The triphylite-lithiophilite series, Li(Fe2+,Mn2+)PO4, of primary phosphate minerals are notable for their susceptibility to alteration and their extensive range of alteration products. This article considers the principal crystallographic motifs that relate the crystal structures of the alteration minerals and their relationships to the parent structures. For alteration under oxidizing conditions the common structural motif is a laueite-like heteropolyhedral layer comprising 7 & Aring; corner-connected octahedral chains, cross-linked by M2(TO4)2 Phi 8 cyclic tetramers. With decreasing temperature of hydrothermal alteration, the structures change, from containing two sets of interpenetrating, quasi-orthogonal, laueite-type layers, to containing one orientation of the laueite-type layers, in two-layer-wide slabs. Alteration minerals formed under supergene conditions, such as the laueite-group minerals have single laueite-type layers interconnected via corner-sharing with hydrated octahedrally coordinated divalent cations. Under reducing conditions, the alteration phases are hydrated minerals, which have structures based on strings of edge-sharing octahedra. They have, in common with the oxidized alteration products, the linking of the octahedral chains by cyclic tetramers that polymerize as kr & ouml;hnkite-related chains. Motifs present in the structures of the alteration phases can also be identified in the parent structures, suggesting that they may be nucleating sites for the formation/growth of the alteration phases.

Fanfaniite, Ca4Mn2+Al4(PO4)6(OH)412H2O, from the H & uuml;hnerkobel pegmatite mine, Bavaria, has been characterised by chemical analyses and synchrotron single-crystal diffraction. The average crystal structure was refined in space group C2/c (cell parameters a = 10.055(2), b = 24.132(5), c = 6.2590(10) & Aring;, beta = 91.35(3)degrees) to compare with reported monoclinic structures of other calcioferrite-group minerals with general formula Ca4AB4(PO4)6(OH)412H2O, A = Mn2+, Fe2+, Mg, B = Al, Fe3+. The average structure contains disordered half-occupied A sites and associated coordinated water molecules. The diffraction data for fanfaniite contains weak reflections that violate the c-glide condition, as also reported for montgomeryite, and in addition contains extremely weak, diffuse reflections requiring a doubling of a, as reported for kingsmountite. Structure refinements were conducted for the noncentrosymmetric C2 model used for montgomeryite and for the P $\bar 1$ model used for kingsmountite. The fanfaniite diffraction data is better explained by the triclinic model with doubled a cell parameter, although the extent of ordering of the A-site cations is considerably lower (56%) than reported for kingsmountite (85%). If the C2 model contributes, it can only be at the scale of the unit cell.

Abstract The crystal structure of the hydrated aluminum phosphate mineral vashegyite from Chvaletice, Czech Republic, was characterized using synchrotron single-crystal diffraction data. The data were indexed with an orthorhombic cell, a = 10.8424(3), b = 14.9140(4), c = 19.3408(5) Å. The c parameter is markedly shorter than that for the originally described mineral (22.67 Å) due to partial dehydration and a shrinking of the separation of the (001) layers of the layer structure. The dehydration results in disorder in the (001) layer stacking, manifested in strong streaking of diffraction spots along c*. A structure solution was obtained in P2an. The solution was unusual in comprising a fully ordered heteropolyhedral layer at z = ½ but a disordered layer of partially occupied sites at z = 0. It was possible to construct AlO4, PO4, and AlO6 polyhedra from the sites in the disordered layer. Groups of the polyhedra formed corner-sharing segments identical to those in the ordered layer. From the spatial relationships between the polyhedra in the ordered and disordered layers, a model was developed for the local layer ordering in space group P21/n. The layers are formed from intergrown Al2(PO4)2Φ7 and Al2(PO4)2Φ8 clusters that form ribbons along [100]. The ribbons are interconnected along [010] via corner-sharing of PO4 tetrahedra with AlO4 tetrahedra to give an open 2D framework of composition Al5(PO4)4(OH)3(H2O)7. The heteropolyhedral framework encompasses 10-sided cavities. H2O molecules occupy sites within the cavities and between the layers, giving an overall formula for partially dehydrated vashegyite of Al5(PO4)4(OH)3(H2O)7·8.7H2O.

