Principal Mineral Research Articles

Discriminating Organic and Conventional Coffee Production Systems Through Soil and Foliar Analysis Using Multivariate Approach

ABSTRACTThis study tested the hypothesis that evaluating soil and leaf nutrient contents is useful to discriminate organic and conventional management systems of coffee plantations. The study consisted of areas planted with Coffea arabica under organic or conventional management located in Espírito Santo, Brazil. We detected significant differences between both management systems when we utilized multivariate statistics to discriminate the areas. In our experiments, the principal mineral leaf nutrients, which acted as indicators were phosphor (P), calcium (Ca), magnesium (Mg), sodium (Na), zinc (Zn), and manganese (Mn), with higher contents in the organic coffee production system. The only mineral nutrient, which showed significantly lower values in leaves as well as in soil of organic coffee is boron (B). The implications of these findings are discussed. However, when using univariate statistics, like ANOVA or t-test, we did not find any significant difference between both management systems, although using the same dataset. Therefore, to discriminate between complex systems, we always recommend to recur to multivariate methodologies that are more adequate for such cases.

MECHANICAL PROPERTIES OF GRANULITE FROM HORNÍ BORY IN BOHEMIAN MASSIF

Granulite represents one of the favourite rock types for the construction of an underground nuclear waste repository in the Czech Republic. Granulite from the Bohemian Massif (locality Horni Bory) was investigated in this study, with a special focus on the evaluation of the rock anisotropy. Investigated rock represents typical fine-grained foliated felsic granulite with principal mineral association: quartz + feldspar (K-feldspar > plagioclase) + garnet + biotite + kyanite and/or sillimanite. Anisotropy was identified in the rock fabric both at macroscopic and microscopic scale. During the laboratory testing, granulite reached considerable high uniaxial compressive strength (UCS) - up to 240 MPa; and brittle type (Class II) of failure occurred. We found that variability of the UCS and Young's modulus were relatively low. On the other hand, variability of the Poisson's ratio and the constants in Hoek-Brown failure criterion in triaxial loading were significantly high. Keywords: granulite, mineral properties, foliation, uniaxial compressive strength, triaxial compressive strength, anisotropic properties DOI 10.35180/gse-2019-0022

Calcium-aluminate mortars at high temperatures: Overcoming adverse conversion effects using clinker aggregates

The effect of elevated temperatures on a calcium aluminate mortar with clinker aggregates is the subject of this paper. After an exposure period of 3 h at temperatures ranging from 25 to 1000 °C, specimens were tested in residual conditions in order to evaluate changes on the mechanical and microstructural properties. A simplified hydration model based on the chemical reactions of the principal minerals is proposed to predict the evolution of matrix composition from the early-age hydration. The improvement of the mechanical properties occurring due to the conversion reactions between 25 °C and 200 °C, is attributed to an increased hydration reaction of both cement and clinker aggregate. Furthermore, when compared to the metastable reactions, an improved interlocking effect at the reactive aggregate interface, and a more dense nature of the stable hydration products, were observed. These phenomena balance the adverse effects promoted by conversion reactions on porosity and mechanical properties.

Hydrochemical classification and multivariate statistical analysis of groundwater from Wadi Sahba area in central Saudi Arabia

