Copper Sulfide Minerals Research Articles

Oxygenated Leaching of Copper Sulfide Mineral under Microwave-Hydrothermal Conditions

A study on microwave assisted chalcocite leaching was carried out with a microwave hydrothermal reactor. The leaching was conducted with thick mineral slurries (50-100g/l). The leaching media is a mixed solution of CuCl2 and NaCl. The investigation included the effect of leaching temperature, quantities of the minerals per unit slurry volume as well as the initial concentration of cupric ions. The results were discussed and compared with using conventional leaching method.

The Phalabowra (Palabora) carbonatite-hosted magnetite-copper sulfide deposit, South Africa: an end-member of the iron-oxide copper-gold-rare earth element deposit group?

Olympic Dam-type iron-oxide copper–gold deposits are widely recognised in terrains with significant Palaeoproterozoic to Mesoproterozoic granitic magmatism. Most researchers favour a magmatic association for these deposits, but none of the 100–2000 Mt recognised copper-bearing deposits has a spatial and/or temporal relationship to an intrusive body of sufficient dimensions to produce the hosting giant breccia and/or hydrothermal systems. In other words, if the recognised ore-bodies are magmatic-hydrothermal, they must be classified as distal deposits. The magnetite–copper–phosphate–rare earth element pipe-like carbonatite-hosted orebody at Loolekop, within the larger Phalabowra Carbonatite Complex, has many features to suggest that it represents an end member of the Olympic Dam-type deposit class hosted within its magmatic source rock. It (1) falls broadly within the appropriate age range, (2) has a similar giant size and low copper grade, (3) is dominated by magnetite, (4) has sulfur-poor copper-sulfide minerals and lacks iron sulfides, (5) is silica-poor, and (6) is enriched in REE, particularly LREE, as well as P, F, U and Th. As an end member of the Olympic Dam-type deposits, the Loolekop orebody can help explain the common siting of the deposits at craton edges or other lithospheric boundaries, where decompression melting of metasomatised mantle can produce volatile-rich alkaline melts (rich in REE, P, F, etc.). Such melts are capable of generating sulfur-deficient volatiles enriched in copper and gold, among other elements, as well as phreatic breccia pipes and associated intense metasomatism, the most common features of the Olympic Dam-type deposits.

Separation of enargite and tennantite from non-arsenic copper sulfide minerals by selective oxidation or dissolution

Selective oxidation of minerals was investigated as a means to separate by flotation the copper sulfide minerals of chalcocite, covellite and chalcopyrite from the arsenic copper sulfide minerals of enargite and tennantite in mixed mineral systems. It was found that a separation of these minerals could be feasible after selective oxidation of their surfaces in slightly acidic pH conditions, or after oxidation and selective dissolution of the surface oxidation products with a complexant in basic pH conditions.

Effects of oils and lubricants on the flotation of copper sulphide minerals

The effects of the addition of oils and lubricants commonly encountered in mining and processing copper sulphide ores on the subsequent flotation of copper minerals was investigated by laboratory scale testing. The project arose as a result of intermittent uncontrollable frothing and a drop in selectivity observed at an Australian copper-gold concentrator. The addition of distillate to the grinding stage actually increased selectivity in the subsequent copper mineral flotation but other oils and lubricants used at the plant had detrimental effects on selectivity and frothing behaviour. A degreaser used in maintenance operations dramatically lowered copper grade and generated a very stable and sticky froth even at low concentrations. Similar detrimental effects on gold metallurgy were also observed. Mineralogical examination of flotation products verified that the decrease in grade of the concentrates was due to the flotation of free gangue minerals and not due to any liberation problems. Possible mechanisms for these effects aer discussed. Anecdotal evidence for these effects abound in discussions held with plant metallurgists, but little published data on these effects have been located.

Studies on the applicability of chelating agents as universal collectors for copper minerals

The efficacy of copper chelating agents as collectors for both copper oxide and sulfide minerals has been assessed through contact angle measurements. Because of the insoluble nature of many of these organic reagents, the use of a suitable solvent was necessary for preparing aqueous solutions. Finite contact angle results are presented as average values for the pH range where only finite contact was observed. The chelating reagents tested were classified according to the type of atoms that bond the metal cation and participate in the closure of the chelate ring. Five different types of bidentate chelating reagents were identified: N–O, O–O, S–N, S–S, and N–N. The most refractory copper mineral was found to be chrysocolla, which exhibited contact angles only with 1-phenylthiosemicarbazide and with potassium octyl hydroxamate. This last reagent proved to have excellent collecting properties for copper oxide minerals and native copper, primarily because of its alkyl chain length.

