The mineralogic associations of arsenic (As) and antimony (Sb) were investigated for the Avon Park Formation (APF) in central Florida to determine its viability for aquifer storage and recovery (ASR). Rock samples were taken from fourteen different cores and samples were taken according to core length, interval samples, and based on areas suspected to contain high levels of arsenic and antimony, such as molds, dissolution fractures, pyrite, clays, and organic matter, targeted samples. Permeable samples were also taken from high permeability zones. In total 373 samples were described in hand specimen and analyzed for bulk rock chemistry. Inductively coupled plasma optical emission spectrometry and hydride generation atomic fluorescence spectrometry were used to determine Fe, Al, Si, Mg, Ca, S, P, Mn, Sr, Mo, As, and Sb in bulk samples, while electron-probe microanalysis was used to analyze Sb, As, Fe, S, Zn, Ca, Mo in discrete minerals. The mineralogic and geochemical investigation showed: (1) bulk As and Sb concentrations within the APF are low; (2) As values range from < 0 .1 to 30.8 mg/kg and Sb from < 0.1 to 6.76 mg/kg; (3) average values are 2.24 mg/kg As and 0.28 mg/kg Sb; (4) pyrite is present as framboids, hollow framboid rings, "honeycomb" pseudo-framboids, small irregularly shaped pieces with topography, and euhedral crystals; it is typically associated with oxidized organic laminations, fractures, and molds; (5) the framboid rings may have been precipitated by a bacteria making them biogenic; (6) euhedral pyrites contain significantly less As than other morphologies while irregular pyrites have the most; (7) individual pyrites range from < 0.1 to 5820 mg/kg As while Sb ranges from < 0.1 to 2470 mg/kg; (8) the samples from zones of high permeability have lower As and Sb averages than those of the other samples: 1.02 mg/kg As and 0.15 mg/kg Sb versus 1.32 mg/kg As and 0.19 mg/kg Sb for interval and 3.16 mg/kg As and 0.37 mg/kg Sb for targeted samples; (9) As is found mainly in pyrite but is possibly from organic matter and clay; (10) overall As concentrations and correlations may be low but individual cores and zones have high values; (11) the APF has appropriately permeable zones for ASR; (12) the success of ASR in the APF formation depends on the degree of geochemical alterations, presence of competing anions and simple organic ligands, and the amount of trace metals sorbed to surfaces versus coprecipitated.

No description available.

It has been common in forestry and agriculture to drain waterlogged areas through ditching in order to cultivate them. The ditches that drain water are usually connected to some watercourse, such as a river. When the water flow of the river decreases and becomes more still, particles will settle and fall to the bottom of the water body and form sediment. If there is an increasing amount of nutrients and metals transported with the water, it could affect the water quality negatively, since an increased amount of nutrients could result in eutrophication and many metals are toxic in high amounts. In the Sangis River there is an increased amount of sediment deposited at the mouth of the river and inside the estuary, which has resulted in the river and the estuary becoming shallower. The origin of the deposited sediments is believed to partly be from ditching. The residents of the village of Sangis have said that it is difficult to cross the estuary by boat because of the deposited sediments, therefore, their wish is for a channel dredged in the Sangis River and its estuary that they can use. The main aim of this master's thesis was to analyse the geochemical status of the surface water and the sediment in the estuary of the Sangis River and to give recommendations for future actions preventing sedimentation of the river channel. The analyse of the geochemical status of the sediment was achieved by sampling six sediment- cores in the estuary and analysing for different parameters. The analyse of the geochemical status of the surface water was achieved by comparing the water quality regarding metal concentrations in the estuary with other nearby rivers and classifying the concentration of phosphorous in the estuary, to determinate if there was an ongoing eutrophication. The following analyses were conducted for the sediment-cores: Element distribution were analysed with P-XRF, pH and electrical conductivity were measured and loss on ignition was also calculated trough combustion of the sub-samples. The results showed for the P-XRF that the dominating main elements were iron, sulfur, calcium and potassium. Iron and sulfur were correlated to each other in all profiles and had a peak between 20-35 cm in the sediment. This indicated that there could be formation of iron sulfides at that depth. Therefore, sub-sample 4.D was analysed with SEM-EDS instrument and framboidal pyrite (FeS2) was detected in the sample. The results from the pH and conductivity showed that the pH-value varies greatly both with depth and between the sediment cores. However, for the conductivity it could be seen how it peaked at around 20-35 cm in all profiles, with the highest EC-value in profile 4. It could be concluded that the surface water in the estuary contains elevated concentrations of copper and that there is an ongoing eutrophication as well. Due to the eutrophication, it has most likely resulted in an increased amount of aquatic plants during the summer. The increased amount of organic material has probably resulted in oxygen-free bottoms, since all the oxygen has been consumed when the organic material has been decomposed. The formation of framboidal pyrite shows that the redox ladder has reached the two last steps, since framboidal pyrite (FeS2) consists of reduced sulfur and dissolved iron and is formed during anoxic conditions. Reduced sulfur forms when sulfate is reduced in order to oxidize organic matter and dissolved iron forms when iron-oxide hydroxides are reduced in order to oxidize organic matter. If dredging is carried out in the Sangis river and its estuary, oxidation of framboidal pyrite will occur, this could result in formation of acid and leachate of metals that were previously bound to framboidal pyrite. The consequences if it leaches into the river and the estuary is that it creates an acidic environment with elevated metal concentrations, where marine life would find it hard to live. The extent and impact of leached acidity and metals needs to be studied further.

