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.

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.

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.

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.

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.

First occurrences from the Hagendorf Süd pegmatite of the secondary phosphate minerals kenngottite, Mn32+Fe43+(PO4)4(OH)6(H2O)2; allanpringite, Fe33+(PO4)2(OH)3 ⚫ 5H2O; iangreyite, Ca2Al7(PO4)2(PO3OH)2(OH,F)15 ⚫ 8H2O; and nizamoffite, MnZn2(PO4)2(H2O)4, are reported with characterisation of their crystal chemistry and phase associations. A synchrotron single-crystal structure refinement for kenngottite shows that it has the same level of disordering (75 %/25 %) of Fe3+ in adjacent octahedra along the 5 Å axis as for type-locality kenngottite from Krásno, Czech Republic. This is explained in terms of 1 : 1 fine-scale mixing of domains of ordered kenngottite-type and souzalite-type structures. Allanpringite occurs in an unusual epitaxial relationship to associated strunzite. The epitaxy is explained by the close metrical and structural match of common planes in the two minerals, (010) for allanpringite and (100) for strunzite. Iangreyite occurs in close association with perhamite in 30 µm spheroids. The characterisation results support a paragenesis of iangreyite from perhamite by selective leaching of silica from the layer structure of perhamite and rejoining of the layers by fusion of AlO4 tetrahedra from adjacent layers into AlO2(OH)3 trigonal bipyramids.

AbstractJahnsite-(CaMnZn), CaMn2+Zn2Fe3+2(PO4)4(OH)2⋅8H2O, is a new jahnsite-group mineral associated with alteration of phosphophyllite at the Hagendorf-Süd pegmatite, Bavaria. It forms as thin yellow crusts and brown epitactic growths on altered phosphophyllite, both of which comprise lath-like crystals in orthogonal orientation, up to 100 μm long. The crystals contain intergrowths of jahnsite-(CaMnZn) and jahnsite-(CaMnMn) on a scale of ~50 μm. The calculated density is 2.87 g cm−3 based on the empirical formula. Optically it is biaxial (–), with α = 1.675(2), β = 1.686(2) and γ = 1.691(2) (white light). The calculated 2V is 68°. Dispersion could not be observed, and the optical orientation is Z = b. Pleochroism was imperceptible. Electron microprobe analyses together with results from Mössbauer spectroscopy gives the formula (Ca0.59Mn0.24)Σ0.83Mn(Zn0.74Mn2+0.48Mg0.18Fe2+0.13Fe3+0.47)Σ2Fe3+2(P0.995O4)4(OH)2.03(H2O)7.97.Jahnsite-(CaMnZn) is monoclinic, P2/a, with a = 15.059(1), b = 7.1885(6), c = 10.031(2) Å, β = 111.239(8)° and V = 1012.1(2) Å3. The recent International Mineralogical Association approved nomenclature system for jahnsite-group minerals was applied to establish jahnsite-(CaMnZn) from the empirical formula. The structural flexibility of jahnsite-group minerals to accommodate cations of quite different sizes in the X and M1 sites is discussed in terms of rotations about the 7 Å axis of two independent octahedra centred at the M3 sites.

Fanfaniite, Ca4Mn2+Al4(PO4)6(OH,F)4.12H2O, is a new secondary phosphate mineral from the Foote spodumene mine, North Carolina, USA and the Hagendorf-Sud pegmatite, Bavaria, Germany. At the Foote mine, it forms radial aggregates up to 0.5 mm in diameter of colourless, transparent, thin blades, flattened on {010} and elongated on [001], associated with whiteite-(CaMnMn). At Hagendorf-Sud, the mineral occurs as isolated very thin laths on the surface of fibrous spheroids of kayrobertsonite and is associated with altered triplitezwieselite and whiteite-(CaMnMn). The measured density (Foote mine) is 2.58(2) g cm-3. Optically, fanfaniite (Foote mine) is biaxial (), with a = 1.573(2), = 1.582(2), ? = 1.585(2) and 2V(meas) = 57(1)degrees. Dispersion was not observed. The optical orientation is: Z = b, X boolean AND c 40 degrees in beta obtuse. Pleochroism was not evident. Electron microprobe analyses gave the empirical formulas Ca3.91 Mn 0.77 2 + Mg0.10Zn0.02Al3.89 Fe 0.21 3 + (PO4)6(OH)3.90(H2O)12.10 (Foote mine) and Ca3.73 Mn 0.76 2 + Mg0.25Zn0.08Al3.89 Fe 0.29 3 + (PO4)6F1.10(OH)3.08(H2O)11.82 (Hagendorf-Sud). Fanfaniite has monoclinic symmetry, space group C2/c, with a = 10.021(4) , b = 24.137(5) , c = 6.226(3) , beta = 91.54(2)degrees and V = 1505(1) 3. The crystal structure was refined to R obs = 0.043 for 1909 unique reflections to a resolution of 0.7 . Fanfaniite is the Mn2+-dominant analogue of montgomeryite. The name honours Luca Fanfani who structurally characterised many phosphate minerals including montgomeryite.

