Structural and compositional variations of basic Cu(II) chlorides in the herbertsmithite and gillardite structure field.

© 2017 The Mineralogical Society. This document is the author’s final accepted version of the journal article. You are advised to consult the published version if you wish to cite from it

The potential of fisheries reserves as a tool for biodiversity conservation : the case of the 25 nautical mile fisheries management zone around Malta

Fisheries reserves (FR) are spatially bounded areas where the harvesting of fisheries resources is restricted in some areas by regulating gear, species captured or fishing period (restricted fishing areas), or forbidden outright (no-take zones) and are designed to protect populations of commercially important stocks from over-exploitation.peer-reviewe

Study Protocol for the COVID-19 Pandemic Adjustment Survey (CPAS): A Longitudinal Study of Australian Parents of a Child 0–18 Years

Background: The COVID-19 pandemic presents significant risks to the mental health and wellbeing of Australian families. Employment and economic uncertainty, chronic stress, anxiety, and social isolation are likely to have negative impacts on parent mental health, couple and family relationships, as well as child health and development. Objective: This study aims to: (1) provide timely information on the mental health impacts of the emerging COVID-19 crisis in a close to representative sample of Australian parents and children (0–18 years), (2) identify adults and families most at risk of poor mental health outcomes, and (3) identify factors to target through clinical and public health intervention to reduce risk. Specifically, this study will investigate the extent to which the COVID-19 pandemic is associated with increased risk for parents’ mental health, lower well-being, loneliness, and alcohol use; parent-parent and parent-child relationships (both verbal and physical); and child and adolescent mental health problems. Methods: The study aims to recruit a close to representative sample of at least 2,000 adults aged 18 years and over living in Australia who are parents of a child 0–4 years (early childhood, N = 400), 5–12 years (primary school N = 800), and 13–18 years (secondary school, N = 800). The design will be a longitudinal cohort study using an online recruitment methodology. Participants will be invited to complete an online baseline self-report survey (20 min) followed by a series of shorter online surveys (10 min) scheduled every 2 weeks for the duration of the COVID-19 pandemic (i.e., estimated to be 14 surveys over 6 months). Results: The study will employ post stratification weights to address differences between the final sample and the national population in geographic communities across Australia. Associations will be analyzed using multilevel modeling with time-variant and time-invariant predictors of change in trajectory over the testing period. Conclusions: This study will provide timely information on the mental health impacts of the COVID-19 crisis on parents and children in Australia; identify communities, parents, families, and children most at risk of poor outcomes; and identify potential factors to address in clinical and public health interventions to reduce risk

