Abstract Sulfide-bearing mineral deposits formed in reduced conditions out of contact with an oxygenated atmosphere. When sulfides in the deposits are exposed by natural erosion or by mining to atmospheric oxygen and water, weathering of the sulfides can produce natural or mining-related acid-rock drainage. The prediction of water quality that results from mining and mineral processing activities has therefore become a high priority in the permitting of mining activities worldwide, in order to prevent the formation of or mitigate the environmental effects of deleterious drainage waters. In addition, estimating the compositions of natural waters that drained mineral deposits prior to mining is crucial to establish appropriate baseline environmental standards at mine sites. There are a variety of techniques currently in use to predict the acidity or metal content of mine-drainage waters, most common of which are static and kinetic testing procedures. In static procedures such as acid-base accounting (White et al., 1997, 1999), the contents of acid-generating sulfide minerals from ores and wastes from a proposed mine are measured and balanced against the measured contents of acid-consuming minerals such as carbonates; based on this balance, the materials are determined to be acid generating or non-acid-generating. In kinetic tests such as column or humidity-cell tests (ASTM, 1996), samples of ores and wastes are allowed to react over a period of time under laboratory conditions with oxidized waters or moist air, and the pH and metal contents of the resulting leachates are then measured.

This study utilizes Pb isotope data to identify flow paths and Pb sources for Mississippi Valley-type ores in the midcontinent of the United States with emphasis on the Old and Nerv Lead Belt subdistricts bf southeast Missouri. Nearly 150 new analyses are reported which characterize the,isotope systematics of both ore samples and Pb hosted by sedimentary rocks away from ore districts. A subset of the samples has been analyzed for sulfur isotopes. The nonore samples contain trace amounts of Pb largely hosted by trace metal-rich FeS2 (termed ''sulfide trace Pb''). These metal-rich sulfide phases are constrained by previous petrographic studies to have precipitated from the mineralizing fluids responsible for Mississippi Valley-type ore formation. Sampling was designed to evaluate the role of potential Cambrian and Ordovician aquifers as transport paths for Pb and S in an area broadly surrounding the locus of lead belt mineralization in southeast Missouri. Analyses are also presented for various leach fractions of rocks (termed ''rock Pb'') associated with these same potential aquifer units.Analyses of ore samples establish important benchmarks with which to compare the nonore samples. Ore samples were analyzed from southeast Missouri and include new data for both galena and nongalena phases (chalcopyrite, sphalerite, dolomite) from the New Lead belt subdistrict (Viburnum Trend subdistrict), and galena from the Old Lead Belt subdistrict and the outlying subdistricts of Annapolis and Indian Creek. Also studied were galena samples from the Central Missouri and Tri-State districts. The new data plus published values from the Northern Arkansas and Upper Mississippi Valley districts are nearly collinear on a uranogenic Pb isotope plot (Pb-206/Pb-204 vs. Pb-207/Pb-204). The slope of the linear regression line through this data is consistent with all the ores having been derived from the approximately 1450 Ma basement in the midcontinent area. However, the ores are very clearly separated on a plot of thorogenic isotope data (Pb-206/Pb-204 vs. Pb-208/Pb-204). Ores from either end of the Illinois basin, the Upper Mississippi Valley and Illinois-Kentucky fluorspar districts, have markedly higher Pb-208/Pb-204 for a given Pb-206/Pb-204 compared to ores from the ore districts in the Ozark region. Conversely, data from main-stage galena samples from the Viburnum Trend (which are commonly cube octahedral in morphology but which may also be disseminated in the host rock) and limited data from the Old Lead Belt are notable for having a lower Pb-208/Pb-204 for a given Pb-206/Pb-204 compared not only to Illinois basin-associated ores but also compared to data from other districts in the Ozark region and even to paragenetically later, and volumetrically minor, cubic-stage mineralization data from the Viburnum Trend itself. Identifying the transport path and source for the Pb-208-depleted main-stage ores of the lead belts was a major goal of this study.Uranogenic Pb isotope data for sulfide trace Pb samples are generally collinear with ore Pb data. This similarity indicates that a basement source is also possible for sulfide trace Pb; however,the thorogenic isotopic plot shows much more complexity. Pb isotope data from samples of dominantly dolomitic Cambrian and Ordovician units younger than the Upper Cambrian Bonneterre Formation form an array which is collinear with data from the Northern Arkansas, Tri State, and Central Missouri districts and with the most radiogenic values from the late-stage cubic mineralization. This array is Significantly enriched in Pb-208 compared to main-stage Viburnum Trend mineralization. Data from the Bonneterre Formation, which hosts ore in the lead belts, show more scatter but tend to show even more Pb-208 enrichment compared to main-stage lead belt data. This trend toward increased scatter and increased Pb-208 enrichment continues to be supported by isotopic data from the underlying, coarse elastic Lamotte Sandstone, which many have postulated as a major aquifer for ore genesis in southeast Missouri. Thus, an extensive data set from a large area surrounding the lead belts failed