The rockbridgeite group has been officially established by the IMA Commission on New Minerals, Nomenclature and Classification. The general formula is based on the structure and is A(2)B(3)(PO4)(3)(OH, H2O)(5), where A = the octahedrally coordinated M2 site, in which divalent cations are ordered, and B = the octahedrally coordinated M1 + M3 sites, which contain predominantly Fe3+, with trace A1. The different rockbridgeite-group minerals are distinguished by the occupancy of the A site. The ideal formula for rockbridgeite is (Fe0.52+Fe0.533+)(2)Fe-3(3+) (PO4)(3)(OH)(5), that for frondelite is ((Mn0.5Fe0.53+)-Fe-2)(2) Fe-3(3+) (PO4)(3)(OH)(5) and that for plimerite is Zn2Fe33+ (PO4)(3)(OH)(4)(H2O). In order to preserve the identity of frondelite and rockbridgeite within the structure-based formalism, these species correspond to mid-series compositions. We describe here the new end-member, ferrorockbridgeite, with dominant Fe2+ in the A site, from the Hagendorf Sild pegmatite mine, Oberpfalz, Bavaria. Electron microprobe analyses, coupled with Mossbauer spectroscopy, gives the empirical formula Fe1.332+Mn0.522+Zn0.03Ca0.05Fe3.033+Al0.01P2.97H6.17O17. The simplified formula is (Fe2+, Mn2+)(2)F-3(3+)(PO4)(3)(OH)(4)(H2O). Ferrorockbridgeite is orthorhombic, space group Bbmm, with a = 13.9880(4), b = 16.9026(5), c = 5.1816(1) angstrom, V = 1225.1 angstrom(3) and Z = 4. The six strongest lines in the X-ray powder diffraction pattern are [d(meas)/angstrom (I) (hkl)]: 4.853 (26) (101), 3.615 (24) (240), 3.465 (33) (301), 3.424 (39) (410), 3.205 (100) (321) and 1.603 (24) (642). Optically, ferrorockbridgeite is biaxial (-) with alpha = 1.763(3), beta = 1.781(calc), gamma = 1.797(3) (white light) and 2V (meas.) = 87(1)degrees from extinction data. The optical orientation is X = c, Y = a, Z = b. The pleochroism is X = blue green, Y = olive green, Z = yellow brown; X approximate to Y > Z.

Ferrirockbridgeite, ideally (Fe-0.67(3+)square(0.33))(2)(Fe3+)(3)(PO4)(3)(OH)(4)(H2O), is a new member of the rockbridgeite group. The type specimen is from the Palermo No. 1 pegmatite in North Groton, Grafton County, New Hampshire, USA. Electron microprobe analysis, coupled with Mossbauer spectroscopy for FeO and thermogravimetric analysis (TGA) for H2O gives the empirical formula Mn2o3 Fe2o-PosMgo oiZno 03Cao 05Fe43 P - 2 87017146 H. Ferrirockbridgeite is orthorhombic, space group Bbmm with a = 13.853(1), b = 16.928(1), c = 5.1917(5) angstrom and Z = 4. Optically, ferrirockbridgeite is biaxial (-), with alpha = 1.875(5), beta = 1.890(calc), gamma = 1.900(5) (measured in white light) and 2V (meas) is 78(1) from extinction data. The dispersion is strong, with r > v. The optical orientation is X = c, Y = a, Z = b. The pleochroism is X = yellow brown, Y = olive brown, Z = dark olive green; Z > Y > X. Crystal structure refinements on ferrirockbridgeite and other oxidized rockbridgeite-group species, including type rockbridgeite and type frondelite, show that oxidation is accompanied by loss of Fe2+ from the M2 site according to the reaction [3Fe2+] -> [2Fe3+ + LI] + Fe2+(removed) + 2e-. A variable portion of the Fe removed from the M2 site becomes trapped at M3 site vacancies. A general formula for oxidized rockbridgeite-group minerals is presented.

