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The interaction between bacteria and minerals is very complicated and has been intensively studied in the laboratory and the field in the last few decades, but the processes and mechanisms of biomineralization and mineral precipitation are still not fully understood and need to be explored further. In the present work, biomineralization experiments were undertaken using Klebsiella pneumoniae LH1, collected from a natural surface environment in an area of outcrops of Cambrian dolomite, in a culture medium with various Mg/Ca molar ratios (0, 3, 6 and 12). The mineral precipitates obtained were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive spectrometer (EDS), Fourier transform infrared spectrometer (FTIR), laser scanning confocal microscopy (LSCM) and X-ray photoelectron spectroscopy (XPS). Cells were analyzed with a scanning transmission electron microscope (STEM), high resolution transmission electron microscope (HRTEM) and selected area electron diffraction (SAED). The composition of amino acids in extracellular polymeric substances (EPS) was also determined. In the experiments it was found that the production of ammonia and the presence of carbonate anhydrase promoted the increase of the medium pH and that minerals are nucleated on the EPS, which consist chiefly of amino acids and negatively-charged organic functional groups. With increasing Mg/Ca ratios, the mineral phases changed, including calcite (100%) at Mg/Ca molar ratio of 0, monohydrocalcite (36.05%) + dypingite (63.95%) at Mg/Ca molar ratio of 3, monohydrocalcite (29.72%) + dypingite (15.48%) + nesquehonite (54.80%) at Mg/Ca molar ratio of 6, and monohydrocalcite (14.2%) + dypingite (1.0%) + nesquehonite (84.80%) at Mg/Ca molar ratio of 12. Some intracellular amorphous calcium- and magnesium-rich inclusions were also detected in K. pneumoniae LH1, suggesting intracellular biomineralization accompanying the extracellular mineral precipitation. This study provides further understanding of the biomineralization processes of microorganisms. [ABSTRACT FROM AUTHOR]

Agroecological landscapes, which promote critical features such as agrobiodiversity, represent valuable global commons. These landscapes are products of ways of life, local knowledge, and rural practices. Recent studies agree on the need to better understand such rooted social-ecological systems by more deeply exploring their human-environment relationships. To address this, we investigated agroecological landscapes in two communities, one in the Andean highlands of northwest Argentina, the other in the Dolomites in northern Italy. This research applies discourse-ethnographic methods to explore how the communities build institutions to protect their culture, how they manage change, and how the environment is perceived and used. Based on the results, we identified several dimensions of farmers' intangible values, their understanding of well-being, and how they contribute to the genesis of landscapes (maize terraces, alpine pastures). This work shows that many interviewees did not perceive nature merely as a resource or service for humans, as suggested by the widely held discourse of agricultural industrialization, and that alternative relationships to nature are possible and do exist in practice. Further, this work raises relevant issues for how to imagine the transition to agricultural systems that do not define well-being only from the perspective of materiality and of humans. [ABSTRACT FROM AUTHOR]

There is currently no quick available method for assessing chemical reactivity of liming materials used to neutralize soil acidity. This study was conducted to assess the effectiveness of a method developed to determine the chemical reactivity of liming materials. The reactivity of five conventional liming materials, biochar, charcoal and wood ash was determined using the method. Liming materials were applied to surface samples of two Ultisols at rates intended to neutralize exchangeable acidity. Physico-chemical and mineralogical properties of liming materials and soils were determined. Soils treated with the liming materials were incubated for 12 weeks in plastic containers using a soil: water ratio of 1:1. The pH and exchangeable acidity of the samples were measured every fortnight. The reactivity of the conventional liming materials was found to be strongly and positively (r = 0.99) correlated with their calcite contents, and strongly and negatively (r = −0.98) correlated with their dolomite contents. Strong positive linear relationships (R2 ≥ 0.79, p <.05) were observed between the reactivity and mean pH of the two soils between the 2nd and the 12th week, while strong negative linear relationship (R2 ≥ 0.79, p <.05) was observed between the reactivity and mean exchangeable acidity of the soils. Conventional liming materials were better than biochar and charcoal in neutralizing acidity. The new method was effective in predicting the ability of liming materials to neutralize exchangeable acidity and to raise the pH of acid soils. It can be used by farmers and lime producers to assess the reactivity of liming materials. [ABSTRACT FROM AUTHOR]

