Brianyoungite, which is chemically and structurally related to hydrozincite, occurs as white rosettes (<100 μm) with gypsum on rubbly limestone within the oxidised zone at Brownley Hill Mine, Nenthead, Cumbria. The mineral contains (wt.%) 71.47 ZnO, 9.90 CO2, 6.62 SO3 and 10.70 H2O+. Based on 29 oxygen atoms, the empirical formula is Zn11.73[(CO3)3.00,(SO4)1.10]4.10(OH)15.88 or ideally Zn3(CO3,SO4)(OH)4. Brianyoungite is either orthorhombic or monoclinic with β very close to 90° Cell parameters determined by electron diffraction and refined from X-ray powder diffraction data are a = 15.724, b = 6.256 and c = 5.427 Å. Density is > 3.93, < 4.09 g/cm3 (meas.) and 4.11 g/cm3 (calc.); Z = 4. Thermogravimetric analysis, IR and XRD powder data (23 lines) are presented.

A new mineral species, franksousaite (IMA2021-096), ideally PbCu(Se6+O4)(OH)2, has been found from the El Dragón mine, Antonio Quijarro Province, Potosí Department, Bolivia. It occurs as short prismatic crystals included in colourless anglesite. Associated minerals are Co-bearing krut'aite–penroseite, chalcomenite, schmiederite, olsacherite, phosgenite, anglesite and cerussite. Franksousaite is blue in transmitted light, transparent with very pale blue streak and has a vitreous lustre. It is brittle and has a Mohs hardness of 2–2½. Cleavage is perfect on {100}. The calculated density is 5.64 g/cm3. An electron microprobe analysis yielded an empirical formula (based on 6 O apfu) of Pb1.02Cu0.98[(Se0.84S0.17)Σ1.01O4)](OH)2, which is simplified to PbCu[(Se,S)O4)](OH)2.

Franksousaite is the Se6+ analogue of linarite, PbCu(SO4)(OH)2. It is monoclinic, with space group P21/m and unit-cell parameters a = 9.8208(3), b = 5.7340(2), c = 4.74980(10) Å, β = 102.683(2)°, V = 260.947(13) Å3 and Z = 2. The crystal structure of franksousaite consists of Jahn-Teller-distorted Cu2+O6 square bipyramids, which form chains along b by sharing trans edges across their square planes. The chains are decorated by SeO4 tetrahedra and linked to one another by hydrogen bonds to form layers parallel to (100). These layers are bound together by double layers of PbO8 and SeO4 polyhedra. The PbO8 polyhedron exhibits one-sided coordination typical of Pb2+ with a stereochemically active 6s2 lone-electron-pair. The major structural difference between franksousaite and linarite lies in the <Se–O> vs. <S–O> bond distances (1.615 vs. 1.482 Å), accounting for the larger unit-cell volume for franksousaite. A comparison of Raman spectra for the four minerals in the linarite group (linarite, franksousaite, munakataite and schmiederite) reveals the obvious differences among them, especially in the range from 700 to 1000 cm–1, indicative of the presence or absence of (Se4+O3)2–, (Se6+O4)2–, and/or (SO4)2– groups.

Creaseyite was first noted in specimens from Tiger, Arizona, and was then found at Wickenburg, Arizona, and Caborca, Sonora, prior to description. It is an oxide zone mineral occurring with wulfenite, willemite, mimetite, chrysocolla, wickenburgite, and ajoite. The composition is [Cu2Pb2(Fe,Al)2Si5O17-6HaO]. Colour Agathia green (R.H.S. 142B) with pale streak, H = 2½, Dmeas = 4.1, calc. 4.01. Crystals are orthorhombic with a 12.483, b 21.395, c 7.283. Z = 4.2Vγ 69° meas; α 1.737, β 1.747, γ 1.768.

