The new mineral pabellóndepicaite (IMA2023-104), Cu2+2(N3C2H2)2(NH3)2(NO3)Cl·2H2O, was found in the guano deposit at Pabellón de Pica, Iquique Province, Chile, where it is a secondary phase formed at the contact between an altered guano deposit and a chalcopyrite-bearing gabbro. Pabellóndepicaite occurs on salammoniac in association with antipinite, bojarite, dittmarite, halite, joanneumite, sampleite, struvite, wheatleyite and whewellite. Crystals are rectangular blades or tablets, up to ∼0.2 mm long, flattened on {001} and elongated along [100] and exhibiting the forms {010}, {001}, {011} and {102}. Crystals are indigo blue and transparent, with vitreous lustre and light indigo blue streak. The mineral is brittle with curved and stepped fracture. The Mohs hardness is ∼2½. Cleavage is perfect on {001} and good on {010}. The density is 1.95(2) g·cm–3. Optically, pabellóndepicaite is biaxial (+) with α = 1.583(3), β = 1.596(3) and γ = 1.644(3) (white light). The 2V is 56(2)° with distinct r > v dispersion. The optical orientation is X = a, Y = b, Z = c and the pleochroism is X light indigo blue, Y indigo blue, Z pale indigo blue; Y > X > Z. The empirical formula is Cu2Cl1.25N9C4H13.75O4.75 (with H, C and N calculated based on the structure). Pabellóndepicaite is orthorhombic, space group Pmma, with cell parameters: a = 7.2118(12), b = 9.0983(15), c = 11.128(3) Å, V = 730.2(2) Å3 and Z = 2. The structure (R1 = 6.65% for 482 I > 2σI reflections) contains two types of polyhedral chains (1) a zig-zag chain of CuN4Cl2 octahedra linked by sharing Cl atoms and the N–N edges of 1,2,4-triazolate groups and (2) a chain of CuN4O2 octahedra alternating with NO3 triangles. The chains are linked to one another by 1,2,4-triazolate groups to form layers with isolated H2O groups in their cavities.

The new mineral theuerdankite, ideally Ag3AsO4, was found in the Alter Theuerdank Mine, Beerberg, St. Andreasberg, Goslar District, Lower Saxony, Germany. Theuerdankite occurs as aggregates of anhedral grains up to 3 mm in size, growing in cavities of strongly supergene-weathered material consisting of native silver and chlorargyrite (but with calcite present). It is dark violet, changing to reddish and black when exposed to the air and light. It has a grey to violet grey streak; when readily fresh, its streak is brownish-red. The Mohs hardness is ~2. It is brittle with no observable cleavage or parting and with a conchoidal fracture. The calculated density is 6.620 g⋅cm–3. In reflected light, theuerdankite is dark grey with a pinkish tint, with no observable bireflectance, pleochroism, or anisotropy. It shows dark red internal reflections. The reflectance values for wavelengths recommended by the Commission on Ore Mineralogy of the International Mineralogical Association are (R, %): 13.3 (470 nm), 12.8 (546 nm), 12.7 (589 nm) and 12.5 (650 nm). The empirical formula (based on 4 apfu) is Ag3.00As1.00O4. Theuerdankite is cubic, space group P$\bar{4}$3n, a = 6.144(2) Å, V = 231.93(13) Å3 and Z = 2. The six strongest powder X-ray diffraction lines are [dobs in Å, (I) hkl]: 3.0736, (22) 200; 2.7502, (100) 210; 2.5106, (55) 211; 1.7050, (36) 320; 1.6249, (44) 321; and 1.3412, (17) 421. The crystal structure of theuerdankite (R1 = 1.69% for 519 reflections having I > 3σ(I)), is isotypic to those of synthetic Ag3AsO4 and Ag3PO4. The Gram–Charlier development describing the higher-order tensors representing the atomic displacement parameters of the silver atom was implemented, documenting that silver tends to behave anharmonically in the theuerdankite structure at room temperature.

The new mineral naalasite (IMA2023–027), NaAl(AsO3OH)2⋅H2O, was found at the Torrecillas mine, Iquique Province, Chile, where it is a secondary alteration phase associated with anhydrite, juansilvaite, magnesiokoritnigite and a lavendulan-like phase. Naalasite occurs in tightly intergrown aggregates and druses of equant crystals. Crystals are light to medium pink and transparent, with vitreous lustre and white streak. The Mohs hardness is ~3½. The density is 3.19(2) g⋅cm–3. Optically, naalasite is uniaxial (+), with ω = 1.630(3) and ɛ = 1.660(3) (white light). The empirical formula (based on 9 O apfu) is Na0.92Al0.61Fe3+0.39As2O9H4.07. Naalasite is trigonal, space group R32, with cell parameters: a = 8.494(4), c = 26.430(13) Å, V = 1651.5(4) Å3 and Z = 9. The structure, refined to R1 = 3.78% for 641 I > 2σI reflections, is based on a loose 3D framework of alternating AsO3OH tetrahedra and AlO6 octahedra. The structure is topologically equivalent to that of nafeasite and can be regarded as its Al analogue, even though nafeasite is monoclinic with space group C2.