The study focusses on investigation of source rock generative characteristics and nature of crude oils from Upper Indus Basin (UIB), Pakistan. The source rock sediments and crude oil samples were geochemically analyzed. These samples belong to Lockhart, Patala, Datta and Kingriali formations from Kohat-Potwar region. The sediments samples were extracted using soxhlet extractor with organic solvents. Soluble organic matter (SOM) and crude oil were fractionated into saturates, aromatics, NSOs and asphaltenes. SOM and Total organic carbon (TOC) values reveal good generative potential of rocks. SOM and TOC values increase with depth which point out the increasing thermal maturity with depth. Bitumen to TOC ratio exhibits that samples are within the oil window. High API gravity, absence of unresolved complex mixture (UCM) and very low sulfur content indicate the non-biodegraded nature of the crude oils. The metals were present in a trace amount. This study provides scientific insight particularly for those involved in oil exploration in region under study. [ABSTRACT FROM AUTHOR]

Epithermal Au-Ag veins of the Hauraki goldfield are mostly hosted by volcanic rocks and are enclosed by extensive zones of hydrothermal alteration that are generally 6–50 km2 in areal extent. The rocks are altered to a variety of hydrothermal minerals; the most common include quartz, adularia, illite, mixed-layered illite-smectite, chlorite, pyrite, calcite, albite and smectite. Some alteration minerals have zoned distributions. Widespread illite grades successively into overlying and bordering illite-smectite and outlying smectite. Significant quartz veins mainly occur in illite-altered rocks, but some can occur in illite-smectite altered rocks. Adularia commonly surrounds veins and can occur in rocks up to >500 m laterally from veins. Ammonium (NH4) minerals, when present, have a restricted distribution occurring laterally <100–300 m from veins. The significance of alteration minerals can be understood from a geothermal context where the system scale zonation of illite, illite-smectite and smectite outline the broad thermal structure of the former hydrothermal system, with illite formed in the hotter portion. Widespread adularia indicates zones of inferred high permeability and the upflow of boiling hydrothermal fluids. Most significant quartz veins occur in rocks altered to adularia and / or illite, restricting the target area, although both minerals can occur >500 m from veins. Where present, NH4-minerals further restrict the target area. [ABSTRACT FROM AUTHOR]

The Ravar-Kuhbanan-Bahabad belt (RKBB) in Central Iran contains several carbonate-hosted non-sulphide Zn (zinc)-Pb (lead) deposits. The Gujer Zn mine area located in the middle of the RKBB was selected as the case study. Due to its large extent, dolomitic envelope in carbonate host rocks can be considered as a more appropriate exploratory target than small Zn-rich gossans or blind karst filling ore. Based on previous studies, the occurrence of red sandstone as a candidate of supplying metal for mineralization and evaporate as sulphate source for mineralized liquids in the vicinity of carbonate rocks can be important exploratory key in the RKBB. Non-sulphide Zn deposits were formed through oxidation of primary Mississippi Valley-type (MVT) deposits in the study area. Remote sensing studies were undertaken using visible to near-infrared (VNIR) and shortwave infrared (SWIR) bands of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) with the objective of lithological mapping. Five traverse lines containing a total of 81 samples were designed and followed with subsequent chemical analysis, thin section studies, and spectroscopy to verify the results. Two types of carbonates, namely, magnesian dolomite as host rock and surrounding calcitic limestone, were realized through using magnesium oxide (MgO) to calcium oxide (CaO) ratio. Based on spectroscopy studies, calcite and dolomite showed distinct absorption features at 2.35 µm and 2.32 µm, respectively, in ASTER band 8 while a shoulder at 2.25 µm was seen in ASTER band 7 for dolomite. Three image processing methods including spectral angle mapper (SAM), linear spectral unmixing (LSU), and mixture-tuned matched-filtering (MTMF) were applied to separate dolomite and limestone. The accuracy of image classification was numerically estimated using a confusion matrix. Limestone with the accuracy of 95.83% was more precisely enhanced using MTMF method compared to SAM and LSU methods. Highest accuracy of 75% for dolomite was obtained through using LSU method. Red sandstone and evaporate units were classified using MTMF and SAM/LSU methods, respectively. Rock units with the highest accuracy were selected and simply overlain on an image of ASTER in a GIS platform to create the potential map of the study area. Results showed that ASTER data can be successfully used to prepare a potential map for regional scale prospecting for carbonate-hosted non-sulphide Zn-Pb deposits in geological setting and climate condition similar to the RKBB. [ABSTRACT FROM AUTHOR]