Acid Pressure Leach Process for Copper Removal. Autoclave processing of low-grade molybdenite concentrates. (1st Report).

The conditions for the selective oxidation of copper and iron sulfide minerals contained in a low-grade molybdenite concentrate during autoclave leaching in acidic media have been studied. The effect of oxygen partial pressure, reaction time and temperature on copper removal has been examined. Oxidation of minerals follows the order; chalcopyrite, pyrite, molybdenite and has been explained from the point of view of electrochemical kinetics. Cementation on iron was used for copper recovery from the leach liquor. The partly oxidized residue consisting of molybdenite and iron (hydro-) oxide can be treated by means of flotation or oxygen pressure leaching in alkaline media to extract molybdenum and rhenium values.

Neoproterozoic Attunga Eclogite in Eastern Australia Margin

Europe is home to some of the largest mining companies in the world. Nevertheless, the separation of the eastern part of Russia from the Continent of Europe, following the watershed divides of the Ural and Caucasus Mountains, reduces the mineral resources particularly with respect to platinum group metals, nickel, and chromium. Five European countries share some resources of nickel (2%) and chromium, and a negligible quantity of platinum group metals.Albania hosts chromium at Bulqiza and Kalimash Massifs, and nickeliferous/laterite nickel ore from Bitincke (35.6 Mt @ 1.2% Ni). Finland contributes chromium from Kemi Intrusion (40 Mt @ 26% Cr2O3, and komatiitic Ni–Cu–PGE from Lomalampi, Kevitsa–Satovaara (240 Mt grading 0.30% Ni, 0.42% Cu, 0.21 g/t Pt, 0.15 g/t Pd, and 0.11 g/t Au), Rytky, and Vaarsa komatiite intrusions. The Bruvann Ni–Cu–Co deposit/mine belongs to the Råna Intrusion in Norway.The significant mineral products of Spain, in terms of value, include copper, zinc, gold, steel, nickel, coal, cement, and alumina. Aguablanca Ni–Cu–PGE magmatic sulfide deposit is the sole open-pit/underground mine. The nickel–copper-sulfide mineralization hosted by gabbronorite occurs as massive, semimassive, and disseminated types I and II ores.

Analysis of alkylxanthate collectors on sulphide minerals and flotation products by headspace analysis gas-phase infrared spectroscopy (HAGIS)

Direct surface analysis by infrared spectroscopy is a useful technique for detection of xanthate species on sulphide minerals. However, infrared detection limits require xanthate dosages that are often one or two orders of magnitude higher than are used in practice. This paper presents an alternative approach to the analysis of collectors on mineral surfaces. A novel gas-phase infrared technique (HAGIS) has been applied to the indirect analysis of ethylxanthate on lead, zinc and copper sulphide mineral surfaces and also on flotation products from copperzinc and leadzinc ores at xanthate concentrations which are comparable to those used in the mineral processing industry. HAGIS relies on the detection of the gas-phase species generated by the thermal decomposition of xanthates adsorbed on mineral surfaces. In this study, the primary decomposition products generated under an air atmosphere include carbonyl sulphide (COS), carbon dioxide (CO 2), carbon disulphide (CS 2) and ethanol. The amounts of these species were compared with product distributions observed for the decomposition of known ethylxanthate complexes. Correlations between the decomposition species provide evidence for the speciation of the collector in the flotation product. The decomposition species can be readily detected from xanthate dosages that are much lower than are the detection limits of traditional, direct surface analysis techniques.

