The crystal structure of mawbyite, PbFe2(AsO4)2(OH)2 has been refined. The mineral is monoclinic, C2/m with a = 9.066(4), b = 6.286(3) c = 7.564(3) Å, β = 114.857(5)°, Z = 2; the structure has been refined to a conventional R = 4.3% using 361 observed reflections [I> 3σ(I)]. The structure contains chains of edgesharing Fe(O,OH)6 octahedra which are linked by AsO4 tetrahedra and Pb atoms in distorted square antiprismatic co-ordination. The hydrogen bonding network in the structure has been modelled using bond valence calculations. Mawbyite is confirmed to be isostructural with tsumcorite and dimorphous with carminite and the relationship between these two structures is discussed.

Edwardsite, Cu3Cd2(SO4)2(OH)6·4H2O, is a new mineral from the Block 14 Opencut, Broken Hill, New South Wales, Australia. It occurs as druses of tabular and bladed crystals up to 0.06 mm in size, associated with niedermayrite and christelite. Edwardsite is pale blue, transparent with vitreous lustre and has excellent cleavage parallel to {100}. Density was not measured but the calculated density, from the empirical formula, is 3.53 g cm–3 and the Mohs hardness is ∼3. Optically, it is biaxial negative with α ∼ 1.74, β = 1.762(4), γ ∼ 1.77 and 2Vcalc. ∼ +62°. The optical orientation is X = b, Y ∼ a, Z ∼ c. Electron microprobe analysis gave (wt.%): CdO 32.43, CuO 28.06, ZnO 2.26, FeO 0.08, SO3 20.35, H2Ocalc. (from crystal-structure analysis) 14.14, totalling 99.32. The empirical formula, calculated on the basis of 18 oxygen atoms is Cu2.77Cd1.98Zn0.22Fe0.01(SO4)2.00(OH)5.95·4.06H2O. Edwardsite is monoclinic, space group P21/c, with a = 10.863(2) Å, b = 13.129(3) Å, c = 11.169(2) Å, β = 113.04(3)°, V = 1465.9(5) Å3 (single-crystal data) and Z = 4. The eight strongest lines in the powder diffraction pattern are [d (Å), (I/I0), (hkl)]: 9.991, (90), (100); 5.001, (90), (200, 21); 4.591, (45), (20); 3.332, (60), (300, 032); 3.005, (30), (03); 2.824, (40), (2); 2.769, (55), (20, 042, 10); 2.670, (45), (2). The crystal structure was determined by direct methods and refined to R1 = 3.21% using 1904 observed reflections with Fo > 4σ(Fo) collected using synchrotron X-ray radiation (λ = 0.773418 Å). The structure is based on infinite sheets of edge-sharing Cuϕ6 (ϕ: O2–, OH) octahedra and Cdϕ7 (ϕ: O2–, H2O) polyhedra parallel to (100). The sheets are decorated on both sides by corner-sharing (SO4) tetrahedra, which also corner-link to isolated Cdϕ6 octahedra, thus connecting adjacent sheets. Moderate-strong to weak hydrogen bonding provides additional linkage between sheets.

Specimens of honey-brown to pinkish-brown globular carbonates encrusting concretionary goethite–coronadite from the oxidized zone at Broken Hill, New South Wales, have compositions in the rhodochrosite–smithsonite series. This may be the first extensive natural occurrence of this solid-solution series. Growth of the carbonates occurred in zones which have near uniform composition. The ratio MnCO3/(MnCO3 + ZnCO3) for each zone bears a linear relationship to the measured d spacing for the 104 X-ray reflections. Because cerussite is the only other mineral associated with the Zn-Mn carbonates and because of an absence of detailed locality information, the paragenetic significance of these minerals cannot be determined. The solutions depositing them may have been derived from the near-surface equivalents of the Zinc Lode horizons.