The central region of Saudi Arabia is underlain by thick sedimentary formations belonging to the Mesozoic and Cenozoic era. These sedimentary formations form a prolific aquifer supplying groundwater for agricultural and domestic usage in and around Riyadh. The region south of Riyadh City is well known for agricultural activities. Wadi Sahba, which is an eastward extension of Wadi Nisah, has readily available groundwater resources in the Cretaceous Biyadh sandstone aquifer to sustain agricultural activities. The objective of the present study was the hydrochemical assessment of groundwater in the area to understand the main hydrological processes which influence groundwater chemistry. To achieve this objective, 20 groundwater samples were collected from agricultural farms in the Wadi Sahba in central Saudi Arabia, and the major physiochemical constituents were analyzed and interpreted. The average TDS value of the analyzed samples is 1578.05 mg/l, whereas the average EC concentration is 3220.05 μS/cm. Groundwater facies classification inferred from the Piper plot shows that groundwater in the study area belongs to the Ca-SO4-Cl type and Ca-Na-SO4-Cl type. The Ca-SO4-Cl type of groundwater facies is influenced mainly by gypsum dissolution and base ion exchange, whereas the Ca-Na-SO4-Cl type is influenced by gypsum and halite dissolution. All the groundwater samples are undersaturated with respect to these two principal mineral phases. The Q-mode cluster analysis results in two main groups of groundwater samples, mainly based on the TDS content. Cluster 1 has an average TDS value of 1980 mg/l, whereas cluster 2 has an average TDS of 1176 mg/l. The groundwater facies identified through the Piper plot reflects the major hydrological processes controlling groundwater chemistry in the area and was found to be more useful in this study as compared to cluster analysis.

Mineralogical Analysis of Sand Roses and Sand Dunes Samples from Two Regions of South Algeria

In this work, it is found that the important minerals in sand dunes and sand roses samples from Anqousa in the south-east of Algeria in Ouargla region and from Charouin in the south-west in Adrar area are the quartz and Gypsum phases. The aim of this study is a qualitative and quantitative minerals evaluations of two areas samples using x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). Granulometric classification and size distribution were carried out using Laser scattering particle size analyser. Numerous observed diffraction peaks confirm the presence of polycrystalline quartz phase in sand dunes samples as principal mineral. In the case of sand roses samples, the diffraction spectra show that the basic mineral is Gypsum. The sand dunes samples infrared absorption spectrum show the characteristic vibration bond peaks for quartz as 460, 695, 779 and 1082 cm− 1, also these analysis reveal the Gypsum characteristic peaks at 1616 and 1620 cm− 1. FTIR spectra enregistred on sand roses samples showed the absorption peaks at 3552, 3492, 3404, 1685, 1620, 669 and 602 cm− 1 indicate the presence of gypsum. Through combination between the results of DRX, FTIR and EDS, it appears that the concentration of quartz in ouargla sand samples is greater than that in Adrar sand, contrariwise the concentration of Gypsum in Adrar sand dunes is the most important. It was deduced that Adrar sand roses have the higher concentration of Gypsum. The grain size varies between 58.953 and 777.141μm with an average value ≈ 213.386 μm for ouargla sand and between 74.219 and 198.531μm with an average value ≈ 132.684 μm for Adrar sand dunes. The obtained results confirm that the two regions can be important sources of quartz and Gypsum as primary materials for many industry applications.

Tracing olivine carbonation and serpentinization in CO2-rich fluids via magnesium exchange and isotopic fractionation

Chemical exchange between seawater and the oceanic crust is thought to play a significant role in the regulation of the global magnesium (Mg) cycle, yet relatively little is known about the rates and mechanisms of Mg exchange in these crustal environments. In this study we experimentally characterize the extent, and nature, of Mg isotope fractionation during the carbonation and serpentinization of olivine (one of the principal minerals found in ultramafic rocks) under hydrothermal conditions. Olivine alteration was found to be incongruent, with the reactant fluid composition varying according to the extent of olivine dissolution and the precipitation of secondary minerals. In mildly acid water (pH ∼ 6.5), olivine dissolved to form Mg-Fe carbonate solid solutions and minor chrysotile. Upon carbonation and a decrease of CO2 in the water, the pH increased to >8, with chrysotile and brucite becoming the dominant alteration minerals. The Mg-rich carbonates preferentially incorporated lighter Mg isotopes, resulting in a ∼0.5‰ increase of the δ26Mg composition of the fluid relative to olivine during the initial carbonation and serpentinization reactions. This was followed by a decrease in δ26Mg under higher pH conditions associated with the formation of brucite. Our experimental and modeling results therefore demonstrate that the δ26Mg composition of fluids involved in olivine alteration reflect the type and quantity of secondary Mg minerals formed, which in turn depend on the pH and CO2 concentration of the water. Comparison of these results with natural groundwaters and geothermal waters from basaltic terrains indicate that the δ26Mg composition of natural waters are likely to also be controlled by mafic rock dissolution and the preferential incorporation of isotopically light Mg into carbonates and isotopically heavy Mg into Mg-Si minerals. Together, these findings improve our understanding of Mg isotope systematics during water-rock interaction, and suggest that δ26Mg may be a useful tool for tracing reactions that are critical to geological CO2 sequestration.

