Presence Of Goethite Research Articles

Decreased Electron Transfer between Cr(VI) and AH2DS in the Presence of Goethite.

9,10-Anthraquinone-2,6-disulfonic acid (AQDS) is commonly used as a model species to examine the influence of quinones on different biogeochemical cycles. The reduced form of this quinone, AHDS, can donate electrons to the toxic metal species Cr(VI), leading to the precipitation of less soluble Cr(III) phases. Due to the environmental abundance of Fe(III) (oxyhydr)oxides, such as goethite (α-FeOOH), it is important to study the role of these mineral phases on the electron transfer reaction between AHDS and Cr(VI). In this study, this electron transfer reaction is examined in the presence and absence of goethite at three different ratios of AHDS/Cr(VI). Ultraviolet-visible spectroscopy is used to qualitatively assess the oxidation state of AQDS during reactions with goethite. Iron K-edge and Cr K-edge X-ray absorption spectroscopy are used to examine the role of goethite in electron transfer and identify Cr(III) phases that form. Goethite inhibits the extent of Cr(VI) reduction to Cr(III), most notably at the highest ratio of AHDS/Cr(VI) investigated. Production of semiquinone radical species may limit electron transfer and decrease the yields of Fe(II) and Cr(III), both in the presence and absence of goethite. Understanding abiotic electron transfer reactions that occur in systems with multiple redox active species is important to determine the contribution of abiotic redox reactions to Fe biogeochemical cycling in natural soils.

Neutral red separation property of ultrasmall-gluconic acid capped superparamagnetic iron oxide nanoclusters coprecipitated with goethite and hematite

Abstract The use of magnetic nanomaterials for the removal of toxic pollutants from water is currently gaining a considerable attention due to their low cost advantage and separation via the use of external magnetic field. However, for efficient functioning, these materials have to be structured in a way that will allow sufficient interaction with the pollutants within a shortest possible time. This can be achieved by employing very small sized nanomaterials such as nanoclusters which bear a very high surface energy and thus exhibit very rapid reactivity. In this report, ultrasmall-gluconic acid capped superparamagnetic iron oxide nanoclusters coprecipitated with goethite and hematite (USPIONCs-Goethem) were synthesized via a new cost-effective green approach and employed for the precipitation of neutral red from aqueous saline solution. The presence of goethite and hematite was verified using powder X-ray diffractiometry. The resulted magnetic- neutral red nanocomposite reassembled as sun-flowery-like nanostructure in the presence of an external magnetic field. A removal efficiency of about 92% was realized within a short time. This approach can be employed for the removal of other similar polyaromatic dyes bearing one or more lone-pair electron sites.

Chemical and nano-mineralogical study for determining potential uses of legal Colombian gold mine sludge: Experimental evidence

The present study is focused on the chemical and nano-mineralogical characterization of sludge from gold mine activities, in order to put forward diverse solution alternatives, where lack of knowledge has been found. The sample was collected from “La Estrella” mine of Suarez, located in Department of Cauca, south-west Colombia. The sludge micro-structure and chemical composition were analyzed using a high resolution transmission electron microscopy (HR-TEM) equipped with a dispersive X-ray detector (EDS). X-ray diffraction technique was employed to identify the mineralogical phases present in the sludge. Additional mineralogical characterization was done by using RAMAN spectroscopy. Main findings points to its potential to be used as a fertilizer, this is why, mine sludge contains macronutrients such as P, Ca and S, together with micronutrients like Cu. However, the presence of goethite could decrease the mobilization of nutrients to soils, thus additional alternatives, for instance, a mixture with humus or another material containing Humic Acids should be done, in order to minimizing its retention effect. Additionally, another possible uses to explore could be as construction and ceramic material or in the wastewater treatment for nutrient retention and organic material removal. Rutile (TiO2 nanoparticles) particles have been also detected, what could cause health concern due to its nanoparticle toxic character, mainly during gold extraction process.

Shifting microbial communities sustain multiyear iron reduction and methanogenesis in ferruginous sediment incubations.

