Diversity Of Metals Research Articles

Artisanal and small-scale mining and the low-carbon transition: Challenges and opportunities

The transition to a low-carbon economy will require an unprecedented change to the energy system. The renewable and energy storage technologies that need to be built are fundamentally different from the ones that will be replaced. They require a greater amount and diversity of metals and minerals than the technologies that they are replacing. This higher demand for materials is likely to require a sharp expansion in the mining and production of a range of materials. The materiality of the low-carbon transition has reopened the historic concept of critical materials, with the EU and the US issuing lists of materials for which specific action is required to ensure security of supply. The supply of a wide range of these materials is met, in part, through artisanal and small-scale mining (ASM) – an industry of rapidly growing importance across many parts of the world. This paper provides the first mapping in the literature of the intersect between critical minerals and ASM production – finding significant overlap between the two concepts. It then examines the implications of this overlap for both ASM and for the low-carbon transition – using examples of copper, cobalt and gold production. The increased demand for critical minerals could lead to an increased production from ASM, with potential environmental and social consequences. Since the pace of energy transitions vary across countries, the demand for critical minerals would also vary in accordance with the countries’ development perspective. This has a further effect on either advancing towards or retreating away from the UN’s Sustainable Development Goals (SDGs) and the paper includes a discussion of the same. The presence of ASM in supply-chains for low-carbon technologies could bring risks to the transition, especially in terms of reputational issues. On the other-hand increased demand could boost employment through ASM, raising incomes for rural workers, whilst the adaptability of ASM production could help solve supply bottlenecks in some material production. This has implications on the vertical and horizontal value chain linkages between the mines and final minerals which then questions the capacity of the country. This uncertainty highlights the importance of understanding the challenges and benefits that could accrue from the overlap between ASM and critical minerals.

Dynamic changes of microbial community composition and diversity in metal contaminated and reclaimed lands assessed by Illumina MiSeq sequencing

Dynamic changes of microbial community composition and diversity in metal contaminated and reclaimed lands assessed by Illumina MiSeq sequencing

Diversity of Metal-Fullerene Framework Structures Regulated by Metal Salts.

Taking into account the diversity of fullerene ligands and metal salts, metal–fullerene frameworks (MFFs) present a variety of structures. Currently, the structural control of MFFs mainly relies on the design and synthesis of fullerene ligands, while the influence of metal building units on the structures has been rarely studied. The present work represents a systematical investigation of fullerene-linked supramolecular architectures incorporating different metal salts. Treatment of a bidentate N,N-donors fullerene ligand (L1) with six metal salts ([Zn(NO3)2·6H2O, Cd(NO3)2·4H2O, Cu(NO3)2·3H2O, Cu(OAc)2·H2O, FeCl2·4H2O and FeCl3·6H2O]) produced six one-dimensional MFFs, i.e., ZnL1(NO3)2(H2O)2 (1), CdL1(NO3)2 (2), Cu(L1)(H2O)2(NO3)2 (3), CuL1(OAc)(CH3O) (4), FeL1Cl2 (5) and FeL1Cl2(FeCl4) (6). Compounds 1–3, built with nitrates with different metal centers (M(NO3)2, M = Zn, Cd, Cu), present a 1D stair-like, 1D zigzag, and 1D linear chain structure, respectively. Compound 4, synthesized with another Cu(II) salt, Cu(OAc)2, displays a dinuclear Cu-Cu connected 1D stair-like chain structure, rather than the single Cu linked 1D linear chain obtained from Cu(NO3)2. Compounds 5 and 6, assembled from iron chloride of different oxidation states (Fe(II)Cl2 and Fe(III)Cl3) reveal a 1D zigzag and a 1D stair-like chain structure, respectively. The results demonstrate the significant influences of metal salts on the structures of metal–fullerene frameworks.