Experimental study and numerical simulation of the dissolution anisotropy of tricalcium silicate

Improving our understanding of the hydration rate of the principal mineral phases of cements is key to better control the mechanical properties of cement paste and of concrete-based products. In the present study, the dissolution kinetics of the principal mineral phase of cement (alite Ca3SiO5), was investigated by combining powder dissolution experiments with face-specific interfacial dissolution rate measurements. Experiments demonstrate the anisotropic reactivity of alite, which suggests that dissolution cannot be described by an isotropic and homogeneous shrinkage of the grains. Numerical simulations show that the dissolution anisotropy results in a gradual increase of the interfacial dissolution rate averaged over the entire crystal, followed by a dramatic drop at greater reaction progress. However, such an interfacial dissolution rate increase cannot counterbalance the decrease of the surface area, such that the hydration rate remains a decreasing function of time. We conclude that the sole variation of the interfacial dissolution rate as a function of the reaction progress cannot account for the early increase of the hydration rate generally reported in the literature, which, instead, may have to be sought in the increase of the specific surface area because of the nucleation and expansion of etch pits at the alite surface.

Analysis of the structural changes of a pellet/powder bentonite mixture upon wetting by X-ray computed microtomography

Abstract Pellet/powder bentonite mixture is one of the candidate materials for sealing plugs in deep geological high-level radioactive waste disposal. This note presents an investigation on the structure changes of this mixture occurring during the saturation process by means of X-ray computed micro-tomography. The test was performed in an infiltration column (60 mm in inner diameter and 120 mm in height). Water was supplied to the two ends of the column and the changes of the sample morphology were observed during a period of 100 days of hydration. Digital Volume Correlation (DVC) technique was used to determine the vertical displacement field of the bentonite powder. A pressure transducer was used to measure the axial swelling pressure during the hydration. The results show that the initial distribution of powder in the inter-pellet pores was not homogeneous; the powder filled almost completely the pores in the zones close to the two ends while air-filled inter-pellet voids were observed in the middle of the column specimen. When water started to infiltrate inside the specimen from both ends, the pellets and the powder grains started to swell (because of the swelling properties of smectite, the principal mineral of bentonite) and filled the voids. That induced at the same time increase of swelling pressure and downward movement of powder grains. The results allowed a better understanding on the hydro-mechanical couplings, at the pellet scale, in the pellet/powder bentonite mixture upon wetting.

The braunite (3Mn2O3·MnSiO3)-rich mineralization in the metasedimentary succession from southern Apennines (Italy): Genesis constraints

A massive Mn-bearing mineralization, extensively exploited until the 70 s, locally occurs in the metasedimentary succession of the southern Apennines (at Mormanno site, Calabria-Lucania border, Italy). The mineralization mainly consists of three types distinguished by the relative percentages of the principal mineral phases: braunite, quartz, Mn oxi-hydroxides and Mn-rich epidote (piemontite). Petrographic observations revealed that the ore underwent medium- to high-grade metamorphism that was responsible of the growth of braunite at the expense of “primary” amorphous Mn oxi-hydroxides and quartz. During metamorphism, piemontite also formed where altered phyllosilicates are present in addition to braunite and quartz, suggesting that the aluminosilicates were source of Al necessary to the epidote crystallization. The most important geochemical features of the ore are high Mn contents (up to 71.6 wt% of MnO), low concentrations of transitional elements (Co + Ni+Cu + Zn < 0.1 wt%), high Ba (up to 4455 ppm) and variable total REEs (14.7 < ΣREEs < 329.7 ppm) contents. These are the typical characteristics of the ocean-floor hydrothermal Mn deposits, similarly to what observed in braunite ores occurring in the Alps and northern Apennines. The high LREE/HREE fractionations and the negative Ce and Eu anomalies characterizing the studied ore, suggest the mineralizing fluid was formed by a mixing solution consisting of a Mn-rich hydrothermal fluid and seawater, which attained the ideal condition for the ore precipitation in a distal oceanic area, far from the submarine hydrothermal vent.