Reactive Fe(III) minerals can influence methane (CH4 ) emissions by inhibiting microbial methanogenesis or by stimulating anaerobic CH4 oxidation. The balance between Fe(III) reduction, methanogenesis, and CH4 oxidation in ferruginous Archean and Paleoproterozoic oceans would have controlled CH4 fluxes to the atmosphere, thereby regulating the capacity for CH4 to warm the early Earth under the Faint Young Sun. We studied CH4 and Fe cycling in anoxic incubations of ferruginous sediment from the ancient ocean analogue Lake Matano, Indonesia, over three successive transfers (500days in total). Iron reduction, methanogenesis, CH4 oxidation, and microbial taxonomy were monitored in treatments amended with ferrihydrite or goethite. After three dilutions, Fe(III) reduction persisted only in bottles with ferrihydrite. Enhanced CH4 production was observed in the presence of goethite, highlighting the potential for reactive Fe(III) oxides to inhibit methanogenesis. Supplementing the media with hydrogen, nickel and selenium did not stimulate methanogenesis. There was limited evidence for Fe(III)-dependent CH4 oxidation, although some incubations displayed CH4 -stimulated Fe(III) reduction. 16S rRNA profiles continuously changed over the course of enrichment, with ultimate dominance of unclassified members of the order Desulfuromonadales in all treatments. Microbial diversity decreased markedly over the course of incubation, with subtle differences between ferrihydrite and goethite amendments. These results suggest that Fe(III) oxide mineralogy and availability of electron donors could have led to spatial separation of Fe(III)-reducing and methanogenic microbial communities in ferruginous marine sediments, potentially explaining the persistence of CH4 as a greenhouse gas throughout the first half of Earth history.

On the Origin of Bastnaesite-(La,Nd,Y) in the Nissi (Patitira) Bauxite Laterite Deposit, Lokris, Greece

A detailed geochemical study and a thorough mineralogical description of the rare-earth elements (REE)-minerals and associated minerals were carried out in two vertical profiles of approximately 4 m length, from the Nissi (Patitira) bauxite laterite deposit, Lokris, Greece, characterized by the presence of goethite in small sizes resembling bacterial cell coated by goethite and a significant REE enrichment. The enrichment of the REE concentrated in bastnaesite-group minerals, the intergrowths between REE-minerals and Al–Ni–silicates with significant sulfur contents and their association with goethite microtextures interpreted as bacteriomorphic, indicate REE remobilization along with iron bio-leaching and re-precipitation on karstified limestone. In addition to the previous-reported hydroxylbastnaesites, a (La,Nd,Y)(CO3)F member of the bastnaesite-group associated with Al–Ni–silicates were identified, the stability of which may reflect the dependence on the source rocks and the local variations of pH-Eh. Interaction between downward percolating water and carbonate rocks seems to be a very effective mechanism for REE fluorocarbonates deposition under alkaline and reducing conditions.

An innovative combination of non-invasive UV–Visible-FORS, XRD and XRF techniques to study Roman wall paintings from Seville, Spain

Abstract This study attempts to establish the advantages and limitations of the combined use of portable UV–Vis-FORS and XRF-XRD portable equipment for the non-invasive characterisation of pigments from Roman wall paintings from Seville, Spain, dated to the first and second century AD. XRD revealed the presence of calcite, dolomite and aragonite, indicating the colour white. Egyptian blue was identified using FORS and XRF, and additional information was obtained with XRD. For the colour green, FORS and mainly FTIR and colorimetry enabled the distinction between glauconite and celadonite, although other techniques were necessary to classify all components of the green areas by determining the presence of cuprorivaite, chlorite and chromium. For the colours yellow and red, the presence of goethite, yellow ochre, cinnabar and haematite was confirmed using FORS and XRF in some cases; the results were corroborated by XRD. Chromatic characterisation and the values of inflection points of FORS spectra enabled a better differentiation between reddish colours (orange, brown, purple and pink). The XRD and XRF techniques revealed that violet was created by mixing red haematite and Egyptian blue and slight variations in FORS spectra confirmed this.