The Val Gardena Formation of the Dolomites region in northern Italy preserves the most significant assemblage of Late Permian tetrapod footprints in the world. More than 120 years of collecting resulted in about 900 publicly accessible specimens from the study area. This huge amount of data is comprehensively revised in the light of recent advances in the study of Late Palaeozoic – Early Mesozoic tetrapod ichnofossils. According to our analyses, the Val Gardena Sandstone Formation includes tracks that can be assigned to cf. Batrachichnus isp. (temnospondyl amphibian), Capitosauroides isp. (amphibian), Dicynodontipus isp. (cynodont therapsid), Dolomitipes accordii n. igen. n. comb. (dicynodont therapsid), cf. Dromopus isp. (neodiapsid), Pachypes dolomiticus (pareiasaurian parareptile), Paradoxichnium problematicum (archosauromorph neodiapsid), Procolophonichnium tirolensis n. comb. (procolophonoid parareptile), cf. Protochirotherium isp. (archosauriform neodiapsid) and Rhynchosauroides pallinii (neodiapsid). The ichnoassociation is dominated by tracks of neodiapsid and parareptilian tetrapods, whereas synapsid and anamniote tracks are rather minor components. It includes 10 out of 12 tetrapod ichnogenera known from Lopingian deposits and thus it constitutes a reference for the Paradoxichnium biochron. It shows striking similarities with other low-latitude non-aeolian contemporaneous ichnoassociations of Europe and North Africa, differences may be linked to the palaeoenvironment. Moreover, it shows a clear Triassic affinity. The new ichnogenus Dolomitipes was registered in Zoobank.org. urn:lsid:zoobank.org:act:5B4D871C-D16A-4E93-8211-CEE08019BA60 [ABSTRACT FROM AUTHOR]

The coloured stones used in buildings and monuments were an indicator of power and wealth during the ancient times. In this study, Tripolis city samples have been compared with Tripolis quarry samples in order to recognise the provenance of the banded travertine blocks in the ancient city. The banded travertine samples have similar mineral compositions and mainly consist of calcite with minor amounts of dolomite, aragonite, clay and iron oxide minerals. These results are also supported by CRS studies. Calcite is in the form of needle-shaped crystals ranging between 0.163–1.418 mm (in city) and 0.303–1.270 mm (in quarry). Tripolis banded travertine samples show the similar compositional spread in terms of major oxide, trace elements. δ13CV-PDB values of banded travertines range from 1.93 to 5.25‰ (in city) and 2.99 to 3.99‰ (in quarry), δ18OV-PDB values change between (−16.93)–(−10.08) ‰ and (−15.93)–(−13.01)‰, respectively. The U–Th radiometric ages are determined between ∼267 and 9 ka in Tripolis city samples and ∼350 and 2 ka in Tripolis quarry samples. The minero-petrographic, geochemical, C–O and U–Th isotope results fairly matched with each other. It seems highly probable that the banded travertines in Tripolis city were extracted from the Tripolis quarry, which is located at the northeast of the antique city with a distance of 3 km. [ABSTRACT FROM AUTHOR]

To investigate the possibilities of utilization of dolomite large size fractions (dropouts) and their effect on plants a five-year experiment was set in 2015. A fertilization value of large fractions (5–7 and 7–10 mm) of dolomite in two doses was studied. The biomass yield of crops in dolomite dropout treatment was around 90% from the treatment using dolomite flour (control). Losses of bases from the soil treated with high doses of dropouts did not exceed the migration losses of the treatment with dolomite flour. Dynamics of dolomite flour dissolution in the soil was empirically modeled. The data prove that high doses of the large-sized dolomite fractions act similarly to standard dolomite flour and have more persistent effects on soil and plants. [ABSTRACT FROM AUTHOR]

We have conducted high pressure far-infrared absorbance and Raman spectroscopic investigations on a natural iron-free dolomite sample up to 40 GPa. Comparison between the present observations and literature results unraveled the effect of hydrostatic conditions on the high pressure dolomite polymorph adopted close to 40 GPa, i.e. the triclinic Dol-IIIc modification. In particular, non-hydrostatic conditions impose structural disorder at these pressures, whereas hydrostatic conditions allow the detection of an ordered Dol-IIIc vibrational response. Hence, hydrostatic conditions appear to be a key ingredient for modeling carbon subduction at lower mantle conditions. Our complementary first-principles calculations verified the far-infrared vibrational response of the ambient- and high pressure dolomite phases. [ABSTRACT FROM AUTHOR]