Diversity of metal and antibiotic resistance genes in Enterococcus spp. from the last century reflects multiple pollution and genetic exchange among phyla from overlapping ecosystems

Arsenic (As), mercury (Hg), and copper (Cu) are among the major historical and contemporary metal pollutants linked to global anthropogenic activities. Enterococcus have been considered indicators of fecal pollution and antibiotic resistance for years, but its largely underexplored metallome precludes understanding their role as metal pollution bioindicators as well. Our goal was to determine the occurrence, diversity, and phenotypes associated with known acquired genes/operons conferring tolerance to As, Hg or Cu among Enterococcus and to identify their genetic context (381 field isolates from diverse epidemiological and genetic backgrounds; 3547 enterococcal genomes available in databases representing a time span during 1900–2019). Genes conferring tolerance to As (arsA), Hg (merA) or Cu (tcrB) were used as biomarkers of widespread metal tolerance operons. Different variants of metal tolerance (MeT) genes (13 arsA, 6 merA, 1 tcrB) were more commonly recovered from the food-chain (arsA, tcrB) or humans (merA), and were shared with 49 other bacterial taxa. Comparative genomics analysis revealed that MeT genes occurred in heterogeneous operons, at least since the 1900s, with an increasing accretion of antibiotic resistance genes since the 1960's, reflecting diverse antimicrobial pollution. Multiple MeT genes were co-located on the chromosome or conjugative plasmids flanked by elements with high potential for recombination, often along with antibiotic resistance genes. Phenotypic analysis of some isolates carrying MeT genes revealed up to 128× fold increase in the minimum inhibitory concentrations to metals. The main distribution of functional MeT genes among Enterococcus faecium and Enterococcus faecalis from different sources, time spans, and clonal lineages, and their ability to acquire diverse genes from multiple taxa bacterial communities places these species as good candidates to be used as model organisms in future projects aiming at the identification and quantification of bioindicators of metal polluted environments by anthropogenic activities.

Solvent-Effected Coordination Variation of Flexible Ligands to Cu(II) for the Formation of 1D and 2D Secondary Building Units for Metal-Organic Frameworks.

Producing more than one structure from the same set of metal and ligand precursors will grant structural diversity in metal-organic framework (MOF) systems. One of the biggest obstacles of getting structural diversity for the late transition metals is that the coordination mode is pretty much fixed by nature. Herein, we show that two different coordination modes to Cu(II) are possible for flexible ligands containing hydrophilic terminal groups through solvent guidance. It is demonstrated that trans,trans-muconic acid (H2muco) ligands coordinate to Cu(II) to form Cu(II) muconate MOFs having a 1D chain structure and a 2D plane structure in water-rich and DMF-rich water-DMF mixed solvent systems, respectively. It is suggested that the interaction between ligands and solvent is responsible for the selective coordination. A similar result was observed from the attempts using the fumaric acid ligand. Our results provide a new direction to obtain diverse secondary building units for the construction of diverse MOFs.

Enzyme activities and microbial functional diversity in metal(loid) contaminated soils near to a copper smelter.

The monitoring of soil metal(loid) contamination is of global significance due to deleterious effects that metal(loid)s have on living organisms. Soil biological properties such as enzyme activities (EAs) are good indicators of metal(loid) contamination due to their high sensitivity, fast response, and low-cost. Here, the effect of metal(loid) contamination on physicochemical properties and microbial functionality in soils sampled from within 10km of a Cu smelter is investigated. Soil composite samples were randomly taken within 2, 4, 6, 8 and10km zones from a mining industry Cu smelter. The EAs of dehydrogenase (DHA), arylsulfatase (ARY), β-glucosidase, urease, and arginine ammonification (AA) were studied as indicators of metal(loid) contamination, which included the ecological dose (ED50) with respect to Cu and As contents. The community level physiological profile (CLPP), functional diversity, and catabolic evenness were evaluated based on the C-substrate utilisation. All EAs decreased in zones with high degrees of metal(loid) contamination, which also had low TOC and clay contents, reflecting long term processes of soil degradation. Positive and strong relationships between EAs and TOC were found. DHA and ARY activities decreased by approximately 85-90% in highly metal(loid) contaminated soils. DHA and AA showed significant ED50 values associated with available Cu (112.8 and 121.6mg CuDTPA kg-1, respectively) and total As contents (30.8 and 31.8mg As kg-1, respectively). The CLPP showed different metabolic profiles along the metal(loid) contamination gradients. Long-term stress conditions in soils close to industrial areas resulted in the decreasing of general biological activity, catabolic capacity, and functional diversity.

Bioresorbable Metals for Biomedical Applications: From Mechanical Components to Electronic Devices.