Microprobe analysis of marshite and miersite from Broken Hill, Australia, demonstrate extensive solid solution between the end-members CuI and AgI, indicating the possibility of a complete solid-solution series. Unit-cell parameters increase from 6.054 Å for marshite to 6.504 Å for miersite, closely following Vegard's Law. The Cu content of iodargyrite is generally below the limit of detection, but one zoned crystal contained 0.28 wt.% Cu. Crystallization of either miersite or iodargyrite at Broken Hill appears to be dependent upon the local availability and ratio of copper, silver and iodine ions.

A study of the composition and unit cell data of a suite of lead-rich minerals of the alunite-jarosite group from the oxidized zone of the ore body at Broken Hill, New South Wales, Australia, has revealed almost complete XO4 (X = As, P, S) solid solution in these minerals at this deposit. The species in the group noted are hidalgoite, hinsdalite, beudantite, segnitite and plumbogummite. These minerals at Broken Hill exhibit a number of growth textures, including oscillatory zoning, colloform banding and replacements. Zoning in these minerals is due to the segregation of Al- and Fe-rich members, and compositions indicate a strong coupling of Fe3+ with and Al with

Nyholmite, Cd3Zn2(AsO3OH)2(AsO4)2·4H2O, from the Block 14 Opencut, Broken Hill, New South Wales, Australia, is a new Cd-Zn arsenate species, isostructural with the minerals of the hureaulite group. The mineral occurs in a quartz-garnet-arsenopyrite matrix as white globules, tufted aggregates of fibrous crystals and radiating hemispheres of thin, colourless, bladed crystals. Associated minerals are goldquarryite, lavendulan-sampleite, scorodite-strengite and gypsum. Individual crystals are up to 0.2 mm in length and 0.05 mm across. The mineral is transparent to translucent with a vitreous lustre. It is brittle with an uneven fracture and a white streak. The Mohs hardness is 3–3.5 and the calculated density is 4.23 g cm–3 for the empirical formula. Electron microprobe analyses yielded CdO 34.58, ZnO 9.72, MnO 3.59, CuO 3.39, Al2O3 0.20, CaO 0.16, PbO 0.37, As2O5 34.55, P2O5 6.29 totalling 92.85 wt.%. The empirical formula, based on 20 oxygen atoms, is Ca0.03Pb0.02 Cd2.80Al0.04Zn1.24-Cu0.44Mn0.53[(AsO4)3.13(PO4)0.92]Σ4.05H1.91·3.79H2O. Nyholmite is monoclinic, C2/c, a = 18.062(4) Å, b = 9.341(2) Å, c = 9.844(2) Å, β = 96.17(3)°, V = 1651.2(6) Å3 (single-crystal data, at 123 K). The six strongest lines in the X-ray powder diffraction pattern are [d(Å),I,(hkl)]: 8.985,30,(200); 8.283,85,(110); 6.169,25,(111); 4.878,25,(002); 3.234,100,(2, 420); 3.079,65,(222, 511); 2.976’45’(113). The crystal structure was solved by Patterson methods and refined using 2045 observed reflections to R1(F) = 3.73%. The structure is characterized by a kinked, five-membered chain of edge-sharing Mφ6 (φ = unspecified anion) octahedra, or pentamer, that extends in the a direction. The pentamers link by sharing corners to form a sheet in the (001) plane. Pentamers are also linked, via corner-sharing, by (As,P)O4 groups forming thick slabs in the (001) plane. The slabs link in the c direction by cornersharing between octahedra and tetrahedra to form a dense heteropolyhedral framework. Moderate to weak hydrogen-bonding provides additional linkage between the slabs.

