Cristiana L. Ciobanu

• The University of Adelaide

Chalcocite, bornite, and chalcopyrite are the main copper minerals in the world-class Olympic Dam Cu-U-Au-Ag deposit, South Australia. Olympic Dam is characterized by systematic, inwards and upwards zonation of Cu-Fe-sulfide assemblages, encompassing chalcopyrite-pyrite, bornite-chalcopyrite, bornite-chalcocite and chalcocite-only zones. Trace elem...

Ehrigite, Bi8Te3, is a new member of the tetradymite group and crystallizes in the trigonal crystal system (space group: Rm, #166). Its cell dimensions are a = 4.519(6) Å, c = 65.182(24) Å, Z = 3, and V = 1152.771(7.554) Å3. Ehrigite occurs as sub-100-micron-sized grains in hedenbergite skarn from the abandoned Good Hope gold mine, Hedley district,...

The incorporation of impurity elements into minerals impacts their physical properties (e.g., reflectance, hardness, and electrical conductivity), but the quantitative relationships between these features and compositional variation remain inadequately constrained. Prior work has shown that gamma-enhancement of reflected light images represents a s...

Chalcopyrite (CuFeS2) and bornite (Cu5FeS4) from the Olympic Dam Cu-U-Au-Ag deposit (South Australia) are characterized using electron backscatter diffraction (EBSD) to identify microstructures and their correlations with trace element concentrations measured by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Natural chalco...

The Irish Orefield is characterised by the presence of both Zn-Pb- and Cu-Ni-As-rich deposits, prospects, and orebodies in similar structural and stratigraphic positions. However, the genetic relationships between these mineralisation types are still debated. In this article, we present new mineralogical, paragenetic, and mineral-chemical observati...

Density functional theory (DFT) is used to obtain structural information of seven members of the tetradymite homologous series: Bi2Te3 (tellurobismuthite), BiTe (tsumoite), Bi4Te3 (pilsenite), Bi5Te3, Bi2Te, Bi7Te3 (hedleyite), and Bi8Te3.

An enrichment in nickel (Ni) or platinum group elements (PGE) is seldom observed in ores of the iron oxide–copper–gold (IOCG) type. This phenomenon is, however, known from a few deposits and prospects in the Carajás Mineral Province, Brazil. The Ni-PGE enrichment is explained, in part, by the spatial association of the IOCG-type ores with altered m...

Furnace slags are potential new sources of critical metals. We undertook a micron- to nanoscale study that addresses speciation, distribution and associations of phases in flash furnace (FF, oxidised) and electric furnace (EF, reduced) slags from the Olympic Dam mining-smelting-refinery operation. Results enable understanding of the behaviour and p...

Abstract Clogauite, ideally PbBi4Te4S3 is the new n = 1 member of the aleksite series, PbnBi4Te4Sn+2, where n is the homologue number. Clogauite is named from the type locality, the Clogau gold mine, Dolgellau Gold belt, Gwynedd, North Wales, United Kingdom. The mineral and name have been approved by the Commission on New Minerals, Nomenclature and...

Sulfosalt assemblages in a specimen from the Boliden Au–Cu–(As) deposit in northern Sweden, comprise micrometre to nanometre scale intergrowths of Se-rich izoklakeite and tintinaite with average formulae and calculated homologue number ( N ) given as: (Cu 1.88 Fe 0.18 ) 2.06 (Pb 22.92 Ag 1.47 Cd 0.01 Zn 0.01 ) 24.41 (Sb 13.12 Bi 8.69 ) 21.8 (S 50.1...

Anode copper is the intermediate product between copper smelting and electrorefining. Anodes are typically 98.5 to 99.8 % pure and require electrorefining to high-purity copper cathode that can be sold to customers. Impurity elements, including Ag, Au, As, Sb, Bi, Se, Te, Sn, Pb, Co, and Ni (alongside minor Fe, Al, and Si), are either dissolved wit...