Substitution in basic secondary Cu(II) chloride minerals

This thesis reports results from a comprehensive crystallographic and spectroscopic investigation of natural and synthetic samples of the basic Cu(II) chloride minerals, with focus on substitution phenomena in the group. A series of composition-induced phase transformations occur in the group. They are possibly anatacamite P1→ clinoatacamite P21/n → paratacamite R3→ herbertsmithite R3m, when Zn is the dominant substituting cation in the formula Cu4-xZnx(OH)6Cl2. The role of paratacamite in this series is poorly understood. It was originally described with the formula Cu2(OH)3Cl, but it is likely its structure is stabilised by the presence of essential Zn. An analogous series with Ni substitution to the end-member R3m phase known as gillardite, which is isostructural with herbertsmithite, also occurs. Based on the group theory, two series of space group symmetries are possible, P1→ R3→ R3m and P1→ C2/m → P21/c → R3m. These possibilities are explored through an analysis of the inherent structural changes related to compositional effects. A crystal from the type specimen of paratacamite (British Museum specimen BM86958), with composition Cu3.71Zn0.29(OH)6Cl2, was analysed by single-crystal X-ray diffraction at several temperatures (100, 200, 300, 353, 393 and 423 K). Its structure at 300 K is confirmed in space group R3for the unit cell a ≈ 13.6, c ≈ 14.0 Å, with a pronounced substructure corresponding to a′ ≈ ½a and c′ ≈ c, in space group R3m (analogous to the structure of herbertsmithite). Paratacamite undergoes a reversible phase transformation to the R3m substructure at elevated temperatures. This establishes that paratacamite is thermodynamically stable at 300 K for the composition studied. The loss of the superstructure at elevated temperature indicates that the substitution phenomenon is statistical between both interlayer metal sites, rather than being preferential at M(1) as has been suggested in the literature. It is suggested that the observed (2+2+2) octahedral configuration at M(2) is a consequence of a superimposition of non-tetragonally elongated Zn(OH)6 octahedra with dynamic (4+2) Jahn-Teller distorted Cu(OH)6octahedra occupying two orientations. In the course of this investigation the single-crystal X-ray structure of two new analogues of paratacamite were determined. One is an Mg-rich specimen from the Quebrada Mine, Camerones, Chile, Cu 3(Mg,Cu)(OH)6Cl2, and the other is a Ni-rich specimen from the Carr Boyd Rocks Mine, Western Australia, Australia, Cu3(Ni,Cu)(OH)6Cl2. The supercell analogous to that reported for paratacamite was identified and the structure was solved in space group R3. Both analogues exhibit a substructure with a' ≈ ½a, c' ≈ c in space group R3m. They are the first examples of naturally occurring substituted paratacamite congeners to be reported. Substitution phenomena in the Mg analogue is confirmed as being statistical in nature by refinement of the site scattering factors of interlayer sites M(1) and M(2). The substitution behaviour in the Ni analogue, as well as paratacamite containing from Zn from the holotype specimen was assumed to be statistical throughout this investigation, but the possibility remains that Zn and Ni preferentially occupy one of the interlayer sites. Furthermore, the single-crystal X-ray structure of naturally occurring Cu3(Co,Cu)(OH)6Cl2from the Torrecillas Mine, Salar Grande provence, Chile, is reported with unit cell parameters and structure analogous to that of herbertsmithite. Raman spectroscopy analyses, supported by single-crystal X-ray diffraction of samples exhibiting a range of compositions, have revealed several trends associated with variation in composition. An examination of both natural and synthetic samples indicate that the transformation series proceeds as P1→ P2 1/c → R3m, with decreasing Cu2+ content in Cu4-xMx(OH)6Cl2. The composition-induced changes in the paratacamite Raman spectrum with high interlayer Cu2+ content, suggests a distortion towards that of anatacamite. With excess substitution for interlayer Cu2+, the structure converges with that of the R3m aristotype. This corresponds to the space group series P1→ R3→ R3m, with decreasing Cu2+content as described above. The stability of paratacamite appears to be dependent on the type of substituting cation. Finally, the synthetic series of Zn- and Ni-substituted members was explored in order to determine the behaviour of the solid state activity coefficient (γ). In clinoatacamite, Zn 2+ occupation exhibits non-ideal behaviour for dilute solid solutions and γ > 1. With increasing Zn content, γ approaches unity near the composition Cu3.80Zn0.20(OH)6Cl2. (NOTE: SOME OF THE SCIENTIC SYMBOLS CAN NOT BE REPRESENTED CORRECTLY IN THE ABSTRACT. PLEASE READ WITH CAUTION AND REFER TO THE ORIGINAL THESIS.

Leverettite from the Torrecillas mine, Iquique Provence, Chile : the Co-analogue of herbertsmithite

The new mineral leverettite (IMA 2013-011), ideally Cu3CoCl 2(OH)6, was found at the Torrecillas mine, Salar Grande, Iquique Province, Chile, where it occurs as a supergene alteration phase in association with akaganéite, anhydrite, chalcophanite, goethite, halite, manganite, pyrite, quartz and todorokite. Crystals of leverettite are steep rhombohedra to 1 mm with {101} prominent and modified by {001}, sometimes forming V-shaped twins by reflection on {102̄}. The crystals can also form finger-like, parallel stacked growths along the c axis. The new mineral is medium to deep green in colour and has a light green streak. Crystals are transparent with a vitreous lustre. Mohs hardness is ~3 and the crystals have a brittle tenacity, a perfect cleavage on {101} and a conchoidal fracture. The measured density is 3.64(2) g cm-3 and calculated density based on the empirical formula is 3.709 g cm-3. Optically, leverettite is uniaxial (-) with o and ε > 1.8 and exhibits pleochroism with O (bluish green) > E (slightly yellowish green). The empirical formula, determined from electron-microprobe analyses is Cu3(Co0.43Cu 0.40Mn0.17Ni0.07Mg0.01) Σ1.08Cl1.87O6.13H6. Leverettite is trigonal (hexagonal), space group R3̄m, unit-cell parameters a = 6.8436(6) and c = 14.064(1) Å, V = 570.42(8) Å3, Z = 3. The eight strongest X-ray powder diffraction lines are [dobs Å(I)(hkl)]: 5.469(90)(101), 4.701(18)(003), 2.905(22)(021), 2.766(100)(113), 2.269(66)(024), 1.822(26)(033), 1.711(33)(220), 1.383(23)(128). The structure, refined to R1 = 0.023 for 183 Fo > 4sF reflections, shows leverettite to be isostructural with herbertsmithite and gillardite