We have analysed a rare occurrence of orange-brown manganotantalite lamellae (visible in hand specimen), intergrown with microlite [(Ca,Na)2(Ta,Nb)2(O,OH,F)7], aggregates of ferrotapiolite, bismuth minerals and apatite to understand more about the mechanisms of crystal growth and secondary modification in Ta-rich minerals. The intergrowth occurs within amblygonite/montebrasite nodules near the quartz core of the highly fractionated rare-metal Li/Be/Ta pegmatite at Rubicon, Karibib, Namibia. Electron microprobe analyses show that manganotantalite lamellae are variable in composition. Primary microlite (Ta2O5 82%, 1.97 Ta a.p.f.u.) forms the matrix mineral between the lamellae. Textural relations suggest an exsolution origin for the lamellae. Manganotantalite is represented by three generations: (1) primary late magmatic; (2) disequilibrium exsolution lamellae; and (3) subsolidus replacement. Crystallization commenced with primary microlite and likely simultaneous intergrowth between ferrotapiolite and a first generation of late-magmatic primary manganotantalite with low Ta (1.1—1.5 a.p.f.u.). On cooling this was followed by exsolution of manganotantalite lamellae, generation (2) with low—medium Ta (1.27—1.7 a.p.f.u.). The replacement of microlite by a highly fractionated late-stage melt rich in Mn2+, Ca2+ with low Na+ finally produces a third generation (3) of manganotantalite with high Ta (1.72—1.99 a.p.f.u.) at the contact with microlite. Native bismuth and bismutite cut across microlite and pseudomorph lamellae as a final hydrothermal replacement. Apatite is ubiquitous at the contact with amblygonite. The stability field of microlite may be extended by incorporation of CaTa2O6-rynersonite and Ca2Ta2O7 — idealized, components in solid solution. However, rynersonite-CaTa2O6 with distorted octahedra has some structural templates which are similar to the structure of pyrochlore (microlite). Hence, via the perovskite/pyrochlore analogy, hypothetical exsolution of manganotantalite-type structures may occur from a microlite (pyrochlore) host by solid-state diffusion via metastable rynersonite-type intermediates. Such a mechanism has the potential to explain the crystallographically controlled intergrowth textures and the compositional heterogeneity.

Żabińskiite, ideally Ca(Al0.5Ta0.5)(SiO4)O, was found in a Variscan granitic pegmatite at Piława Górna, Lower Silesia, SW Poland. The mineral occurs along with (Al,Ta,Nb)- and (Al,F)-bearing titanites, a pyrochlore-supergroupmineral and a K-mica in compositionally inhomogeneous aggregates, ∼120 μm × 70 μm in size, in a fractured crystal of zircon intergrown with polycrase-(Y) and euxenite-(Y). Żabińskiite is transparent, brittle, brownish, with a white streak, vitreous lustre and a Mohs hardness of ∼5. The calculated density for the refined crystal is equal to 3.897 g cm–3, but depends strongly on composition. The mineral is non-pleochroic, biaxial (–), with mean refractive indices ≥1.89. The (Al,Ta,Nb)-richest żabińskiite crystal,(Ca0.980Na0.015)∑=0.995(Al0.340Fe3+0.029Ti0.298V0.001Zr0.001Sn0.005Ta0.251Nb0.081)∑=1.005[(Si0.988Al0.012)O4.946F0.047(OH)0.007)∑=5.000];60.7 mol.% Ca[Al0.5(Ta,Nb)0.5](SiO4)O; is close in composition to previously described synthetic material. Żabińskiite is triclinic (space group symmetry A1) and has unit-cell parameters a = 7.031(2) Å, b = 8.692(2) Å,c = 6.561(2) Å, α = 89.712(11)°, β = 113.830(13)°, γ = 90.352(12)° and V = 366.77 (11) Å3. It is isostructural with triclinic titanite and bond-topologically identical with titanite and other minerals of the titanite group.Żabińskiite crystallized along with (Al,Ta,Nb)-bearing titanites at increasing Ti and Nb, and decreasing Ta activities, almost coevally with polycrase-(Y) and euxenite-(Y) from Ca-contaminated fluxed melts or early hydrothermal fluids.