Non-classical pyriboles (NCPs) have tetrahedral silicate chains (Ibeam) of multiplicity higher than single (pyroxene) or double (amphibole) Ibeams and are known from amphiboles in altered mafic-ultramafic complexes. NCPs, their polysomatic sequences, and inherent chain-width disorder are petrogenetic tools for interpreting igneous and metamorphic p...

Electron backscatter diffraction (EBSD) methods are used to investigate the presence of microstructures in pyrite from the giant breccia-hosted Olympic Dam iron–oxide copper gold (IOCG) deposit, South Australia. Results include the first evidence for ductile deformation in pyrite from a brecciated deposit. Two stages of ductile behavior are observe...

Together with silver (Ag) and gold (Au), which are almost always recovered, the impurity elements, arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), lead (Pb), selenium (Se) and tellurium (Te) are major components of anode slimes, a by-product of the electrorefining of impure copper. The Olympic Dam electrorefinery, South Australia, generates ra...

Density functional theory methods are applied to crystal structures and stabilities of phases from the aleksite homologous series, PbnBi4Te4Sn+2 (n = homologue number). The seven phases investigated correspond to n = 0 (tetradymite), 2 (aleksite-21R and -42R), 4 (saddlebackite-9H and -18H), 6 (unnamed Pb6Bi4Te4S8), 8 (unnamed Pb8Bi4Te4S10), 10 (hit...

The cooling paths and kinetics in the system Cu-Fe-O are investigated by the empirical micro- and nanoscale analysis of slags from the flash furnace smelter at Olympic Dam, South Australia. We aim to constrain the exsolution mechanism of delafossite (Cu¹⁺Fe³⁺O2) from a spinel solid solution (magnetite, Fe3O4) and understand why cuprospinel (CuFe2O4...

Ore minerals provide important insights into the complex interplay of magmatic, tectonic and hydrothermal processes that lead to the formation of mineral deposits. Besides their main economic constituents, ore minerals also contain trace elements that are valuable for modeling the space-time evolution of a mineralizing system, for dating ore minera...

The Mount Weld rare earth element (REE) deposit, Western Australia, is one of the largest of its type on Earth. Current mining exploits the high-grade weathered goethite-bearing resource that lies above, and which represents the weathering product of a subjacent carbonatite. The mineralogy, petrography, deportment of lanthanides among the different...

Increasing volumes of geological and geochemical evidence suggest that evaporites can be involved in the formation of Fe skarn systems and may play a critical role in ore-forming processes. Despite this, the timing and mechanisms of evaporite assimilation and its consequences for the Fe mineralization remains poorly constrained. Jinshandian (Edong...

’Invisible gold’ in pyrite refers to gold occurring either within the sulfide lattice or as discrete nanoparticles (NPs, <100 nm-diameter). The physical form of invisible gold is widely considered to be controlled by the As concentration, with stability fields for lattice-bound versus Au-NPs defined by an empirical Au-As solubility curve. We undert...

Garnet is a key and defining mineral of skarns and associated metalliferous deposits. Variation in garnet composition, commonly expressed by the proportions of different endmembers, is widely used to determine the physical‐chemical features of hydrothermal fluids. Skarn garnets from the Fujiashan W‐Cu‐Mo deposit, eastern China, were investigated by...

Tin-bearing magnetite is reported from several types of magmatic-hydrothermal ore deposits. The question of whether tin is incorporated within solid solution, as Sn⁴⁺, or as nanoinclusions remains open, however. We report a micron- to nanoscale investigation of Sn (Mg, Si)-bearing magnetite from serpentinite in the Dulong Zn-Sn-In skarn, South Chin...

Hematite (α-Fe2O3) and magnetite (Fe3O4) readily accommodate a wide range of minor and trace elements from across the periodic table at up to wt.% concentrations. This prompts the question of whether these common minerals can also host rare earth elements (lanthanides, Y and Sc; REEs)? If so, what is the chemical and physical nature of the elements...

New mineralogical, geochemical, and geochronological data are presented for the Island Dam prospect, Olympic Cu-Au Province, South Australia. Skarn assemblages comprising actinolite/phlogopite + K-feldspar + magnetite suggest the presence of calcareous protoliths at Island Dam and indicate high-temperature alkali-calcic alteration in the early stag...