Modeling the cyanide heap leaching of cupriferous gold ores: Part 1: Introduction and interpretation of laboratory column leaching data

A kinetic and thermodynamic model of cyanide heap leaching of copper-bearing gold ores was developed in order to facilitate the evaluation and treatment of these complex ores [F. Coderre, Modeling the cyanide heap leaching of cupriferous gold ores. M.A.Sc. Thesis, U. British Columbia, 1998.]. In this first paper on the work, the behaviour of copper minerals in cyanide solutions is reviewed, and data from a series of laboratory column leaching tests performed under different influent cyanide concentrations are presented and interpreted in support of model development. The cyanide leaching is shown to occur in four distinct stages: (1) reductive dissolution of Cu(II) salts, during which copper and gold precipitate as cyanide salts, and no gold appears in the column effluent; (2) redissolution of the copper and gold cyanide precipitates; (3) leaching of copper sulphide minerals and elemental gold; and (4) free cyanide breakthrough in the effluent, which is accompanied by the appearance of dissolved iron from the redissolution of metal hexacyanoferrates. During the leaching step, it appears as if elemental gold dissolves in the absence of free cyanide, but that the copper sulphides do not.

Use of chelating agents as collectors in the flotation of copper sulfides and pyrite

Fourteen reagents that are potentially capable of chelating with a metal ion on the surface of the major copper sulfide minerals and pyrite were evaluated for their effectiveness in floating these sulfides. The reagents studied fall into the classes of mercaptobenzole mutations, thiouronium, thionocarbamates, thiourea, imidazole mutations, oximes, hydroxyquinoline and xanthogen formate. The best overall copper sulfide collector was an imidazoline (1-Hy doxy ethyl - 2-Heptadecenyl), but it also proved to be an excellent collector for pyrite. Its potency as a pyrite collector can be reduced by structural alteration, but at some loss in its collecting power for the copper sulfides. The effectiveness of many of these potential collectors can be changed by minor alterations to the collector molecule and, to a lesser extent, by pH adjustment. The general order of mineral floatability with these reagents is chalcopyrite = chalcocite > covellite > bornite » pyrite. The flotation of malachite is generally similar to that of the copper sulfides, indicating the special effectiveness of copper in the crystal lattice for collector attachment.

Zeta potential study of the oxidation of copper sulfide minerals

The zeta potential of the copper sulfide minerals, chalcocite, covellite, chalcopyrite, bornite, enargite and tennantite was measured as a function of pH and oxidising conditions. The changes in zeta potential observed in this study are consistent with the presence of a copper hydroxide layer covering a metal-deficient sulfur-rich surface and with the extent of this copper hydroxide coverage increasing with oxidation conditions. The existence of these surface species and their percentage were also confirmed by X-ray photoelectron spectroscopy. Analysis of the zeta potential data revealed that during the acid titration of the minerals, dissolution of the surface copper hydroxide layer occurs at pH values less than 8 while during the base titration, precipitation of copper hydroxide on the mineral surface is observed at pH values higher than 6. Hysteresis between the zeta potential acid and base titration curves was only observed in oxidising conditions and is attributed to the dissolution of the minerals at acidic pH values. The following ranking for the oxidation of these minerals is obtained: chalcocite>tennantite>enargite>bornite>covellite>chalcopyrite.

Geology and Copper Sulphide Mineralization of the Salmagorskii Ring Igneous Complex, Kola Peninsula, NW Russia

The Salmagorskii igneous complex represents a rare example of peralkaline rocks containing significant copper sulphide mineralization presented by chalcopyrite, djerfisherite and cubanite. Data on the geological structure of the complex and the copper sulphide–apatite mineralization related to its foidolitic peralkaline rocks have been obtained from drilling in recent years. The sequence of rocks (dunite–clinopyroxenite–melilitolite–ijolite–urtite–melteigite–carbonatite) forms a perfect concentric zoning within the pluton indicating that fractional crystallization was the predominant petrogenetic process. Copper sulphide mineralization formed at the post-magmatic stage, when recrystallization processes within earlier ijolite and melteigite took place under the influence of a fluid rich in CO2, H2O, alkalis, S, P, Cu, and Cl.

Geology and Copper Sulphide Mineralization of the Salmagorskii Ring Igneous Complex, Kola Peninsula, NW Russia