The mineral has orthorhombic symmetry, space group Aba2, with cell parameters a = 11.995(2), b = 24.692(5) and c = 9.920(2) & Aring;. The structure was refined to wR(obs) = 0.063 for 3558 reflections with I > 3 sigma(I). It is built from double heteropolyhedral layers parallel to (010) with [Ca(H2O)(6)](2+) hydrated cations and H-bonded H2O in the interlayer region. The heteropolyhedral layers comprise seven-member rings of corner-connected ZnO4 and PO4 tetrahedra and Fe23+O10 dimers of edge-shared octahedra. From the refined structural model the formula is established as [Ca(H2O)(6)](2)Zn4Fe83+(PO4)(8)(OH)(12)(H2O)(4)& centerdot;4H(2)O. The jungite specimen also contains crystals that indexed with triclinic cell parameters, a approximate to 11.95, b = 10.05, c = 9.9 & Aring;, alpha approximate to 86.7, beta =89.9 and gamma = 83.4 degrees. They gave poor diffraction due to multiple components with different orientations, but it was possible to extract intensity data for a single component and solve the structure. The model contains identical double heteropolyhedral layers parallel to (010) as in the orthorhombic mineral, but differs in that the Ca atoms are coordinated predominantly to layer anions. The formula obtained from the structural model is [Ca-2(H2O)(5)]Zn4Fe83+(PO4)(8)(OH)(12)(H2O)(4)& centerdot;2H(2)O, corresponding to a dehydrated form of jungite, with a contraction in the layer spacing from 12.35 to 10.0 & Aring;.

Fluormacraeite, [(H2O)K]Mn-2(Fe2Ti)(PO4)(4)[OF](H2O)(10) & sdot; 4H(2)O, is a new monoclinic member of the paulkerrite group from the Pl & ouml;ss berg pegmatite, Upper Palatinate, Bavaria, Germany. It was found in specimens of magnesium-bearing triplite. Associated minerals are spherical blue phosphosiderite, pink-coloured strengite micro-crystals, white fluorapatite globules, light-yellow leucophosphite, black-green rockbridgeite, and reddish-brown cacoxenite. Fluormacraeite occurs as isolated pale-yellow rhombic tablets, flattened on (010) with diameters in the range of 50 to 150 mu m and thicknesses on the order of 10 to 30 mu m. The crystal forms are {010}, {001}, and {111}. The calculated density for the empirical formula and single-crystal unit-cell volume is 2.39 g cm(-3). Optically, fluormacraeite crystals are biaxial (+), with alpha=1.610(3), beta=1.620(3), and gamma=1.644(3) (measured in white light). The calculated 2V is 66.5 degrees. The optical orientation is X=b, Y=c, and Z=a. The empirical formula from electron microprobe analyses and structure refinement is (A1)[K-0.14(H2O)(0.76)](Sigma 0.90) (A2)[K-0.79(H2O)(0.21)](Sigma 1.00) (M1)(MnMg0.25)(Sigma 2.00) (M2+M3)(FeAl0.13TiMg0.01)(Sigma 3.00) (PO4)(4.00) (X)[O0.94F0.81(OH)(0.25)](Sigma 2.00)(H2O)(10) & sdot; 3.90H(2)O. Fluormacraeite has monoclinic symmetry with space group P2(1)/c and unit-cell parameters a=10.546(2) & Aring;, b=20.655(1) & Aring;, c=12.405(1) & Aring;, beta=90.09(1)degrees, V=2702.1(6) & Aring;(3), and Z=4. The crystal structure was refined using synchrotron single-crystal data to wR(obs)=0.0559 for 5646 reflections with I>3 sigma(I). Fluormacraeite is isostructural with the paulkerrite-group minerals pleysteinite, macraeite, rewitzerite, hochleitnerite, fluor-rewitzerite, sperlingite, and paulkerrite, with ordering of K and H2O at different A sites (A1 and A2) using the general formula A1A2M1(2)M2(2)M3(PO4)(4)X-2(H2O)(10) & sdot; 4H(2)O. It is the F analogue of macraeite, with OF replacing O(OH) at the X2 sites. The general crystal-chemical properties of the monoclinic paulkerrite-group minerals are compared.

