The new mineral species barlowite, ideally Cu4FBr(OH)6, has been found at the Great Australia mine, Cloncurry, Queensland, Australia. It is the Br and F analogue of claringbullite. Barlowite forms thin blue, platy, hexagonal crystals up to 0.5 mm wide in a cuprite-quartz-goethite matrix associated with gerhardtite and brochantite. Crystals are transparent to translucent with a vitreous lustre. The streak is sky blue. The Mohs hardness is 2–2.5. The tenacity is brittle, the fracture is irregular and there is one perfect cleavage on {001}. Density could not be measured; the mineral sinks in the heaviest liquid available, diluted Clerici solution (D &3.8 g/cm3). The density calculated from the empirical formula is 4.21 g/cm3. Crystals are readily soluble in cold dilute HCl. The mineral is optically non-pleochroic and uniaxial (–). The following optical constants measured in white light vary slightly suggesting a small variation in the proportions of F, Cl and Br: ω 1.840(4)–1.845(4) and ε 1.833(4)–1.840(4). The empirical formula, calculated on the basis of 18 oxygen atoms and H2O calculated to achieve 8 anions and charge balance, is Cu4.00F1.11Br0.95Cl0.09(OH)5.85. Barlowite is hexagonal, space group P63/mmc, a = 6.6786(2), c = 9.2744(3) Å , V = 358.251(19) Å3, Z = 2. The five strongest lines in the powder X-ray diffraction pattern are [d(Å )(I)(hkl)]: 5.790(100)(010); 2.889(40)(020); 2.707(55)(112); 2.452(40)(022); 1.668(30)(220).

Plimerite, ideally ZnFe 3+ 4 (PO 4 ) 3 (OH) 5 , is a new mineral from the Block 14 Opencut, Broken Hill, New South Wales. 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 3.5À4, D(meas.) = 3.67(5) g/cm 3 and D(calc.) = 3.62 g/cm 3 (for the empirical formula). Optically, it is biaxial negative with a = 1.756(5), b = 1.764(4), g = 1.767(4) and 2V(calc.) of À63º; 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) Å 3 (single-crystal data) and Z = 4. Strongest lines in the X-ray powder diffraction pattern are [d (Å ), I, hkl]: . Electron microprobe analysis yielded (wt.%): PbO 0.36, CaO 0.17, ZnO 20.17, MnO 0.02, Fe 2 O 3 29.82, FeO 2.98, Al 2 O 3 4.48, P 2 O 5 32.37, As 2 O 5 0.09, H 2 O (calc) 6.84, total 97.30 (Fe 3+ /Fe 2+ ratio determined by Mössbauer spectroscopy). The empirical formula calculated on the basis of 17 oxygens is Ca 0.02 Pb 0.01 Zn 1.68 Fe 2+ 0.28 Fe 3+ 2.53 Al 0.60 P 3.09 As 0.01 O 17.00 H 5.15. 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-Ka radiation, CCD area detector). The structure of plimerite is isotypic with that of rockbridgeite and is based on face-sharing trimers of (Mf 6 ) octahedra which link by sharing edges to form chains, that extend in the b-direction. Chains link to clusters comprising pairs of corner-sharing (Mf 6 ) octahedra that link to PO 4 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. *

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Middlebackite is a new supergene mineral formed in the upper levels of the Iron Monarch quarry, South Australia. It occurs as aggregates of blue, prismatic crystals up to 0.3 mm across comprising individual crystals up to 0.05 mm in length associated with atacamite and mottramite. Crystals are translucent with a vitreous lustre and have a pale blue streak. Middlebackite is brittle with one perfect cleavage and uneven fracture. Mohs hardness is ~2. The calculated density is 3.64 g cm–3. Crystals are biaxial (+) with α = 1.663(4), β = 1.748(4) and γ = 1.861(4) (measured in white light). The calculated 2V is 86.7°. Pleochroism is X = colourless, Y = very pale blue and Z = dark sky blue; Z > Y > X. The empirical formula unit, based on six oxygen atoms per formula unit is Cu2.00(C2O4)Cl0.02(OH)1.98. Middlebackite is monoclinic, space group P21/c with a = 7.2597(15), b = 5.7145(11), c = 5.6624(11) Å, β = 104.20(3)°, V = 227.73(8) Å3 and Z = 2. The five strongest lines in the powder X-ray diffraction pattern are [d(Å), (I), (hkl)]: 7.070 (16) (100), 3.739 (100) (11$\bar{1}$), 2.860 (18) (020), 2.481 (12) (12$\bar{1}$) and 2.350 (9) (300). The crystal structure was refined from synchrotron single-crystal X-ray diffraction data to R1 = 0.0341 for 596 observed reflections with F0 > 4σ(F0). The structure is based on sheets of edge- and corner-sharing octahedra parallel to the bc plane. Sheets link in the a direction via oxalate anions.