The ideal formula for flurlite has been revised to Zn4Fe3+(PO4)(3)(OH)(2)(H2O)(7) center dot 2H(2)O and its Mn analogue, manganflurlite (IMA2017-076), ZnMn32+Fe3+(PO4)(3)(OH)(2)(H2O)(7) center dot 2H(2)O has been found on two specimens of phosphophyllite from the Hagendorf-Sud pegmatite, Oberpfalz, Bavaria, Germany. Manganflurlite occurs as long, very thin, rectangular laths, up to 0.5 mm long and less than 10 mu m thick. Laths are elongated on [1 0 0], flattened on {0 0 1} and exhibit the forms {1 0 0}, {0 1 0} and {0 0 1}. The mineral is orange brown in colour and transparent with a vitreous iridescent lustre and buff streak. Crystals are flexible and elastic with irregular fracture, and three cleavages: perfect on {0 0 1}, good on {1 0 0} and {0 1 0}. The Mohs' hardness is ca. 21/2. The measured density is 2.73(2) g cm(-3). At room temperature, the mineral dissolves rapidly in dilute HCl. Optically, manganflurlite is biaxial (-), with alpha = 1.623(calc), beta = 1.649(2), gamma = 1.673(2) (white light); 2V = 86(1)degrees. The dispersion is r > nu, slight; the optical orientation is X = c, Y = b, Z = a. The pleochroism is X = pale yellow brown, Y = orange brown, Z = light yellow brown, Y > Z > X. Electron microprobe analyses for crystals from the holotype specimen gave the empirical formula Zn(Mn1.512+Fe0.692+Zn0.68Mg0.08)(Sigma 2.)(96)(Fe0.953+Al0.05)(Sigma 1.00)(PO4)(3)(OH)(1.)(92)(H2O)(9.)(08). Manganflurlite is monoclinic, P2(1)/m, a = 6.4546(8), b = 11.1502(9), c = 13.1630(10)angstrom A, = beta = 99.829(5)degrees, V = 933.44(16) angstrom(3) and Z = 2. The crystal structure, refined including all protons to R-obs = 0.034 for 2219 observed reflections [I > 3 sigma I], shows the mineral to be isostructural with flurlite. These minerals have a heteropolyhedral layer structure that is a topological isomer of the schoonerite structure.

Synchrotron single-crystal structure refinements for five schoonerite-group minerals (SGMs) from the Hagendorf Sud, Bavaria, and Palermo No.1, New Hampshire, pegmatites were combined with results from previous studies on type schoonerite and the SGMs wilhelmgumbelite and schmidite to evaluate the main crystallochemical relations between the minerals. Elements Zn and Fe3+ are essential to the structure and are ordered in specific sites, while Mn and Fe are distributed relatively uniformly over three octahedral sites, M1, M2 and M3. The Mn/(Mn + Fe) atomic ratio is relatively constant for the samples studied, similar to 0.26-0.31, and is close to this ratio in the primary phosphate, triphylite, from which the SGMs are derived. The main crystallochemical variations are due to different degrees of oxidation of the Fe, which ranges from 45% of the total Fe as Fe3+ in green SGMs, to 98% of the Fe as Fe3+ in red SGMs. The Fe oxidation state is linked to a significant structural change, whereby Zn in a trigonal bipyramidal site, Zn-[5], is partially partitioned into an adjacent tetrahedral site, Zn-[4], when the amount of Fe as Fe3+ increases above 70% There is an apparent correlation between the extent of partitioning of Zn, and cation deficiency in the M3 site, leading to a general formula for SGMs: [([4])(Zn,Fe)(x)([5])(Zn,Fe)(1-x)] M1 M2 (M3(1-x)square(x)) Fe3+(PO4)(3)(OH)(y)(H2O)(9-y)center dot 2H(2)O; where square = vacancy and x <= 0.3. The sites M1, M2 and M3 contain varying amounts of Fe2+, Fe3+, Mn2+ and Zn, with minor Mg. The different SGMs are distinguished by the dominant-cations and their oxidation states in the M1, M2 and M3 sites. Wilhelmgumbelite has M1 = Fe3+, M2 = Fe3+, M3 = Fe2+, while schmidite has M1 = (Fe0.53+Mn0.52+), M2 = (Fe0.53+Mn0.52+), M3 = Zn and schoonerite has M1 = Mn2+, M2 = Fe2+, M3 = Fe2+. One of the SGMs studied was found to have a new ordering of dominant-cations of dominant-valency, with M1 = (Fe0.53+Mn0.52+), M2 = (Fe0.53+Mn0.52+), M3 = Mn2+, and it has subsequently been approved as the new mineral wildenauerite (IMA 2017-058).