to identify the isotopic tracks of Pb-208-depleted main-stage lend belt mineralization in aquifer units hosting sulfide-associated Pb, but did identify potential aquifers associated with dolomitic, post-Bonne-terre Cambrian rocks for Pb transport to less Pb-rich Mississippi Valley-type districts such as Tri-State, Northern Arkansas, and Central Missouri.The sulfide trace Pb samples present data which show that they are systematically enriched in S-32 (i.e., delta(34)S < 10%) compared to samples of main-stage ores of the Viburnum Trend (delta(34)S > 10 parts per thousand), although isotopically heavy trace sulfides are localized in the upper Bonneterre Formation. Combined Pb and S isotope data for sulfide trace Pb samples do not reflect the signature expected of a single, unique Mississippi Valley-type ore-forming fluid for the lead belts but are indicative of a fluid which could have represented the isotopically light S and slightly Pb-208-enriched end member of a mixture.Pb isotope data from leaches of rock samples from the Bonneterre Formation (a predominantly carbonate unit) and the elastic Lamotte Sandstone are easily distinguishable. On a thorogenic isotope plot, the Bonneterre Formation results, from both limestones and dolomites, form a linear array that is in good agreement with the array formed by sulfide trace Pb samples hosted by carbonate rock units (i.e., exclusive of the Lamotte Sandstone). The combined Pb isotope array, which we term the ''midcontinent carbonate Pb line'' is interpreted to reflect both sources of Pb (primary limestone and premineralization dolomite) and sinks (trace Pb,in sulfides and ore-stage hydrothermal dolomite). The slope of the uranogenic plot for the midcontinent carbonate Pb line, which gives an age similar to that of both ores and basement rocks, is interpreted to indicate an ultimate basement source for the uranium in these units, but some preferential transport and incorporation of U over Th did occur during formation of these rocks.A major finding of this study is that thorogenic Pb isotope data on sock Pb from the Lamotte Sandstone (supported by published data on Pb trapped in presumed ore-stage authigenic K feldspar) yield the Pb-208-depleted isotope signature expected for rocks of a transport path of main-stage Pb. The marked contrast between the lower Pb-208 values for rock Pb and higher Pb-208 values for sulfide-associated Pb in the Lamotte Sandstone is interpreted to reflect the geochemical evolution of this formation during the mineralizing event. Initially the Lamotte Sandstone contained hematite as a result of early diagenetic processes (i.e., red-bed formation). During early stages of ore genesis in southeast Missouri, fluids transported through the Lamotte Sandstone were buffered to high f(o2) (low H2S) by this hematite. The lack of H2S allowed effective leaching and transport of high concentrations of Pb (and probably Cu) by the warm saline brines. The source of this lead was probably the Lamotte Sandstone itself plus the upper (weathered?) portion of the Precambrian basement. Subsequently, bleaching (hematite removal) permitted the accumulation of H2S in the Lamotte Sandstone aquifer fluids. This transition from H2S-free to H2S-bearing fluids also coincided with a shift in Pb source from weathered and modified rocks (Lamotte Sandstone and upper basement), to much more thorogenic Pb in the unweathered basement.Other potential source regions for southeast Missouri Pb can be ruled out on the basis of data from this study. Both sulfide trace Pb and ores from the Illinois basin region are markedly enriched in Pb-208 compared to main-stage ores of the lead belts and thus did not contribute significantly. Likewise, analyses of rock Pb in the Reelfoot rift and sulfide trace Pb in sediments immediately adjacent to the rift margin are collinear with Illinois basin Pb isotopes on a thorogenic Pb plot and thus sediments of the rift are unsuitable Pb sources. The isotopic systematics of both Illinois basin and Reelfoot rift ores and sedimentary Pb samples are indicative of Pb leached from unmodified basement.Based on the results of this study, the main-stage ores of the southeast Missouri lead belts involved the mixing of fluids traveling along three separate aquifers. Most of the Pb, and specifically the distinctive Pb-208-depleted component, was transported through the Lamotte Sandstone. Isotopically heavy H2S migrated in the upper Bonneterre Formation (Sullivan Siltstone Member), and both Ph and isotopically light H2S were migrating in the carbonate section (exclusive of the upper Bonneterre). These fluids were forced to mix by profound sedimentological changes in the vicinity of the St. Francois Mountains. The Lamotte Sandstone locally pinches out against basement highs, and the overlying Bonneterre Formation undergoes a facies change from a fine-grained, basinal shale and micrite-confining bed, to a more porous and permeable dolomite. Both these changes permitted upward movement of fluid from the Lamotte Sandstone. Simultaneously, the fluid migrating in the upper Bonneterre Formation was forced to disperse because of the pinchout of the Sullivan Siltstone Member. Finally, the fluid carrying isotopically light H2S and Pb from the carbonates was plumbed into the ore zone along porous ''white rock'' zones which pinch out near the ore zones but extend for long distances to the south. This specific fluid-mixing hypothesis explains many key isotopic and textural characteristics of the ores. Ores formed stratigraphically higher in the section were progressively less influenced by Pb derived from the Lamotte Sandstone-basement and contain a progressively larger fraction of Ph derived from the carbonate portion of the section.