This study investigates jarosite formation and stability patterns at the abandoned Davis Pyrite Mine in Rowe, Massachusetts. Jarosite, an iron-sulfate hydroxide, is found in acid mine drainage (AMD) environments, in acid sulfate soils, and on Mars. Jarosite and the iron oxides goethite and hematite are present at the site. Soil samples from the site were examined by XRD, SEM, and EDS. Five mineralogical areas were found, based on mineral abundance patterns. Jarosite exists in four of these areas. Two jarosite morphologies were identified. “Variable” jarosite, with partly-dissolved crystals of about 0.5 to 5 micrometers diameter, exists in spoil pile samples. “Donut” jarosite, with tightly-packed, sharp-edged crystals less than 0.5 micrometers that form a thin mantle on the surface of a second mineral, exists in native soil samples. Donut jarosite has not been previously characterized. These jarosite morphologies are controlled by the presence and relative mobility of pyrite oxidation products Fe and SO4, which in turn are controlled by water saturation levels. Three pathways are possible. On Path 1, both ions are mobile, go into solution, and variable jarosite forms at a distance from the pyrite source. On Path 2, only sulfur ions are mobile, an iron-oxide gossan develops. No jarosite forms. On Path 3, neither ion is mobile, and donut jarosite forms. On this path, Fe and SO4 ions are trapped in a thin film of stagnant water covering the pyrite. When sufficient ions are present, donut jarosite precipitates.

<p> The East South C (E.S.C.) ore zone at the Dickenson Mine, Red Lake, is a major auriferous banded sulphide orebody which cross-cuts sulphide facies banded iron formation (S.F.B.I.F.) near its eastern termination. Pyrite was obtained from sulphide-rich portions of the ore zone as well as from sulphide-poor E.S.C. mineralization not spatially associated with S.F.B.I.F., S.F.BI.F., shear zone hosted mineralization such as the 1492 and F ore zones, and from quartz-carbonate vein mineralization in the South C ore zone. Forty-three pyrite separates from the zones were analyzed by Atomic Absorption Spectrophotometry for Co and Ni, in order to determine the origin of the E.S.C. ore zone. The average Ni and Co content of these pyrites are as follows: S.F.B.I.F.,7.9 and 13.6 ppm respectively; remobilized S.F.B.I.F. 10.3 and 13.6; carbonatized S.F.B.I.F. 10.9 and 22.6; South C 14.9 and 50.6; 1492 zone 34.1 and 28.4; F-zone 11.2-27.6; sulphide-poor E.S.C. 26.2 and 48.4 and sulphide-rich E.S.C., 17.91 and 16.63.</p> <p> High and variable Co values were found to be associated with carbonate-rich samples, irrespective of the type of mineralization and low and similar Co values were found in all carbonate-poor samples irrespective of their origin. Therefore, the Co content of pyrite cannot be used as a discriminant of genetically dissimilar pyrite. The Ni content in pyrite from S.F.B.I.F. is low and constant, while in shear zone and vein mineralization it is higher and more variable. The E.S.C. ore zone has similar values to that found in the epigenetic mineralization, however, a few sulphide-rich samples are similar to those found in S.F.B.I.F., suggesting a bimodal source of sulphide for the E.S.C.. It is proposed that the hydrothermal system which produced the E.S.C., 1492, F and South C ore zones, locally incorporated sulphides from the S.F.B.I.F. to produce the sulphide-rich mineralization found at the eastern extremity of the E.S.C. ore zone.</p> / Thesis / Bachelor of Science (BSc)

