation developed by hydrothermal alteration of hedenbergite in a second stage of skarn formation.

Veins cutting the Brioverian sediments at Le Pulec, Jersey, were worked in the 1870s for silver and lead. Investigation of the mineralogy of both the sediments and cross-cutting veins has shown a complex mineralization history. Siltstones close to the contact with the North-West granite have been bleached, silicified, and dolomitized, and this has been accompanied by the introduction of pyrite, marcasite, and arsenopyrite. Later vein mineralization contains sphalerite and ferroan dolomite accompanied by lesser amounts of galena and chalcopyrite and minor quantities of argentian tetrahedrite, native antimony, bournonite, cubanite, plagionite, and stibnite. The mineral assemblage is unlike the other mineral occurrences of Jersey that have previously been described.

Myrmekite-like intergrowths in the Lewisian gneiss and the igneous complex of Loch Borolan are described. The intergrowths are of diverse mineral composition but have many features in common with myrmekite and it is shown that they result from the constriction of a previously existing mineral during the growth, in the solid state, of the host mineral. More than one stage of intergrowth is often found and these stages can be correlated with geological events.

At two localities on the outskirts of the township of Broken Hill—near the De Bavay shear zone, and at ‘The Piggery’—W. R. Browne reported unusual rock types rich in barium. His statement is accompanied by an analysis by H. P. White (analyst to the Mines Dept.) of one of these rocks, which contains 9·23% BaO. Subsequently S. R. Nockolds and E. G. Zies examined the felspars of the rock analysed by White with a view to ascertaining whether they are barium-containing varieties.

In view of the very high barium content of some of the occurrences now being investigated, much higher than that of the rock examined by Nockolds and Zies, a further mineralogical investigation was undertaken with the results recorded below. The rocks under examination were light-coloured gneisses containing up to 15% BaO. They are distributed as lenses and streaks in an acid gneiss. A specimen of the latter rock was analysed and found to contain only 0·09% BaO. The barium was found to occur in four felspars, one being a new variety of celsian. The minerals studied were celsian, calciocelsian, hyalophane, and barium-plagioclase. A careful search was made for other barium silicate minerals such as sanbornite, but none was found.

An occurrence of a celadonite-like mineral in a weathered basalt in the Lake District has been investigated by X-ray diffraction, X-ray fluorescence, electron microprobe, and infra-red spectroscopic methods. The bulk composition of the mineral corresponds to an aluminous-glauconite. The data show that the mineral is most probably a celadonite-muscovite or celadonite-illite mixture, although a celadonite-phengite cannot be entirely discounted. Approximately 10% smectite layers are also present. The results suggest that re-examination of many aluminous glauconites may show them to be mixtures of this type.

Daliranite, ideally PbHgAs2S6, a new sulphosalt from the Zarshouran Au-As deposit, Takab region, Iran, occurs as a rare sulphosalt species at the Carlin-type Zarshouran Au-As deposit North of the town of Takab in the Province of West Azarbaijan, Iran. The new species is associated with orpiment, rarely with galkhaite, hutchinsonite and cinnabar. The strongly silicified matrix of the specimens has veinlets of sphalerite, with rare inclusions of galena and various (Cu)-Pb-As(Sb) sulphosalts. Daliranite occurs as matted nests of acicular and flexible fibres up to 200 μm in length and a width less than a few μm. The colour is orange-red with a pale orange-red streak and the lustre is adamantine. The mineral is transparent and does not fluoresce. The Mohs hardness is <2. Electron microprobe analyses give the empirical formula Pb0.95Tl0.01Hg1.04As2.10S5.91, ideally PbHgAs2S6, a new sulphosalt from the Zarshouran Au-As deposit, Takab region, Iran; the calculated density is 5.93 g cm–3. Unit-cell parameters were determined by an electron-diffraction study and refined from X-ray powder data. Daliranite is monoclinic primitive with a = 19.113(5) Å, b = 4.233(2) Å, c = 22.958(8) Å, β = 114.78(5)°, V = 1686.4 Å3 and Z = 8, a:b:c = 4.515:1:5.424, space group P2, Pm or P2/m. The strongest X-ray powder-diffraction lines [d in Å, (I), (hkl)] are: 8.676, (80), (200); 4.654, (50), (401); 3.870, (40), (211); 3.394, (50), (113); 3.148, (40b), (602); 2.892, (50), (600); 2.724, (100), (703); 2.185, (50), (319). The formula shows a sulphur excess which may correspond to S—S bonding (persulphide). The new sulphosalt is a late phase in the crystallization sequence, and was formed after orpiment, contemporaneously with quartz II, at a temperature between 157 and 193°C. The name honours Dr Farahnaz Daliran (University of Karlsruhe, Germany) in recognition of her outstanding contributions to research on ore deposits, especially Au, Zn and Fe, in Iran.

The structural states of alkali feldspars from the eastern end of the Galway Granite show transitions from orthoclase to microcline as a result of late deformation. Analyses of twenty samples for SiO2, Al2O3, TiO2, Fe2O3, CaO, Na2O, K2O, S, Cu, Zn, Ga, Rb, Sr, Ba, and Pb agree with previously determined orders of entry of elements into the ‘alkali site’. A relationship between this order of entry and the melting points of feldspar end-members is discussed.

Sweetite, naturally occurring Zn(OH)2 with tetragonal symmetry, has been found at Milltown, near Ashover, Derbyshire. It occurs as colourless or whitish bipyramids up to 1 mm in size scattered over the surface of colourless fluorite cubes. The cell dimensions are α 8,222 and c 14.34Å with Z = 20. The strongest lines of the X-ray powder pattern are (d, I, hkl): 4.53 37 (112); 3.572 60 (004,202,211); 2.922 100 (213,220); 2.708 18 (105,204); 2.257 17 (224,215,321); 1.840 11 (226,420,413); 1.764 24 (316). Sweetite is uniaxial negative, ω 1.635, ɛ 1.628. Dmeas is close to 3.33 and Dcalc 3.41. Chemical analysis gave 84.3% ZnO and 17.0% H2O, while theoretical figures for Zn(OH)2 are 81.9 and 18.1% respectively.

The Zn-spinel gahnite has been discovered in the ∼3.75 Ga Isua Greenstone Belt, West Greenland. It is light blue-green to colourless in hand specimen and colourless in thin section as opposed to most other gahnites which are dark green to brown. The gahnites from Isua have very low Fe and Mg contents, and their compositions are thus close to the endmember gahnite. The gahnite was formed, during metamorphism, from sphalerite, in the absence of Fe-rich sulphides.

Schultenite, PbHAsO4, known only from Tsumeb, Namibia, has been identified from a second occurrence: near North Bend, King County, Washington, USA. It occurs as euhedral crystals in a quartz-arsenopyrite-galena vein. It has a measured density of 6.07(3) g/cm3 and a calculated density of 6.079(4) g/cm3. The white to colourless crystals have a white streak, adamantine lustre, and fluoresce dull yellow under long wave ultraviolet light. Schultenite is monoclinic. Pa or P2/a; the unit cell parameters refined from the X-ray powder diffraction data are: a 5.827(3), b 6.743(3), c 4.847(3) Å, β 95.34(5)°; V 189.6(1) Å3; Z = 2; a:b:c = 0.8642:1:0.7188. The forms {010}, {001}, and {3̄22} were observed on the Washington schultenite crystals.