Characteristics of the Ahmadabad hematite/barite deposit, Iran – studies of mineralogy, geochemistry and fluid inclusions

Abstract The Ahmadabad hematite/barite deposit is located to the northeast of the city of Semnan, Iran. Geostructurally, this deposit lies between the Alborz and the Central Iran zones in the Semnan Subzone. Hematite-barite mineralisation occurs in the form of a vein along a local fault within Eocene volcanic host rocks. The Ahmadabad deposit has a simple mineralogy, of which hematite and barite are the main constituents, followed by pyrite and Fe-oxyhydroxides such as limonite and goethite. Based on textural relationships between the above-mentioned principal minerals, it could be deduced that there are three hydrothermal mineralisation stages in which pyrite, hematite and barite with primary open space filling textures formed under different hydrothermal conditions. Subsequently, in the supergene stage, goethite and limonite minerals with secondary replacement textures formed under oxidation surficial conditions. Microthermometric studies on barite samples show that homogenisation temperatures (TH) for primary fluid inclusions range from 142 to 256°C with a temperature peak between 200 and 220°C. Salinities vary from 3.62 to 16.70 NaCl wt% with two different peaks, including one of 6 to 8 NaCl wt% and another of 12 to 14 NaCl wt%. This indicates that two different hydrothermal waters, including basinal and sea waters, could have been involved in barite mineralisation. The geochemistry of the major and trace elements in the samples studied indicate a hydrothermal origin for hematite and barite mineralisation. Moreover, the Fe/Mn ratio (&gt;10) and plots of hematite samples of Ahmadabad ores on Al-Fe-Mn, Fe-Mn-(Ni+Co+ Cu)×10, Fe-Mn-SiX2 and MnO/TiO2 – Fe2O3/TiO2 diagrams indicate that hematite mineralisation in the Ahmadabad deposit occurred under hydrothermal conditions. Furthermore, Ba and Sr enrichment, along with Pb, Zn, Hg, Cu and Sb depletion, in the barite samples of Ahmadabad ores are indicative of a low temperature hydrothermal origin for the deposit. A comparison of the ratios of LaN/YbN, CeN/YbN, TbN/LaN, SmN/NdN and parameters of Ce/Ce* and La/La* anomalies of the hematite, barite, host volcanic rocks and quartz latite samples to each other elucidate two important points: 1) the barite could have originated from volcanic host rocks, 2) the hematite could have originated from a quartz latite lithological unit. The chondrite normalised REE patterns of samples of hematite barite, volcanic host rocks and quartz latite imply that two different hydrothermal fluids could be proposed for hematite and barite mineralisation. The comparison between chondrite normalised REE patterns of Ahmadabad barite with oceanic origin barite and low temperature hydrothermal barite shows close similarities to the low temperature hydrothermal barite deposits.