Characterizing the chemical state and physical disposition of uranium that has persisted over geologic time scales is key for modeling the long-term geologic sequestration of nuclear waste, accurate uranium-lead dating, and the use of uranium isotopes as paleo redox proxies. X-ray absorption spectroscopy coupled with molecular dynamics modeling dem...

The accelerated pace of transition to green energy technologies has led to increased demand for rare-earth elements (REEs). Fluorocarbonates from the bastnäsite [REE(CO 3 )F]—synchysite [CaREE(CO 3 ) 2 F] group are abundant in nature and the dominant REE minerals in the >10 billion ton Olympic Dam Cu–U–Au–Ag deposit, South Australia. Intergrowths o...

The first U-Pb hematite dates are reported for the Mantoverde and Carmen de Cobre iron oxide copper-gold (IOCG) deposits in the northern segment of the Coastal Cordillera, Chile. Samples contain low U, low radiogenic Pb, and relatively high common Pb components. Nevertheless, laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) d...

Multivariate statistical analysis encompasses a range of methods that can fingerprint mineralization, alteration, and host-rock signatures within an ore system, thus assisting in interpretation of ore deposit models and supporting exploration programs. We utilize numeric interpolation of metals (Fe, Cu, and U), principal component analysis (PCA), a...

Breccia-hosted Sr-(Pb-Zn) mineralization from the Shizilishan deposit (Edong district, eastern China) is located at the contact between a Lower Cretaceous (∼139 Ma) quartz diorite porphyry stock and Triassic evaporite-bearing limestone/dolomite sequences. Backscatter electron imaging, electron probe microanalysis, and laser ablation (multicollector...

New critical metal (CM) resources can be identified by improved knowledge of products obtained during processing of complex copper ores. Olympic Dam, South Australia, is a giant (>10 bill. tonne) IOCG deposit. On-site mining-smelting-refining operations produce copper cathodes, U3O8 concentrate, and gold and silver bullion. The deposit is also a gl...

Ancient metamorphic processes are recorded by the formation of metallic-Pb nanospheres in zircon, a product of internal Pb mobilisation and thermally driven concentration. Here, metallic-Pb nanospheres formed within an ore deposit are characterised for the first time using high-angle annular dark field scanning transmission electron microscopy and...

Lead-Bi-Sb-sulfosalts are some of the largest 2D structures known from nature that have been explored in terms of their suitability as a new class of semiconductors for photovoltaic applications. Their structures are built by simple PbS-or SnS-derived modules sliced along different crystallographic directions. The modules are combined within blocks...

Lead-Bi chalcogenides of the aleksite homologous series occur as trace constituents of many Au-bearing ore deposits and are defined chemically by the formula Pb n Bi 4 Te 4 S n+2. Their synthetic analogs show considerable potential as topological insulators and in thermoelectric energy conversion. These mixed-layer compounds can be built from odd-n...

Bi8Te3 is a member of the tetradymite homologous series, previously shown to be compositionally and structurally distinct from hedleyite, Bi7Te3, yet inadequately characterized structurally. The phase is identified in a sample from the Hedley district, British Columbia, Canada. Compositions are documented by electron probe microanalysis and structu...

Laser ablation-inductively coupled plasma-mass spectrometry and electron-probe microanalysis were used to investigate the trace-element contents of sphalerite, chalcopyrite and pyrite from the Plaka Pb-Zn-Ag deposit. Using petrographic observations, the analytical results could be linked to the temporal evolution of the Plaka ore-forming system. Sp...

We used high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) to image the crystal structures of four minerals in the Bi4X3 isoseries (X = Te, Se, S), a subgroup of the tetradymite homologous series: ikunolite (Bi4S3), laitakarite (Bi4Se2S), joséite-B (Bi4Te2S), and joséite-A (Bi4TeS2). The four minerals are isostruct...

The Pefka Cu-Au-Te-In-Se and nearby St Philippos Pb-Zn-Bi-Sn-Ge-Ga-In vein- and breccia-type deposits in western Thrace, Greece, display strong similarities, but also differences in terms of mineralization style, ore mineralogy, and chemistry, and host rock compositions. The Pefka mineralization consists of two crosscutting vein systems with high s...

