At the Black Mountain porphyry Cu-Au deposit in the Baguio district, Northern Luzon (Philippines), pre- and synmineralized rocks preserve magmatic and hydrothermal minerals (e.g., plagioclase, amphibole, titanite, and epidote) spanning the complete paragenesis of the deposit. Strontium isotope values in early crystallized plagioclase phenocrysts from all felsic porphyries can be divided into two types

Propylitic alteration, characterized by the occurrence of chlorite and epidote, is typically the most extensive and peripheral alteration facies developed around porphyry ore deposits. However, exploration within this alteration domain is particularly challenging, commonly owing to weak or nonexistent whole-rock geochemical gradients and the fact that similar assemblages can be developed in other geologic

High-resolution, quantitative imaging of epidote from the Ann Mason fault block, Yerington district, Nevada, using scanning electron microscopy (SEM), X-ray fluorescence (XRF), and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) has revealed at least two types of epidote (type 1 and type 2), each with different major and trace element chemistry. Type 1 epidote is coarser grained

In porphyry ore deposit models, the propylitic alteration facies is widely interpreted to be caused by convective circulation of meteoric waters. However, recent field-based and geochemical data suggest that magmatic-derived fluids are likely to contribute to development of the propylitic assemblage. In order to test this hypothesis, we determined the oxygen and hydrogen isotope compositions of propylitic

The giant, high-grade Resolution porphyry Cu-Mo deposit in the Superior district of Arizona is hosted in Proterozoic and Paleozoic basement and in an overlying Cretaceous volcaniclastic breccia and sandstone package. Resolution has a central domain of potassic alteration that extends more than 1 km outboard of the ore zone, overlapping with a propylitic halo characterized by epidote, chlorite, and

The Highland Valley Copper porphyry deposits, hosted in the Late Triassic Guichon Creek batholith in the Canadian Cordillera, are unusual in that some of them formed at depths of at least 4 to 5 km in cogenetic host rocks. Enrichments in ore and pathfinder elements are generally limited to a few hundred meters beyond the pit areas, and the peripheral alteration is restricted to narrow (1–3 cm) halos

Exploration for porphyry deposits in the past few decades has become increasingly expensive, with new discoveries often occurring at considerable depths or obscured through extensive postmineralization cover (Schodde, 2017; Cooke et al., 2020a). Given these complexities, new exploration techniques or novel applications of known techniques are needed to ensure continued discoveries into the future.

Hydrothermal white mica in the Highland Valley district, British Columbia, is present in high-temperature alteration assemblages in early halo veins and in intermediate-temperature sericitic alteration assemblages in D-type veins. Pale-gray white micas characterize early halo veins in the Valley and Bethsaida zone porphyry Cu-Mo deposits, whereas pale-green white micas form texturally similar vein

The mineral chemistry of epidote and chlorite from the propylitic halo at El Teniente, in samples collected at distances up to 6.6 km from the deposit center, was determined by microprobe and laser ablation-inductively coupled plasma-mass spectrometry. Results show that both minerals systematically incorporated a range of trace elements that define a much larger footprint to the system than is easily

The Highland Valley Copper porphyry Cu (±Mo) district is hosted in the Late Triassic Guichon Creek batholith in the Canadian Cordillera. Fracture-controlled sodic-calcic alteration is important because it forms a large footprint (34 km2) outside of the porphyry Cu centers. This alteration consists of epidote ± actinolite ± tourmaline veins with halos of K-feldspar–destructive albite (1–20 XAn) ± fine-grained

The Collahuasi district of northern Chile hosts several late Eocene-early Oligocene world-class porphyry Cu-Mo deposits, including Rosario, Ujina, and Quebrada Blanca deposits, and associated high-sulfidation epithermal mineralization at La Grande. Mineralization is hosted by intermediate to felsic intrusive and volcanic rocks of the upper Paleozoic to Lower Triassic Collahuasi Group, which experienced

Banded Iron Formations to Iron Ore: An Integrated Genesis Model. Desmond Fitzgerald Lascelles. 2018. Nova Science Publishers. Series: Geology and Mineralogy Research Developments. 185 Pp. Paperback ISBN 978-1-53610-971-9; ebook ISBN: 978-1-53610-982-5 Price: US$95.00This book documents in three sections the personal views of Dr. Des Lascelles on (1) the genesis of banded iron formations (BIFs), (2)

