Listvenite–lode association at the Barramiya gold mine,Eastern Desert,Egypt

Several occurrences of gold-bearing quartz veins are situated along the east–northeast-trending Barramiya–Um Salatit ophiolitic belt in the central Eastern Desert of Egypt. In the Barramiya mine, gold mineralization within carbonaceous, listvenized serpentinite and adjacent to post-tectonic granite stocks points toward a significant role of listvenitization in the ore genesis. The mineralization is related to quartz and quartz–carbonate lodes in silicified/carbonatized wallrocks. Ore minerals, disseminated in the quartz veins and adjacent wallrocks are mainly arsenopyrite, pyrite and trace amounts of chalcopyrite, sphalerite, tetrahedrite, pyrrhotite, galena, gersdorffite and gold. Partial to complete replacement of arsenopyrite by pyrite and/or marcasite is common. Other secondary phases include covellite and goethite. Native gold and gold–silver alloy occur as tiny grains along micro-fractures in the quartz veins. However, the bulk mineralization can be attributed to auriferous arsenopyrite and arsenic-bearing pyrite (with hundreds of ppms of refractory Au), as evident by electron microprobe and LA-ICP-MS analyses.The mineralized quartz veins are characterized by abundant carbonic (CO₂ ± CH₄ ± H₂O) and aqueous-carbonic (H₂O–NaCl–CO₂ ± CH₄) inclusions along intragranular trails, whereas aqueous inclusions (H₂O–NaCl ± CO₂) are common in secondary sites. Based on the fluid inclusions data combined with thermometry of the auriferous arsenopyrite, the pressure–temperature conditions of the Barramiya gold mineralization range from 1.3 to 2.4 kbar at 325–370 °C, consistent with mesothermal conditions. Based on the measured δ³⁴S values of pyrite and arsenopyrite intimately associated with gold, the calculated δ³⁴S_Σs values suggest that circulating magmatic, dilute aqueous-carbonic fluids leached gold and isotopically light sulfur from the ophiolitic sequence. As the ore fluids infiltrated into the sheared listvenite rocks, a sharp decrease in the fluid fO₂ via interaction with the carbonaceous wallrocks triggered gold deposition in structurally favorable sites.     

Distribution and behavior of heavy metals in a river polluted by acid mine drainage in the Dabaoshan mine area, China

Acid mine drainage （AMD） has been recognized as a major environmental pollution problem over past decades. This pollutant effluent is complex and is characterized by elevated concentrations of iron and sulfate, low pH, and high concentrations of a wide variety of metals depending on the host rock geology. Massive inadvertent discharges from acid mines have given rise to dramatic cases of ecological damage. These events indicate an improved understanding of the mechanism controlling metal transport to the river is important, since the aquatic ecology will be affected, to some degree, dependent on the phase （dissolved or particulate） in which the metal is transported. In this study, polluted water samples were collected along the Hengshi River near the Dabaoshan mine, Guangdong, China, in April 2005. The concentrations of dissolved Cu, Zn, Cd and Pb have been determined using ICP-MS and the chemical speciation of those metals in suspended particles was examined using BCR methods and SEM/EDX mineralogical analysis. Combining these two sets of data, the intention was to develop geochemical concepts, which explain the behavior of Cu, Zn, Cd and Pb in particle-water interactions of heavy metals in AMD. The results show that the dissolved heavy metals exhibited non-conservative behavior in the Hengshi River. The dissolved and particulate Cu, Zn, Cd and Pb have the similar spatial distribution, which decreased gradually along the river except in the lower reaches because of the absorption-desorption between dissolved and particulate phases. Although the metal concentrations in both phases were elevated, dissolved metals were dominant and had the maximum concentrations in the low pH region.     