Hemimorphic crystals of four M1+-M3+-diarsenates (M1+ = Li, Na; M3+ = Al, Sc, Ga) were prepared by mild hydrothermal methods (T = 493 K) at very low pH values of ~1–1.5. The crystalst ructures of all compounds were determined using single-crystal X-ray diffraction data (Mo-Kα, CCD detector, 293 K) and were found to be isotypic with gittinsite (CaZrSi2O7), and the later described synthetic compound LiFeAs2O7. Crystaldat a for LiAlAs2O7, LiScAs2O7, LiGaAs2O7 and NaScAs2O7, respectively, are: space group C2 (no. 5), a = 6.583(1), 6.790(1), 6.638(1), 6.959(1), b = 8.007(2), 8.532(2), 8.181(2), 8.712(2), c = 4.635(1), 4.845(1), 4.696(1), 4.817(1) Å, β = 104.13(3), 103.75(3), 104.01(3), 102.05(3)°, V = 236.92(9), 272.64(9), 247.43(9), 285.6(1) Å3; Z = 2. The structure models were refined anisotropically to R1(F) = 0.0152, 0.0157, 0.0144, 0.0199, respectively.

The non-centrosymmetric framework structure contains isolated As2O7 groups (in staggered configuration; As–O–As angles show a narrow range between 130.32(16) and 139.8(2)°) which share their O ligands with MO6 (M = Al, Sc, Ga) octahedra and distorted Li/NaO4 tetrahedra. The strongly distorted LiO4 tetrahedra exhibit an average Li–O bond length of 2.071 Å, but four longer Li–O bonds (between 2.781–3.042 Å) also contribute to give a reasonable bond-valence sum for the Li atoms, and reflect an effective [4+4]-coordination. The Na compound is also characterized by four short and four long Na–O bonds; the Na atom appears slightly overbonded. The average Sc–O bond length in the two Sc representatives is 2.083 and 2.097 Å.

Details of the topology and crystal chemistry are discussed in comparison with those of gittinsite and other diarsenates, and correlations are noted. A reevaluation of the geometry of As2O7 groups in 58 presently known and structurally characterized inorganic diarsenates shows a mean As–O–As angle of 124.2° (excluding 180° angles). The As–O bond lengths to the central bridging O atom are elongated to a mean value of 1.755 Å, whereas all other bond lengths are shortened (mean value 1.666 Å); the overall mean As–O bond length is 1.688 Å.

Lukkulaisvaaraite, Pd14Ag2Te9, is a new platinum-group mineral discovered in the Lukkulaisvaara intrusion, northern Russian Karelia, Russia. In polished section crystals are ~40 mm across, rimmed by tulameenite and accompanied to varying degrees by telargpalite and Bi-rich kotulskite. Lukkulaisvaaraite is brittle, has a metallic lustre and a grey streak. Values of VHN20 fall between 339 and 371 kg mm–2, with a mean value of 355 kg mm–2, corresponding to a Mohs hardness of ~4. In plane-polarized light, lukkulaisvaaraite is light grey with a brownish tinge, has strong bireflectance, light brownish-grey to greyish-brown pleochroism and distinct to strong anisotropy; it exhibits no internal reflections. Reflectance values of lukkulaisvaaraite in air (R1, R2, in %) are: 40.9, 48.3 at 470 nm, 47.6, 56.4 at 546 nm, 52.1, 61.0 at 589 nm and 57.5, 65.2 at 650 nm. Five electron microprobe analyses of natural lukkulaisvaaraite gave the average composition Pd 52.17, Ag 7.03 and Te 40.36, total 99.61 wt.%, corresponding to the empirical formula Pd14.05Ag1.88Te9.06 based on 25 atoms; the average of nine analyses on synthetic lukkulaisvaaraite is Pd 52.13, Ag 7.31 and Te 40.58, total 100.02 wt.%, corresponding to Pd13.99Ag1.93Te9.08. The mineral is tetragonal, space group I4/m, with a = 8.9599(6), c = 11.822(1) Å , V = 949.1(1) Å3 and Z = 2. The crystal structure was solved and refined from the powder X-ray diffraction (XRD) data of synthetic Pd14Ag2Te9. Lukkulaisvaaraite has a unique structure type and shows similarities to that of sopcheite (Ag4Pd3Te4) and palladseite (Pd17Se15). The strongest lines in the powder XRD pattern of synthetic lukkulaisvaaraite [d(Å),I,hkl] are: 2.8323(58)(130,310), 2.8088(92),(213), 2.5542(66)(312), 2.4312(41)(321,231), 2.1367(57)(411,141), 2.1015(52)(233,323), 2.0449(100)(314), 2.0031(63)(420,240), 1.9700(30)(006), 1.4049(30)(246,426), 1.3187(36)(543,453). The mineral is named for the type locality, the Lukkulaisvaara intrusion in Russian Karelia.