Abstract Schmidite, Zn(Fe3+0.5Mn2+0.5)2ZnFe3+(PO4)3(OH)3(H2O)8 and wildenauerite, Zn(Fe3+0.5Mn2+0.5)2Mn2+Fe3+(PO4)3(OH)3(H2O)8 are two new oxidised schoonerite-group minerals from the Hagendorf-Süd pegmatite, Hagendorf, Oberpfalz, Bavaria, Germany. Schmidite occurs as radiating sprays of orange–brown to copper-red laths on and near to altered phosphophyllite in a corroded triphylite nodule, whereas wildenauerite forms dense compacts of red laths, terminating Zn-bearing rockbridgeite. The minerals are biaxial (+) with α = 1.642(2), β = 1.680(1), γ = 1.735(2) and 2Vmeas = 81.4(8)° for schmidite, and with α = 1.659(3), β = 1.687(3), γ = 1.742(3) and 2Vmeas = 73(1)° for wildenauerite. Electron microprobe analyses, with H2O from thermal analysis and FeO/Fe2O3 from Mössbauer spectroscopy, gave FeO 0.4, MgO 0.3, Fe2O3 23.5, MnO 9.0, ZnO 15.5, P2O5 27.6, H2O 23.3, total 99.6 wt.% for schmidite, and FeO 0.7, MgO 0.3, Fe2O3 25.2, MnO 10.7, ZnO 11.5, P2O5 27.2, H2O 24.5, total 100.1 wt.% for wildenauerite. The empirical formulae, scaled to 3 P and with OH– adjusted for charge balance are Zn1.47Mn2+0.98Mg0.05Fe2+0.04Fe3+2.27(PO4)3(OH)2.89(H2O)8.54 for schmidite and Zn1.11Mn2+1.18Mg0.05Fe2+0.08Fe3+2.47(PO4)3(OH)3.25(H2O)9.03 for wildenauerite. The two minerals have orthorhombic symmetry, space group Pmab and Z = 4. The unit-cell parameters from refinement of powder X-ray diffraction data are a = 11.059(1), b = 25.452(1) and c = 6.427(1) Å for schmidite, and a = 11.082(1), b = 25.498(2) and c = 6.436(1) Å for wildenauerite. The crystal structures of schmidite and wildenauerite differ from that of schoonerite in having minor partitioning of Zn from the [5]Zn site to an adjacent vacant tetrahedral site [4]Zn, separated by ~1.0 Å from [5]Zn. The two minerals are distinguished by the cation occupancies in the octahedral M1 to M3 sites. Schmidite has M1 = M2 = (Fe3+0.5Mn2+0.5) and M3 = Zn and wildenauerite has M1 = M2 = (Fe3+0.5Mn2+0.5) and M3 = Mn2+.

A non-stoichiometric frondelite from the Hagendorf Siid pegmatite, Bavaria, has been studied using chemical and thermal analyses, electron diffraction (ED), Mossbauer spectroscopy and synchrotron single-crystal structure analysis. The structural formula, with occupancies of the M1, M2 and M3 sites given in sequence, is (Fe3+) (Mn0.672+Zn0.20Fe0.052+Fe0.703+)(Sigma 1.65)(Fe-2.30(3+)) (PO4)(3) (OH) 4.9 (H2O)(0.1). The non-stoichiometric frondelite contains an excess of 0.3 atoms in the M3 site and a deficiency of 0.35 atoms in the M2 site. The ED patterns show rows of reflections that violate the reflection extinctions for Bbmm, and which are due to a local ordering of Fe3+ and vacancies in the M3 sites. Based on the ED results, a model was developed in space group Pnma, in which (100) planes containing corner-shared octahedral dimers of M3 atoms are ordered on a scale of similar to 6 nm. The Pnma model was refined successfully against the synchrotron single-crystal data. Non-stoichiometry can be explained within the Pnma local-order model by distortions at the M3 sites in non-stoichiometric regions, where local, barbosalite-like, trimeric chains of face-sharing octahedra are formed.