Bioresorbable metals and metal alloys are of growing interest for myriad uses in temporary biomedical implants. Examples range from structural elements as stents, screws, and scaffolds to electronic components as sensors, electrical stimulators, and programmable fluidics. The associated physical forms span mechanically machined bulk parts to lithographically patterned conductive traces, across a diversity of metals and alloys based on magnesium, zinc, iron, tungsten, and others. The result is a rich set of opportunities in healthcare materials science and engineering. This review article summarizes recent advances in this area, starting with an historical perspective followed by a discussion of materials options, considerations in biocompatibility, and device applications. Highlights are in system level bioresorbable electronic platforms that support functions as diagnostics and therapeutics in the context of specific, temporary clinical needs. A concluding section highlights challenges and emerging research directions.

Ancillary ligand enabled structural and fluorescence diversity in metal–organic frameworks: application for the ultra-sensitive detection of nitrofuran antibiotics

Fabrication and engineering of two new MOFs with flexible dipyridyl ligands for the fluorescence turn-off detection of antibiotics.

Synthesis of Yolk/Shell heterostructures MOF@MOF as biomimetic sensing platform for catechol detection

Metal-organic frameworks (MOFs) have potential as heterogeneous biomimetic catalysts due to their high surface area, tunable porosity, and diversity of metals and functional groups. However, the activity and substrate specificity of pure monomeric MOFs still must be improved. Here, a size-selective MOF coating on the external surface of a biomimetic MOF is used to overcome these limitations of pure monomeric MOFs. The synthesis process of the biomimetic material involved first the coating of porous coordination network (PCN-222) cores with polyvinylpyrrolidone (PVP) as a structure-directing agent and then the modification of zeolitic imidazolate frameworks (ZIF-8). The yolk/shell PCN-222@ZIF-8-based sensor showed high selectivity for catechol but not for dopamine or L-DOPA. The PCN-222@ZIF-8 hybrid material-based sensor displayed 10 times more sensitivity than the PCN-222-based sensor, with low limit of detection (LOD) at 33 nmol L−1. Thus, ZIF-8 is a shell which allows the diffusion of specific substrate to the active sites of the PCN-222 and enriches the substrate. Furthermore, the PCN-222@ZIF-8 exhibits solvent adaptability, which overcomes the drawback of the natural HRP enzyme. This work opens a new avenue for construction of MOF@MOF biomimetic sensors and other applications.

Diversity of metals and metal-interactive bacterial populations in different types of Arctic snow and frost flowers: Implications on snow freeze-melt processes in a changing climate

Arctic snow has been shown to be a reactive interface for key physical, chemical, and microbiological processes, affecting the Arctic's oxidation, biodiversity, radiation, and climate. To explore the potential links between snow-borne metal contaminants and metal-interactive bacteria, to freezing/melting processes, we performed concurrent chemical characterization, genomic, and morphological analysis of five different Arctic snowpack (accumulated, blowing, fresh falling, surface hoar, and wind pack snow) and frost flower in Utqiaġvik (Barrow), Alaska, using Montreal urban snow as reference. Several complementary analytical techniques, including triple quad ICP-MS/MS along with various chromatography techniques, thermal ionization mass spectrometer (TIMS), high-resolution transition electron microscopy with electron dispersive X-ray spectroscopy (HR-TEM/EDS), and next generation sequencing (NGS), were deployed. Distinct metal composition and bacterial distribution among samples were observed. The concentration of 27 different transition, post-transition, rare, and radioactive metals were determined in molten snow and frost flower, as well as filtered samples. The range of three highest detected metal concentrations among samples were: Hg (3.294–134.485 μg/L), Fe (0.719–34.469 μg/L), and Sr (1.676–19,297.000 μg/L). NGS analysis led to the identification of metal interacting bacteria in all types of snow and frost flowers in the Arctic (blowing snow (1239), surface hoar snow (2243), windpack (2431), frost flowers (1440)), and Montreal urban snow (5498)) with specific bacterial genera such as: Acinetobacter, Arcenicella, Azospirillum (surface hoar snow), Arthrobacter, Paenibacillus (blowing snow), and Cycloclasticus, OM182 clade (frost flower). Several types of bacteria with confirmed or associated ice nucleation activity were observed in different types of snow, and frost flower including Pseudomonas genera (e.g., Pseudomonas fluorescens), Flavobacterium, Corynebacterium, and Pseudoxanthomonas. The implications of the above findings to snow-air interactions including nanoparticles, namely during melting and freezing cycles, and to probe the impact of various natural and anthropogenic activities are herein discussed.