Semiquantitative spectrographic analyses for 30 elements, atomic absorption analyses for bismuth, copper, gold, lead, and zinc, and colorimetric analyses for molybdenum and tungsten, all made on 229 rock samples from the Virgilina copper district and vicinity, North Carolina-Virginia, are reported here in detail.Localities for all samples are given in latitude and longitude.Brief sample descriptions are included.Rocks analyzed include granite, greenstone, various metavolcanic rocks, metasediments, and vein quartz.Gold i;s present in amounts ranging from 0.02 parts per million (ppm) to 15 ppm in 71 samples and is detectable but less than the limit of determination (0.02 ppm) in the rest of the samples.A few samples contain small amounts of bismuth, molybdenum, and tin.Cll 1-m chip sample, greenstone containing light-gray fragmental layers and one cross-cutting quartz vein 2.5 cm thick; sample from west side of cut.C12 0.6-m chip sample, mixed greenstone and quartz; east side of old shaft.CIS 1-m chip sample, vein quartz containing minor greenstone; south wall of old shaft and in main ore vein.C14 0.6-m chip sample, greenstone, minor silicified zones about 5 cm thick; west wall of old shaft.C15 0.6-m chip sample, gray phyllite.C16 Composite sample, quartz vein, 2-7 cm thick, minor clay and limonite.C17 1-m chip sample, greenish-gray schist, minor amounts of vein quartz.CIS 0.3-m chip sample, vein quartz containing minor amount of schist.C19 0.3-m chip sample, vein quartz; sheared, containing minor amounts of chlorite, hematite, and gray phyllite.C20 0.3-m chip sample, greenstone, light-greenish-gray, contains a few 1-2 cm quartz-chlorite lenses.C21 0.3-m chip sample, silicified greenstone and one-third vein quartz.Luce-Howard mine (C22-C28): C22 0.6-m chip sample, vein quartz, contains chlorite and gray phyllite.C23 0.6-m chip sample, vein quartz, contains chlorite and gray phyllite.C24 0.2-m chip sample, vein quartz, sheared, contains some gray phyllitic greenstone.C25 1.3-m chip sample, olive-gray greenstone saprolite.C26 1.3-m chip sample, similar to C25 but east of C24.C27 0.2-m chip sample, greenstone and vein quartz.C28 1-m chip sample, vein quartz, sheared.Redbank mine: C29 Composite sample, unweathered, moderate-greenish-gray greenstone from dump near old stamp mill.Luce-Howard mine (C30-C38): C30 0.3-m chip samples, vein quartz, sheared, contains chlorite.C31 1.3-m chip sample, olive-gray greenstone saprolite.C32 1.3-m chip sample, olive-gray greenstone saprolite, contains four 1-3 cm quartz veins.C33 1.3-m chip sample, greenish-gray schist containing vein quartz and pyrite.C34 1-m chip sample, greenish-gray schist, minor pyrite.C35 0.3-m chip sample, vein quartz and schist.C36 1.3-m chip sample, schistose, felsic to mafic, fragmental rock, contains minor amounts of pyrite (?), weathered.C37 0.3-m chip sample, vein quartz, sheared.C38 0.6-m chip sample, greenstone, footwall of sample 37. C39 3-m chip sample, vein quartz.C40 1-m chip sample, vein quartz.C41 1-m chip sample, gray felsic pyroclastic phyllite.C42 0.5-m composite sample of tailings, green sand and brown clay, Redbank mine.Milton 15-min quadrangle: MN1 1-m chip sample, quartz-muscovite schist saprolite; trace pyrite.MN2 1-m chip sample, quartz-muscovite schist saprolite; trace pyrite.MN3 1-m chip sample, weathered, quartz-muscovite schist; very fine-grained pyrite, altered to limonite.MN4 1-m chip sample, similar to MN3.