Yuhengtang is a representative slate-hosted Au deposit in the Jiangnan orogenic belt, South China, with a reserve of ca. 55 t Au and an average grade of ~3.9 g/t. Gold mineralization is characterized by veinlet and disseminated ores comprising native gold, auriferous pyrite and arsenopyrite. Paragenesis of the Yuhengtang deposit can be divided into...

Silician magnetite within ~1.85 Ga lithologies hosting the ~1.6 Ga Wirrda Well iron oxide copper gold (IOCG) prospect, South Australia, was examined at the nanoscale. The magnetite is oscillatory-zoned with respect to the density and orientation of nanometer-scale inclusions, among which Si-Fe-nanorods and Al-rich amphibole (as much as hundreds of...

Trace/minor element variation in pyrite is a feature that has proved invaluable for reconstructing a wide range of geological processes. Routine reflectance observations commonly fail to constrain this variation due to the typically subtle and barely perceptible change in reflectance brought about by deviation from ideal stoichiometry. Such differe...

In both nature and synthetic experiments, the common iron oxide haematite (a-Fe2O3) can incorporate significant amounts of U into its crystal structure and retain radiogenic Pb over geological time. Haematite is a ubiquitous component of many ore deposit types and, therefore, represents a valuable hydrothermal mineral geochronometer, allowing direc...

Economic interest in indium (In) and other critical metals has accelerated efforts to understand how such elements occur in nature and the controls on their mineralogy. In this contribution, the distribution of In and other trace elements in the Dulong Zn–Sn–In deposit, China, is described, using a holistic approach which targets not only sulfides...

Micrometer- to submicrometer-scale indium-rich domains are preserved within sphalerite included in hornfels-hosted pyrrhotite from the Dulong polymetallic skarn, Yunnan, China. The nano-mineralogy of the ZnS-bearing blebs was investigated using scanning transmission electron microscopy on thinned foils extracted in situ from pyrrhotite. Indium inco...

Texturally complex minerals can provide critical information on dynamic hydrothermal processes. This study combines cathodoluminescence (CL), laser ablation-inductively coupled plasma mass spectrometry (LA–ICP–MS), and high-resolution femtosecond laser ablation multi-collector inductively coupled plasma mass spectrometry (fs–LA–MC–ICP–MS) analyses,...

The supergiant Olympic Dam Cu-U-Au-Ag deposit in South Australia is a type example of the iron-oxide copper–gold (IOCG) deposit family. Hosted entirely within heterogeneous breccia in 1.59 Ga granite, the deposit contains a volumetrically substantial and mineralogically diverse component of carbonate minerals. Carbonate minerals are always associat...

Magnetite is the dominant Fe-oxide at the Acropolis IOCG prospect, Olympic Dam district, South Australia. Complementary microbeam techniques, including scanning transmission electron microscopy (STEM), are used to characterize titanomagnetite from veins in volcanic rocks and Ti-poor magnetite from a granite body with uplifted position in the volcan...

Pyrite commonly incorporates a wide range of trace and minor elements, which in turn may modify some of the mineral’s physical and chemical properties. Published band position data for the Raman spectra of pyrite show a wide variation, and the relationship between band position and the trace/minor element incorporation in pyrite is poorly constrain...

Zircon from three distinct granites within the Samphire Pluton, South Australia, are characterised at the micron- to nanoscale. Sensitive high-resolution ion microprobe (SHRIMP) U-Pb zircon dating generated 207Pb/206Pb weighted average ages of 1586 ± 9.3 Ma, 1583.2 ± 8.5 Ma and 1578 ± 9.5 Ma, respectively. Although zircons from all three granites d...

Preferential removal of W relative to other trace elements from zoned, W–Sn–U–Pb-bearing hematite coupled with disturbance of U–Pb isotope systematics is attributed to pseudomorphic replacement via coupled dissolution reprecipitation reaction (CDRR). This hematite has been studied down to the nanoscale to understand the mechanisms leading to compos...