The Salmagorskii igneous complex represents a rare example of the carbonatite body of the Phalaborwa complex in South peralkaline rocks containing significant copper sulphide minAfrica contains one of the world’s largest copper deposits, eralization presented by chalcopyrite, djerfisherite and cubanite. but contrary to many other similar intrusions, it is charData on the geological structure of the complex and the copper acterized by the lack of niobium mineralization (Versulphide–apatite mineralization related to its foidolitic peralkaline woerd, 1986; Eriksson, 1989). On the other hand, even rocks have been obtained from drilling in recent years. The sub-economic copper sulphide ores (except for Phalsequence of rocks (dunite–clinopyroxenite–melilitolite–ijolite–urtite– aborwa) are rather uncommon in alkaline rocks and melteigite–carbonatite) forms a perfect concentric zoning within the carbonatites. This paper presents the first data on copper pluton indicating that fractional crystallization was the predominant mineralization from mafic peralkaline rocks of the Salpetrogenetic process. Copper sulphide mineralization formed at the magorskii complex. post-magmatic stage, when recrystallization processes within earlier Alkaline–ultramafic ring igneous complexes in the Kola ijolite and melteigite took place under the influence of a fluid rich Alkaline Province (Kukharenko et al., 1965), as well as in CO2, H2O, alkalis, S, P, Cu, and Cl. other regions (Woolley, 1987; Kogarko et al., 1995; Vasiliev & Zolotukhin, 1995), are usually concentrically zoned, pipe-like intrusions in which ultramafic rocks (dunite or clinopyroxenite) occupy the central parts of the complexes and melilitolites with foidolites surround

Chemical mobility of gold in the porphyry-epithermal environment

Using recently published experimental data, we have calculated the solubility of gold for simplified magmatic fluids that cool between 500 degrees and 300 degrees C. The starting fluid has the following characteristics: P = 1 kbar, Sigma Cl = 2.0 m, Sigma KCl/Sigma NaCl = 0.25, pH fixed by muscovite + K feldspar + quartz, f (sub O 2 ) fixed by SO 2 /H 2 S, and a (sub H 2 S) fixed by magnetite + pyrite. Parallel calculations were performed asstuning no drop in pressure during cooling (isobaric model) or an instantaneous drop in pressure to 500 bars, resulting in separation of a dense brine and a low-salinity vapor (boiling model). The isobaric model applies to magmas emplaeed at hypozonal or mesozonal depths, whereas the boiling model is more appropriate for shallow porphyry deposits.In the isobaric model, gold solubility is initially dominated by AuCl 2 (super -) at 500 degrees C, 1 kbar. If H 2 S levels are high (pyrite stable), the dominant complex shifts to Au(HS) 2 (super -) upon cooling below approximately 450 degrees C, and solubilities remain elevated (> 100 ppb) over the entire temperature range. If H 2 S levels are low (magnetite stable), gold solubility decreases steadily to 300 degrees C, with AuCl 2 (super -) the dominant complex throughout. Thus, gold dissolved in H 2 S-rich fluids will tend to be carried away from the parent magma, whereas gold in H 2 S-poor fluids will tend to precipitate closer to the source. At 500 degrees C, gold solubility as AuCl 2 (super -) is highest for fluids that are oxidized (SO 2 /H 2 S > 1), acidic. highly saline, and potassium rich. Gold may precipitate in response to a number of mechanisms, including cooling, pH increase, and dilution.Magmatic fluids that evolve from shallow porphyry, bodies are apt to boil shortly after leaving the melt, at which point most of the dissolved gold will partition along with chloride into the brine phase. This metal-rich fluid, because of its high density, will tend to sink or reflux near the parent intrusion, possibly forming an Au-rich porphyry Cu deposit. Mass balance calculations suggest that magmatie brines will initially be undersaturated with respect to metallic gold, although the metal may still precipitate as Au-rich copper sulfide minerals (iss, bornite). During boiling, most of the H 2 O and H 2 S will partition into the coexisting vapor phase. As this vapor cools, it may recondense into a low-salinity, H 2 S-rich xvater of mixed magmatie-meteoric heritage that has a high potential for dissolving and remobilizing significant quantities of gold as Au(HS) 2 (super -) . Migration of this fluid to shallower levels may eventually form epithermal deposits of low- or high-sulfidation affinity, depending on the pH-buffering capacity of the wall rocks, and the extent of direct magmatie involvement. Lack of contact with retrograde, H 2 S-rich magmatic-meteoric waters may be a prerequisite for the preservation of early Au-rich porphyry-style mineralization and may also explain the observed association between gold and hypogene iron oxide alteration in many porphyry deposits.Whether or not there is a direct temporal link betxveen ore-forming processes in the porphyry and epithermal regimes, an intrusive event may be important as a means of introducing a large quantity of low-grade gold which is then available for later remobilization and concentration by circulating fluids of nonmagmatic origin. Moreover, an early porphyry event may cause widespread sulfidation of surrounding rocks. Later fluids of meteoric origin circulating through this pyrite-rich wall rock will have H 2 S concentrations that remain elevated during cooling and ascent, increasing the chances of forming a large, high-grade epithermal gold deposit.