Indiana University-Purdue University Indianapolis (IUPUI) / The Ordovician (485-444 Ma) was a highly dynamic period, characterized by significant evolutionary and climatic change. Paleozoic fauna which evolved during the Great Ordovician Biodiversification Event (GOBE) populated extensive epicontinental seaways. Major sea level fluctuations during The Hirnantian glaciation are believed to have led to a mass extinction event at the End Ordovician. However, a reassessment of Early Paleozoic fossil assemblages suggests the onset of extinctions began in the mid-Katian, ~3 million years before the Hirnantian. The Kope formation, within the North American succession of the Katian, was deposited during the peak biodiversification of the GOBE at the point which a biological crisis begins. The well-studied series of interbedded shale and fossiliferous limestone beds, deposited within a shallow epeiric sea, provide ideal sedimentological and paleontological context to interpret sediment geochemistry recorded at the onset of a global mass extinction. For a high-resolution section of the Kope, δ34Spyrite show an extraordinary range of variability, up to 64.5‰, with systematic oscillations throughout the core. The isotope signal represents a mix of pyrite formed at the time of deposition and during diagenesis. As sea levels fluctuated, the amount of sediment delivery influenced the connection of sediment porewaters to overlying seawater sulfate and the location of the sulfate reduction zone, which in turn, masked the primary signal. Reactive iron data suggest low oxygen concentrations in the water column, however fossil assemblages found throughout the Kope suggest otherwise. Changes in sedimentation can mask the water column signal, so these data also capture an aggregate signal. δ15Nbulk show an upsection decrease of 4.4‰, followed by a 3.4‰ increase. Though this excursion can be interpreted as a switch to increased denitrification in a low oxygen environment, the fossil record suggests the data capture localized diagenetic reactions that occur below an oxic water column. Perturbations in the ocean-climate system is often based on the interpretation of stable isotope excursions, and although excursions are diagnostic of changes to biogeochemical cycles, they may not fully account for diagenetic reactions that mask primary signals. The results from the Kope demonstrate strong localized, not global, controls on the sediment geochemistry.

The abiotic oxidation of pyrite requires the supply of oxygen and water only. In abiotic systems, pyrite oxidation may proceed via several paths, with multiple steps in each of the paths. Defect sites (S-deficient, Fe3+ bearing sites) on the pyrite surface have been shown reported to be the initial reaction sites on pristine pyrite surfaces. In neutral to slightly acidic solutions (3.5<pH<7), ferric iron hydroxide patches will form on the surface. These patches have been shown to be the predominant sites for electron exchange. Efforts were undertaken to suppress the electron transfer at these sites to inhibit pyrite oxidation. It has been shown that pyrite oxidation can be controlled by exposing the pyrite to phosphate under relatively high pH values (pH above 5.0). However, phosphate ceases to function as an inhibitor under lower pHs. The use of two-tail phospholipids instead of phosphate to inhibit the pyrite oxidation proved to be very effective under abiotic conditions. The purpose of the present study is to determine if the use of two-tail phospholipids can be extended to systems that have bacteria present. Batch experiments were conducted in which pyrite slurries were treated with two-tailed lipid either before or after exposure to bacteria. Iron release into the solution was used as a reaction progress variable and Atomic Force Microscopy was used to study the distribution of lipids and bacteria on the pyrite surface. AFM images showed that the formation of 7nm lipid bilayers contributes to the majority of lipid structures on pyrite surface. The bilayers render the pyrite surface hydrophobic and inhibit the reaction of water with the surface, which is known to be a critical reactant. AFM images also showed that phospholipids are capable of displacing a large fraction of bacteria attached to pyrite, reducing the oxidation rate of the mineral. However, addition of heterotrophic bacterial (Acidiphilum acidophilum) to the system resulted in the increase in pyrite oxidation rate again. Cross-linking of the 23:2 dyne phospholipids by exposing the lipid to UV light greatly enhanced the stability of the lipid in the presence of the heterotrophic bacteria. UV pretreated lipid layers reduced pyrite oxidation in the presence of heterotrophic bacteria for up to 30 days. / Chemistry