Environmental impacts of the abandoned mercury mine in Podljubelj, Slovenia

The Podljubelj mercury mine lies in the NW part of Slovenia. The ore is of hydrothermal-vein type. The ore deposit was exploited between the years 1557 and 1902. Total production of the mine was 110000 tons of ore （360 tons of Hg）. A smelter located close to the mine had been in operation since 1855. The waste material from the mine and the smelter was dumped in close vicinity of the mine. Total quantity of the waste has been estimated at 170000 tons. In order to establish environmental impacts, soil and stream sediment samples were investigated. Soil samples were collected at two different depths （horizons A and B） in a 100 m grid within an 88 ha area. In the vast area also 11 samples of stream sediments were considered. Heavy metals were determined by means of cold vapor atomic absorption spectrometry CV-AAS after aqua regia digestion. Based on the chemical analyses of samples, the estimated mercury mean for soils is 3.67 mg/kg （0.35-244 mg/kg） for horizon A and 1.39 mg/kg （0.17-71.7 mg/kg） for horizon B. The estimated mercury mean for stream sediments is 0.64 mg/kg （0.065-1.36 mg/kg）. The concentrations of mercury in soils generally decrease with depth and distance from the mine. The highest content of Hg was determined in a sample taken in the immediate vicinity of the smelter （719 mg/kg）. The results have shown that on the 9 ha of the study area, the contents of Hg in soils exceeded the officially set limit value for soils （10 mg/kg）. High contents of Hg in soil around the abandoned smelter are a consequence of former atmospheric emissions and technological losses. High contents of Hg were also found in the mine and smelter waste dump. At the edges of the study area and in the samples of stream sediments, Hg concentrations are low.     

Arsenic mobility from arsenopyrite-rich gold mine waste in Snow Lake, Manitoba, Canada

Local water contamination by arsenic can be caused by gold mining activities as in Snow Lake, Manitoba. This project was to f＇md the source （s） and pathways of the arsenic contamination and describe arsenic attenuation in ground and surface water. The project was initiated because arsenic concentrations average 16.0 mg/L in one groundwater monitoring well （MW17）. One potential source of arsenic is the 50 year-old Arsenopyrite Residue Stockpile （ARS）, 100 m upgrade of MW17. Between 1948 and 1959, 250000 tons of cyanide treated, arsenopyrite concentrate were stored in a waste rock impoundment, which was left open until 2000 when it was capped with layers of waste rock, clay and silt to minimize water infiltration and the oxidative release of arsenic.     

Stream water geochemistry from mine wastes in Peña de Hierro,Riotinto area,SW Spain: a case of extreme acid mine drainage

In this work we have studied the geochemistry of stream waters arising from waste dumps at the Peña de Hierro mine (Iberian Pyrite Belt, SW Spain), and we have correlated them with the mineralogical and geochemical characteristics of the wastes to asses the source and factors affecting the release of trace elements. The mineralogical composition and geochemistry of 58 borehole samples of waste dumps were studied in the <2 mm fraction. Twenty-eight water samples collected in winter and summer from streams emerging from the waste dumps were analysed for pH, Eh, conductivity, temperature, sulphates and major and trace elements. The leachates from pyrite-rich volcanic tuffs produced very acidic waters, usually with pHs below 2 and reaching values as low as 0.7. The partial dissolution of gossan, which is mainly composed of Fe oxy-hydroxides and is rich in trace elements, released high concentrations of Fe_tot (up to 33 g/L), As (up to 72), Mo (up to 11 mg/L). On the other hand Cd, Zn and Pb reached up to 0.85, 142 and 0.42 mg/L, respectively, in the stream arising from roasted pyrite ashes and other pyritic wastes. Several elements such as Al, Fe, As, Co, Cu and Mo were strongly correlated with the pH, but Cd and Zn were not correlated under such acidic conditions. The precipitation of jarosite seems to be an important factor in the retention of Pb. The mobility sequence of trace elements shows that Co, Zn and Cd were among the most mobile elements; Cu, As and Mo had intermediate mobility, and Pb was the most immobile. This work shows that uncontrolled waste dumping increases the pollution potential, and a selective management could reduce the release of trace elements into stream waters and mitigate the contamination.     