Biogeochemical studies of metal-tolerant plants from southern Morocco

An expedition to Southern Morocco was undertaken to study and collect the poorly documented metal-tolerant flora of the Bou Azzer region. The areas visited are underlain by ultramafic rocks with associated cobalt-nickel arsenide mineralization and chromium carbonates (Bou Azzer), and by volcano-sedimentary rocks with associated copper sulphide mineralization (Bléida). Biogeochemical studies were made of metals in many species, of which the five most common are Anvillea garcinii subsp. radiata, Ononis natrix (goat-root), Laiandula multifidia (lavender), Convolaulus trabutianus (morning-glory), and Artemisia herba-alba (sagebrush). Results show differences in the ability of each species to accumulate metals. Ononis concentrates most of the ore-forming elements to highest levels. However, because of its more widespread occurrence, Anuillea is a more appropriate sample medium for biogeochemical surveys. From chemical analysis of its stems, zones of concealed mineralization can be identified where conventional soil analysis is less definitive.

Identification of SLF1 as a New Copper Homeostasis Gene Involved in Copper Sulfide Mineralization in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, at least 12 genes are important for cells to propagate in medium containing elevated concentrations of copper salts (J. Welch, S. Fogel, C. Buchman, and M. Karin, EMBO J. 8:255-260, 1989). Complementation studies were carried out on a copper-sensitive mutation (cup14) from this group. A new yeast gene, designated SLF1, was identified as a multicopy suppressor of the cup14 mutation. Slf1 is important for the physiological process of copper sulfide (CuS) mineralization on the surface of cells cultured in medium containing copper salts. CuS mineralization causes the cells to turn brown. Disruption of SLF1, which is located close to the telomere region of chromosome IV, leads to limited copper sensitivity, and the resulting cells lack the normal brownish coloration when grown in CuSO4-containing medium. Overproduction of Slf1 in wild-type cells confers superresistance to CuSO4 and enhances the coloration of cells cultured in the presence of CuSO4. Upon addition of KCN to Cu-grown cells, the brownish coloration was bleached instantly, and copper ions were solubilized. These data are consistent with Slf1-dependent accumulation of CuS complexes on the cell surface. Disruption of SFL1 also results in loss of the ability of yeast cells to deplete Cu but not Cd ions from the growth medium, whereas overexpression enhances Ca depletion ability and the resulting deposition of CuS particles. It is proposed that Slfl participates in a copper homeostasis pathway, distinct from the Cup1 detoxification system, that leads to sulfide generation and CuS biomineralization on the cell surface. This process may coordinate with the Cup1 pathway at different copper concentrations to prevent copper-induced toxicity.

Depositional environments of the Meso- to Neoproterozoic Ghanzi-Chobe belt, northwest Botswana

The Ghanzi-Chobe belt comprises a volcano-sedimentary basin sequence located in northwest Botswana. This sequence started to accumulate at about 1106 Ma ago and was deformed during the Pan-African event between approximately 750 and 500 Ma. The stratigraphy consists of an older Kgwebe Formation and a younger Ghanzi Group. The Kgwebe Formation represents the first phase of basin evolution that involved extensional tectonics and intracratonic rifting with subsequent bimodal volcanism and the development of lacustrine to fluvial systems. The Ghanzi Group represents the second phase of basin evolution marked by an extensive rift enlargement episode, resulting in a shallow marine basin with the deposition of siliciclastic sedimentary rocks and carbonate beds. The marine basin consisted of a shallow shelf environment dominated by storm and fairweather conditions. Stratabound copper sulphide mineralization was deposited at a redox interface between an alluvial facies and a marine transgressive sequence. The final development of the sedimentary environment involved a progradational shoreline with the deposition of a red arenite facies. Intermediate sub-environments consisted of mixed clastic-carbonate lagoons and possible progradational deltas. Rifting in the Ghanzi-Chobe belt was aborted before the development of an ocean resulting in a failed intracontinental rift basin.