Sulfide minerals are a major source of metals; however, certain sulfide minerals, such as pyrite and pyrrhotite, are less desirable. Froth flotation is a commonly used separation technique, which requires the use of several reagents to float and depress different sulfide minerals. Xanthate, a thiol collector, has gained immense usage in sulfide minerals flotation. However, some sulfides are naturally hydrophobic and may float without a collector. Iron sulfides, such as pyrite and pyrrhotite, are few of the most abundant minerals, yet economically insignificant. Their existence with other sulfide minerals leads to an inefficient separation process as well as environmental problems, such as acid mine drainage during mining and processing and SO2 emissions during smelting process. A part of the present study is focused on understanding their behavior, which leads to undesired flotation and difficulties in separation. The major reasons for the undesired flotation are attributed to the collectorless hydrophobicity and the activation with heavy metal ions. To better understand the collectorless hydrophobicity of pyrite, Electrochemical Impedance Spectroscopy (EIS) of freshly fractured pyrite electrodes was used to study the oxidation and reduction of the mineral. The EIS results showed that the rate of reaction increases with oxidation and reduction. At moderate oxidizing potentials, the rate of reaction is too slow to replenish hydrophilic iron species leaving hydrophobic sulfur species on the surface. However, at higher potentials, iron species are replaced fast enough to depress its flotation. Effects of pH and polishing were also explored using EIS. Besides collectorless hydrophobicity, the activation of pyrrhotite with nickel ions and interaction with xanthate ions makes the separation more difficult. DETA and SO2 are commonly used as pyrrhotite depressants; however, the mechanism is not very well understood. Contact angle measurements, cyclic voltammetry and Tafel studies have been used to elucidate the depressing action of DETA and SO2. It was observed that DETA and SO2 complement each other in maintaining lower pulp potentials and removing polysulfides. DETA also helps in deactivating pyrrhotite. Therefore, the combined use of DETA and SO2 leads to the inhibition of both the collectorless flotation and the adsorption of xanthate. The adsorption of xanthate on sulfide minerals is a mixed-potential mechanism, i.e., the anodic oxidation of xanthate requires a cathodic counterpart. Normally, the cathodic reaction is provided by the reduction of oxygen. However, oxygen can be replaced by other oxidants. Ferric ions are normally present in the flotation pulp. Their source could be either iron from the grinding circuit or the ore itself. The galvanic studies were carried out to test the possibility of using ferric ions as oxidants and positive results were obtained. Tafel studies were carried out to measure the activation energies for the adsorption of ethylxanthate on several sulfide minerals. Pyrite, pyrrhotite (pure and nickel activated), chalcocite and covellite were studied in 10-4 M ethylxanthate solution at pH 6.8 at temperatures in the range of 22 – 30 0C. The Tafel studies showed that xanthate adsorbs as dixanthogen (X2) on pyrite and pyrrhotite, nickel dixanthate (NiX2) on nickel-activated pyrrhotite and cuprous xanthate (CuX) on both chalcocite and covellite. However, the mechanism for xanthate adsorption on each mineral is different. The free energy of reaction estimated from the activation energies are in good agreement with thermodynamically calculated ones. / Ph. D.