Utilization of Nkpuma-Akpatakpa clay in ceramics: characterization and microstructural studies

Nkpuma – Akpatakpa clay was analysed for its ceramics suitability. Chemical, mechanical and spectral characterization of the clay was carried out to obtain more information from this clay found in commercial quantity at Ebonyi State Nigeria. The XRD analysis showed that the principal minerals in the clay are quartz, qandilite, aragonite, Muscovite and anatase. FTIR showed the stretching vibrations for Si – O at 685.8cm –1 showing the presence of Quartz. The frequency at 1431cm-1 is due to (CO3)2- stretching mode vibration or C – O stretching of Aragonite and the band at 2467.6 is due to OH- stretching. Bands observed at 984.7 and 987.7cm –1 correspond to Al – O bending vibrations which suggest the presence of muscovite in the clay and SEM studies were also carried out and reported. Porosity of the clay was 0.88% considered too small for refractory, thermal insulation and other high porosity desired ceramics applications. Value obtained for Fe2O3 was &gt; 1.7% which accounted for why the clay did not fire white. The values for M.O.R was &gt;40KgF/cm2. The refractoriness was &lt;13400C. Chemical characterization showed the presence of fluxing oxides at elevated levels which are responsible for the poor refractoriness and limits the utilization of the clay to low or mid-temperature ceramics products.Keywords: Nkpuma-Akpatakpa clay, Ceramics, Characterization, Qandilite, FTIR, Bulk density

Alumina sludge's Influence on the physicochemical characteristics of CPJ55cement

Partial replacement of the Portland cement CPJ55 ingredients by various quantities of alumina sludge (AS), produced during drinking water plant sludge, was used in the preparation of mortar mold with dimensions 40×40×160 mm. The characterization of materials is carried out by X-ray fluorescence (XRF), Xray diffraction (XRD), free lime dosing, and the mechanical tests. Analysis of the chemical composition by XRF shows that the studied alumina sludge is mainly composed of aluminum oxide, silica, which is correlated with the principal mineral phases identified in the XRD analysis results. It is demonstrated that adding 5% of the alumina sludge in Portland cement does not affect the mineralogy of final product. Nevertheless, the compression and flexural strength tests (in 28 days) conducted on mortar sample comprising 5% sludge elucidate that it belongs to cement mortar class of type 32.5 R.

Chloride penetration through cement material based on dredged sediment and shell powder

This paper is aimed to evaluate the influence of marine sediments and shell powders on the chloride penetration through composite cement materials. The sediments have high water and chloride contents and calcite, quartz, illite and kaolinite as principal minerals. The shell powders are entirely composed of calcium carbonate and traces of other impurities. Four mixtures of treated sediments and shell powders at 650 and 850 °C are added to Portland cement at 8, 16 and 33% by weight. Substituted pastes and mortars are tested at different chloride exposure conditions. It is shown that the partial cement replacement of CEM I with sediments and shell powders can decrease the corrosion risk of the reinforcing steel of concrete by changing the microstructure of the material due to the compacting effect and extending more ions to react with chlorides. Hence, the free chlorides in the pore solution were reduced.

The Role of Water Glass in the Flotation Separation of Fine Fluorite from Fine Quartz

Fluorite is the principal mineral of fluorine and usually coexists with quartz in deposits. The removal of fine quartz in fluorite concentrate is the main problem in fluorite flotation. In this study, the flotation tests on fluorite, quartz and a weight equivalent mixture (all less than 10 μm) using water glass (with different modulus) as depressants and sodium oleate as collector were conducted. The mechanism of fine quartz entering the fluorite concentrate was investigated through optional observations and rheology measurements on the flotation pulp. The particle interactions between fine fluorite and quartz under flotation-related conditions were analyzed through zeta potential measurements and DLVO calculations. The results revealed that there existed strong hetero-coagulation between fluorite and quartz particles in the flotation pulp, which could be the main reason for the quartz entering the fluorite concentrate in the flotation process. Water glass with higher modulus could eliminate the hetero-coagulation more totally but inevitably influences the flotability of fluorite.