At the Hagendorf-Sud pegmatite, Bavaria, phosphophyllite plays an important paragenetic role in the formation of numerous Zn-bearing secondary phosphate minerals. We report the results of studies conducted on the alteration of phosphophyllite in a heavily corroded triphylite nodule from the 67m level of the pegmatite mine. The most abundant secondary phosphate minerals associated with phosphophyllite are oxidized schoonerite-group minerals, including the new mineral schmidite, Zn-[5]([6]) ((Fe-0.5(3+) Mn-0.5(2+))(2)ZnFe3+(PO4)(3) (OH)(3)(H2O)(6)center dot 2H(2)O, whose formation is contemporaneous with phosphophyllite. The phosphophyllite crystals in the nodule are characteristically covered with a composite rind of epitactic Zn-rich jahnsite crystals on the phosphophyllite surface overlain by an orange-yellow amorphous Zn-bearing ferric phosphate and/or green mitridatite. The jahnsite crystals are compositionally zoned into two-phase domains based on their Ca/Zn contents. The low-Zn domains are jahnsite(CaMnMn) whereas the high-Zn domains correspond to a potentially new species, "jahnsite-(CaMnZn)". The amorphous phase coating the jahnsite crystals has Zn levels similar to those in jahnsite, and is probably derived from its alteration. Its properties are consistent with it being a Zn-bearing santabarbaraite. Younger idiomorphic crystals of laueite, earlshannonite and zincostrunzite occur on the phosphophyllite rind. The laueite crystals have a surface layer, similar to 5 mu m thick, in which Mn is replaced completely by a 1: 1 atomic mixture of ZnthornMg, giving a composition oZn(0.5)Mg(0.5)Fe(2)(3+)(PO4)(2)(OH)(2)center dot 8H(2)O. The composition of the surface phase is explained by configurational-entropy stabilisation. The earlshannonite crystals commonly grow epitactically on the laueite, yet despite the close association, they are Zn-bearing only, with very low Mg contents. Single-crystal structure refinements have been done on both (ZnthornMg)-bearing laueite and Zn-bearing earlshannonite and all H atoms were located in both cases. Structural models are presented for the epitactic growth of jahnsite on phosphophyllite and earlshannonite on laueite.

The new mineral zincoberaunite, ideally ZnFe3+ 5(PO4)4(OH)5·6H2O, the Zn analogue of beraunite, is found in the Hagendorf South granitic pegmatite, Hagendorf, Bavaria, Germany, in two associations: (1) with potassium feldspar, quartz, jungite, phosphophyllite and mitridatite (the holotype) and (2) with flurlite, plimerite, Zn-bearing beraunite, schoonerite, parascholzite/scholzite, robertsite and altered phosphophyllite (the cotype). Zincoberaunite occurs as radial or randomly oriented aggregates of flexible fibers up to 1.5 mm long and up to 3 μm thick. D calc is 2.92 g/cm3 for the holotype and 2.94 g/cm3 for the cotype. Zincoberaunite is optically biaxial (–), α = 1.745(5), β = 1.760(5), γ = 1.770(5), 2V meas = 80(5)°. Chemical composition of the holotype (electron probe microanalyser; H2O by gas chromatography of ignition products) is: MgO 0.28 wt%, CaO 0.47 wt%, ZnO 7.36 wt%, Al2O3 0.88 wt%, Fe2O3 42.42 wt%, P2O5 31.63 wt%, H2O 16.2 wt%, total 101.1 wt%. The empirical formula calculated on the basis of 27 oxygen atoms per formula unit is (Zn0.83Ca0.08Mg0.06)∑0.97(Fe3+ 4.88Al0.16)∑5.04(PO4)4.09(OH)4.78 · 5.86H2O. Zincoberaunite is monoclinic, space group C2/c; refined unit cell parameters (for the holotype at room temperature and the cotype at 100 K, respectively) are: a 20.837(2) and 20.836(4), b 5.1624(4) and 5.148(1), c 19.250(1) and 19.228(4) Å, β 93.252(5) and 93.21(3)°, V 2067.3(3) and 2059.2(7) Å3, Z = 4. The crystal structure of the holotype specimen has been refined by the Rietveld method (R p = 0.30 %; R B = 0.18 %) whereas the structure of the cotype has been solved from the single crystal data and refined to R 1 = 0.056 based on 1900 unique reflections with I > 2σ(I). The strongest reflections of the powder X-ray diffraction pattern of the holotype specimen [(d, Å) (I, %) (hkl)] are: 10.37 (100) (200), 9.58 (32) (002), 7.24 (26) (20–2), 4.817 (22) (111), 4.409 (13) (112), 3.483 (14) (11–4, 600), 3.431 (14) (404), 3.194 (15) (006, 31–4), 3.079 (33) (314).

