Determination of Abrasiveness in Copper-Gold Sulfide Ores: A Contribution to the Geometallurgical Model of the Sossego Deposit

The geological context of this study is established in the iron oxide-copper-gold (IOCG) deposit of Sossego (Canaã dos Carajás, Brazil), where hydrothermal alterations in shear zones concentrated the metals of interest and added new characteristics to the metavolcanic-sedimentary and granite rocks. The mineral transformation of rocks by hypersaline fluids enriched in metals and silica also modifies some metallurgical properties, such as abrasiveness. Special bench tests on rock drill cores are used in mapping the abrasiveness of rocks, with the Bond abrasion test being more commonly used in the mining industry, but it has a restrictive sampling protocol and mass requirement for geometallurgical studies. As a counterpoint, the test of the Laboratoire Central des Ponts et Chaussées/Central Laboratory of Bridges and Roads (LCPC) requires a smaller amount of fine material and a finer granulometric range. The study on the use of LCPC was implemented in 40 samples, using Bond Ai as a reference. The results showed a strong correlation between both methodologies (R2 = 95%), validating the use of LCPC to quantify abrasiveness in the Sossego mine. It was also possible to classify the most abrasive lithologies.

A new mineral assemblage from the diorite complex in the Fe-Oxide-Cu-Au ores of the Kis-Kuel deposit (Eastern Yakutia, Russia)

This research continues our investigations of the iron-oxide copper-gold deposits in the Western Verkhoyansk region, where recent years efforts of the IGABM SB RAS led to the discovery of a new gold Kiskuel deposit. The Kis-Kuel intrusion-related IOCG deposit in Eastern Yakutia (Russia) with a wide range of mineral styles has a direct genetic link with a cooling intrusion during its formation. The IOCG worldwide and the Kis-Kuel deposit have common features for this style - the abundance of iron oxides and low of sulfides. Magmatic contribution to the Kis-Kuel deposit is significant. Intrusive rocks range from diorite to granodiorite in composition. The Kiskuel deposit hosted in diorites and granodiorites; xenoliths confirming deep mineralization represented by pyrrhotite (main), pyrite, chalcopyrite, and clinosafflorite (Co, Fe, Ni)As2, chromite, pentlandite. Clinosafflorite localized at the contact of pyrrhotite and chalcopyrite and at the contact of pyrrhotite and biotite. Chalcopyrite is found in intergrowth with pyrrhotite, were it forms bands and lenses. Parallel to the biotite cleavage, the thinnest layers of chalcopyrite are common. Clinosafflorite is rare and discovered in hydrothermal cobalt-nickel ores of the Bou-Azzer (Morocco), Cobalt (Canada), Glassberg (Germany), Silver Mine (England) and several others. Mineralization of rich mica processes occur in connection with the chromite, pentlandite, chalcopyrite, pyrite, and pyrrhotite; a common feature of the mineralized dark-colored rock is phlogopite abundance, ilmenite, potassium feldspar, calcite, rarely quartz; clinoenstatite metasomaticaly replaced with phlogopite and dolomite. This new evidence supports a magmatic-hydrothermal model for the formation of IOCG deposit in the Kis-Kuel, where iron-oxide mineralization sourced from intermediate magmas. The deep complex predominantly composed of chromite, ilmenite, magnetite, pentlandite, and clinocafflorite; less of galena and sphalerite. Many diverse mineraization systems from Kis-Kuel classified together as iron oxide copper-gold (IOCG) deposits. The obtained data suggest deep ore-bearing structure of the Kis-Kuel ore-magmatic cluster with the potential for discovering of a new mineral ores style. All of this help in developing a new robust prospecting model.

The Mina Justa Iron Oxide Copper-Gold (IOCG) Deposit, Peru: Constraints on Metal and Ore Fluid Sources

Iron oxide copper-gold (IOCG) deposits are major sources of Cu, contain abundant Fe oxides, and may contain Au, Ag, Co, rare earth elements (REEs), U, and other metals as economically important byproducts in some deposits. They form by hydrothermal processes, but the source of the metals and ore fluid(s) is still debated. We investigated the geochemistry of magnetite from the hydrothermal unit and manto orebodies at the Mina Justa IOCG deposit in Peru to assess the source of the iron oxides and their relationship with the economic Cu mineralization. We identified three types of magnetite: magnetite with inclusions (type I) is only found in the manto, is the richest in trace elements, and crystallized between 459° and 707°C; type Dark (D) has no visible inclusions and formed at around 543°C; and type Bright (B) has no inclusions, has the highest Fe content, and formed at around 443°C. Temperatures were estimated using the Mg content in magnetite. Magnetite samples from Mina Justa yielded an average δ56Fe ± 2σ value of 0.28 ± 0.05‰ (n = 9), an average δ18O ± 2σ value of 2.19 ± 0.45‰ (n = 9), and Δ’17O values that range between –0.075 and –0.047‰. Sulfide separates yielded δ65Cu values that range from –0.32 to –0.09‰. The trace element compositions and textures of magnetite, along with temperature estimations for magnetite crystallization, are consistent with the manto magnetite belonging to an iron oxide-apatite (IOA) style mineralization that was overprinted by a younger, structurally controlled IOCG event that formed the hydrothermal unit orebody. Altogether, the stable isotopic data fingerprint a magmatic-hydrothermal source for the ore fluids carrying the Fe and Cu at Mina Justa and preclude significant input from meteoric water and basinal brines.

Recognising Mineral Deposits from Cover; A Case Study Using Zircon Chemistry in the Gawler Craton, South Australia

Detrital zircon grains preserved within clasts and the matrix of a basal diamictite sequence directly overlying the Carrapateena IOCG deposit in the Gawler Craton, South Australia are shown here to preserve U–Pb ages and geochemical signatures that can be related to underlying mineralisation. The zircon geochemical signature is characterised by elevated heavy rare-earth element fractionation values (GdN/YbN ≥ 0.15) and high Eu ratios (Eu/Eu* ≥ 0.6). This geochemical signature has previously been recognised within zircon derived from within the Carrapateena orebody and can be used to distinguish zircon associated with IOCG mineralisation from background zircon preserved within stratigraphically equivalent regionally unaltered and altered samples. The results demonstrate that zircon chemistry is preserved through processes of weathering, erosion, transport, and incorporation into cover sequence materials and, therefore, may be dispersed within the cover sequence, effectively increasing the geochemical footprint of the IOCG mineralisation. The zircon geochemical criteria have potential to be applied to whole-rock geochemical data for the cover sequence diamictite in the Carrapateena area; however, this requires understanding of the presence of minerals that may influence the HREE fractionation (GdN/YbN) and/or Eu/Eu* results (e.g., xenotime, feldspar).

Relationship between Selected Major, Minor, and Trace Elements in Iron Oxide–Copper–Gold Deposits, an Example from the Unique Sin Quyen Deposit (Lào Cai Province, North Vietnam)

—We study the relations between several selected elements present in the Sin Quyen IOCG deposit, Lào Cai, North Vietnam, and interpret the obtained correlations, especially with a coefficient higher than 0.7. The correlations with high coefficients are mainly observed for the elements belonging to the chalcophile group (Cu, Ag, Au, Te, and Bi) and for the relation between uranium and Ag, Au, Cu, Pb, and Bi. Although the S-, Fe-, and REE-bearing minerals are predominant in the studied deposit, no strong correlation between them and the other elements was observed, even with Cu. The phenomena are primarily explained based on the geochemical properties of the mentioned elements and the characteristics of IOCG deposits.