Permian-Triassic granites and associated tin deposits are widespread in the Eastern and Western belts of Peninsular Malaysia. The ages and key controlling factors of tin mineralization, however, are poorly constrained. Cassiterite separates from the Sintok and Rahman tin deposits in the Western belt, and Bandi, Setahum, Lembing, and Cherul tin deposits in the Eastern belt have U-Pb ages of 218.9 ±

The Productora Cu-Au-Mo deposit is hosted by a Cretaceous hydrothermal breccia complex in the Coastal Cordillera of northern Chile. The current resource, which includes the neighboring Alice Cu-Mo porphyry deposit, is estimated at 236.6 Mt grading 0.48% Cu, 0.10 g/t Au, and 135 ppm Mo. Local wall rocks consist of a thick sequence of broadly coeval rhyolite to rhyodacite lapilli tuffs (128.7 ± 1.3 Ma;

The North and South Flank deposits are located on the flanks of the Weeli Wolli anticline at Mining Area C in the central Hamersley Province. Supergene martite-goethite mineralization is hosted within the Marra Mamba Iron Formation and is developed over a strike length of more than 60 km. This multibillion metric ton resource has been drilled out on a 150- × 50- to 50- × 50-m grid, thus providing us

Quartz dioritic impact melt dikes around the 1.85 Ga Sudbury Igneous Complex, locally referred to as offset dikes, are well endowed with respect to Ni-Cu-platinum group elements (PGE). However, only those dikes proximal (<6 km) to the main mass of the Sudbury Complex are mineralized at an economic grade and, in places, host world-class deposits. We report on a new discovery of such heavily mineralized

The Jiaodong gold province, the largest gold producer in China, formed in a setting dominated by a 30-m.y. episode of Izanagi plate rollback and widespread extension, concomitant with late Mesozoic craton destruction. This study presents new high precision in situ sensitive high-resolution ion microprobe (SHRIMP) U-Th-Pb and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) U-Pb

Ore Deposits: Origin, Exploration, and Exploitation. Sophie Decrée and Laurence Robb, Editors. 2019. ISBN 978-1-119-29053-7. American Geophysical Union and John Wiley and Sons, Inc., Geophysical Monograph 242. 272 Pp. Price: US$199.95 (Hardcover); US$159.99 (ebook).In Ore Deposits: Origin, Exploration, and Exploitation, available in both hardcopy and e-book, editors Sophie Decrée and Laurence Robb

Analytical methods used by commercial assay laboratories have improved enormously in recent years. Inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectrometry methods now report analyses for half of the periodic table with exceptional detection limits and precision. It is becoming commonplace for mining companies to use such methods routinely for the analysis

The East Eagle Ni-Cu-platinum group element deposit is a conduit-type deposit located in northern Michigan, in close spatial proximity to the currently producing Eagle deposit. Massive and semimassive (net-textured) sulfide mineralization at East Eagle occurs approximately 800 m lower in the stratigraphic sequence than that at Eagle and only ~200 m above the contact between Proterozoic and Archean

The Kuntabin Sn-W deposit, located in southern Myanmar, is characterized by abundant greisen-type and quartz vein-type cassiterite and wolframite mineralization. We have conducted multiple geochronological methods and isotope and trace element analyses to reveal the age and evolution of the Kuntabin magmatichydrothermal system.Zircon U-Pb dating of the two-mica granite yielded a weighted mean 206Pb/238U

The solubility of molybdenum trioxide (MoO3(s)) in aqueous solutions has been investigated experimentally at 250°, 300°, and 350°C and saturated water vapor pressure, and total Na concentrations ranging from 0 to 3 molal (m). Results of these experiments show that the solubility of MoO3(s) increases with increasing temperature and at 350°C can reach several thousand parts per million at high salinity

The Rosen copper veins in southeastern Bulgaria are recognized for the first time as an iron oxide-copper-gold (IOCG) district. The veins are located in the East Srednogorie segment of the Carpathian-Balkan calc-alkaline volcano-plutonic arc and were formed during an end-stage interval of extreme slab rollback and intra-arc rifting, which gave rise farther east to seafloor spreading in the Western

Recognizing if and how Au is remobilized, in solid, melt, or fluid state, is critical for understanding the origin of high-grade ore zones in Au deposits. When evidence for Au remobilization can be demonstrated, then primary versus secondary processes can be distinguished, resulting in a more complete understanding of Au deposit formation. To address this, samples from two Au deposits, Jerome and Kenty