A sequential dissolution technique was used to partition constituent elements from selected drill core samples of the Central Oklahoma aquifer into association with various forms in which they might exist.The procedure extracts elements into five fractions: soluble (0.25 M KC1), ligand exchangeable (0.1 M KH2PO4), acid extractable (4 M HC1), oxidative acid decomposable (KC1O3 + concentrated HC1), and strong mixed acid digestible (HF + HNO3 + HC1O4).The mobility of metals was also assessed using a NaHCO3 extraction technique followed by a sequential NaHCO3 + NaOCl extraction.The NaHCO3 extraction technique was used to mimic waters in the aquifer and the sequential NaHCO3 + NaOCl was used to mimic the oxidizing nature of the ground water and to assess the importance of oxidation processes.The sequential analytical procedures used were designed to aid identifying sources of, and the processes responsible, for the mobilization into the ground water of potentially toxic naturally occurring trace substances including arsenic, chromium, selenium, and uranium.Analytical results on 86 core samples are presented for 5 major elements (Al, Ca, Fe, Mg, and Na) and 8 minor or trace elements (As, Ba, Cr, Mn, Se, Sr, U, and V).The core samples were selected to represent typical as well as enriched rocks.»

The geochemical analyses of B-horizon soil samples and outcrop rock samples from central Oklahoma have been completed by the U.S. Geological Survey.Geochemical analyses of surficial materials in central Oklahoma is part of a ground-water-quality assessment of the Central Oklahoma Aquifer, Oklahoma pi .lotstudy of the National Water-Quality Assessment (NAWQA) Program, which is intended to identify and explain major factors affecting ground-water quality.The Central Oklahoma aquifer underlies approximately 8,000 square kilometers of central Oklahoma and is a major source of ground water for municipal, industrial, commercial, and domestic usage.Detailed studies of water chemistry and hydrology coupled with the results of geochemical analyses of solid constituents of the aquifer will be used to understand rock-water interaction within the aquifer.Analytical results and summary statistics for 44 elements have been compiled based on the analyses of 293 B-horizon soil samples and 362 outcrop rock samples.The samples were analyzed by inductively coupled plasma-atomic emission spectroscopy to determine the concentrations of 38 elements; arsenic and selenium abundances were determined by hydride generation-atomic absorption spectroscopy, and uranium and thorium concentrations were measured by delayed neutron activation analysis.In addition, boron and zirconium concentrations in the outcrop rock samples were determined using direct-current arc optical emission spectroscopy.semiquantitative direct-current-arc atomic emission spectrographic (AES) method (Grimes and Marranzino, 1968).All analysis were performed at the U.S.