Dynamic response of enzymatic activity and microbial community structure in metal(loid)-contaminated soil with tree-herb intercropping

Tree-herb intercropping was proposed for use in remediation of metal(loid)-contaminated soil. Changes in the enzymatic activities and microbial communities in contaminated soil during tree-herb intercropping were studied through dynamic sampling in a greenhouse experiment. Two herb plants, Pteris vittata L. (W) and Arundo donax L. (L), and two tree plants, Morus alba L. (S) and Broussonetia papyrifera L. (G), were selected for tree-herb intercropping, namely SL, GL, GW, SW, and GSLW intercropping. The activities of four enzymes, dehydrogenase activity (DHA), urease activity (UA), sucrase activity (SA) and acid phosphatase activity (APA), are involved in N, C, P cycling and were measured colorimetrically, while the bacterial and arbuscular mycorrhizal (AM) fungal community structures were determined using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). The results showed that tree-herb intercropping could effectively recover enzymatic activity, and bacterial and AM fungal diversity in metal(loid)-contaminated soil. Compared with treatment without plants, the SA and APA activity after the five tree-herb intercropping treatments were significantly (p < 0.05) increased by 1.64–2.51 times and 2.35–5.70 times after 270 d of cultivation, respectively. Meanwhile, the Shannon-Wiener indexes for bacteria and AM fungi increased by 13.6–17.7% and 20.0–36.9%, respectively. Soil DHA, UA, and SA were slightly affected by tree-herb intercropping; however, APA was further significantly enhanced by SL, GL, and GSLW intercropping when compared to the monoculture treatments after 270 d of cultivation. These results indicated that tree-herb intercropping could effectively mitigate the toxic effects of metal(loid)s on soil enzyme activities and microbial community structures and enhance the potential for ecological remediation of metal(loid)-contaminated soil in mining areas.

Functional diversity of microorganisms in metal- and alkali-contaminated soils of Central and North-eastern Slovakia

A field-based study and laboratory tests were undertaken to determine the functional diversity of microorganisms in metal- and alkali-contaminated soils in Central and North-eastern Slovakia where iron ore and magnesite have been mined and processed for a long time. To improve the understanding of the functional diversity of microorganisms, we examined the effects of environmental factors on the functional diversity of microorganisms in metal- and alkali-contaminated soils in the emission field of heaps and tailings impoundments of iron ore mines (Central Spiš) and magnesite factories (Jelšava and Lubeník). Biolog&lt;sup&gt;®&lt;/sup&gt; Eco Plates were used to determine and assess metabolic profiles of microbial communities. The examined area of Central Spiš showed extremely high values of Hg and Cu and the values of Zn, Cd, Pb and Cr exceeding the permissible limit were determined. Soil reaction was extremely acidic to strongly acidic. The Jelšava and Lubeník area was characterized by alkaline contamination and the soil reaction was slightly acidic to strongly alkaline. The values of Cr, Mn, and Mg exceeding the permissible limit were measured there. The results indicate harmful and even toxic contamination. Our results showed that the diversity of microorganisms was different in the investigated areas and it was significantly influenced by environmental factors such as soil reaction, bulk density, porosity, and heavy metals Hg, Pb, Cr, Zn, Cu, Mn and Mg. Based on the results of the Shannon index, we can conclude that the diversity was low to moderate (2.5–3.3) and medium (3.3–4.0). Correlations between functional diversity of microorganisms and soil reaction, Hg, Cr, and Cu were determined. Our findings are decisive for understanding the microbial diversity in metal- and alkali-contaminated soils and they can be used to assess the quality and health of soil, as well as for scientific applications of remediation techniques.

The structural diversity of heterocycle-fused potassium cyclopentadienides.

Cyclopentadienides of d- and f-elements are highly important complexes with undoubted potential for practical applications. Annelation of a heterocyclic fragment with an η5-ring results in substantial improvement of the catalytic properties of these compounds, called “heterocenes”; the investigation of metal coordination with these specific ligands is a highly important problem. We prepared potassium derivatives 5–8 of heterocycle-annelated cyclopentadienes with different structures – derivatives of cyclopenta[1,2-b:4,3-b′]dithiophene (1), indeno[2,1-b]indole (2), indeno[1,2-b]indole (3), and indeno[1,2-b]indolizine (4) and studied the crystal and molecular structures of these salts by X-ray diffraction. We found that heterocycle-fused cyclopentadienides demonstrate remarkable diversity in metal–ligand coordination modes and crystal packing, with formation of two-dimensional polymeric (5), linear polymeric (6), tetrameric (7) and monomeric (8) structures. The NMR spectral data and results of DFT modeling indicate an increase in electron density in the cyclopentadienyl fragment, and this effect was found to be larger in the derivative of the new indolizine ligand precursor 4. The results of our study will be used in the design of next-generation catalysts of α-olefin polymerization.