The Eastern Gabbro, Coldwell Complex, hosts several geochemically and mineralogically distinct Cu-platinum group element (PGE) deposits, including the high-grade W Horizon (>100 ppm Pd-Pt-Au over 2 m). Several magmatic and/or hydrothermal models have previously been proposed to explain the range of enrichment in PGEs observed in the Marathon deposit, but no work has integrated textural and compositional

In the paper, “Geometallurgical Concepts Used in Industrial Mineral Production,” by Steinar L. Ellefmo, Kurt Aasly, Aleksandra Lang, Veena S. Vezhapparambu, and Camilo A.M. Silva (v. 114, no. 8, p. 1553), a publication listed in references cites the authors’ names incorrectly as Rahmanpour, M., and Osanloo, M. The correct reference is below. In addition, the correct citation of this paper on p. 1544

Accelerated carbonation of ultramafic mine tailings has the potential to offset CO2 emissions produced by mining ores from Cu-Ni-platinum group element, podiform chromite, diamondiferous kimberlite, and historical chrysotile deposits. Treatments such as acid leaching, reaction of tailings with elevated concentrations of gaseous CO2, and optimization of tailings pore water saturation have been shown

Current portable X-ray fluorescence (pXRF) technology can rapidly and inexpensively yield concentrations of geologically significant elements, typically with instrument detection limits below several tens of parts per million. Based on conventional XRF whole-rock geochemical data, both the Ishikawa alteration index and the chlorite-carbonate-pyrite index increase with proximity to sulfide mineralization

Jiaodong gold deposits are mainly sited along faulted contacts between Upper Jurassic Linglong granite and Precambrian basement metamorphic rocks or Lower Cretaceous Guojialing granite. Long-standing controversies relate to timing of gold mineralization and granite-gold relationships. In this study, gold-related muscovite consistently provides concordant 40Ar/39Ar plateau ages of 120 ± 2 Ma (2σ) for

Surface samples of hypogene alunite that cement late breccia bodies from the El Salvador porphyry copper district of Chile were recently dated. One alunite sample over the principal Turquoise Gulch porphyry deposit has a 40Ar/39Ar total gas age of 40.64 ± 1.04 Ma, overlapping the age of a late latite intrusion. Two other samples associated with quartz-alunite replacement of rhyolite, ~750 m southwest

Earth’s Oldest Rocks (2nd Edition). Martin van Kranendonk, Vickie Bennett, and Elis Hoffmann, Editors. 2018. Elsevier. 1112 Pp. Paperback ISBN 978-0-444639011; eBook ISBN 978-0-444639028. Price: $US225.Earth’s Oldest Rocks focuses on the first 1.5 billion years of our planet’s history, covering the period from its accretion from the solar nebula to a time when plate tectonics is thought to be the modus

Hydromagmatic Processes and Platinum-Group Elements in Layered Intrusions. Alan Boudreau. Pp. 275. Cambridge University Press. 2019. ISBN 978-1-108416009.Hardcover, US$125.00. E-book, US$89.99.A group of petrologists met in South Africa in 2018, on the holy ground of the Bushveld Complex, to hold a conference commemorating the 50th anniversary of the publication of Wager and Brow’s seminal text, Layered

The Xiangdong W(-Sn) deposit is hosted in the Dengfuxian multiphase granites (biotite, two-mica, and muscovite granites) within the Nanling Range metallogenic belt in south China. Previous studies suggested that the W(-Sn) mineralization in the Xiangdong deposit is related to the Late Jurassic two-mica granite, whereas recently W-Sn–bearing quartz veins have also been identified in muscovite granite

Metallic sublimates coated by sulfides and chlorides line the vesicle walls of mafic volcanic lava and bombs from Kīlauea, Vesuvius, Etna, and Stromboli. The metallic sublimates were morphologically and compositionally similar among the volcanoes. The highest concentrations of S and Cl occurred on the surface of the sublimates, while internally they had less than 1 wt % S and Cl in most cases, leading

Precise constraints on the source and evolution of ore-forming fluids of Carlin-type gold deposits in the Golden Triangle (south China) are of critical importance for a better understanding of the ore genesis and a refined genetic model for gold mineralization. However, constraints on the source of ore fluid components have long been a challenge due to the very fine grained nature of the ore and gangue