Uso combinado de dos biorreactores en la biolixiviación de un mineral sulfurado de cobre

Bioleaching of sulphide ores using mesophiles microorganisms is an alternative way, economically viable, for certain inexpensive metals recovery. Generally, in these processes some problems become from the direct contact of microorganisms with the ore (deposits, toxicity of ions on the bacteria, etc.). To prevent these troubles, an indirect methodology with the so called bioreactors to generate the leaching medium may be used. These are supports saturated with attached bacteria through which fresh liquid medium is precolated to generate the lixiviant solution. In this paper a two combined bioreactors system is proposed; one of them, previously used, generates oxidant medium through the use of Thiobacillus ferrooxidans and other, introduced in this work, produces sulphuric acid medium using Thiobacillus thiooxidans. This combined system has been used to leach a copper sulphide mineral with an important recovery of the metal. The sulphuric acid producing bioreactor prevented troubles associated with jarosites deposits on the ore, which appear at low pH. At the same time a high concentration of oxidant agent (Fe(III) ion) is maintained during the process.

S K- and L-edge XANES and electronic structure of some copper sulfide minerals

The S K and L-edge x-ray absorption near-edge structures (XANES) of low bornite, cubanite, chalcocite, covellite, enargite and tetrahedrite have been measured with synchrotron radiation. The near-edge features are interpreted based on comparison with the S K- and L-edge spectra of chalcopyrite and a MO/energy band structure model. The XANES spectra of these sulfides reflect the DOS of unoccupied S s-, p- and d-like states near and above the Fermi level. In tetrahedral Cu-Fe sulfides, the Fe3+ 3d crystal field band has much more significant DOS of unoccupied S 3p-and 3s-like states than the Cu+ 3d crystal field band. For Cu sulfides, the Cu+ 3d crystal field band has the higher DOS of S 3p- and 3 s-like states in tetrahedral structure than in structures with the triangular CuS3 cluster. The shifts in both S K- and L-edges correlate approximately linearly with the energy gap.

Skarn CuAu orebodies of the Gunung Bijih (Ertsberg) district, Irian Jaya, Indonesia

The major CuAu skarn deposits of the Gunung Bijih (Ertsberg) district in central Irian Jaya are products of hydrothermal systems that developed in association with Pliocene magma emplacement in an active continental margin. The CuAu skarn orebodies occur within a Cretaceous to Tertiary sedimentary sequence that was deformed as the northern Australian continental margin entered a north-dipping subduction zone at ∼ 12 Ma. The intermediate-composition intrusions consist of fine-grained porphyritic stocks, dikes, and sills that have K-Ar ages ranging from 2.7 to 4.4 Ma. Most intrusions are slightly potassic, but these data could be affected by alteration. The skarn orebodies in the Ertsberg district are hosted in deformed lower Tertiary New Guinea Group carbonate strata along the periphery of the Pliocene Ertsberg intrusion. Major skarn orebodies include the Ertsberg (GB), the Ertsberg East (GBT) complex, including the GBT, the Intermediate Ore Zone (IOZ) and the Deep Ore Zone (DOZ), and the Dom. Chalcopyrite is the dominant ore mineral in the GB and Dom orebodies, whereas bornite dominates in the GBT complex. Native Au occurs within bornite and chalcopyrite in GB and GBT ores. The district calc-silicate alteration assemblages are characterized by high-temperature skarn minerals, including forsterite, monticellite, and minor melilite. Diopsidic clinopyroxene is common, particularly in GBT. Anhydrite and phlogopite are abundant in the GBT complex, and the anhydrite:calcite ratio increases with depth from GBT to DOZ where anhydrite is ubiquitous and calcite rare. At least three types of garnets have been identified at the Dom and show a progressive increase in ferric iron content. Garnet decreases with depth in the GBT complex. Talc, serpentine, tremolite-actinolite, and chlorite are common retrograde minerals. Copper sulfide mineralization is texturally associated with early retrograde alteration. Differences among the skarn orebodies are related in part to variable protolith composition that affected skarn development within different stratigraphic positions. Distinctive fossil replacement textures preserved within skarn indicate that the Oligocene-Miocene Ainod Formation is the most likely protolith for the GB and Dom orebodies. The GBT and upper IOZ orebodies probably are hosted by the Eocene Faumai Formation. The DOZ and lower IOZ orebodies, dominated by magnesian skarn alteration, appear to be developed in a dolomitic unit within the lower New Guinea Limestone Group, which probably is equivalent to the Paleocene Waripi Formation.