Corrosion product transformations in alkaline baths under pressure and high temperature: The sub‐critical stabilisation of marine iron artefacts stored under atmospheric conditions

In the context of conservation of ferrous cultural heritage, dechlorination processes of archaeological iron artefacts are studied in subcritical conditions which consist of immerging an artefact inside an alkaline bath under pressure (30 bar) and temperature (160 °C). Submarine archaeological environments lead to the presence of chlorides inside the corrosion layers. After exposure to the atmosphere following excavation, initial corrosion phases evolve. Chlorides remain trapped inside the structure of corrosion products particularly during the crystallisation of akaganeite. Stabilisation treatment objectives are to remove chlorides from the corrosion layers and to obtain more stable phases. A Roman archaeological bar has been studied on cross‐section before and after treatment in sub‐critical conditions. Less stable phases, such as ferrihydrite and akaganeite, transformed into hematite. That was confirmed by the use of synthetic and pure phases treated in the same conditions. The presence of goethite before and after the treatment in the corrosion profile raises the question of its reactivity during dechlorination process. Akaganeite has been synthesised and compared to archaeological powder sampled on an artefact. The results highlight reactivity differences indicating that sub‐critical transformation processes are not only dependent on the nature of phases but also on intrinsic physical characteristics.

Impact of the Red Mud Disposal on Several Floodplain Lagoons of the Lower Orinoco River

This paper identifies the effects of red mud spills on several lagoons of the Orinoco River located surrounding the red mud deposits. Chemical and mineralogical analyses of sediments indicate that the geochemical signature of red mud is evident in Los Caribes and Guadita lagoons, with elevated concentrations of Fe, Al, and Na and the presence of goethite and hematite as the major mineral phases. Water quality analyses indicate that these lagoons have elevated values of dissolved oxygen, pH, conductivity, and dissolved Ca, Na, Ni, and Al. Also, elevated concentrations of Ca, Mg, and Mn in sediments suggest the precipitation of calcite, brucite a Mn-oxyhydroxides due to high pH values. Although Los Cardonales lagoon also showed evidence of red mud deposition, the enrichment of Mn, Zn, Ni, and Cd in sediments from this lagoon could be associated with wastewaters coming from landfills. The absence of vascular plants and the low abundance of fish communities in several lagoons can be related with the high pH values and the elevated concentrations of dissolved Al. The high concentrations of Fe and Mn in sediments of these lagoons can have adverse effects on benthic organisms, according to International Guidelines. Even though this lagunar system is impacted by red mud spills, hyperalkaline conditions (pH > 13) were not found in superficial waters. Thus, dissolved trace element concentrations (Fe, Zn, Mn, Cr, Cu, Cd, and Pb) in waters were not high, mainly due to trace elements are immobilized by sorption or coprecipitation at circum-neutral pH.

Non-thermal plasma synthesis of sea-urchin like α-FeOOH for the catalytic oxidation of Orange II in aqueous solution

In this study, a template-free synthesis of iron oxyhydroxide nanostructures by gliding arc plasma at atmospheric pressure was evaluated. The results showed that exposure of a Mohr’s salt solution to the plasma discharge induces a rapid oxidation–precipitation of iron(II) into a non-porous and amorphous iron(III) (hydr) oxide. After ageing in temporal post-discharge for three hours, the amorphous iron (hydr) oxide was transformed into crystalline goethite (α-FeOOH). The presence of goethite was confirmed by FTIR, Raman spectroscopy and thermogravimetric analysis. Textural analyses showed that the material is mesoporous with a BET surface area of 134m2g−1. SEM pictures revealed that the plasma-synthesized goethite particles consist of sea-urchin like hollow spheres. The catalytic activity of such goethite in the Fenton degradation of Orange II (organic dye) showed that this material can be used as heterogeneous catalyst for effective removal of organic pollutants from wastewater. This study establishes that the plasma discharge of gliding arc type can be used as a green and cheap efficient route for the synthesis of porous metal oxide nanostructures.

Photocatalytic degradation of polycyclic aromatic hydrocarbon benzo[a]pyrene by iron oxides and identification of degradation products

Photocatalytic decay profiles of polycyclic aromatic hydrocarbon (PAH) benzo[a]pyrene (B[a]P) have been investigated on various synthesized iron oxides and on soil surfaces under a set of diverse conditions. Samples were analysed using the developed HPLC procedure. Results of the present study demonstrate fastest photodisintegration of B[a]P on goethite followed by haematite, magnetite, akaganeite and maghemite, respectively. The effect of soil pH, irradiation wavelength and iron oxide and oxalic acid dose on the degradation of B[a]P was evaluated. The studies revealed enhancement in photodegradation in the presence of oxalic acid due to the occurrence of fenton like reaction. The results showed faster B[a]P degradation under short wavelength UV radiation. Rate constants in acidic, neutral and alkaline soils under optimum dissipation conditions were 1.11×10−2, 7.69×10−3 and 9.97×10−3h−1, respectively. The study indicates that iron oxides along with oxalic acid are effective photocatalyst for the remediation of benzo[a]pyrene contaminated soil surfaces. The degradation products of B[a]P in the soils of different pH in presence of goethite were identified and degradation pathways proposed. Peaks due to toxic metabolites such as diones, diols and epoxides disappear after 120h in all the three soils.