Metal- and Multicarboxylate-Dependent Structural Diversity in Metal–Organic Frameworks with Acylamide-Based Ligand

Three new metal–organic frameworks, [Co2(L)2(ip)2·(H2O)4] (1), [Cu(L)(ip)·(H2O)2] (2), [Cd(µ-H2O)(L)(oip)·(H2O)3.5] (3) (ip = isophthalate, H2oip = 5-hydroxyl-isophthalate), built by acylamide-based ligand and multi-carboxylate ligand were synthesized and structurally characterized by X-ray crystallography. Complex 1 crystallizes in monoclinic space group P21, with a = 9.9171(3), b = 31.9531(10), c = 10.1780(3) A, β = 118.8270(10)°. Complex 2 crystallizes in the monoclinic space group Cc, with a = 17.7490(3), b = 9.7363(2), c = 18.1202(3) A, β = 115.0090(10)°. Complex 3 crystallizes in the monoclinic space group P21/c, with a = 9.7670(5), b = 30.3199(15), c = 10.3277(5) A, β = 102.1680(10)°. All these compounds feature 2D 44 layers with two-fold interpenetration. Herein we describe the crystal structures of [Co2(L)2(ip)2(H2O)2]·(H2O)2 (1), [Cu(L)(ip)·(H2O)2] (2), [Cd(µ-H2O)(L)(oip)·(H2O)3.5] (3) (ip = isophthalate, H2oip = 5-hydroxyl-isophthalate). All these compounds feature 2D 44 layers with two-fold interpenetration.

Metal flux as an alternative parameter in evaluating the resource potential for co-rich ferromanganese crusts

ABSTRACTWe propose a geochemical parameter, “metal flux” in evaluating hydrogenetic Co-rich ferromanganese crust deposits in the Pacific seamount area, that is based on physical, chemical, and geological characterization of the integrated growth piles of crusts. We calculated the metal flux for fifteen sites from different depths ranging between 900-6000m from different seamounts. The secular and areal variations of metal flux indicate a strong geological controls, and also can be a reliable tool for estimating an economic potential of the crusts. The Co flux decreases with increasing water depth, followed by almost constant flux of Ni and Mn. The Al and Fe fluxes vary with regions, indicating higher values in the western regions near the island arc probably related to a supply from the Asian continents. The results imply that Co, a redox sensitive metal element, is controlled by redox conditions of seawater, while Fe and Al are by terrigenous input. The metal flux reflects global and regional conditions and controls the compositional diversity of metals, thus consequently, the parameter can be a reliable powerful tool to estimate or single out more potential areas.

Microbial Response to Soil Liming of Damaged Ecosystems Revealed by Pyrosequencing and Phospholipid Fatty Acid Analyses.

AimsTo assess the effects of dolomitic limestone applications on soil microbial communities’ dynamics and bacterial and fungal biomass, relative abundance, and diversity in metal reclaimed regions.Methods and ResultsThe study was conducted in reclaimed mining sites and metal uncontaminated areas. The limestone applications were performed over 35 years ago. Total microbial biomass was determined by Phospholipid fatty acids. Bacterial and fungal relative abundance and diversity were assessed using 454 pyrosequencing. There was a significant increase of total microbial biomass in limed sites (342 ng/g) compared to unlimed areas (149 ng/g). Chao1 estimates followed the same trend. But the total number of OTUs (Operational Taxonomic Units) in limed (463 OTUs) and unlimed (473 OTUs) soil samples for bacteria were similar. For fungi, OTUs were 96 and 81 for limed and unlimed soil samples, respectively. Likewise, Simpson and Shannon diversity indices revealed no significant differences between limed and unlimed sites. Bacterial and fungal groups specific to either limed or unlimed sites were identified. Five major bacterial phyla including Actinobacteria, Acidobacteria, Chloroflexi, Firmicutes, and Proteobacteria were found. The latter was the most prevalent phylum in all the samples with a relative abundance of 50%. Bradyrhizobiaceae family with 12 genera including the nitrogen fixing Bradirhizobium genus was more abundant in limed sites compared to unlimed areas. For fungi, Ascomycota was the most predominant phylum in unlimed soils (46%) while Basidiomycota phylum represented 86% of all fungi in the limed areas.ConclusionDetailed analysis of the data revealed that although soil liming increases significantly the amount of microbial biomass, the level of species diversity remain statistically unchanged even though the microbial compositions of the damaged and restored sites are different.Significance and Impact of the studySoil liming still have a significant beneficial effects on soil microbial abundance and composition > 35 years after dolomitic limestone applications.