The Lower to Middle Ordovician Tøyen Shale in southern Sweden, a biostratigraphically well-dated siliciclastic mudstone unit, shows 18 distinct authigenic cements that include sulfides, carbonates, silicates, clays, and phosphates. Marcasite, sphalerite, galena, and six texturally distinct types of pyrite characterize the sulfides whereas only one type of dolomite and three different generations of calcite are observed in this unit. Quartz, phosphate, and organic matter occur as only one generation each. Authigenic clay minerals are represented by chlorite and kaolinite. The paragenetic sequence of cements is subdivided into the two pre-burial carbonates, succeeded by ten relatively early burial cements, and six late burial cements, the kaolinite being the latest of them all and potentially being of Cretaceous age. Based on textural relationships, the paragenetic sequence of alterations started with dolomite precipitation followed by calcite, and then five different generations of pyrite. All eleven other phases post-date these initial seven cements in the Tøyen Shale. [ABSTRACT FROM AUTHOR]

Hydrothermal influences on heavy oil were simulated in laboratory conditions. The experimental model was composed of oil, calcite, dolomite, and manganese oxide. Oil to dominant mineral ratio was 1:1, where the content of manganese oxide was 5%. The hydrothermal reactions were carried out under the reservoir temperatures of 250-300°С and a pressure of 1-2 MPa. As a result of treatment, aromaticity of oil increased, while H:C ratio decreased from 1.92 to 1.61. The structures of newly formed light fractions were characterized by low molecular aromatic compounds, which were the destruction products of resins. The treatment provided removal of nitrogen and sulfur from crude oil, hence, decreasing the viscosity of products. The genotype of crude oil did not change. The quantitative changes in the ratio of isoprenoid alkanes to the linear ones were evaluated via geochemical coefficients of group composition. [ABSTRACT FROM AUTHOR]

In the present investigation, beneficiation of a low-grade dolomite fines was carried out with the aim to remove the siliceous gangue content. Extensive experimental studies on direct and reverse flotation were carried out on low-grade ore by varying the critical process variables, and the performance was compared. The experimental results show that it is possible to reduce the silica content following both direct and reverse flotation processes. Further, direct flotation results show better control over the quality of the product while reverse flotation has an edge on the product yield. [ABSTRACT FROM AUTHOR]

Based on core data, thin section and logging, this study investigates the basic characteristics and occurrence regularities of the Ordovician buried-hill carbonate reservoir in the Bozhong 21-2 tectonic belt. Results show that the reservoir lithology is primarily limestone, followed by dolomite, dolomitic limestone or limey dolomite, and silty mudstone. The reservoir spaces are primarily composed of secondary porosity. These reservoirs can be divided vertically into weathered-crust karst reservoirs and inner dissolution-type reservoirs. The distribution of reservoirs is controlled chiefly by karstification. The high karst units in the study area are favorable for the development of the two reservoir types. [ABSTRACT FROM AUTHOR]

In the upper greenschist to granulite grade rocks of the Willyama Supergroup at Broken Hill, Australia, earlier recognition of metamorphosed graded bedding in siliciclastic metasedimentary rocks led to interpretations of these rocks as deep-water turbidites. However, graded beds can also be deposited in shelfal environments below storm wave base. This study identified other tempestite features including wave oscillation ripples, hummocky cross-stratification and swaley cross-stratification indicating that deposition took place above the wave base of the larger storms. Albitised metasedimentary rocks of the upper Thackaringa Group show structures such as swaley cross-stratification typical of shallow-water conditions above fair-weather wave base. Deposition of the Broken Hill Group commenced with muddy Allendale Metasediments conformable on the Thackaringa Group. The Ettlewood Calc-Silicate Member, originally a dolomitic, siliceous sediment, is interpreted as coastal sabkha indicating onset of a marine transgression. The Parnell Gneiss represents a volcanic or volcaniclastic interruption, heralding gradually increasing input of sand in the Freyers Metasediments reaching a maximum in middle Freyers Metasediments, followed by an abrupt reversion to mud, still influenced by wave action. An open marine shelf is interpreted, possibly 30 m deep (no more than 100 m) in the final stage of a developing rift. The Broken Hill Group terminated with the massive Hores Gneiss volcanic unit. Sedimentation of the siliciclastic Sundown Group took place in similar conditions, commencing with a muddy interval overlying the Hores Gneiss. The shallowing produced by ∼90 m thickness of volcanic/volcaniclastic Hores Gneiss was compensated by subsidence. Paragon Group deposition commenced with substantial black mud, resulting from isolation from the sand supply and probably isolation from the sea. A fresh connection to the sea led first to the deposition of dolomitic carbonate (King Gunnia Calc-Silicate Member), then to deposition of parallel-laminated fine sand below wave base (upper Cartwrights Creek Metasediments), followed by ripple cross-laminated sand above wave base (Bijerkerno Metasediments). The Dalnit Bore Metasediments show abundant very thin graded silt–mud units possibly deposited below storm wave base, and thicker units of stacked wave oscillation ripples deposited above the wave base of larger storms. The Broken Hill orebody is hosted by altered Broken Hill Group metasedimentary rocks deposited at water depths of ∼30 m. Unless the ore fluid temperature was less than 150°C, it is likely that the orebody formed below the seafloor: at such shallow-water depths, the confining pressure would be inadequate to suppress boiling of hotter rising hydrothermal fluids. [ABSTRACT FROM AUTHOR]