Laueite/stewartite epitaxy was studied using single-crystal diffraction applied to a composite crystal from Hagendorf-S & uuml;d, Bavaria. The orientation relationships between the crystals of the two minerals was facilitated by using a non-conventional B $\bar {1}$ space group setting for stewartite, giving unit cells with parallel axes and with as = 2al, bs = bl and cs = 2cl. Face indexing of the crystals of the two minerals confirmed the epitaxial relationship, with the {100} and {010} faces parallel. The plane of epitaxy is {010}. Refinement of laueite and stewartite datasets extracted from the composite-crystal data collection showed a significant decrease in the mean Mn-site bond distances in laueite, consistent with chemical analyses of the crystals that gave site compositions of Mn0.92Fe3+0.08 for stewartite and Mn0.66Mg0.17Fe3+0.17 for laueite. The epitaxial growth of laueite on {010} planes of stewartite appears to have been initiated by a change in solution chemistry. Possible paragenesis of the secondary phosphate minerals from primary triphylite is discussed.

Cuprozheshengite, Pb4CuZn2(AsO4)(2)(PO4)(2)(OH)(2), is a new mineral species from Yunnan, China. It occurs as sub-millimeter greenish-blue hemispherical aggregates of microscopic blade-like crystals on hemimorphite and is closely associated with veszelyite and galena. Cuprozheshengite is brittle with irregular fracture and has a Mohs hardness of 2 1/2 -3 and perfect cleavages on {011}. The calculated density is 5.91 g/cm(3). The empirical chemical formula of the holotype is (Pb3.97Na0.04Ca0.01)(Sigma 4.02)Cu-1.06 Zn-2.09(AsO4)(2)[(P0.84As0.12Si0.01)(Sigma 0.97)O-4]2(OH)(2) based on 18 O atoms per formula unit. Cuprozheshengite is triclinic, space group P1, with unit-cell parameters a = 4.7977(8), b = 8.5789(8), c = 10.3855(9) & Aring;, alpha = 97.270(8)degrees, beta = 101.902(12)degrees, gamma = 91.495(11)degrees, V = 414.30(9) & Aring;(3), and Z = 1. Cuprozheshengite is a member of dongchuanite group, whose general formula is A(4)(VI)B(IV)B(2)(X1O(4))(2)(X2O(4))(2)(OH)(2), where A is an interlayer cation with Pb being dominant; B are transition metals with two crystallographic positions, B-IV has tetrahedral coordination and is fully occupied by Zn, while B-VI has octahedral coordination and is dominated by Zn or Cu; X1 and X2 are cations with tetrahedral coordination, occupied by As and P. Like other dongchuanite group minerals, the structural framework of cuprozheshengite is composed of two heteropolyhedral columns along [100]. Type 1 columns comprise corner-linked [(BO4)-B-IV] and [X2O(4)] tetrahedra. Each tetrahedron is connected with three other tetrahedra in the columns. Type 2 columns have alternating [(BO4)-B-VI(OH)(2)] octahedra with pairs of corner-connected [X1O(4)] tetrahedra. These two columns are connected by corner-sharing between [(BO4)-B-IV] and [X1O(4)] tetrahedra to form layers parallel to (011). Pb atoms occupy two independent sites between the layers. Cuprozheshengite is named as the copper analog of zheshengite. Single-crystal X-ray diffraction reveals that As and P order over the X1 and X2 sites, with As tending to occupy X1. Density functional theory (DFT) calculations confirm the occupancy propensity of As benefiting structural stability. The structural and stability studies of cuprozheshengite may have implications for local environmental governance. As a stable mineral in the water and elemental cycles after weathering, cuprozheshengite still has the potential to continually crystallize, fixing As into a stable crystalline waste form.