Zincostrunzite (IMA2016-023), ZnFe3+2(PO4)2(OH)2·6.5H2O, is a new secondary phosphate mineral from the Sitio do Castelo tungsten mine in Portugal and the Hagendorf-Sud pegmatite in Germany. At Sitio do Castelo, zincostrunzite was derived from the alteration of triplite–zwieselite. At Hagendorf-Sud, it was found in a nodule of former triphylite that had been replaced by phosphophyllite and minor apatite. At Sitio do Castelo, zincostrunzite occurs as prisms up to 2 mm long. At Hagendorf-Sud, the mineral makes up portions of needles that are up to about 5 mm long. Crystals are elongated on [0 0 1] with the prism forms {0 1 0} and {1−1 0} and poorly formed terminations, probably {0 0 1}. Twinning is ubiquitous by 180° rotation on [0 1 0] with the composition plane {1−2 0}. Zincostrunzite crystals from Sitio do Castelo are light brownish yellow; those from Hagendorf-Sud are silvery white. The lustre is vitreous to silky and the streak is white. Crystals are brittle with irregular, splintery fracture and at least one perfect cleavage parallel to [0 0 1]; probably either {1− 1 0} or {1 0 0}. The Mohs’ hardness is about 2½. The measured density (Sitio do Castelo) is 2.66(1) g cm−3. At room temperature, the mineral is slowly soluble in dilute HCl and rapidly soluble in concentrated HCl. Optically, crystals are biaxial (−), with α = 1.620(2), β = 1.672(2), γ = 1.720(2) (white light); 2 V meas. = 89.5(5)°; 2 V calc. = 85.1°; orientation is Z ^ c = 3°; X ≈ a *; pleochroism is X nearly colourless, Y light brownish yellow, Z darker brownish yellow ( X 4σ F ] for a crystal from Sitio do Castelo. The mineral is isostructural with other members of the strunzite group, except for an additional split H2O site near the (½,0,0) centre of symmetry, which accounts for the additional 0.5 H2O in the ideal formula. The extra H2O site may be present in some crystals of other strunzite-group minerals, as its presence cannot be determined without a structure refinement.

Kayrobertsonite, MnAl2(PO4)(2)(OH)(2)center dot 6H(2)O, is a new secondary phosphate mineral from the Hagendorf Sud pegmatite, Hagendorf, Oberpfalz, Bavaria, Germany and the Foote Lithium Company mine, Kings Mountain district, Cleveland County, North Carolina, USA. Kayrobertsonite crystals occur as intergrown masses of snow-white, soft, finely fibrous needles, less than 5 mu m in diameter and no more than 100 mu m in length. Quantitative analysis of Foote mine kayrobertsonite gave the empirical formula: Mn0.97Ca0.03Fe0.02Al1.87(PO4)(2)(OH)(1.62)F-0.03(H2O)(0.38)center dot 6H(2)O; and for Hagendorf Sud kayrobertsonite: Mn0.92Ca0.06Fe0.02Al1.87(PO4)(2) (OH)(1.19)F-0.42(H2O)(0.39)center dot 6H(2)O. Foote mine kayrobertsonite crystals are biaxial (-), with indices of refraction alpha = 1.530(1), beta = 1.554(1), gamma = 1.566(1), measured in white light; 2V(meas.) is 70.3(5)degrees, while 2V(calc.) is 69.6 degrees. The mineral is nonpleochroic. The orientation of the crystals is Z approximate to c (length slow). Kayrobertsonite is triclinic, space group P (1) over bar, with the unit-cell parameters: a = 10.049(2), b = 10.205(2), c = 6.083(1) angstrom, alpha = 91.79(3), beta = 99.70(3), gamma = 98.02(3), V= 607.9(2) angstrom(3) and Z = 2 (Foote mine). The polyhedral framework in kayrobertsonite has the same topology as that in nordgauite, but with replacement of F by OH at the bridging anion sites. The main crystal chemical change from nordgauite to kayrobertsonite is a doubling of the number of water molecules in the [001] channels.