Role of goethite during air-oxidation of PAH-contaminated soils

The impact of goethite on air-oxidation of PAH-contaminated soils was studied through two sets of experiments. (i) Soil extractable organic matter (EOM) and (ii) whole coking plant soils were oxidized at 60 and 100°C for 160d, with/without goethite. Organic matter (OM) mineralization was monitored via CO2 production and polycyclic aromatic compounds (PACs) oxidation was investigated by GC–MS analyses. The decrease in EOM and PAH contents, and the oxygenated-PAC production observed during EOM oxidation, were enhanced by the presence of goethite. PACs were likely transformed at the goethite surface through electron transfer process. Mass carbon balance revealed a transfer from EOM to the insoluble organic fraction indicating condensation/polymerization of organics. Soil oxidation induced a decrease in EOM, PAH but also in oxygenated-PAC contents, underscoring different oxidation or polymerization behavior in soil. The goethite addition had a lesser impact suggesting that indigenous minerals played an important role in PAC oxidation.

Effect of pipe corrosion product–goethite–on the formation of disinfection by-products during chlorination

The effect of goethite on the formation of disinfection by-products (DBPs) during chlorination was investigated under various reaction times, pH, and chlorine concentrations. The experimental results indicated that in the presence of goethite, the formation of DBPs was enhanced as pH and chlorine concentration increased. The enhancement of DBP formation could be attributed to the generation of hydroxyl radical (⋅OH), which could oxidize natural organic matter (NOM) in water and produce more DBP precursors to react with chlorine. X-ray diffraction (XRD) and scanning electron microscope (SEM) analyses of goethite revealed that goethite may adsorb NOM on its surface and modify NOM structure. The reaction mechanisms of goethite-enhanced DBP formation were proposed in three steps: (1) the oxidation of NOM into small molecules available as DBP precursors by ⋅OH from the reaction between ferrous ions on goethite surface and chlorine; (2) the adsorption and modification of NOM on goethite surface responsible for increasing chlorine consumption; and (3) the presence of ferric ions on goethite surface promoted the formation of DBPs.

Reduction of U(VI) by Fe(II) during the Fe(II)-accelerated transformation of ferrihydrite.

X-ray absorption spectroscopy has been used to study the reduction of adsorbed U(VI) during the Fe(II)-accelerated transformation of ferrihydrite to goethite. The fate of U(VI) was examined across a variety of pH values and Fe(II) concentrations, with results suggesting that, in all cases, it was reduced over the course of the Fe(III) phase transformation to a U(V) species incorporated in goethite. A positive correlation between U(VI) reduction and ferrihydrite transformation rate constants implies that U(VI) reduction was driven by the production of goethite under the conditions used in these studies. This interpretation was supported by additional experimental evidence that demonstrated the (fast) reduction of U(VI) to U(V) by Fe(II) in the presence of goethite only. Theoretical redox potential calculations clearly indicate that the reduction of U(VI) by Fe(II) in the presence of goethite is thermodynamically favorable. In contrast, reduction of U(VI) by Fe(II) in the presence of ferrihydrite is largely thermodynamically unfavorable within the range of conditions examined in this study.