AbstractHydroxylbenyacarite, (H2O)2Mn2(Ti2Fe)(PO4)4[O(OH)](H2O)10⋅4H2O, is a new paulkerrite-group mineral from the El Criollo mine, Cordoba Province, Argentina (IMA2023–079). It was found in specimens of altered triplite, in association with bermanite, phosphosiderite, quartz, strengite and manganese oxides.Hydroxylbenyacarite occurs as light greenish-yellow rhombic tablets with dimensions of typically 20 to 50 μm, occasionally to 400 μm. The crystals are flattened on {010}, slightly elongated on [001] and bounded by the {111} and {010} forms. The calculated density is 2.32 g cm–3. Optically, hydroxylbenyacarite crystals are biaxial (+), with α = 1.608(3), β = 1.624(3), γ = 1.642(3) (measured in white light) and 2V(meas.) = 88(2)°. The calculated 2V is 87.5°. The empirical formula is Ca0.06A[K0.46(H2O)0.88□0.66]Σ2.00M1(Mn1.52Mg0.02Fe2+0.35□0.11)Σ2.00M2+M3(Fe3+1.21Al0.02Ti1.77)Σ3.00(PO4)4X[F0.16(OH)0.70O1.14]Σ2.00(H2O)10⋅3.77H2O.The average crystal structure for hydroxylbenyacarite has space groupPbcaand unit cell parametersa= 10.5500(3) Å,b=20.7248(5) Å,c= 12.5023(3) Å,V= 2733.58(12) Å3andZ= 4. It was refined using single-crystal data towRobs= 0.074 for 2611 reflections withI> 3σ(I). The crystal structure contains corner-connected linear trimers of Ti-centred octahedra that share corners with PO4tetrahedra to form 10-member rings parallel to (010). K+cations and water molecules are located in interstitial sites within the rings. Additional corner-sharing of the PO4tetrahedra with MnO2(H2O)4octahedra occurs along [010] to complete the 3D framework structure. A new eight-coordinated interstitial site, previously unreported for paulkerrite-group minerals, is occupied by Ca2+cations. Weak diffuse diffraction spots in reconstructed precession images for hydroxylbenyacarite violate theaandbglide plane extinctions forPbcaand are consistent with local, unit-cell-scale regions of monoclinic,P21/cstructure, in which ordering of the interstitial K+and Ca2+cations occurs.

Single -crystal X-ray diffraction data sets for pleysteinite, [(H 2 O)K]Mn 2 Al 3 (PO 4 ) 4 F 2 (H 2 O) 10 4H 2 O, and hochleitnerite, [(H 2 O)K]Mn 2 (Ti 2 Fe)(PO 4 ) 4 O 2 (H 2 O) 10 4H 2 O, collected using a synchrotron microfocus beam, gave monoclinic unit cells, in contrast to previously reported orthorhombic cells obtained using laboratory -based sealed -tube diffractometer data. The differences are attributed to twinning in crystals of the two minerals. As the laboratory diffractometer beam diameter of the sealedtube SXRD is larger than the crystals that were analyzed, the diffraction results were averaged over the different twin domains, whereas those obtained with the synchrotron microfocus beam gave diffraction data wholly or predominantly from a single domain. Data from the synchrotron datasets give a = 10.440(5) & Aring;, b = 20.588(5) & Aring;, c = 12.234(2) & Aring;, 13 = 90.38(1) degrees for pleysteinite and a = 10.547(2) & Aring;, b = 20.577(4) & Aring;, c = 12.373(2) & Aring;, 13 = 90.09(3) degrees for hochleitnerite. The crystal structures for both minerals were re fi ned in P 2 1 / c, giving R obs = 0.059, 0.058 for 5951, 6718 re fl ections with I . 3 r ( I ), respectively. The ideal formulae for the two minerals in this setting conform to the general formula A 1 A 2 M 1 2 M 2 2 M 3(PO 4 ) 4 X 2 (H 2 O) 10 4H 2 O, with K and H 2 O ordered at separate A sites, whereas K and H 2 O were disordered over a single A site in the orthorhombic models (space group Pbca ). Crystal -chemical aspects of the paulkerrite-group minerals, pleysteinite, hochleitnerite, paulkerrite, rewitzerite, and macraeite, are compared and discussed.