Ecandrewsite, the zinc analogue of ilmenite, is a new mineral which was first described from the Broken Hill lode in 1970 and discovered subsequently in ores from Little Broken Hill (New South Wales) and the San Valentin Mine, Spain. The name ‘ecandrewsite’ was used in a partial description of the mineral in ‘Minerals of Broken Hill’ (1982), thereby establishing the Little Broken Hill locality, specifically the Melbourne Rockwell Mine, as the type locality. Microprobe analysis of ecandrewsite from the type locality gave ZnO 30.42 (wt.%), FeO (total Fe) 11.37, MnO 7.64, TiO2 50.12, total 99.6%, yielding an empirical formula of (Zn0.59Fe0.24Mn0.17)1.00Ti0.99O3 based on 3 oxygen atoms. All compositions from Little Broken Hill and the San Valentin Mine are ferroan manganoan ecandrewsite. The strongest lines in the X-ray powder diffraction data are (d in Å, (hkil), I/Io):2.746, (104), 100; 2.545, (110), 80; 1.867, (024), 40; 3.734, (012), 30; 1.470, (3030), 30; 1.723, (116), 25. Ecandrewsite is hexagonal, space group RR3¯ assigned from a structural study, with a = 5.090(1), c = 14.036(2)Å, V = 314.6(3)Å3, Z = 6, D(calc.) = 4.99. The mineral is opaque, dark brown to black with a similar streak, and a submetallic lustre. In plane polarized light the reflection colour is greyish white with a pinkish tinge. Reflection pleochroism is weak, but anisotropism is strong with colours from greenish grey to dark brownish grey. Reflectance data in air between 470 and 650 nm are given. At the type locality, ecandrewsite forms disseminated tabular euhedral grains up to 250 × 50 µm, in quartz-rich metasediments. Associated minerals include almandine-spessartine, ferroan gahnite and rutile. The name is for E. C. Andrews, pioneering geologist in the Broken Hill region of New South Wales. Type material consisting of one grain is preserved in the Museum of Victoria (M35700). The mineral and name were approved by the IMA Commission on New Minerals and Mineral Names in 1979.

Hoganite, copper(II) acetate monohydrate, and paceite (pronounced ‘pace-ite’), calcium(II) copper(II) tetraacetate hexahydrate, occur as isolated crystals embedded in ferruginous gossan from the Potosi Pit, Broken Hill, New South Wales, Australia. They are associated with goethite, hematite, quartz, linarite, malachite, azurite, cerussite and cuprian smithsonite. Hoganite is bluish green with a pale blue streak and a Mohs hardness of 1½; it possesses perfect {001} and distinct {110} cleavages and has a conchoidal fracture. Chemical analysis of hoganite gave (wt.%) C 23.85; H 3.95; Cu 31.6; Fe 0.4; O (by difference) 40.2, yielding an empirical formula of C4H7.89O5.07Cu1.00Fe0.01. The simplified formula is C4H8O5Cu or Cu(CH3COO)2.H2O, the mineral being identical to the synthetic compound of the same formula. Single-crystal X-ray data for hoganite are: monoclinic, space group C2/c, a = 13.162(3), b = 8.555(2), c = 13.850(3)Å, β = 117.08(3)°, Z = 8. The density, calculated from single-crystal data, is 1.910 g cm−3. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl)] 6.921 (100) (011); 3.532 (28) (202); 6.176 (14) (200); 3.592 (11) (22); 5.382 (10) (11); 2.278 (10) (204); 5.872 (9) (002). Hoganite (orientation presently unknown) is biaxial positive with α = 1.533(2), β = 1.541(3), γ = 1.554(2), 2V(meas.) = 85(5)°, 2V(calc.) = 76.8°, dispersion is r < v, medium (white light); it is strongly pleochroic with X = blue, Y = pale bluish, Z = pale bluish green and absorption X > Y > Z. The mineral is named after Graham P. Hogan of Broken Hill, New South Wales, Australia, a miner and well-known collector of Broken Hill minerals.