Oxidation of pyrite can significantly affect properties and the behavior of soil and rock in civil construction. Problems with pyritic rock and soil extend globally and across many disciplines. Consequences of pyrite oxidation include heave, concrete degradation, steel corrosion, environmental damage, acid mine drainage, and accelerated weathering of rock with concomitant effects on strength and stability. Affected disciplines include soil science, mining, engineering geology, geochemistry, environmental engineering, and geotechnical engineering. While pyrite problems may be well known in their respective disciplines, there has been to date relatively little cross-disciplinary communication regarding problems with pyritic geomaterials. Thus, there is a need to establish an inter-disciplinary and inter-regional awareness regarding the effects of pyrite oxidation and their prevention or mitigation. This engineering research is a compilation of information about geotechnical problems and engineering behavior of pyritic rock and soil, the underlying physicochemical processes, site investigation strategies, and known problematic formations. Several case histories documenting consequences of pyrite oxidation are provided. The results of chemical analyses performed on pyritic shale samples from a formation with acknowledged heave problems are presented. Digital data and ESRI's ArcGIS digital mapping program were used to create maps showing results of sampling and testing performed during this study. Appendices include mitigation options, results of a practitioner survey, chemical test procedures, a glossary, a visual identification key for sulfidic geomaterials, and a summary table of the literature review for this research. / Master of Science

Jämtlands berggrund består till stora delar av sedimentära bergarter som har genomgått olika grader av metamorfos under den kaledoniska orogenesen. I Östersunds centrala delar påträffas nästan enbart svartskiffer med låg metamorfosgrad. På flera platser i Östersund har det uppkommit skador på byggnader till följd av svällning i skiffern. Svällning uppstår när berggrunden exponeras för luft och vatten. Pyrit och kalcit som finns i skiffern reagerar och bildar gips, vilket orsakar volymökning. Under arbetet genomfördes laborativt svällförsök, där en del av proverna hölls torrt medan en del fuktades. Proverna undersöktes vidare med röntgendiffraktion för att kvantifiera mineralhalter. Svällförsöket genomfördes i syfte att utveckla en metod för bedömning av svällrisk i projekteringsskede för nya anläggningar i berg. För att förhindra skador till följd av svällning har flertal åtgärder testats, där försöken har inneburit att stänga ute syre från berggrunden genom att hålla berggrunden under grundvattennivån eller på olika sätt försegla exponerade bergytor. Det finns flertal faktorer som påverkar svällbenägenhet, i arbetet diskuteras bland annat påverkan av svavelhalt, pH och temperatur. Slutligen observerades &lt;0,1wt% gips i samtliga prover från undersökningsområdet genom XRD analys, samtliga prover hade även en låg halt av pyrit och magnetkis. De låga halterna och standardavvikelse för analysmetoden medförde att skillnad i mineralogi före och efter utfört svällförsök ej kunde påvisas. Det är fortsatt viktigt att ha i åtanke att berggrunden i området har rätt förutsättningar för svällning även om resultaten inte visar någon skillnad i gipshalt före och efter utfört svällförsök. / Jämtlands bedrock mainly consists of sedimentary rocks that has been metamorphosed during the Caledonian orogenesis. In the central parts of Östersund almost only black shale with a low grade of metamorphism is encountered. Damages on buildings has occurred due to swelling in shale in several places in Östersund. Swelling occurs when the bedrock is exposed to water and air. Pyrite and Calcite in the shale reacts and forms gypsum, which causes volume expansion. During this study laboratory swelling tests were performed, where one part of the samples was kept dry while the other part was exposed to water. The samples were examined with x-ray diffraction to quantify the mineral content. The swelling tests were performed with the purpose of evaluating XRD as a method for predicting the swelling risk in the early stage of planning for new facilities in the bedrock.To prevent damages caused by swelling several methods have been tested, where the attempts included shutting out oxygen from the bedrock by keeping it below the ground water level and by sealing the rock surface in different ways. There are multiple factors that affects the swelling risk, this work discusses influence from sulfur content, pH and temperature. Lastly &lt;0,1wt% gypsum was observed in all samples from the survey area through XRD analysis, a low amount of pyrite and pyrrhotite was also seen in all samples. The low amounts in combination with standard deviation in the analysis made it difficult to prove any difference in mineralogy due to the swelling tests. Hence it is still important to keep in mind that the bedrock in the area has the right conditions for swelling even though the results show no difference in the amount of gypsum between the dry and wet samples.