Establishing timescales for iron oxide copper-gold (IOCG) deposit formation and the temporal relationships between ores and the magmatic rocks from which hydrothermal, metal-rich fluids are sourced is often dependent on low-precision data, particularly for deposits that formed during the Proterozoic. Unlike accessory minerals routinely used to trac...

The halogens Cl and Br are sensitive indicators for the origin of ore-forming fluids. Here, we use a combination of microchemical and microscopic methods to show that measurable concentrations of these elements commonly occur as atomic-scale substitutions in hydrothermal sphalerite. Furthermore, the Cl/Br ratios of halogen-rich sphalerites are indi...

Proximal and distal garnets from skarns at Jiaduobule, Tibet, are used to demonstrate how variation in the fluid composition and parameters such as salinity, pH, fO2, and \({\text{X}}_{{\rm CO}_{2}}\) will impact on rare earth element (REE) distribution in garnets, and also to constrain skarn evolution across the orefield from proximal (Fe minerali...

The IOCG deposit at Olympic Dam (South Australia) is hosted within the Roxby Downs Granite, which displays a weakly mineralised contact to the orebody (hereafter ‘outer shell’). In a mineralogical-geochemical characterisation of Fe-oxides from the outer shell, we show silician magnetite (Si-magnetite) and HFSE-bearing hematite define the early stag...

The Blackbush uranium prospect (~12,580 tonnes U at 85 ppm cut-off) is located on the Eyre Peninsula of South Australia. Blackbush was discovered in 2007 and is currently the single example of sediment-hosted uranium mineralisation investigated in any detail in the Gawler Craton. Uranium is hosted within Eocene sandstones of the Kanaka Beds and, su...

Spatial associations between banded iron formation and iron-oxide Cu-Au (IOCG) style mineralization are well documented in the Gawler Craton (South Australia), but the possible genetic relationships between these two distinct types of mineralization are hitherto unclear. A texturally conspicuous generation of coarse-grained silician magnetite, inte...

Pyrite is the most common sulphide in a wide range of ore deposits and well known to host numerous trace elements, with implications for recovery of valuable metals and for generation of clean concentrates. Trace element signatures of pyrite are also widely used to understand ore-forming processes. Pyrite is an important component of the Olympic Da...

Metallic-Pb nanospheres (M-PbNs) are documented within zircon from Archean ultrahigh-temperature metamorphic terranes (UHT; [1,2]). Radiogenic Pb mobilized from radiation-damaged domains in zircon predating the metamorphic event is trapped as M-PbNs. Dating using nanoSIMS, shows the M-PbNs record the UHT event [3]. Here we report M-PbNs in zircon f...

Aluminum-phosphate-sulfate (APS) minerals of the alunite supergroup are minor components of uranium-bearing copper ores from the Olympic Dam deposit, South Australia. They typically represent a family of paragenetically late replacement phases after pre-existing REE-bearing phosphates (fluorapatite, monazite, and xenotime). Characterization with re...

The Acropolis prospect is a vein-style magnetite (±apatite ±hematite) system located ~20 km southwest from the giant Olympic Dam iron-oxide copper gold (IOCG) deposit, South Australia. A whole rock dataset comprising 4,864 core samples from fourteen drillholes was analysed using multivariate statistics to understand and identify geochemical signatu...

Minerals form in all types of chemical and physical environments [...]

Banded iron formation (BIF)-derived iron ore deposits of the Middleback Ranges, Eyre Peninsula, South Australia, are hosted within Archean to Paleoproterozoic basement in the southeastern Gawler Craton. Mafic sills and dikes are associated with the orebodies throughout the belt and although described previously, have never been studied in detail. T...

Bi-Pb-chalcogenides of the aleksite series represent homologous mixed-layer compounds derived from tetradymite (Bi2Te2S). Considering tetradymite as composed of five-atom (Bi2Te2S) layers, the named minerals of the aleksite homologous series, aleksite (PbBi2Te2S2) and saddlebackite, (Pb2Bi2Te2S3) have been considered as phases formed by regular sta...