Fluor-rewitzerite, [(H2O)K]Mn2(Al2Ti)(PO4)4(OF)(H2O)10⋅4H2O, is a new monoclinic member of the paulkerrite group, from the Hagendorf-Süd pegmatite, Oberpfalz (Upper Palatinate in English), Bavaria, Germany. It occurs on the walls of vugs in corroded zwieselite, in association with Zn- and Al-bearing earlshannonite, fluorapatite, jahnsite-(CaMnMn) and Al-rich strunzite. Fluor-rewitzerite forms clusters of colourless stubby prisms up to 0.1 mm long that are flattened on {010}; elongated along [100]; and show the forms {100}, {010}, {001}, {111} and {111‾}. Twinning occurs by 2-fold rotation about c. The measured density is 2.42(2) g cm−3. Optically, fluor-rewitzerite crystals are biaxial (+), with α = 1.569(3), β = 1.582(3), γ = 1.602(3) (white light) and 2V(meas) = 78(1)°. The empirical formula from electron microprobe analyses and structure refinement is A1[(H2O)0.85K0.15]Σ1.00A2(K1.00) M1(Mn2+1.50Mg0.09Fe2+0.41)Σ2.00M2+M3(Al1.70Ti4+0.89Fe3+0.42)Σ3.01(PO4)3.99X(O1.09F0.92)Σ2.01(H2O)10⋅4.12H2O. Fluor-rewitzerite has monoclinic symmetry with space group P21/c and unit-cell parameters a = 10.407(1) Å, b = 20.514(2) Å, c = 12.193(1) Å, β = 90.49(2)°, V = 2603.0(4) Å3 and Z = 4. The crystal structure was refined using synchrotron single-crystal data to Robs=0.058 for 6186 reflections with I>3σ(I). Fluor-rewitzerite is the fluoride analogue of rewitzerite, with F dominant over OH at the X sites of the general formula A1A2M12M22M3(PO4)4X2(H2O)10⋅4H2O.

Sperlingite, (H2O)K(Mn2+Fe3+)(Al2Ti)(PO4)(4)[O(OH)][(H2O)(9)(OH)]& sdot;4H(2)O, is a new monoclinic member of the paulkerrite group, from the Hagendorf-S & uuml;d pegmatite, Oberpfalz, Bavaria, Germany. It was found in corrosion pits of altered zwieselite, in association with columbite, hopeite, leucophosphite, mitridatite, scholzite, orange-brown zincoberaunite sprays and tiny green crystals of zincolibethenite. Sperlingite forms colourless prisms with pyramidal terminations, which are predominantly only 5 to 20 mu m in size, rarely to 60 mu m and frequently are multiply intergrown and are overgrown with smaller crystals. The crystals are flattened on {010} and slightly elongated along [100] with forms {010}, {001} and {111}. Twinning occurs by rotation about c. The calculated density is 2.40 g & sdot;cm(-3). Optically, sperlingite crystals are biaxial (+), alpha = 1.600(est), beta = 1.615(5), gamma = 1.635(5) (white light) and 2V (calc.) = 82.7 degrees. The optical orientation is X = b, Y = c and Z = a. Neither dispersion nor pleochroism were observed. The empirical formula from electron microprobe analyses and structure refinement is (A1)[(H2O)(0.96)K-0.04](Sigma 1.00)(A2)(K-0.52 square(0.48))(Sigma 1.00)(M1)(Mn0.602+Mg0.33Zn0.29Fe0.773+)(Sigma 1.99)(M2+M3)(Al1.05Ti1.334+Fe0.623+)(Sigma 3.00)(PO4)(4)(X)[F-0.19(OH)(0.94)O-0.87](Sigma 2.00)[(H2O)(9.23)(OH)(0.77)](Sigma 10.00)& sdot;3.96H(2)O. Sperlingite has monoclinic symmetry with space group P2(1)/c and unit-cell parameters a = 10.428(2) & Aring;, b = 20.281(4) & Aring;, c = 12.223(2) & Aring;, beta = 90.10(3)degrees, V = 2585.0(8) & Aring;(3) and Z = 4. The crystal structure was refined using synchrotron single-crystal data to wR(obs) = 0.058 for 5608 reflections with I > 3 sigma(I). Sperlingite is the first paulkerrite-group mineral to have co-dominant divalent and trivalent cations at the M1 sites; All other reported members have Mn2+ or Mg dominant at M1. Local charge balance for Fe3+ at M1 is achieved by H2O -> OH- at H2O coordinated to M1.