Several gold deposits hosted mainly by Variscan granites and Precambrian to Palaeozoic metasediments occur in the northwestern part of Portugal. Most of these deposits were mined by the Romans (in the period I BC to II AD) as open pits and surface galleries. The Castromil-Serra da Quinta gold deposit is an important example of such a mined site; it occurs in the Dúrico-Beirã Au province located in the Central Iberian Zone (CIZ) in the western branch of European Variscan belt, mainly on the eastern flank of the Valongo anticline. Open pits and underground galleries at Castromil-Serra da Quinta exploited the gossan formed from the weathering of primary mineralization. The gossan is composed essentially of goethite, scorodite and clay minerals. A recent drilling campaign at Castromil-Serra da Quinta has provided samples of the primary mineralization below the oxidation level. Different modes of gold occurrence are defined based on metallographic studies of both the gossan and drill cores. Gold I occurs encapsulated in primary sulfide minerals, mainly arsenopyrite and pyrite; Gold II is also associated with the main primary sulfides, but occurs along grain boundaries and in microfractures of the sulfides or in associated quartz veins; and Gold III occurs as free gold particles in iron oxides within the gossan. In the gossan samples, it is difficult to distinguish whether the gold particles hosted in oxides correspond to Gold I, Gold II, or both, so these particles are described as Gold I–II and they are commonly surrounded by very much smaller particles of Gold III. Scanning electron microscope (SEM) and electron probe microanalysis (EPMA) data for the different gold particles reveal that Gold I is poorer in Ag (~15.5–39.76%) than Gold II (37.46–51.45%), whereas Gold III corresponds to native gold (<16.11% Ag). Gold III is thought to reflect gold enrichment in the upper level of the deposit, resulting from weathering processes that affected the primary Au (Bi) mineralization.