Arsenic and antimony contamination in the vicinity of Yata gold mine, Guizhou, China

The ores of the Yata gold mine in China are rich in arsenic and antimony, so the exploitation of this mine may also lead to the release of As and Sb to adjacent environments, such as stream water, stream sediment, soil, plants, and crops. To understand the environmental impact of mine tailings, samples of water, sediment, soil, plant and crop were collected and analyzed. In summer of 2005, the tailings dump was seriously flushed by a heavy flood, and the mine waste was transported far away. Samples were collected in December of 2004 and January of 2006, respectively, and the impact of the flood on the release of toxic elements was evaluated. The result shows that the Yata creek, which drains the mining area, was severely contaminated by As and Sb. The dissolved As and Sb in water are 86-1140 μg/L and 65-370 μg/L, the particulate As and Sb are 38-2100 μg/L and 25-420 μg/L, whereas As and Sb in the sediment are 190-760 μg/g and 69-210 μg/g, respectively. In water environment, As and Sb show a similar feature to SO4^2- since As and Sb exist dominantly as anions--H2AsO4^-, HAsO4^2- and SbO3^-. In contrast to Fe, Cu, Pb, Zn, which migrate mostly in particulate form, As and Sb tend to transport in dissolved form.     

Structural analysis of the Tabaco anticline,Cerrejón open-cast coal mine,Colombia, South America

The Tabaco anticline is a 15 km long, south plunging, east-vergent anticline in northern Colombia, close to the transpressional collisional margin between the Caribbean and South American plates. In the Cerrejón open-cast coal mine, systematic mapping of coal seams in the middle to upper Paleocene Cerrejón Formation has yielded an exceptional dataset consisting of 10 horizontal slices (sea level to 90 m elevation, regularly spaced at 10 m intervals) through the anticline. Coal seams and fault traces in these slices are used to construct a 3D model of the anticline. This 3D model shows tighter folds within lower coal seams, NW-vergent thrusts and related folds on the gentler western limb, and strike-slip faults on the steeper eastern limb. Fault slip-tendency analysis is used to infer that these two faulting styles resulted from two different stress fields: an earlier one consistent with thrusting and uplift of the Perijá range, and a later one consistent with strike-slip faulting (Oca, Ranchería and Samán faults). Our preferred interpretation is that the anticline developed its eastern vergence during the early stages (late Paleocene-early Eocene) of tilting of the Santa Marta massif. Later NW-vergent thrusting on the western limb (early to middle Eocene) was related to western propagation of the Perijá thrust system. These results contribute to the understanding of the structural evolution of the area. They are also a good example of the complex interplay between detachment folding, thrusting, and strike-slip faulting during the growth of a km-size fold in a transpressive setting.     

Geochemical characteristics of acid mine drainage and sediments from coal mines, Shanxi Province, China

In this study, geochemical characteristics of acid mine drainage （AMD） and its sediments from the Malan and Sitai coalmines, Shanxi Province, China, were investigated. Many analytical approaches such as IC, ICP-MS, XRD, XRF, and modeling calculation of hydrogeochemistry using PHREEQCI software were employed. The AMD is characterized by higher concentrations of iron and sulfate, a low pH, and elevated concentrations of a wide variety of heavy metals. The results of modeling calculation by PHREEQCI software demonstrate the metals in AMD are present mainly as Me^n＋ and MeSO4^n-2 species. The sediments of AMD are composed mainly of iron-beating minerals such as goethite and schwertmannite, which are controlled by pH, Fe and SO4^2- concentrations. The schwertmannite mineral has been found for the first time in China.     