The Grasshopper prospect, located 23 km west-southwest from Dillon, Montana, presents exposed zones of phyllic alteration assemblages comprising the early and late phyllic styles. The mineral chemistry of white micas from both phyllic alteration zones was evaluated by short-wave infrared spectroscopy, electron microprobe analysis, and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS)

The Tongkuangyu copper deposit in the Zhongtiaoshan region, southern Trans-North China orogen, is hosted by a poorly constrained sequence of Paleoproterozoic volcano-sedimentary (quartz-sericite schist and biotite schist) and granitic rocks that have been metamorphosed to lower greenschist facies and variably deformed. The deposit has previously been proposed to be either a porphyry-type or a sediment-hosted

Orogenic Au deposits have contributed the majority of Au recovered globally throughout history. However, the mechanism that concentrates Au to extremely high bonanza grades in small domains within these deposits remains enigmatic. The volume of fluid required to provide extreme Au endowments in localized occurrences is not reflected in field observations (e.g., in the extent of quartz veining or hydrothermal

New SHRIMP U-Pb data from dioritic to granodioritic synmineral intrusions associated with the Jebel Ohier porphyry copper deposit (mineral inventory, including NI43-101-compliant total inferred and indicated resources, of 593 million tonnes [Mt] at 0.33% Cu and 0.05 ppm Au, for 1.953 Mt of contained Cu and 933,600 oz of Au at 0.15% Cu cutoff) in the Red Sea Hills of northeastern Sudan have bracketed

To better understand processes leading to porphyry Mo deposit formation, the metal content, volatile content, and crystallization conditions of melt inclusions from pre- and synmineralization intrusions in six porphyry(-skarn) Mo deposits of northeastern China (Aolunhua, Hashitu, Lanjiagou, Songbei, Wanbaoyuan, and Yangjiazhangzi) were investigated by means of laser ablation-inductively coupled plasma-mass

President Doug Kirwin, dear Councilors and members of SEG, dear colleagues and friends: I am standing in for a big bunch of admirers from different fields of economic geology, who all think it is high time for Anthony Williams-Jones to receive the Penrose Gold Medal. Your fans, Willy, include leading exploration consultants like Dick Sillitoe, senior academics like Steve Scott, Jim Franklin, Steve

In addition to the members of the Editorial Board, the following were kind enough to serve, during 2019, as reviewers of manuscripts submitted to Economic Geology for publication.Pedro Acosta-GóngoraNikolay AkinfievJohn AleinikoffRodney AllenAlexey AriskinJames AustinTimothy BakerSarah-Jane BarnesStephen BarnesEleanor BerrymanPeter BettsThomas BissigNigel BlameyLauren BlignautD. Scott BohleMaria BoniLaura

This remarkable volume provides a fascinating and extremely comprehensive review of the mining industry of a relatively small country that has nevertheless played such an important role in the socio-economic development of Sub-Saharan Africa since the earliest days of gold exploitation by the region’s indigenous peoples ca. 600 A.D. The two editors, geologist Martin Prendergast and mining engineer

Economic Geology thanks the following individuals for book reviews that they prepared for the 2019 volume of the journal. Their reviews appear on the page indicated by the number that follows each name.

Economic Geology is an independent journal published by the Society of Economic Geologists, Inc. Papers submitted to the journal will be evaluated on the basis of appropriateness for the journal, suitability of topic, and quality and significance of the research. Do not send manuscripts that have already been published or accepted for publication elsewhere, that reiterate previously published material

The newly discovered Shuangjianzishan Ag-Pb-Zn deposit, with 145 Mt of ore grading 128.5 g/t Ag (locally up to 32,000 g/t) and 2.2 wt % Pb + Zn, is located in the Great Hinggan Range metallogenic belt, northeastern China, and is currently the largest Ag deposit in Asia. The Ag-Pb-Zn orebodies occur as veins and are hosted primarily by a Permian slate. Recent drilling and core logging have identified

The Mt. Carlton Au-Ag-Cu deposit, northern Bowen basin, northeastern Australia, is an uncommon example of a sublacustrine hydrothermal system containing economic high-sulfidation epithermal mineralization. The deposit formed in the early Permian and comprises vein- and hydrothermal breccia-hosted Au-Cu mineralization within a massive rhyodacite porphyry (V2 open pit) and stratabound Ag-barite mineralization