The new mineral hrabákite (IMA2020-034) was found in siderite–sphalerite gangue with minor dolomite–ankerite at the dump of shaft No. 9, one of the mines in the abandoned Příbram uranium and base-metal district, central Bohemia, Czech Republic. Hrabákite is associated with Pb-rich tučekite, Hg-rich silver, stephanite, nickeline, millerite, gersdorffite, sphalerite and galena. The new mineral occurs as rare prismatic crystals up to 120 μm in size and allotriomorphic grains. Hrabákite is grey with a brownish tint. Mohs hardness is ca. 5–6; the calculated density is 6.37 g.cm–3. In reflected light, hrabákite is grey with a brown hue. Bireflectance is weak and pleochroism was not observed. Anisotropy under crossed polars is very weak (brownish tints) to absent. Internal reflections were not observed. Reflectance values of hrabákite in air (Rmin–Rmax, %) are: 39.6–42.5 at 470 nm, 45.0–47.5 at 546 nm, 46.9–49.2 at 589 nm and 48.9–51.2 at 650 nm). The empirical formula for hrabákite, based on electron-microprobe analyses (n = 11), is (Ni8.91Co0.09Fe0.03)9.03(Pb0.94Hg0.04)0.98(Sb0.91As0.08)0.99S7.99. The ideal formula is Ni9PbSbS8, which requires Ni 47.44, Pb 18.60, Sb 10.93 and S 23.03, total of 100.00 wt.%. Hrabákite is tetragonal, P4/mmm, a = 7.3085(4), c = 5.3969(3) Å, with V = 288.27(3) Å3 and Z = 1. The strongest reflections of the calculated powder X-ray diffraction pattern [d, Å (I)(hkl)] are: 3.6543(57)(200); 3.2685(68)(210); 2.7957(100)(211); 2.3920(87)(112); 2.3112(78)(310); 1.8663(74)(222); and 1.8083(71)(302). According to the single-crystal X-ray diffraction data (Rint = 0.0218), the unit cell of hrabákite is undoubtedly similar to the cell reported for tučekite. The structure contains four metal cation sites, two Sb (Sb1 dominated by Pb2+) and two Ni (with minor Co2+ content) sites. The close similarity in metrics between hrabákite and tučekite is due to similar bond lengths of Pb–S and Sb–S pairs. Hrabákite is named after Josef Hrabák, the former professor of the Příbram Mining College.

This work presents a detailed study of platinum-group mineral (PGM) assemblages from the Malaya Kamenushka River placer, whose formation is associated with the weathering of the Kamenushensky Uralian–Alaskan type massif, Middle Urals, Russian Federation. The deposit is characterised by the dominance of isoferroplatinum, together with significant numbers of inclusions of Os–Ir–Ru alloys and platinum-group element (PGE) sulfides. A study of the Os–Ir–Ru alloys permitted recognition of two types of iridium with different morphology and composition. The similarity of the PGM assemblages from the Malaya Kamenushka River placer and the lode mineralisation of the Kamenushensky massif is demonstrated. A comparison of PGM assemblages from the Malaya Kamenushka River placer with other placers and massifs of the Ural platinum belt demonstrates significant differences in the number of Os–Ir–Ru inclusions. Such differences for minerals of refractory elements cannot be explained by the vertical zoning of the lode mineralisation. Most probably this is associated with the enrichment of the primary substrate with Os, Ir and Ru and/or the degree of melting, depending on the chosen model of formation of the Uralian–Alaskan type massifs.

Steady-state tremolite dissolution rates, at far-from-equilibrium conditions, were measured as a function of aqueous silica and magnesium activity, pH from 1.9 to 6.7, and temperature from 25 to 150ºC. Calcium is released from tremolite faster than either Mg or Si throughout most of the experiments even after these latter elements attained steady-state release rates. The preferential removal of Ca releases fine Mg-Si rich needle-like fibres from the tremolite, probably promoting its toxicity. In contrast, Mg was released in stoichiometric or near to stoichiometric proportion to Si once steady-state was attained. Measured steady-state tremolite dissolution rates based on Si release can be described using

where r+ signifies the BET surface area-normalized forward tremolite steady-state dissolution rate, AA refers to a pre-exponential factor = 6610–3 mol cm–2 s–1, EA designates an activation energy equal to 80 kJ mol–1, R represents the gas constant, T denotes absolute temperature, and ai refers to the activity of the subscripted aqueous species. This rate expression is consistent with tremolite dissolution rates at acidic pH being controlled by the detachment of partially liberated silica tetrahedra formed from the exchange of Mg2+ for two protons near the mineral surface after the near-surface Ca has been removed. Nevertheless, Mg release rates from tremolite are ~3 orders of magnitude slower than those from forsterite and enstatite suggesting that tremolite carbonation will be far less efficient than the carbonation of these other Mg-silicate minerals.