Bulky bis(imidazole) and 2‐sulfoterephthalate Assisted 3‐D Cu(II) and 2‐D Mn(II) Coordination Polymers: Topology, Diversity in Metal Containing Nodes and Spectral Elucidation

AbstractThis work presents the synthesis of a 3‐D Cu(II) framework represented by a 4,6‐c 2‐nodal net of the type fsc employing the bifunctional template group sulfonate‐carboxylate and the dia precursor (dia=9,10‐di(1H‐imidazol‐1‐yl)anthracene). The high versatility of the N‐donor and carboxylate ligands also yields a 2‐D Mn chain described by a pcu primitive cubic net. The solvent‐dependent EPR studies for both the CPs are also illustrated. Variable temperature magnetic susceptibility confirms that both ferromagnetic and antiferromanetic interactions coexist in 1 among the different geometrical arrangement of Cu(II) ions.

Structural diversity in metal–organic nanoparticles based on iron isopropoxide treated lignin

The magnetic nature of iron-containing nanoparticles enables multiple high-end applications.

Si‐bearing metal and niningerite in Almahata Sitta fine‐grained ureilites and insights into the diversity of metal on the ureilite parent body

AbstractA detailed mineralogical and chemical study of Almahata Sitta fine‐grained ureilites (MS‐20, MS‐165, MS‐168) was performed to shed light on the origin of these lithologies and their sulfide and metal. The Almahata Sitta fine‐grained ureilites (silicates &lt;30 μm grain size) show textural and chemical evidence for severe impact smelting as described for other fine‐grained ureilites. Highly reduced areas in Almahata Sitta fine‐grained ureilites show large (up to ∼1 mm) Si‐bearing metal grains (up to ∼4.5 wt% Si) and niningerite [Mg&gt;0.5,(Mn,Fe)&lt;0.5S] with some similarities to the mineralogy of enstatite (E) chondrites. Overall, metal grains show a large compositional variability in Ni and Si concentrations. Niningerite grains probably formed as a by‐product of smelting via sulfidation. The large Si‐Ni variation in fine‐grained ureilite metal could be the result of variable degrees of reduction during impact smelting, inherited from coarse‐grained ureilite precursors, or a combination of both. Large Si‐bearing metal grains probably formed via coalescence of existing and newly formed metal during impact smelting. Bulk and in situ siderophile trace element abundances indicate three distinct populations of (1) metal crystallized from partial melts in MS‐20, (2) metal resembling bulk chondritic compositions in MS‐165, and (3) residual metal in MS‐168. Almahata Sitta fine‐grained ureilites developed their distinctive mineralogy due to severe reduction during smelting. Despite the presence of E chondrite and ureilite stones in the Almahata Sitta fall, a mixing relation of E chondrites or their constituents and ureilite material in Almahata Sitta can be ruled out based on isotopic, textural, and mineral‐chemical reasons.

Ages and Sources of Components of Zn-Pb, Cu, Precious Metal, and Platinum Group Element Deposits in the Goodsprings District, Clark County, Nevada