Adsorption of gluconate and uranyl on C-S-H phases: Combination of wet chemistry experiments and molecular dynamics simulations for the binary systems

As a first step in developing better molecular scale understanding of the effects of organic additives on the adsorption and mobility of radionuclides in cement under conditions of geological nuclear waste repositories, two complementary approaches, wet chemistry experiments and molecular dynamics (MD) computer simulations, were applied to study the sorption behaviour of two simple model systems: gluconate and uranyl on calcium silicate hydrate phases (C-S-H) – the principal mineral component of hardened cement paste (HCP). Experimental data on sorption and desorption kinetics and isotherms of adsorption for gluconate/C-S-H and U(VI)/C-S-H binary systems were collected and quantitatively analysed for C-S-H samples synthesised with various Ca/Si ratios (0.83, 1.0, 1.4) corresponding to various stages of HCP aging and degradation. Gluconate labelled with 14C isotope was used in order to improve the sensitivity of analytical detection technique (LSC) at particularly low concentrations (10−8–10−5 mol/L). There is a noticeable effect of Ca/Si ratio on the gluconate sorption on C-S-H, with stronger sorption at higher Ca/Si ratios. Sorption of organic anions on C-S-H is mediated by the presence of Ca2+ at the interface and strongly depends on the surface charge and Ca2+ concentration. In parallel, classical MD simulations of the same model systems were performed in order to identify specific surface sorption sites most actively involved in the sorption of gluconate and uranyl on C-S-H and to clarify molecular mechanisms of adsorption.

Characteristics of ‘Gadhi’ soil

‘Gadhi’ is a small hill-sized soil deposit found in the villages of the Maharashtra state of India. The villagers have been using ‘Gadhi’ soil (GS) over many generations for the construction of houses and have found that it offers excellent seasonal comfort, sufficient strength and durability. Native people say that older generations traditionally prepared GS by mixing unknown ingredients in the local black cotton soil (BCS). To obtain an insight into the advantageous properties of GS as a building material, its physical, mineralogical, chemical and dielectric characteristics are studied and compared with those of BCS. GS is a silty soil with medium to high plasticity, and BCS is clay of high plasticity. X-ray diffraction analysis of BCS and GS revealed kaolinite as the principal clay mineral, the crystallinity of GS and the amorphous nature of BCS. X-ray fluorescence spectrometry provided their elemental analysis. Chemical analysis showed the oxide contents, with lower concentrations of iron oxide and higher silica in GS as compared with BCS. Scanning electron microscope analysis of GS was used to study inter-molecular bonding and showed kaolinite sheets on quartz crystals. The dielectric constant of GS revealed its nature as an insulating material. This database will be useful for future studies on correlation analyses between BCS and GS and its stabilisation process.

Oolitic ores in the Bakchar iron-ore cluster (Tomsk Oblast)

Oolitic iron ores are typified, and their morphology and composition are studied. Special attention is focused on the character of distribution of valuable and harmful admixtures and determination of the principal minerals concentrating these elements. As a result of this study, three types of ores are identified, such as “loose” ores, cemented ores with glauconite–chlorite–clay cement, and well-cemented ores with siderite cement. The morphology and composition of the ore oolites are characterized. The forms of occurrence of calcium phosphates (anapaite) and phosphates of rare-earth elements (monazite, cularite) that are related to the harmful phosphorus admixture are described. According to the analysis of the elemental composition, the fractions of (–1…+0.2) and (–1…+0.1) mm in the western and eastern segments, respectively, may be promising for processing.

A study of flotation characteristics of monazite, hematite, and quartz using anionic collectors

Rare earth element (REE) minerals found in most South Australian ore deposits are in complex association with gangue minerals, typically hematite and quartz. Monazite, a phosphate mineral containing mainly light REEs, is one of the principal minerals found in South Australian REE-bearing deposits. Froth flotation, which exploits the differences in the physicochemical properties of minerals, has proven to be effective in the beneficiation of REE minerals. The physicochemical properties of monazite, hematite, and quartz including zeta potential, contact angle, and floatability were determined in this investigation. Sodium oleate, sodium dodecyl sulphate, and hydroxamic acid were employed as collectors. Electroacoustic zeta potential measurements were used to identify the interaction between monazite, hematite, and quartz and the selected collectors. The capillary rise method was used to determine the contact angle of the three minerals. Single mineral flotation using Denver microflotation cell was carried out to confirm physicochemical properties measured. It is shown that the contact angle of the minerals is dependent on the collector type used. The isoelectric point (IEP) of monazite, hematite, and quartz occurred at pH of 6.5, 6.9, and 2.2, respectively. The zeta potential results also suggest that the collectors chemisorb onto monazite and hematite surfaces with a corresponding change in IEP values. Single mineral flotation results demonstrated that monazite and hematite could be floated by the selected collectors; however, low or no quartz flotation was observed in some cases. Results from electrokinetic and contact angle measurements are consistent with that of the floatability of monazite, hematite, and quartz.