Hydroxylbenyacarite, (H2O)(2)Mn-2(Ti2Fe)(PO4)(4)[O(OH)](H2O)(10)center dot 4H(2)O, is a new paulkerrite-group mineral from the El Criollo mine, Cordoba Province, Argentina (IMA2023-079). It was found in specimens of altered triplite, in association with bermanite, phosphosiderite, quartz, strengite and manganese oxides. Hydroxylbenyacarite occurs as light greenish-yellow rhombic tablets with dimensions of typically 20 to 50 mu m, occasionally to 400 mu m. The crystals are flattened on {010}, slightly elongated on [001] and bounded by the {111} and {010} forms. The calculated density is 2.32 g cm(-3). Optically, hydroxylbenyacarite crystals are biaxial (+), with alpha = 1.608(3), beta = 1.624(3), gamma = 1.642(3) (measured in white light) and 2V(meas.) = 88(2)degrees. The calculated 2V is 87.5 degrees. The empirical formula is Ca-0.06(A)[K-0.46(H2O)(0.88)square(0.66)](Sigma 2.00)(M1)(Mn1.52Mg0.02Fe0.352+square(0.11))(Sigma 2.00)(M2+M3)(Fe1.213+Al0.02Ti1.77)(Sigma 3.00)(PO4)(4)(X)[F-0.16(OH)(0.70)O-1.14](Sigma 2.00)(H2O)(10)& sdot;3.77H(2)O. The average crystal structure for hydroxylbenyacarite has space group Pbca and unit cell parameters a = 10.5500(3) angstrom, b =20.7248(5) angstrom, c = 12.5023(3) angstrom, V = 2733.58(12) angstrom(3) and Z = 4. It was refined using single-crystal data to wR(obs) = 0.074 for 2611 reflections with I > 3 sigma(I). The crystal structure contains corner-connected linear trimers of Ti-centred octahedra that share corners with PO4 tetrahedra to form 10-member rings parallel to (010). K+ cations and water molecules are located in interstitial sites within the rings. Additional corner-sharing of the PO4 tetrahedra with MnO2(H2O)(4) octahedra occurs along [010] to complete the 3D framework structure. A new eight-coordinated interstitial site, previously unreported for paulkerrite-group minerals, is occupied by Ca2+ cations. Weak diffuse diffraction spots in reconstructed precession images for hydroxylbenyacarite violate the a and b glide plane extinctions for Pbca and are consistent with local, unit-cell-scale regions of monoclinic, P2(1)/c structure, in which ordering of the interstitial K+ and Ca2+ cations occurs.

Macraeite, [(H2O)K]Mn2(Fe2Ti)(PO4)4[O(OH)](H2O)10 ⋅ 4H2O, is a new monoclinic member of the paulkerrite group, from the Cubos–Mesquitela–Mangualde pegmatite, Mangualde, Portugal. It was found in phosphate nodules of weathered triplite, heterosite, and lithiophilite. Associated minerals are strengite, triplite, bermanite, phosphosiderite, and switzerite. Macraeite forms colourless to light-greenish-yellow pseudo-rhombic dodecahedral-shaped crystals up to 0.15 mm. The crystals are equant with forms {010}, {001}, {111}, and {1‾11}. The calculated density is 2.39 g cm−3. Optically, macraeite crystals are biaxial (+), with α=1.605(3), β=1.611(3), γ=1.646(3) (measured in white light), and 2V(meas) = 45(3)°. The empirical formula from electron microprobe analyses and structure refinement is A1[(H2O)0.83K0.17]Σ1.00 A2[K0.65(H2O)0.35]Σ1.00 M1(Mn1.98□0.022+)Σ2.00 M2(Fe1.093+Al0.31Ti0.524+Mg0.08)Σ2.00 M3(Ti0.664+Fe0.343+)Σ1.00 (PO4)4 X[O0.87F0.53(OH)0.60]Σ2.00(H2O)10 ⋅ 4H2O. Macraeite has monoclinic symmetry with space group P21/c and unit-cell parameters a=10.562(2) Å, b=20.725(4) Å, c=12.416(2) Å, β=90.09(3)°, V=2717.8(9) Å3, and Z=4. The crystal structure was refined using synchrotron single-crystal data to wRobs=0.065 for 4990 reflections with I>3σ(I). Macraeite is isostructural with the paulkerrite-group minerals rewitzerite and paulkerrite, with ordering of K and H2O at different A sites (A1 and A2) of the general formula A1A2M12M22M3(PO4)4X2(H2O)10 ⋅ 4H2O, whereas in the orthorhombic member, benyacarite, K and H2O are disordered at a single A site.