Role of iron oxy-hydroxides on settling behaviour of red mud

Nine bauxite samples from Brazil and one from Ghana were submitted to alkaline digestion at 145°C. All initial samples and their red muds were chemically analysed and characterised by X-ray diffraction and Mössbauer spectroscopy at 298 and 77 K. The settling rates of all red muds were also measured. It was observed that the presence of goethite in the bauxite has a profound effect on the settling rate of the red mud produced in the Bayer process. The goethite possess high Al-for-Fe substitution and/or nanometric crystallites, and decreases the settling rate. The dissolution of this goethite during the caustic digestion at 145°C was also observed, leading to the formation of hematite. Finally, the hematite in the red muds presents crystals with larger sizes in comparison with those in the original bauxites.On a soumis à la digestion alcaline à 145°C, neuf échantillons de bauxite du Brésil et un échantillon du Ghana. On a analysé chimiquement tous les échantillons initiaux et leurs boues rouges et on les a caractérisés par diffraction des rayons x et par spectroscopie Mössbauer à 298 K et à 77 K. On a également mesuré la vitesse de sédimentation de toutes les boues rouges. On a observé que la présence de goethite dans la bauxite avait un effet important sur la vitesse de sédimentation de la boue rouge produite par le procédé Bayer. La goethite possède une substitution élevée d’Al pour le Fe et/ou des cristallites nanométriques, et elle diminue la vitesse de sédimentation. On a également observé la dissolution de cette goethite lors de la digestion caustique à 145°C, qui menait à la formation d’hématite. Finalement, l’hématite des boues rouges présente des cristaux de plus grandes tailles en comparaison à ceux des bauxites originales.

Plutonium sorption and precipitation in the presence of goethite at 25 and 80 ○C

Abstract We have examined the sorption of aqueous Pu(IV) and intrinsic Pu colloids to goethite across a Pu concentration range that spans the solubility of Pu(IV) hydrous oxide, at 25 and 80 ℃, and after equilibration for over 100 days. The strong affinity of aqueous Pu(IV) for the goethite surface is explained by the epitaxial growth of bcc Pu4O7 nano-particles on goethite. The 3–5 nm Pu4O7 nano-particles are strictly associated with goethite, widely dispersed across the goethite surface, and stable over the timescale of months at both 25 and 80 ℃. There is no indication that the sorbed Pu4O7 nano-particles alter to PuO2 over time. Intrinsic Pu colloids were identified by TEM as 3–5 nm PuO2 nano-particles. They exhibit a weaker association with the goethite surface. Aggregation of PuO2 nano-particles was observed. There is no indication that the PuO2 nano-particles, once formed, will alter to Pu4O7 on goethite. Based on supernatant Pu concentrations, PuO2 nano-particle aggregation behavior is consistent with Pu(IV) hydrous oxide precipitation.

Effects of iron oxides on the rheological properties of cementitious slurry

Iron oxide has been considered a promising host for immobilizing and encapsulating radioactive 99Tc (t1/2=2.1×105 year), which significantly enhances the stability of 99Tc within a cementitious waste form. However, the flow behavior of cementitious slurry containing iron oxide has never been investigated to ensure its workability, which directly influences the preparation and performance of the cementitious waste form monolith. Variation in the rheological properties of the cementitious slurry were studied using rheometry and ultrasonic wave reflection to understand the effects of various iron oxides (magnetite, hematite, ferrihydrite, and goethite) during the cement setting and stiffening processes. The rheological behavior significantly varied with the addition of different chemical compounds of iron oxides. Complementary microscopic characteristics such as colloidal vibration currents, morphology, and particle size distributions further suggest that the most adverse alteration of cement setting and stiffening behavior caused by the presence of goethite may be attributed to its acicular shape.

Biodegradation of methyl parathion in the presence of goethite: The effect of Pseudomonas sp. Z1 adhesion

In this research, the influence of goethite on biodegradation kinetic of methyl parathion was investigated in the presence of Pseudomonas sp. Z1. Semipermeable membrane experiments were performed to demonstrate the role of adhesion of degrading bacteria to surface of goethite in biodegradation of methyl parathion. Sorption of methyl parathion and bacteria onto goethite particles were also measured to assess the distribution of methyl parathion and bacteria between water and goethite surface. The first-order degradation rate constant of methyl parathion in different concentrations of goethite was in the order of 0.1 g L−1 > 0.01 g L−1 > 0 g L−1 > 1 g L−1 > 20 g L−1, suggesting the presence of low concentrations of goethite accelerated the biodegradation of methyl parathion and high concentrations of goethite inhibited this biodegradation process. According to the result of semipermeable membrane experiment, when no bacterial attachment occurred in the system, the promotive effect of 0.1 g L−1 goethite for microbial degradation was disappeared and the inhibition effect of 20 g L−1 goethite increased. The results clearly demonstrated that the adhesion of bacteria to goethite was beneficial to the biodegradation of methyl parathion. The information obtained is of fundamental significance for the understanding of microbial degradation of organic pollution in soil.