This paper presents new data on the metasomatic development of zoned ultramafic balls from Fiskenaesset, West Greenland. Field and petrographic evidence indicate retrogression of original ultrabasic inclusions in acid country rock gneisses to serpentinemagnesite assemblages, followed by regional metamorphism and consequent development of the zonal structure upon metasomatic re-equilibration via a supercritical aqueous fluid phase confined to grain boundaries. The balls show varying degrees of deviation from an ideal sequence (antigorite-talc-tremolite-hornblende-chlorite-country rock) intimated by non-equilibrium thermo-dynamics, the currently accepted conceptual framework for the discussion of diffusion metasomatism.

Major and trace-element variations behave in a similar manner to those reported from other zoned ultramafic balls but fail to define the original country rock ultrabasic discontinuity unambiguously. It is tentatively suggested that application of the apparently systematic deviations from ideality may provide additional evidence.

The presence of a hornblende zone and absence of a continuous biotite zone are two significant differences from other zoned ultramafic bodies. The former may suggest increased mobility of the aluminium species at Fiskenaesset, the latter a lower temperature of formation or smaller K2O content of the gneissic hosts.

Semi-aquatic and native plants collected from a mining site in the Iberian Pyrite Belt were analysed. Semi-aquatic plants showed enrichment of Cu (1.2—11 times), Zn (1.3—6 times), Pb (5—8 times) and As (24—1300 times) relative to typical concentrations in plants of the same species growing at uncontaminated sites. Translocation factors indicate limited internal metal transportation from roots to shoots. Infrared spectroscopy identified aromatic and aliphatic C-H (CH2) groups, S-O complexes and kaolinite in semi-aquatic plants.

Andychristyite, PbCu2+Te6+O5(H2O), is a new tellurate mineral from Otto Mountain near Baker, California, USA. It occurs in vugs in quartz in association with timroseite. It is interpreted as having formed from the partial oxidation of primary sulfides and tellurides during or following brecciation of quartz veins. Andychristyite is triclinic, space group P1̄, with unit-cell dimensions a = 5.322(3), b= 7.098(4), c = 7.511 (4) Å, α = 83.486(7), β = 76.279(5), γ = 70.742(5)°, V = 260.0(2) Å3 and Z = 2. It forms as small tabular crystals up to ∼50 μm across, in sub-parallel aggregates. The colour is bluish green and the streak is very pale bluish green. Crystals are transparent with adamantine lustre. The Mohs hardness is estimated at between 2 and 3. Andychristyite is brittle with an irregular fracture and one perfect cleavage on {001}. The calculated density based on the empirical formula is 6.304 g/cm3. The mineral is optically biaxial, with large 2V, strong dispersion, and moderate very pale blue-green to medium blue-green pleochroism. The electron microprobe analyses (average of five) provided: PbO 43.21, CuO 15.38, TeO3 35.29, H2O 3.49 (structure), total 97.37 wt.%. The empirical formula (based on 6 O apfu) is: Pb0.98Cu2+0.98Te6+1.02O6H 1.96. The Raman spectrum exhibits prominent features consistent with the mineral being a tellurate, as well as an OH stretching feature confirming a hydrous component. The eight strongest powder X-ray diffraction lines are [dobs in Å(I)(hkl)]: 6.71(16)(010), 4.76(17)(110), 3.274(100)(120,102,012), 2.641(27)(102, 211, 112), 2.434(23)(multiple), 1.6736(17)(multiple), 1.5882(21)(multiple) and 1.5133(15)(multiple). The crystal structure of andychristyite (R1 = 0.0165 for 1511 reflections with Fo > 4σF) consists of stair-step-like hcp polyhedral layers of Te6+O6 and Cu2+O6 octahedra parallel to {001}, which are linked in the [001] direction by bonds to interlayer Pb atoms. The structures of eckhardite, bairdite, timroseite and paratimroseite also contain stair-step-like hcp polyhedral layers.