AbstractRewitzerite, K(H2O)Mn2(Al2Ti)(PO4)4[O(OH)](H2O)10⋅4H2O, is a new monoclinic member of the paulkerrite group, from the Hagendorf-Süd pegmatite, Oberpfalz, Bavaria, Germany. It was found in specimens of altered zwieselite, in association with rockbridgeite. Rewitzerite forms clusters of colourless elongated hexagonal-shaped prisms, up to 0.1 mm long. The crystals are flattened on {010} and elongated along [100], with forms {010}, {001}, {111} and {$\bar{1}$11}. The calculated density is 2.33 g⋅cm–3. Optically, rewitzerite crystals are biaxial (+), with α = 1.585(2), β = 1.586(2), γ = 1.615(2) (measured in white light) and 2V(meas) = 25(2)°. The empirical formula from electron microprobe analyses and structure refinement is A1[K0.77(H2O)0.23]A2[H2O] M1(Mn2+0.82Mg0.64Fe3+0.43□0.11)Σ2.00M2+M3(Al1.51Ti4+1.06Fe3+0.43)Σ3.00(PO4)4X[(OH)0.54F0.42O1.04]Σ2.00(H2O)10⋅4H2O, where □ = vacancy.Rewitzerite has monoclinic symmetry with space group P21/c and unit-cell parameters a = 10.444(2) Å, b = 20.445(2) Å, c = 12.2690(10)Å, β = 90.17(3)°, V = 2619.8(6) Å3 and Z = 4. The crystal structure was refined using synchrotron single-crystal data to wRobs = 0.068 for 5894 reflections with I > 3σ(I). The crystal structure has the same topology as that for orthorhombic paulkerrite-group minerals but differs primarily in having an ordering of K+ and H2O molecules in different A sites, whereas they are disordered at a single A site in the orthorhombic members of the group.

Whiteite-(CaMnFe), CaMn2+Fe22+Al2(PO4)4(OH)2 ⋅ 8H2O, is a new whiteite-subgroup member of the jahnsite group from the Hagendorf-Süd pegmatite, Oberpfalz, Bavaria, Germany. It was found in vugs in an altered feldspar area of a specimen composed predominantly of rockbridgeite, with hureaulite and relic triphylite. Other associated minerals in small vugs in the specimen were strengite and laueite. Whiteite-(CaMnFe) occurs as sprays and clusters of colourless to pale yellow, rod-like crystals, with diameters of typically 10 to 50 µm and lengths up to ∼ 500 µm. The crystals are flattened on {001} and elongated along [010]. The measured density is 2.80(2) g cm−3. Optically, whiteite-(CaMnFe) crystals are biaxial (+), with α=1.608(3), β=1.612(3), γ=1.624(3) and 2V(meas.) = 59(1)∘. The empirical formula from electron microprobe analyses and structure refinement is (Ca0.70Mn0.30)Mn(Fe1.232+Mn0.49Mg0.29Zn0.06)(Al1.88Fe0.123+)(PO4)3.96(OH)2(H2O)8. Whiteite-(CaMnFe) is monoclinic, P2 /a, a=14.925(5), b=7.0100(14), c=10.053(2) Å, β=111.31(2)∘, V=979.9(4) Å3 and Z=2. The crystal structure was refined using single-crystal data to wRobs=0.052 for 1613 reflections with I>3σ(I). Site occupancy refinements confirm the ordering of dominant Ca, Mn and Fe2+ in the X, M1 and M2 sites, respectively, of the general jahnsite-group formula XM1M22M32(H2O)8(OH)2(PO4)4.

Pleysteinite, [(H2O)0.5K0.5]2Mn2Al3(PO4)4F2(H2O)10 ⚫ 4H2O, is the aluminium analogue of benyacarite, from the Hagendorf-Süd pegmatite, Oberpfalz, Bavaria, Germany. It was found in specimens of altered zwieselite, in association with nordgauite, fluellite, rockbridgeite, pyrite and columbite. Pleysteinite occurs as isolated and small aggregates of colourless, stubby prisms that are typically 10 to 30 µm wide and up to 100 µm long. The crystals are flattened on {010} and bounded by {111}, {100} and {001} planes. The calculated density is 2.34 g cm−3. Optically, pleysteinite crystals are biaxial (+), with α=1.566(2), β=1.580(2), γ=1.600(2) (measured in white light) and 2V(meas.) = 80(1)∘. The empirical formula from electron microprobe analyses and structure refinement is [(H2O)0.50K0.50]2(Mn1.20Mg0.49Fe0.272+Zn0.05)∑2.01(Al1.63Fe0.203+Ti0.194+)∑2.02(Al0.56Ti0.444+) (PO4)4.02[F0.58O0.31(OH)0.11]2(H2O)10 ⚫ 3.92H2O. Pleysteinite has orthorhombic symmetry, with space group Pbca and unit-cell parameters a = 10.4133(8) Å, b=20.5242(17) Å, c=12.2651(13) Å, V=2621.4(4) Å3 and Z=4. The crystal structure was refined using single-crystal data to wRobs=0.054 for 1692 reflections with I>3σ(I). The crystal structure contains corner-connected linear trimers of Al-centred octahedra that share corners with PO4 tetrahedra to form 10-member rings parallel to (010). K+ cations and water molecules are located in the rings. Additional corner-sharing of the PO4 tetrahedra with Mn(H2O)4O2 octahedra occurs along [010] to complete the 3D framework structure.