This study integrates new geologic mapping and structural analysis with previous work near Walnut Canyon and Telegraph Canyon to address the style and magnitude of shortening and the relationship between contractional structures and porphyry preservation and localization between the Ray and Resolution porphyry copper deposits. Cenozoic extensional structures were superimposed on earlier contractional

High-grade hematite mineralization is widely developed in banded iron formations (BIFs) worldwide. However, in the North China craton where Neoarchean-Paleoproterozoic BIFs are abundant, economic high-grade hematite ores are scarce. High-grade hematite ores hosted in the Paleoproterozoic Yuanjiacun BIFs represent the largest occurrence of this type of ore in the North China craton. The orebodies are

At the Antamina deposit, Peru, accurate classification of exoskarns and endoskarns can be problematic when textures are mottled. In this study, we use whole-rock geochemical compositions (62 elements) of 221 samples to differentiate texturally similar endoskarns and exoskarns by comparing their compositions to least altered precursors (wall rocks and intrusive rocks). We present a simple method for

The iron oxide-apatite (IOA) deposits of the eastern Adirondack Highlands, New York, are historical high-grade magnetite mines that contain variable concentrations of rare earth element (REE)-bearing apatite crystals. The majority of the deposits are hosted within sodically altered Lyon Mountain granite gneiss, although some deposits occur within paragneiss, gabbro, anorthosite, or potassically altered

The juxtaposition of a Triassic evaporite diapir with the organic matter-rich Fahdene Formation (Albian-Vra-conian) along major faults in the Slata ore district raises the question of the roles played by halokinesis, hydrocarbons, and tectonics in mineralization. The Slata mining district, located in the Tunisian salt diapiric zone, contains Ba-Pb-(± Zn) ore hosted in the Aptian carbonates. The mineralogical

The Florida Canyon evaporite-related Zn-Pb sulfide deposit, in northern Peru, is one of the largest Mississippi Valley-type deposits in South America. Triassic carbonate and former evaporite-bearing rocks of the Pucará Group host the orebodies that constitute two different styles: (1) predominantly stratabound ore associated with hydrocarbon-rich porous dolostones and evaporite dissolution breccias

Pyrite (FeS2) is a typical container of Pt in ores of magmatic and hydrothermal origin and in some carbonrich ores of sedimentary-diagenetic origin. Knowledge of the state of Pt disseminated in the matrix of pyrite, including local atomic environment (type of atoms in the nearest and distant coordination shells, coordination numbers, interatomic distances) and oxidation state, is necessary for physical-chemical

Geometallurgy is an interdisciplinary field aimed at describing potential ore deposits in terms that mine planners and economists can use to design and run profitable mining operations. The major geologic contribution to the field is defining the spatial variability of potential and active mining resources so that planning and scheduling can accurately predict the economic performance and environmental

The Phoenix mine and predecessor operations in north-central Nevada have produced an aggregate of 5.2 Moz of gold and 550 million pounds of copper from an Eocene-aged Au-Cu porphyry-related skarn. The complex skarn mineralogy intimately associated with ore-grade mineralization poses significant challenges to blasting, mining, comminution, and process operations. These challenges are rooted in highly

Geometallurgy has developed since the 1970s, primarily on metallic ore operations. In parallel, industrial mineral operations have been optimized through detailed deposit knowledge and market development, without making specific reference to geometallurgical concepts. The Norwegian mining industry is dominated by industrial mineral and construction material operations, and, in this paper, key differences

Mineralogy is a fundamental characteristic of a given rock mass throughout the mining value chain. Understanding bulk mineralogy is critical when making predictions on processing performance. However, current methods for estimating complex bulk mineralogy are typically slow and expensive. Whole-rock geochemical data can be utilized to estimate bulk mineralogy using a combination of ternary diagrams

The Cadia East porphyry deposit, located approximately 20 km south of Orange, New South Wales, Australia, contains a significant resource of copper and gold. This resource is hosted within the Forest Reefs Volcanics and is spatially and temporally associated with the Cadia Intrusive Complex. To extract ore, the underground mine currently uses the block cave mining method. The Cadia East geotechnical

Geometallurgy aims to develop and deploy predictive spatial models based on tangible and quantitative resource characteristics that are used to optimize the efficiency of minerals beneficiation and extractive metallurgy operations. While most current applications of geometallurgy are focused on the major commodity to be recovered from a mineral deposit, this contribution delineates the opportunity