Lixiviação de naftaleno em solos urbanos da região metropolitana do Recife, PE

Os principais atributos edáficos relacionados com a lixiviação de naftaleno nos solos consistem na granulometria, no teor de matéria orgânica e na composição mineralógica das frações silte e argila. Este trabalho objetivou determinar os valores da dispersão e do retardamento do naftaleno em amostras de solos coletadas nas proximidades de tanques de armazenamento de combustíveis localizados em Recife, PE. Os experimentos de lixiviação foram realizados em colunas contendo amostras deformadas e foram modelados usando a equação de convecção-dispersão, que foi ajustada aos dados experimentais com o emprego do software CXTFIT 2.0. Os resultados indicaram que solos arenosos oferecem menor resistência à lixiviação de naftaleno e que a presença de goethita, juntamente com a matéria orgânica, é possivelmente o principal fator responsável pelo retardamento do transporte desse composto no conjunto de amostras estudadas.

Soil formation and mineralogy of a Rhodic Luvisol — insights from magnetic and geochemical studies

Relict terra rossa soil from the most south-eastern part of Bulgaria, characterized by transitional Mediterranean climate, has been comprehensively studied by integrating magnetic, geochemical and spectroscopic methods to reveal the origin, pedogenic processes and phases in soil development of this particular soil type. The red colored Rhodic Luvisol is developed on metamorphosed Triassic limestones. Magnetic methods, which include thermomagnetic analysis of susceptibility, isothermal remanent magnetization (IRM) acquisition and thermal demagnetization, IRM component analysis, hysteresis measurements, low-temperature (down to 10K) IRM behavior, anhysteretic remanence and frequency dependent susceptibility, indicate the presence of three major magnetic phases — maghemite, hematite (Hm) and goethite (Gt). Hematite and goethite are identified also by diffuse reflectance spectroscopy (DRS). Depth variations of the ratio Hm/(Hm+Gt), deduced from the DRS spectra show higher hematite content in the upper soil horizons (A+B), while goethite's contribution is enriched in the lowermost part of the profile. A similar ratio, based on the established magnetic proxies for hematite and goethite, was constructed and its variations were compared with the DRS data. The magnetic proxy for Hm/(Hm+Gt) reflects the variations in the remanence-carrying mineral fraction of hematite and goethite and the obtained difference with the DRS data are ascribed to the presence of the paramagnetic (or superparamagnetic) goethite in the A and illuvial Bt1 and Bt2 horizons. The low ratio Feo/Fed between dithionite (Fed)- and oxalate (Feo)-extractable iron, and the large proportion of extractable iron with respect to total iron (Fed/Fetot) indicate an advanced degree of weathering. Depth variations of magnetic parameters and ratios (χlf, χfd, S-ratio) suggest magnetic enhancement with SP–SD maghemite grains, accompanied by magnetically stable magnetic carriers in the soil, while the parent material is magnetically depleted. Based on grain-size variations of the pedogenic maghemite phase, deduced from a χARM vs. χfd plot, and variations in the content of hematite and goethite in depth, in the uppermost part of the profile, aging of the pedogenic iron oxides is assumed (grain growth from SP to SD and larger), while in the bottom part of Bt1 and the Bt2, changes only in the concentration of maghemite are inferred. The presence of goethite in different parts of the profile and the mineralogy of Fe–Mn nodules are linked to more recent (Holocene) pedogenic changes in the profile. Analyses of trace and rare earth element content and magnetic data suggest possible contributions of aeolian dust flux from Sahara during the soil formation.

Analysis of rocks around capital of Kingdom of Saudi Arabia using laser induced breakdown spectroscopy

We present laser-induced breakdown spectroscopic studies of variety of rock samples around capital of Kingdom of Saudi Arabia. The samples were collected from East, West, North, and South about 20 km from city centre. Nd:YAG laser (1064 nm) in conjunction with MS257 Spectrograph (Oriel instrument) equipped with ICCD camera is used to record the LIBS data. The emission spectra of these samples have been recorded as functions of laser irradiance. The elemental composition and the relative abundance in each sample are found to be quite different. Quantities of Iron, Calcium, Carbon, Silicon, Aluminum, and Oxygen are detected in these samples. In samples from East, West and South, Iron and Silicon dominates. Dominant elements from North are Calcium and Silicon. Presence of Oxygen proves the existence of oxides in all samples. The color of the samples indicates the presence of Goethite and Hematite, oxides of Iron.