The vein-type barite mineralization of the Draïssa ore field, Ougarta; SW- Algeria: mineralogy, trace elements and halogens

The Draissa barite vein system in the Ougarta district is located in southwestern Algeria. It is the principal mineral deposit of economic interest of the area. The mineralization is hosted by Cambrian sedimentary rocks that unconformably overlie Precambrian formations. The mineralized structures consist mostly of barite and quartz with minor sulfide minerals and trend dominantly NE-SW, NW-SE, and E-W. Siliceous alteration zones are associated with the vein system. Samples of barite ore are characterized by low total REE contents ranging from 9 to 50 ppm and positive Eu (2–2.15 ppm) and Y (1.2–11.1 ppm) anomalies, indicating hydrothermal activity during mineralization. Halogen data of the barite show that the Cl/Br molar ratio is 189:571 and the Na/Br ratio is 34:376, indicating that the sulfur was derived from seawater. The Ba-enrichment trend in the volcanic rocks of Draissa is interpreted as possible probable source of the Ba (424–3039 ppm Ba). It appears that the barite-quartz deposits were formed in two stages. Endogenous fluids deposited the primary vein materials, consisting of quartz associated with copper sulfides. Exogenous fluids (cold seawater) became heated during ascendant fluid movement. Mineralization was governed by convective motions and the barite and galena fillings were deposited in openings created by normal faulting.

Determination of acid forming potential of massive sulfide minerals and the tailings situated in lead/zinc mining district of Balya (NW Turkey)

Weathering of sulfide minerals is a major source of acid production in nature and especially in mining territories. Pyrite is not the only principal mineral that generates acid drainage: other sulfide minerals (sphalerite, galena, chalcopyrite, etc.) may also be responsible for acid production. In addition to massive sulfide minerals, sulfide-bearing mine tailings may also produce acid drainage due to oxidation and hydrolysis reactions in waste dumps. The lead/zinc (Pb/Zn) mining region in Balya and Balıkesir, in Turkey, has operated mines intensively since the 1860s; so that characterization of the sulfide minerals and tailings situated and formed around the mining site is of great importance to secure a sustainable environment. For this purpose, acid production and neutralization potentials of massive sulfide ores of the region, and in the Pb/Zn process facility mine tailings from ten different points of tailings dam, have been determined by applied conventional Acid-Base Accounting (ABA) and Net Acid Generation (NAG) static tests after chemical and mineralogical analysis. The NAG pH and net acid production potential (NAPP) values were compared on a chart in order to classify the samples as either acid generating or non-acid generating. According to the comparisons, the sulfide minerals were classified as potentially acid forming (PAF). Massive pyrite had the highest NAPP and NAG pH value of 1966.6 kg H2SO4/ton and 1.91, respectively and the galena had the lowest NAPP value of 558.9 kg H2SO4/ton. However, the sphalerite NAG leachate pH value of 4.30 was the highest in sulfide minerals so that the sphalerite plotted near the uncertainty reference border in the PAF zone. In the mine tailings, NAPP values of 105.9 kg H2SO4/ton on average and the NAG pH values of over 7.5 were determined. In addition to these tests, water leaching (agitation test) was carried out on tailings in order to generate more information. The tailings did not generate acidic leachates as they lie on limestone bed rock which neutralized the acidity.