The Goodsprings district, Clark County, Nevada, includes zinc-dominant carbonate replacement deposits of probable late Paleozoic age, and lead-dominant carbonate replacement deposits, copper ± precious metal-platinum group element (PGE) deposits, and gold ± silver deposits that are spatially associated with Late Triassic porphyritic intrusions. The district encompasses ~500 km2 although the distribution of all deposits has been laterally condensed by late Mesozoic crustal contraction. Zinc, Pb, and Cu production from about 90 deposits was ~160,000 metric tons (t) (Zn > Pb >> Cu), 2.1 million ounces (Moz) Ag, 0.09 Moz Au, and small amounts of PGEs—Co, V, Hg, Sb, Ni, Mo, Mn, Ir, and U—were also recovered. Zinc-dominant carbonate replacement deposits (Zn > Pb; Ag ± Cu) resemble Mississippi Valley Type (MVT) Zn-Pb deposits in that they occur in karst and fault breccias in Mississippian limestone where the southern margin of the regional late Paleozoic foreland basin adjoins Proterozoic crystalline rocks of the craton. They consist of calcite, dolomite, sphalerite, and galena with variably positive S isotope compositions ( δ 34S values range from 2.5–13‰), and highly radiogenic Pb isotope compositions (206Pb/204Pb >19), typical of MVT deposits above crystalline Precambrian basement. These deposits may have formed when southward flow of saline fluids, derived from basinal and older sedimentary rocks, encountered thinner strata and pinch-outs against the craton, forcing fluid mixing and mineral precipitation in karst and fault breccias. Lead-dominant carbonate replacement deposits (Pb > Zn, Ag ± Cu ± Au) occur among other deposit types, often near porphyritic intrusions. They generally contain higher concentrations of precious metals than zinc-dominant deposits and relatively abundant iron oxides after pyrite. They share characteristics with copper ± precious metal-PGE and gold ± silver deposits including fine-grained quartz replacement of carbonate minerals in ore breccias and relatively low S and Pb isotope values ( δ 34S values vary from 0–~4‰; 206Pb/204Pb <18.5). Copper ± precious metal-PGE deposits (Cu, Co, Ag, Au, Pd, and Pt) consist of Cu carbonate minerals (after chalcocite and chalcopyrite) and fine-grained quartz that have replaced breccia clasts and margins of fissures in Paleozoic limestones and dolomites near porphyritic intrusions. Gold ± silver deposits occur along contacts and within small-volume stocks and dikes of feldspar porphyry, one textural variety of porphyritic intrusions. Lead isotope compositions of copper ± precious metal-PGE, gold ± silver, and lead-dominant carbonate replacement deposits are similar to those of Mojave crust plutons, indicating derivation of Pb from 1.7 Ga crystalline basement or from Late Proterozoic siliciclastic sedimentary rocks derived from 1.7 Ga crystalline basement. Four texturally and modally distinctive porphyritic intrusions are exposed largely in the central part of the district: feldspar quartz porphyry, plagioclase quartz porphyry, feldspar biotite quartz porphyry, and feldspar porphyry. Intrusions consist of 64 to 70 percent SiO2 and variable K2O/Na2O (0.14–5.33) that reflect proportions of K-feldspar and albite phenocrysts and megacrysts as well as partial alteration to K-mica; quartz and biotite phenocrysts are present in several subtypes. Albite may have formed during emplacement of magma in brine-saturated basinal strata, whereas hydrothermal alteration of matrix, phenocrystic, and megacrystic feldspar and biotite to K-mica, pyrite, and other hydrothermal minerals occurred during and after intrusion emplacement. Small volumes of garnet-diopside-quartz and retrograde epidote-mica-amphibole skarn have replaced carbonate rocks adjacent to one intrusion subtype (feldspar-quartz porphyry), but alteration of carbonate rocks at intrusion contacts elsewhere is inconspicuous. Uranium-lead ages of igneous zircons vary inconsistently from ~ 180 to 230 Ma and are too imprecise to distinguish age differences among intrusion subtypes; most ages are 210 to 225 Ma, yielding a mean of 217 ± 1 Ma. K-Ar and 40Ar/39Ar ages of magmatic (plagioclase, biotite) and hydrothermal (K-mica) minerals span a similar range (183–227 Ma), demonstrating broadly contemporaneous intrusion emplacement and hydrothermal alteration but allowing for multiple Late Triassic magmatic-hydrothermal events. Imprecision and range of isotopic ages may have resulted from burial beneath Mesozoic and Tertiary strata and multiple intrusion of magmas, causing thermal disturbance to Ar systems and Pb loss from zircons in intrusions. Separate late Paleozoic (zinc-dominant carbonate replacement deposits) and Late Triassic (all other deposits) mineralizing events are supported by form, distribution, and host rocks of metal deposits, by hydrothermal mineral assemblages, isotope compositions, metal abundances, and metal diversity, and by small intrusion volumes. These characteristics collectively distinguish the Goodsprings district from larger intrusion related carbonate replacement districts in the western United States. They can be used to evaluate proximity to unexposed porphyritic intrusions associated with PGE and gold ± silver mineralization.