Different types of fine-grained sediments associated with acid mine drainage in the Libiola Fe–Cu mine area (Ligurian Apennines,Italy)

Different types of fine-grained chemical precipitates were characterized in the surroundings of the pyrite-chalcopyrite mine of Libiola (Northern Italy). Both water chemistry and sediment composition were used to investigate metal mobility near the mine area. Local drainage waters were very acidic (with a pH as low as 2.5) and were rich in dissolved metals (Fe, Al, Cu, Zn, Mn, Ni). Sediments associated with low pH water (pH <4.5) were ochreous mixtures of schwertmannite and goethite with traces of jarosite. Their chemistry was dominated by Fe and they had, compared to other sediments investigated, low concentrations of other metals. When the acidity decreased gradually, other precipitates formed. At a pH of approximately 5, a poorly crystalline, whitish, Al-rich precipitate occurred. At a pH between 6 and 7, a poorly crystalline, blue, Cu (Zn) rich phase was present. These “sequential” precipitation events progressively reduced the metal loading typical of the acidic mine water when there was a gradual mixing with normal water. When a sudden mixing between normal waters (pH ∼8, Ca–HCO₃, low metal bearing) and acidic waters took place, a rapid flocculation occurred of mixed precipitates containing Fe, Al and trace elements.     

Nature and practical implications of heterogeneities in the geochemistry of zinc-rich,alkaline mine waters in an underground F–Pb mine in the UK

Water pollution arising from base metal sulphide mines is problematic in many countries, yet the hydrogeology of the subsurface contaminant sources is rarely well-characterized. Drainage water pumped from an active F–Pb mine in northern England has unusual chemistry (alkaline with up to 40 mg.l⁻¹ Zn) which profoundly impacts the ecology of the receiving watercourse. Detailed in-mine surveys of the quantity and quality of all ground water inflows to the mine were made. These revealed major, temporally persistent heterogeneities in ground water quality, with three broad types of water identified as being associated with distinct hydrostratigraphic units. Type I waters (associated with the Firestone Sill aquifer) are cool (<10°C), Ca–HCO₃–SO₄ waters, moderately mineralized (specific electrical conductance (SEC)≤410 μS.cm⁻¹) with <4 mg.l⁻¹ Zn. Type II waters (associated with the Great Limestone aquifer) are warmer (≈15°C), of Ca–SO₄ facies, highly mineralized (SEC≤1500 μS.cm⁻¹) with ≤40 mg.l⁻¹ Zn. Type III waters (in the deepest workings) are tepid (>18°C), of Ca–HCO₃–SO₄ facies, intermediately mineralized (SEC≤900 μS.cm⁻¹) with ≤13 mg.l⁻¹ Zn, and with significant Fe (≤12 mg.l⁻¹) and Pb (≤8 mg/l). Monotonic increases in temperature and Cl⁻ concentration with depth contrast with peaks in total mineralization, SO₄ and Zn at medium depth (in Type II waters). Sulphate, Pb and Zn are apparently sourced via oxidation of galena and sphalerite, which would release each metal in stoichiometric equality with SO₄. However, molal SO₄ concentrations typically exceed those of Pb and Zn by 2–3 orders of magnitude, which mineral equilibria suggest is due to precipitation of carbonate “sinks” for these metals. Contaminant loading budgets demonstrate that, although Type II waters amount to only 25% of the total ground water inflow to the mine, they account for almost 60% of the total Zn loading. This observation has important management implications for both the operational and post-abandonment phases of the mine life cycle.     