Oldsite (IMA2021-075), ideally K2Fe2+[(UO2)(SO4)2]2(H2O)8, is a new uranyl sulfate mineral found on specimens from the North Mesa Mine group, Temple Mountain, San Rafael district, Emery County, Utah, USA. It is a secondary mineral occurring with alum-(K), halotrichite, metavoltine, quartz, römerite, stanleyite, sulphur, szomolnokite and mathesiusite. It forms rectangular blades flattened on {010} and elongated on [001], reaching ~0.3 mm in length. Crystals are yellow in colour, transparent with a vitreous lustre; the streak is very pale yellow. The mineral is non-fluorescent. Cleavage is excellent on {100} and perfect on {010}; the Mohs hardness is ~2. Crystals are brittle with irregular, splintery fracture. The density measured by flotation in a mixture of methylene iodide and toluene is 3.31 g⋅cm–3; the calculated density is 3.298 g⋅cm–3 for the empirical formula and 3.330 g⋅cm–3 for the ideal formula. Oldsite is biaxial (+), with α = 1.552(2), β = 1.556(2) and γ = 1.588(2) (measured in white light). The 2V measured directly on a spindle stage is 37(1)°; the calculated 2V is 39.6°. Dispersion is r < v, moderate. The optical orientation is X = b, Y = a and Z = c. The mineral is non-pleochroic. The empirical formula of oldsite (on the basis of 28 O apfu) is K1.93(Fe2+0.53Zn0.31V3+0.09Mg0.08)Σ1.02[(U0.98O2)(S1.01O4)2]2(H2O)8. The Raman spectrum is dominated by the vibrations of SO42– and UO22+ units. Oldsite is orthorhombic, Pmn21, a = 12.893(3), b = 8.276(2), c = 11.239(2) Å, V = 1199.2(5) Å3 and Z = 2. The five strongest powder X-ray diffraction lines are [dobs, Å (I, %) (hkl) ]: 8.29 (59) (010), 6.47 (82) (200), 5.10 (62) (210), 4.65 (100) (012, 211) and 3.332 (55) (022, 221). The crystal structure of oldsite was refined from single-crystal X-ray data to R = 0.0258 for 2676 independent observed reflections, with Iobs > 3σ(I). Oldsite is an Fe2+ analogue of svornostite; its crystal structure is based upon infinite chains of uranyl-sulfate polyhedra, which comprises pentagonal UO7 bipyramids sharing four of their equatorial vertices with sulfate tetrahedra such that each tetrahedron is linked to two uranyl bipyramids to form an infinite chain (the free, non-linking equatorial vertex of the uranyl bipyramid is an H2O group). The broader discussion on the origin and composition of uranyl sulfate minerals is made. The new mineral name honours American mineralogist, Dr. Travis A. Olds for his contribution to uranium mineralogy.

The new beudantite-group mineral oberwolfachite, ideally SrFe3+3(AsO4)(SO4)(OH)6, was discovered in two localities: Clara mine, Oberwolfach, Schwarzwald, Baden-Württemberg, Germany (holotype) and Monterniers mine, Lantignié, Rhône, Auvergne-Rhône-Alpes, France (cotype). The associated minerals are quartz, baryte, hematite, illite, goethite, beudantite and dussertite (Clara) and arsenogoyazite, jarosite, graulichite-(Ce), goethite and hematite (Monterniers). Oberwolfachite forms yellow to brown platy crystals up to 1 mm across or thick outer zones of mixed (oberwolfachite–beudantite) crystals up to 3 mm across. The lustre is adamantine and the streak is yellow. A distinct cleavage on {0001} is observed. Calculated density is 3.874 g⋅cm–3. The infrared spectra are given. The chemical composition of the holotype/cotype samples are (wt.%, b.d.l. = below detection limit): K2O 1.25/1.86, SrO 6.41/11.15, BaO 8.13/0.45, PbO 2.18/b.d.l., Al2O3 0.16/0.23, Fe2O3 38.99/39.98, La2O3 1.68/not determined, Ce2O3 1.28/2.06, P2O5 0.12/b.d.l., As2O5 17.55/16.55, SO3 12.86/14.99, H2O (calculated) 8.72/9.05, total 99.33/96.62. The empirical formula of the holotype sample is (Sr0.38Ba0.33K0.16Pb0.06La0.06Ce0.05)Σ1.04(Fe3+3.03Al0.02)Σ3.05[(SO4)1.00(AsO4)0.95(PO4)0.01](O6.16H6.00). The crystal structures of both samples were determined using single-crystal X-ray diffraction data and refined to R = 3.13% (holotype, 293 K) and 2.65% (cotype, 170 K). Oberwolfachite is trigonal, R${\bar 3}$m, with a = 7.3270(3) Å, c = 17.0931(9) Å and V = 794.70(8) Å3 (holotype), and a = 7.298(2) Å, c = 16.908(3) Å and V = 779.8(4) Å3 (cotype); Z = 3. The strongest lines of the powder X-ray diffraction pattern of holotype [d, Å (I, %)(hkl)] are: 5.95 (56)(101), 3.664 (37)(110), 3.117 (16)(021), 3.082 (100)(113), 2.548 (15)(024), 2.280 (22)(107), 1.983 (26)(303) and 1.832 (19)(220).