A temperature-induced reversible transformation between paratacamite and herbertsmithite

The crystal chemistry of paratacamite has been re-evaluated by studying a crystal from the holotype specimen BM86958 of composition Cu3.71Zn0.29(OH)6Cl2 using single-crystal X-ray diffraction at 100, 200, 300, 353, 393 and 423 K. At 300 K paratacamite has space group TeX with unit-cell parameters a 13.644 and c 14.035 Å and exhibits a pronounced subcell, a′ = ½a and c′ = c, analogous to that of the closely related mineral herbertsmithite, Cu3Zn(OH)6Cl2. Between 353 and 393 K, paratacamite undergoes a reversible phase transformation to the herbertsmithite-like substructure, space group TeX , unit-cell parameters a 6.839 and c 14.072 Å (393 K). The transformation is characterised by a gradual reduction in intensity of superlattice reflections, which are absent at 393 and 443 K. On cooling from 443 to 300 K at ~10 K min−1, the superlattice reflections reappear and the refined structures ( TeX ) of the initial and recovered 300 K states are almost identical. The complete reversibility of the transformation establishes that paratacamite of composition Cu3.71Zn0.29(OH)6Cl2 is thermodynamically stable at ambient temperatures. The nature of the rhombic distortion of the M(2)O6 octahedron is discussed by considering two possibilities that are dependent upon the nature of cation substitution in the interlayer sites

The single-crystal X-ray structure of gagarinite-(Ce)

The single-crystal X-ray structure of gagarinite-(Ce) has been solved using a cleavage fragment taken from the type specimen of "zajacite-(Ce)". The mineral is hexagonal, space group P6 3/m, with a 6.0861(12) and c 3.6810(8) Å. It is isomorphous with gagarinite-(Y), with Ce 3+ dominating the REE site. The mineral name "zajacite-(Ce)" is discredited, and the mineral is renamed gagarinite-(Ce)

Paratacamite-(Ni), Cu3(Ni,Cu)Cl2(OH)6, a new mineral from the Carr Boyd Rocks mine, Western Australia

Paratacamite-(Ni)(IMA 2013-013), Cu3(Ni,Cu)Cl2(OH)6, is a new Ni-rich mineral with the paratacamite structure. It occurs in the Carr Boyd Rocks nickel mine, Western Australia, as a supergene alteration phase in association with gillardite, spaugolite and gypsum. Paratacamite-(Ni)occurs as aggregates of equant rhombohedral crystals up to ca2 mm in size and exhibits the forms {101}, {021} and {001}. The mineral is dark green with a light-green streak, transparent and has a vitreous lustre. It has good cleavage on {1011}. Measured and calculated densities are 3.70 and 3.735 g cm-3, respectively. Optically, paratacamite-(Ni) is uniaxial (-) with ѡ and E > 1.8. The average of eight electron-microprobe analyses gave the empirical formula Cu3(Ni0.71 Cu0.27 Co0.02)Cl2(0H)6. The new mineral is trigonal, space group R3, with a=13.682(2) and c=13.916(2) Å,V=2256.0(7) Å3 and Z=12. The strongest reflections in the X-ray powder diffraction pattern are [dobs Å(1)(hkl)]: 5.445(81)(021),4.637(13)(003), 4.505(8)(202),2.894(21)(401),2.751(100)(223), 2.254(65)(404), 1.815(14) (603) and 1.708(9)(440). The structure refined to R1 = 0.0225 and ѡR2 = 0.0660 for 314 reflections with Fobs> 4σ(Fobs). The (2+2+2) Jahn-Teller distortion present in the M(2)O6 octahedron suggests that the new mineral is close to the limit of Cu2+ substitution by Ni2+

Copper and cobalt mineralization from the Desolation prospect, Mount Isa Block, Queensland

The Desolation prospect, some 50 km south of Cloncurry, north-west Queensland, is host to a remarkable array of secondary cobalt and copper arsenate and phosphate minerals, including the comparatively rare species clinoclase, Cu3AsO4(OH)3, and the secondary cobalt minerals heterogenite–3R, CoOOH, and erythrite, Co3(AsO4)2.8H2O. Excellent micro- and hand specimens of these species can be collected in dump material and on joints in cherts adjacent to an oxidized, fault-hosted sulphide body. While elevated Co values can be traced to Co- and Ni-rich pyrite, the origin of As in the secondary suite is unclear