Right to food,right to mine? Competing human rights claims in Bangladesh

The right to food is increasingly evoked by a range of actors, but there is not sufficient critical analysis of distinct interpretations of what this right means in practice. Through examination of a mineral extraction project with agricultural implications, this article explores diverse human rights narratives and illuminates associated corporate efforts to minimize recognition of food as a fundamental right. A British mining company proposes the Phulbari open pit coal mine in an agriculturally important region of Bangladesh. Highly contested by affected populations, clashes in 2006 between the police and protestors turned deadly in the area. In February 2012, a group of UN Special Rapporteurs cautioned the Government of Bangladesh regarding human rights violations associated with the planned mine. They warned that the project would displace hundreds of thousands of people, while destroying fertile agricultural land. In contrast, an ongoing publicity campaign by the corporation attempts to promote their intervention as a positive step, fully compliant with international human rights and corporate social responsibility standards. Taking this case as an exemplar, the article illuminates the pursuit of mining profit and the distinct use of human rights narratives by corporations and UN Special Rapporteurs. These diverse actors represent the layering of voices weighing in on mineral extraction and associated right to food concerns. Collectively, these layered narratives represent a new terrain for the promotion and contestation of mining and highlight the need to scrutinize mining practices in light of social responsibility and human rights claims being voluntary and self-regulated.     

Evolution of mine-pool chemistry at the Sydney Coalfield, Nova Scotia, Canada, and its implications for mine decommissioning

The Sydney Coalfield is the largest in Atlantic Canada in which about 100 coal mines with varied lifespan have been opened since 1720. In the Glace Bay sub-basin, coal seams subcrop close to the Atlantic coast and dip seaward. Coal has been mined at 〉1200 m depth and 11 km from the coastline. Deposited possibly under a marine influence, the coals are enriched in pyrite. During mining abundant acidic sulfates such as melanterite, rozenite, copiapite and halotrichite have accumulated in the underground workings due to pyrite oxidation. The dissolution of these efflorescent salts upon mine flooding at closure gives rise to acidic mine pools wherever insufficient acid-neutralizing materials are present. A major challenge of mine decommissioning in the area is to prevent the discharge of this acidic water into the open ocean. Water monitoring in the 1B Hydraulic System, which consists of ten mines connected at various depths by natural or man-made conduits, shows that the mine pool chemistry varies with the mining practice employed. Although coal has invariably been mined by the room and pillar method, the extent of pillar removal varies from mine to mine. In mines with minimal pillar removal, coal extraction could be as low as 45%, leaving much pyrite for oxidation prior to eventual flooding and an acidic mine pool occurs. In contrast, in mines with extensive pillar removal, coal extraction could amount to 85%, leaving much less pyrite for oxidation. Moreover, the extensive pillar removal caused the collapse of the overlying strata which in some areas include limestone. The infilling of mine workings with carbonate-rich material offsets the effects of acidic effiorescent salts and a mine pool with near-neutral pH results. Geochemical modeling has affirmed the control of local water chemistry by the prevalent mineral assemblage.     

Modified acid–base accounting model validation and pH buffer trend characterisation in mine drainage at the AngloGold Ashanti Obuasi mine in Ghana,West Africa

Acid–base accounting (ABA) is a static test used to evaluate pre-mining drainage quality of ores with interpretations based on a reference 3-data point model. The method is often complemented with a kinetic test to ensure certainty of results. The challenges associated with both methods compel companies to rely on only the ABA test, thereby compromising on the long-term drainage quality. This paper validates a proposed 4-data point model that was used to establish a 20% increase in the alkaline amendment of ores at the AngloGold Ashanti Obuasi Mine in Ghana. The validation was done using model limits, the robustness of coefficient of determination and model factor sequence variation. Acidification trends and mineralogical data evaluation of tailings were used to characterise pH buffer trends in mine drainage. The modified 4-data point model, which incorporates a vital kinetic test factor into the ABA model, provides a criterion for the adjustment of carbonate amendment value to improve acid neutralisation in the drainage; this would reduce (1) cost of experimentation, (2) turnaround time for analyses, (3) complexities associated with both test methods. From the XRD data, alunite and goethite are present in tailings to provide sustained pH buffering in drainage beyond the scope of the modified model, while the characterised pH buffer trend could be used for monitoring drainage quality.     