No of analysis15 3 3 74 24 12 16 25 5 5 TBZ .1 Locality where placer gold/platinum sample collected x3~Locality where lode gold sample collected

The geochemical analyses of subsurface Permian rocks from eight cored test wells in the Central Oklahoma aquifer have been completed by the U.S. Geological Survey.This study is part of the National Water-Quality Assessment (NAWQA) Program which is intended to identify and explain major factors affecting water quality.The Central Oklahoma aquifer underlies approximately 3000 square miles of central Oklahoma and is the major source of ground water for municipal, industrial, commercial and domestic usage.Future development of the aquifer may be limited because concentrations of arsenic, chromium, selenium, and residual gross-alpha activity locally exceed government drinking water standards.In addition, high concentrations of uranium are also locally present.Detailed studies of water chemistry and hydrology coupled with the results of geochemical analyses of solid constituents of the aquifer will be used to understand rock-water interaction within the aquifer.The principal lithologies of the Permian rocks in the aquifer are mainly interbedded "red bed" sandstones, mudstones, and siltstones.Nine test holes were cored through these rocks at different locations: one in an area of good water quality and eight in areas with known contamination of one or more of the above elements.Samples were collected from eight of the test holes to represent lithological variations within each core.The samples were analyzed by inductively coupled plasma-atomic emission spectroscopy to determine the concentrations of 40 elements; arsenic and selenium abundances were determined by hydride generation-atomic absorption spectroscopy, and uranium and thorium concentrations were measured by delayed neutron activation analysis.Chemical analyses of 549 subsurface rock samples collected from the core show average concentrations of 7.3 parts per million (ppm) arsenic, 56 ppm chromium, 1.4 ppm selenium (for the 346 samples with reported values above the 0.1 ppm detection level), and 3.64 ppm uranium.Abundances as great as 62 ppm arsenic, 170 ppm chromium, 110 ppm selenium, and 123 ppm uranium were detected locally in the rocks. DESCRIPTION OF DATA TABLESTables 3-9 list the analyses for the drill core samples.The data are arranged so that column 1 contains the assigned sample number.Column 2 gives the depth interval sampled in feet.Because of a special feature such as a reduction spot or distinct color variation, a subjectively selected sample was occasionally collected.These samples are shown at a single depth or at an interval of 0.1-0.3feet.Column 3 shows a simplified description of the lithology.The remaining columns give analytical values.Columns marked ICP are induction coupled plasma-atomic emission spectrometric analyses, HGAA indicates hydride generation-atomic absorption spectroscopic analyses, and DNAA refers to delayed neutron activation analyses.The first eight ICP columns (Al, Ca, Fe, K, Mg, Na, P, and Ti) report values in percent.All other values are reported in part per million (ppm).If no value is shown for an element, the element was not detected at the lower limit of detection given for that element.The precision of the ICP-AES technique permits the use of two significant figures.Because of the formatting used in the computer program that produced tables 3-9, some values listed in the columns for elements reported as percent carry a nonsignificant digit to the right of the significant digits.The ICP-AES determinations for Ag, Au, Bi, Cd, Ho, Mo, Sn, Ta, and U were all below the lower limits of detection shown in table 1; consequently, the columns for these elements have been deleted from the tables.The exception is NOTS7-30 which had a reported ICP-AES U value of 100 ppm.A brief statistical summary for each drill hole is presented at the end of tables 3-9, a statistical summary for all 549 samples analyzed is given in table 10, and a statistical summary by lithology (sandstone, siltstone, mudstone, mixed lithologies, conglomerate, and claystone) is shown in table 11.The mixed lithology group represents location in the core where interbedding of lithologies was at too small of a scale to sample separately.Sample NOTS6-110 is a mixture of mudstone and dolostone nodules and was not included in the statistics of any of the lithologies.The Count row or column shows the number of reported values for each element.The statistical values for Maximum, Minimum, Average, Standard Deviation, and Variance are based only on the reported values.The Median value is based on the total population of each element.