Manganrockbridgeite, Mn22+Fe33+(PO4)(3)(OH)(4)(H2O), is a new member of the rockbridgeite group, from the Hagendorf-Sud pegmatite, Oberpfalz, Bavaria. It occurs in association with frondelite, kenngottite, hureaulite and hematite. It forms compact intergrowths and clusters of shiny greenish black blades up to 200 mu m long and 20 mu m wide but only a few micrometres thick. The crystals are elongated on [100] and flattened on {001}, with perfect cleavage parallel to {001}. Individual thin blades are green in transmitted light and red under crossed polars. The calculated density is 3.40 g cm(-3). Manganrockbridgeite is biaxial (+/-), with alpha = 1.795(5), beta = 1.805(calc), gamma = 1 :815(5) (white light) and 2 V (meas.) = 90(2)degrees. The empirical formula from electron microprobe analyses, Mossbauer spectroscopy and crystal structure refinement is (Mn1.072+Fe0.692+Fe0.163+)(Sigma 1.92)(Fe3+)(2.88)(PO4)(3)(OH)(3.64)(H2O)(1.44). Manganrockbridgeite has monoclinic symmetry with space group P2(1)/m and unit-cell parameters a = 5.198(2), b = 16.944(5), c = 7.451(3) angstrom, beta = 110.170(9)degrees, V = 616.0(4) angstrom(3) and Z = 2. The crystal structure was refined using both laboratory and synchrotron single-crystal diffraction data. Whereas other rockbridgeite-group minerals have orthorhombic symmetry with a statistical distribution of 50% Fe3+ C / 50% vacancies in M3-site octahedra forming face-shared chains along the 5.2 angstrom axis, monoclinic manganrockbridgeite has full ordering of Fe3+ and vacancies in alternate M3 sites along the 5.2 angstrom axis.

Abstract. Hochleitnerite, [K(H2O)]Mn2(Ti2Fe)(PO4)4O2(H2O)10 ⋅ 4H2O, is a new paulkerrite-group mineral from the Hagendorf-Süd pegmatite, Oberpfalz, Bavaria, Germany. It was found in specimens of altered zwieselite, in association with fluorapatite, rockbridgeite, columbite and sub-micrometre rods of uranophane. Hochleitnerite occurs as isolated and intergrown pale-yellow, diamond-shaped tablets with thicknesses reaching 50 µm and lengths of 120 µm. The crystals are flattened on {010}, slightly elongated on [001], and bounded by the {111} and {010} forms. The calculated density is 2.40 g cm−3. Optically, hochleitnerite crystals are biaxial (+), with α= 1.615(2), β= 1.621(2) and γ= 1.645(2) (measured in white light). The calculated 2V is 53.8∘. The empirical formula is [K(H2O)](Mn1.512+Fe0.492+)Σ2.00(Ti1.624+Fe0.193+Al0.15)Σ2.96(PO4)4.00[O1.50F0.23(OH)0.27]Σ2.00(H2O)10 ⋅ 4H2O. Hochleitnerite has space group Pbca and unit-cell parameters a= 10.5513(3) Å, b= 20.6855(17) Å, c= 12.4575(4) Å, V= 2718.96(15) Å3 and Z= 4. The crystal structure was refined using single-crystal data to wRobs= 0.082 for 2242 reflections with I > 3σ(I). The crystal structure contains corner-connected linear trimers of Ti-centred octahedra that share corners with PO4 tetrahedra to form 10-member rings parallel to (010). K+ cations and water molecules are located within the rings. Additional corner sharing of the PO4 tetrahedra with MnO2(H2O)4 octahedra occurs along [010] to complete the 3D framework structure.