Letšeng diamond mine,Lesotho: a variant of Kimberley-type pyroclastic kimberlite emplacement

The Letšeng Diamond Mine comprises two ~91 Ma kimberlite pipes. An update of the geology is presented based on the 2012–2017 detailed investigation of open pit exposures and all available drillcores which included mapping, logging and petrography. Each of the steep-sided volcanic pipes comprises a number of phases of kimberlite with contrasting diamond contents which were formed by the emplacement of at least four batches of mantle-derived magma. The resulting range of textures includes resedimented volcaniclastic kimberlite (RVK), Kimberley-type pyroclastic kimberlite (KPK), coherent kimberlite (CK) and minor amounts of hypabyssal kimberlite (HK). The pipes are compared with KPK occurrences from southern Africa and worldwide. Many features of the Letšeng pipes are similar to KPK infilled pipes particularly those of the widespread Cretaceous kimberlite province of southern Africa. The differences displayed at Letšeng compared to other large KPK pipe infills described from around the world are attributed to the marginal or melnoitic nature of the magma and the upper diatreme to crater setting of the Letšeng pipes, where processes become extrusive. It is concluded that the pipes comprise a variant of Kimberley-type pyroclastic kimberlite emplacement. The classification of many of the Letšeng rocks as KPK is important for developing the internal geology of the pipes as well as for predicting the distribution of diamonds within the bodies.

     

Zinc contamination in river water and sediments at Taisyu Zn–Pb mine area,Tsushima Island,Japan

Tsushima Island is one of the oldest zinc-lead mining areas in Japan. River water and sediment samples were collected mainly from Taishu area to determine the contamination level of Zn and to clarify its behaviour in the natural system. Among the water samples analysed, 64% exceeded the standard environmental limit of 0.03 µg ml^− 1 for Zn. In most cases, Zn concentration in sediment samples also exceeded the standard value, and the concentration varied from 86.75–7490.07 µg g^− 1. The mineralogical constituents in sediments were almost similar and quartz had the strongest peak, but the interior part of the ores had many minerals, with galena having the highest proportion. Considering the enrichment factor values (EFc), 12 samples have values of more than 50, indicating a high pollution load for Zn. This study revealed that the sulphide ores, and contaminated sediments, are the possible contamination sources of Shiine River, and Zn dissolution occurred by reactions, such as desorption and ion exchange.     

Geochemical characteristics of the coal gangues from the Du’erping coal mine,Xishan coalfield,North China

Inductively coupled plasma mass spectrometry, inductively coupled plasma optical emission spectroscopy, hydride generation-atomic fluorescence spectrometry, emission spectrometry, X fluorescence spectrometry, and X-ray diffraction were employed to study the geochemistry and mineralogy of coal gangues from Nos. 2, 3, and 8 coal seams of the Du’erping coal mine, Xishan coalfield, Taiyuan, Shanxi Province. The study revealed that compared with the sedimentary cover, upper continent crust, Carboniferous-Permian coal from North China, as well as most coal in China, coal gangues from Nos. 2 and 3 coal seams are rich in Li, Be, Sc, Cr, Cu, Ga, Ba, Th, Nb, Cd, Pb, Ta and rare-earth elements, and coal gangues from No. 8 coal seam are rich in Li, Sc, V, Cr, Ga, U, and rare-earth elements. Compared with the Carboniferous-Permian coal from North China and most coal in China, coal gangues from Nos. 2, 3 and 8 seams are rich in Rb, V, Cs and Sr. Therefore, The Du’erping coal gangues in the Xishan coalfield are rich in most hazardous trace elements and rare-earth elements, wherein the contents of Ga and Li reach the industrial grade and have significance for industrial utilization. On the whole, coal gangues of the Shanxi Formation from the Permian are rich in more trace elements than those of the Carboniferous Taiyuan Formation. The distributions of REE show obviously dipping rightwards with negative Eu anomalies. The contents of rare-earth elements in the three seams are quite different. All of the above indicate that the source of the rare-earth elements is terrigenous debris. Minerals in No. 2 seam identified by X-ray diffraction mainly include quartz, kaolinite, in addition to calcite, pyrite, apatite, epidote, and epsomite. No. 3 seam mainly contains quartz, kaolinite, in addition to a small amount of sodium feldspar, calcium nitrate, iron ore, gypsum, and vivianite. No. 8 seam mainly contains kaolinite, dickite, quartz, illite, and a small amount of hematite and U. The correlations between major elements and trace elements in coal gangues of the Du’erping coal mine analyzed by using SPSS (Statistical Product and Service Solutions) indicate that the trace alkali elements and rare-earth elements occur mainly in such clay minerals as kaolinite.     