Survey publications showing principally analytical results, geochemical signatures, mineralogical data, and sample locality maps of placer

The Koyukuk-Chandalar mining district of the Brooks Range mineral belt in north-central Alaska contains numerous placer gold deposits but few known lode gold sources. Gold grains, collected from 46 placer localities and 6 lode gold sites in the district, were analyzed for Ag and 37 trace elements utilizing direct current-arc optical emission spectroscopy. When possible, several measurements were made on each sample and averaged. Gold content was calculated by the summation of the 38 elements determined and subtracting from 100. The objectives of our study were to characterize the deposits by defining the type and number of distinct geochemical characteristics for the Au, to determine relationships of Au in placer deposits to possible lode sources (placer and lode), to identify possible primary sources of placer gold, and to study processes of placer formation. Interpretation of results emphasize that the Au grains are almost invariably ternary (Au-Ag-Cu) alloys. The average Cu content is 0.040% and the average Ag content and fineness [(Au/Au+Ag)×1,000] are 10.5% and 893 parts per thousand, respectively, for the 46 placer localities.

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Table 5. Spectrographic analyses for the -30-mesh fraction of the heavy-mineral-concentrate samples from placer gold samples from the Fortymile mining district, Eagle quadrangle, Alaska......

Ag SUM of X Cu Zn Poulder Creek Ga Bench #4 Pb As unsorted Sb Cd Bi Te

The Precambrian basement rocks of the Midcontinent are mostly buried under thick layers of sedimentary rocks.These predominantly igneous basement rocks have been largely unexplored and may contain vast mineral resources.Samples of core from 45 drill holes were analyzed by induction coupled plasmaatomic emission spectrometry for major, minor, and trace elements.The results provide metallogenic comparison of subsurface Precambrian rock types in and near Missouri.5. Reduce to dryness and redissolve the HC1 residue in 10 ml of 2.4 N HC1.6. Transfer filtrate, to 13 x 100 mm test tube, add 10 yl of Photo Flo 200 solution , cap, shake, and save for analysis.7. Using a wash bottle, wash residue from filter paper into the original beaker and reduce to dryness.8. Add 5 ml of concentrated HNO^ and 15 ml of concentrated HC1, cover and digest for 1 hour at 150 °C.9. Remove cover and wash with distilled H20, reduce to dryness.10.Redissolve aqua regia residue in 10 ml of 2.4 N HC1, gently heat while covered, filter, transfer filtrate to 13 x 100 mm test tube, add 10 yl of Photo Flo 200 solution, cap, shake, and save for analysis.11.Wash residue twice with 2.4 N HC1 and twice with distilled H20.12. Discard wash solution and using a wash bottle, transfer washed residue into a 50 ml teflon beaker.13.Add 5 ml of concentrated HNOo and 15 ml of concentrated (48/0 HF. 14.Heat at 150 °C until all acid is boiled off and fumes have subsided.15.Add 15 ml of 2.4 N HC1 and 5 ml of saturated boric acid solution (50 g/1).16.Heat gently for 10-15 minutes or long enough to evaporate 2-3 ml of solution.Cool and transfer HF/HN03 filtrate to a graduate cylinder, wash beaker with 2.4 N HC1 and add to cylinder to make 20 ml total volume.Transfer to 13 x 100 mm test tube, add 10 yl Photo Flo 200 solution, cap, shake, and save for analysis * Photo Flo 200 solution is a wetting agent produced by the Eastman Kodak Company.

We have applied partial digestion procedures, primarily oxalic acid and aqua regia leaches, to several regional geochemical reconnaissance studies carried out using Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) analytical methods. We have chosen to use these two acids because the oxalic acid primarily attacks those compounds formed during secondary geochemical processes, whereas aqua regia will digest the primary sulfide phases as well as secondary phases. Application of the partial digestion technique has proven superior to total digestion because the concentration of metals in hydromorphic compounds and the sulfides is enhanced relative to the metals bound in the unattacked silicate phases. The aqua regia digestion attacks and leaches metals from the mafic chain silicates and the phyllosilicates (coordination number of VI or more), yielding a characteristic geochemical signature, but does not leach appreciable metal from many other silicates.