The new triazolate mineral bojarite (IMA2020-037), Cu3(N3C2H2)3(OH)Cl2⋅6H2O, is found in a guano deposit located at the Pabellón de Pica Mountain, Iquique Province, Tarapacá Region, Chile. Associated minerals are salammoniac, halite, nitratine and belloite. Bojarite occurs as blue fine-grained porous aggregates up to 1 mm × 3 mm × 5 mm combined typically in interrupted earthy crusts. The mineral is brittle. The Mohs hardness is 2. Dcalc = 2.057 g cm–3. The IR and Raman spectra show the presence of the 1,2,4-triazolate anion and H2O molecules. Bojarite is optically isotropic and n = 1.635(2) (λ = 589 nm). The chemical composition (electron-microprobe data for Na, Mg, Fe, Cu and Cl; H, C and N contents measured by gas chromatography on products of ignition at 1200°C; wt.%) is: Na 0.22, Mg 0.74, Fe 0.99, Cu 29.73, Cl 13.62, N 20.4, C 11.6, H 3.3, O (calculated by stoichiometry) 19.93, total 100.53.

The empirical formula is (Cu2.68Mg0.17Fe0.10Na0.05)Σ3(N3C2H2)2.755[(OH)][Cl2.19(H2O)3.77(OH)0.04]Σ6⋅2.3H2O. The idealised formula is Cu3(N3C2H2)3(OH)Cl2⋅6H2O. The crystal structure of bojarite was refined based on powder X-ray diffraction data, using the Rietveld method. The final agreement factors are: Rp = 0.0225, Rwp = 0.0310 and Robs = 0.0417. The new mineral is cubic, space group Fd$\bar{3}$c; a = 24.8047(5) Å, V = 15,261.6(5) Å3 and Z = 32. The strongest reflections of the powder X-ray diffraction pattern [d, Å (I,%)(hkl)] are: 8.83 (31)(220), 7.19 (100)(222), 6.23 (35)(400), 5.077 (28)(422), 4.194 (28)(531), 3.584 (23)(444), 2.865 (28)(660, 751) and 2.723 (22)(753, 842).

The new leucophosphite-group mineral ammoniotinsleyite is found in a guano deposit located on the Pabellón de Pica Mountain, Iquique Province, Tarapacá Region, Chile. Associated minerals are halite, gypsum, salammoniac and clay minerals. Ammoniotinsleyite occurs as pink to pale violet globular aggregates up to 3 mm across with individual single crystals ~10–15 μm. The mineral is brittle. Its Mohs hardness is 4. Dmeas. = 2.42(2) g cm–3 and Dcalc. = 2.451 g cm–3. The IR spectrum shows the presence of NH4+ and PO43– groups and H2O molecules. Ammoniotinsleyite is optically biaxial (+), α = 1.557(2), β = 1.559 (calc.), γ = 1.563(2) (λ = 589 nm); and 2Vmeas. = 75(10)°. The chemical composition (K, Mg, Ca, Al, Fe and P from electron-microprobe data; H, C and N measured by gas chromatography on products of ignition at 1200°C; wt.%) is: (NH4)2O 7.25, K2O 1.50, MgO 0.42, CaO 0.34, Al2O3 29.91, Fe2O3 2.36, P2O5 43.97, H2O 14.89, CO2 below detection limit, total 100.64. The empirical formula is [(NH4)0.88K0.10Ca0.02)]Σ1.00(Al1.86Fe3+0.09Mg0.03)Σ1.98(PO4)1.96(OH)1.05⋅2.11H2O. The idealised formula is (NH4)2Al2(PO4)2(OH)⋅2H2O. The crystal structure of ammoniotinsleyite was refined based on powder X-ray diffraction data, using the Rietveld method. The final agreement factors are: Rp = 0.0071, Rwp = 0.0093 and Robs = 0.0167. The new mineral is isostructural with tinsleyite, spheniscidite and leucophosphite. It is monoclinic, space group P21/n, a = 9.5871(1) Å, b = 9.6089(1) Å, c = 9.6467(2) Å, β = 103.4461(8)°, V = 864.31(2) Å3 and Z = 4. The strongest reflections of the powder X-ray diffraction pattern [d,Å(I,%)(hkl)] are: 7.56(23)($\bar{1}$01), 6.71(79)(011, 110), 5.947(100)(101, $\bar{1}$11), 4.676(36)(002, 200), 3.032(28)($\bar{1}$13, 031, 130), 2.958(25)($\bar{2}$22, 310, $\bar{1}$31) and 2.635(29)($\bar{2}$31).