Influences of ore formation on biomarkers in the Kupferschiefer from the Lubin mine, Poland

Molecular biomarkers are the important maturity parameters for sedimentary organic matter.They have also been widely used for determining the maturity of organic matter in ore deposits. However,during the study of organic matter in the Kupferschiefer from the Lubin mine, it had been found that the biomarkers were influenced by sulfide formation. In order to probe into the degree of influence on biomarkers, seven samples collected from a Kupferschiefer section from the Lubin mine were analyzed by various geochemical methods. The results indicated that in the samples with higher copper contents, the values of biomarkers are lower than in the samples with lower copper contents. In highly mineralized samples, hydrogen donation for thermochemical sulfate reduction (TSR) occurred in alkylated phenanthrenes and naphthalenes, leading to the decrease of 12 biomarker parameters during the Kupferschiefer mineralization.     

Trace element mobility in mine waters from granitic pegmatite U–Th–REE deposits,Bancroft area,Ontario

Small, low-grade, granitic pegmatite U–Th–REE deposits are found throughout the Grenville geological province of eastern Canada. Groundwater quality at historical mining properties in the Bancroft area was investigated in order to better understand the mobility of trace elements that may pose health risks if there is renewed development of this class of mineral deposit. Groundwater samples were obtained from diamond drill holes, flowing adits and flooded mine shafts. Uranium occurs almost entirely in the dissolved (<0.45 μm) phase and is found at concentrations reaching 2579 μg/L. The Canadian maximum acceptable concentration for U in drinking water (0.02 mg/L) was exceeded in 70% of samples. Regulatory limits for ²²⁶Ra (0.5 Bq/L) and for ²¹⁰Pb (0.2 Bq/L) were generally exceeded in these samples as well. Speciation modeling indicates that over 98% of dissolved U is in the form of highly mobile uranyl-Ca–carbonate complexes known to inhibit U adsorption. Uranium concentrations in groundwater appear to be correlated with the uranothorite content of the deposits rather than with their U grade. Uranothorite may be more soluble than uraninite, the other ore mineral, because of its non-ideal composition and metamict structure. Thorium, released concomitantly with U during the dissolution of uranothorite and thorian uraninite, exhibits median and maximum total concentrations of only 0.1 and 11 μg/L, respectively. Mass balance and stoichiometric considerations indicate that almost all Th is immobilized very close to its source. The sums of total light REE (La–Gd) concentrations have median and maximum values of 6 and 117 μg/L, respectively. The sums of total heavy REE (Tb–Lu) concentrations have median and maximum values of 0.8 and 21 μg/L, respectively. Light REE are derived mainly from the dissolution of metamict allanite whereas the sources of heavy REE are widely dispersed among accessory minerals. Fractionation patterns of REE in the dissolved phase are flat or concave, with negative Ce anomalies associated with more oxic groundwaters. The data suggest preferential LREE and HREE complexation with organic and carbonate ligands in the dissolved phase, respectively. Fractionation patterns in the suspended particulate phase exhibit decreasing enrichment with atomic number from La to Gd and a flat profile from Tb to Lu. This is explained by preferential sorption of LREE and uniform sorption of HREE. Manganese particulates are the most likely sorbents. Potential health risks from Th or REE in mine waters are unlikely due to the very low mobility of these elements. Uranium, on the other hand, exhibits high mobility in shallow, oxic groundwaters and drainage from some mine adits may require mitigation.