The Wirrda Well and Acropolis prospects, ~25km south from the Olympic Dam deposit, are among several dozen examples of iron-oxide copper gold (IOCG) mineralisation forming a 600km-long province in the eastern Gawler Craton, South Australia. IOCG systems across the province differ in terms of host lithology, iron-oxide mineral associations, intensit...

The Acropolis prospect is a vein-style magnetite (±apatite ±hematite) system located ~20 km southwest from the giant Olympic Dam iron-oxide copper gold (IOCG) deposit, South Australia. A whole rock dataset comprising 4,864 core samples from 14 drillholes was analysed using multivariate statistics to understand and identify geochemical signatures of...

Titanomagnetite from Fe-Ti-V ores of the Lanjiahuoshan deposit, Panzhihua layered intrusion, Southwest China, was investigated at the nanoscale. The objectives were to establish the composition of exsolution phases and their mutual relationships in order to evaluate the sequence of exsolution among oxide phases, and assess mechanisms of ore formati...

A Multi-platform Microanalysis Approach to Unravelling Geological Problems: a Case Study from Olympic Dam South Australia - Volume 25 Supplement - A.K.O. Netting, B.P. Wade, M.R. Verdugo-Ihl, L. Courtney-Davies, C.L. Ciobanu, N. Cook, K. Ehrig, A. Slattery, S. Gilbert, K. Neubauer

Scheelite (CaWO4), a hydrothermal mineral commonly displaying enrichment in Mo (up to 16%) and/or rare earth elements (REE), is the main economic mineral in the Gaojiabang porphyry-skarn type W-Mo deposit, East China. Based on microscopic observations and in-situ LA-ICP-MS and LA-MC-ICP-MS analysis, three groups of scheelite, each with different ge...

Titanite textures and geochemistry have been investigated from the Roxby Downs Granite, host to the Olympic Dam Fe-oxide Cu-U-Au-Ag deposit, South Australia. Three textural subtypes of titanite are documented: primary magmatic (cores and rims); late/interstitial; and secondary (low T recrystallisation). Magmatic cores are defined by enrichment in L...

Metal zonation is an important feature of low-temperature carbonate-hosted Zn-Pb deposits. Its origin, however, remains poorly understood. In this article, we use the Lisheen deposit in Ireland as a case study to show how thermodynamic modelling can explain these zonation patterns. Based on input data derived from fluid inclusion studies, bulk ore...

Enargite, Cu3AsS4, is a relatively common sulphide mineral and is considered diagnostic for deposits of intermediate- to high-sulphidation type. Analysis of enargite-bearing samples from deposits in the Zijinshan porphyry - high-sulphidation epithermal Cu-Au orefield, southeastern China, provides evidence for the diversity of trace elements that ma...

The Acropolis prospect, 20 km southwest from the Olympic Dam Cu-U-Au-Ag deposit, South Australia, is a vein-style magnetite (±apatite ±hematite) system. A whole-rock dataset comprising 4864 core samples from 14 drillholes was analysed using multivariate statistical analyses to understand and identify geochemical signatures of mineralization, as wel...

Metal nanoparticles (NP) in minerals are an emerging field of research. Development of advanced analytical techniques such as Z-contrast imaging and mapping using high-angle annular dark field scanning transmission electron microscopy (HAADF STEM) allows unparalleled insights at the nanoscale. Moreover, the technique provides a link between micron-...

Titanite textures and chemistry have been investigated from the Roxby Downs Granite, host to the Olympic Dam Cu–U–Au–Ag deposit, South Australia. Three textural subtypes of titanite are documented: primary magmatic (cores and rims); deuteric; and hydrothermal (low T recrystallisation). Magmatic cores are defined by enrichment in LREE (~ 3 wt%), Nb...

The petrography and geochemistry of zircon offers an exciting opportunity to better understand the genesis of, as well as identify pathfinders for, large magmatic–hydrothermal ore systems. Electron probe microanalysis, laser ablation inductively coupled plasma mass spectrometry, high-angle annular dark-field scanning transmission electron microscop...