Paceite is dark blue with a pale blue streak and a Mohs hardness of 1½; it possesses perfect {100} and {110} cleavages and has an uneven fracture. Chemical analysis of paceite gave (wt.%) C 21.25; H 5.3; Ca 9.0; Cu 14.1; O (by difference) 50.35, yielding an empirical formula of C8H23.77O14.23Ca1.02-Cu1.00. The simplified formula is C8H24O14CaCu or CaCu(CH3COO)4.6H2O, the mineral being identical to the synthetic compound of the same formula. Unit-cell data (refined from X-ray powder diffraction data) for paceite are: tetragonal, space group I4/m, a = 11.155(4), c = 16.236(17)Å, Z = 4. The density, calculated from refined cell data, is 1.472 g cm−3. The strongest lines in the X-ray powder pattern are [dobs (Iobs) (hkl)] 7.896 (100) (110); 3.530 (20) (310); 5.586 (15) (200); 8.132 (8) (002); 9.297 (6) (101); 2.497 (4) (420); 3.042 (3) (321). Paceite is uniaxial positive with ω = 1.439(2) and ɛ = 1.482(3) (white light); pleochroism is bluish with a greenish tint (O), pale bluish with a greyish tint (E), and absorption O ⩾ E. The mineral is named after Frank L. Pace of Broken Hill, New South Wales, Australia, an ex-miner and well-known collector of Broken Hill minerals.

Plimerite, ideally Zn (PO4)3(OH)5, is a new mineral from the Block 14 Opencut, Broken Hill, New SouthWales. It occurs as pale-green to dark-olive-green, almost black, acicular to prismatic and bladed crystals up to 0.5 mm long and as hemispherical aggregates of radiating acicular crystals up to 3 mm across. Crystals are elongated along [001] and the principal form observed is {100} with minor {010} and {001}. The mineral is associated with hinsdalite-plumbogummite, pyromorphite, libethenite, brochantite, malachite, tsumebite and strengite. Plimerite is translucent with a pale-greyish-green streak and a vitreous lustre. It shows an excellent cleavage parallel to {100} and {010} and distinct cleavage parallel to {001}. It is brittle, has an uneven fracture, a Mohs’ hardness of 3.5–4, D(meas.) = 3.67(5) g/cm3 and D(calc.) = 3.62 g/cm3 (for the empirical formula). Optically, it is biaxial negative with α = 1.756(5), β = 1.764(4), γ = 1.767(4) and 2V(calc.) of –63º; pleochroism is X pale-greenish-brown, Y pale-brown, Z pale-bluish-green; absorption Z > X > Y; optical orientation XYZ = cab. Plimerite is orthorhombic, space group Bbmm, unit-cell parameters: a = 13.865(3) Å, b = 16.798(3) Å, c = 5.151(10) Å, V = 1187.0(4) Å3 (single-crystal data) and Z = 4. Strongest lines in the X-ray powder diffraction pattern are [d (A˚ ), I, hkl]: 4.638, (50), (111); 3.388, (50), (041); 3.369, (55), (131); 3.168, (100), (132); 2.753, (60), (115); 2.575, (90), (200); 2.414, (75), (220); 2.400, (50), (221); 1.957, (40), (225). Electron microprobe analysis yielded (wt.%): PbO 0.36, CaO 0.17, ZnO 20.17, MnO 0.02, Fe2O3 29.82, FeO 2.98, Al2O3 4.48, P2O5 32.37, As2O5 0.09, H2O (calc) 6.84, total 97.30 (Fe3+/Fe2+ ratio determined by Mössbauer spectroscopy). The empirical formula calculated on the basis of 17 oxygens is Ca0.02Pb0.01Zn1.68Al0.60P3.09As0.01O17.00H5.15. The crystal structure was solved by direct methods and refined to an R1 index of 6.41% for 1332 observed reflections from single-crystal X-ray diffraction data (Mo-Kα radiation, CCD area detector). The structure of plimerite is isotypic with that of rockbridgeite and is based on face-sharing trimers of (Mϕ6) octahedra which link by sharing edges to form chains, that extend in the b-direction. Chains link to clusters comprising pairs of corner-sharing (Mϕ6) octahedra that link to PO4 tetrahedra forming sheets parallel to (001). The sheets link via octahedra and tetrahedra corners into a heteropolyhedral framework structure. The mineral name honours Professor Ian Plimer for his contributions to the study of the geology of ore deposits.