The particle interaction behavior is important in flotation process, and the interaction energy calculation is helpful for evaluating this behavior. This study investigates and compares the floatability of magnesite, dolomite, and quartz in single mineral flotation and artificial mixture flotation with dodecylamine (DDA) as collector. The results showed that while the pH, dissolved ions, and competitive adsorption had a minor influence on their floatability, fine magnesite and dolomite largely decreased the recovery of quartz. Scanning electron microscope (SEM) analysis on the flotation products demonstrated severe masking of fine particles on the surface of quartz. The extended-DLVO (Derjaguin–Landau–Verwey–Overbeek) theory was applied to calculate the interaction energy between the mineral particles, and the results showed that the interaction force between magnesite and quartz and between dolomite and quartz was attractive; therefore, fine magnesite and dolomite particles were easily masked on the surface of quartz. The calculation results agree with the experiment results and explain the mechanism of particles’ interaction and the reasons for the differences in single mineral flotation and artificially mixed minerals flotation. [ABSTRACT FROM PUBLISHER]

Dolomite collected from Surat Thani Province in Thailand was investigated for use as a sorbent for the removal of divalent heavy metal cations from an aqueous solution. The sorbent had a surface area of 2.46 m2/g and a pH of zero point charge (pHzpc) of 9.2. Batch sorption was used to examine the effect of the pH (pH 3–7) on the sorption capacity of Cd2+, Pb2+and Zn2+, alone or together as an equimolar mixture at various concentrations. Alone, each heavy metal cation was adsorbed faster at a higher pH, where the sorption of Cd2+and Pb2+fitted a Langmuir isotherm, but Zn2+sorption best fitted a Freundlich isotherm. Under equimolar competitive sorption, the sorption capacity of each cation was decreased by 75.8% (0.29–0.07 mM/g), 82.8% (0.53–0.09 mM/g), and 95.7% (0.84–0.04 mM/g) for Cd2+, Pb2+and Zn2+, respectively, compared to that with the respective single cation. Desorption of these heavy metal cations from dolomite was low, with an average desorption level of 0.06–17.4%. Furthermore, since dolomite is readily available and rather cheap, it is potentially suitable for use as an efficient sorbent to sorb Cd2+and Pb2+, and perhaps Zn2+, from contaminated water. [ABSTRACT FROM PUBLISHER]

One of the most important elements of furnaces, boilers and other heating units is the structure (lining), usually made of silica-alumina, basic or special refractories. The basic refractories are materials that are increasingly in demand and whose manufacturing involves necessarily the use of MgO and CaO. In this article, the description and characterization of magnesite (MgCO3) and dolomite (Mg,Ca(CO3)2) and their contribution in industrial ceramics-refractories have been reviewed. [ABSTRACT FROM AUTHOR]

Wettability alteration in porous media is one of themechanisms for enhancing oil recovery through injecting low-salinity water into carbonate reservoirs, in which active ions can remove the carboxylic oil component from the rock surface, altering the rock's wettability toward a water-wet condition. This study investigated the concomitant effects of low-salinity water and hydrophilic SiO2 nanoparticles on oil-wet dolomite rock. Results revealed that low-salinity water coupled with hydrophilic nano-SiO2 in oil-wet dolomite rock remarkably affected the wettability alteration of the rock, showing that the simultaneous presence of ions in water and hydrophilic nano-SiO2 led to considerable wettability alteration compared with using just low-salinity water. [ABSTRACT FROM AUTHOR]

Palynological analysis of the Shishtu 2 Member (Shishtu Formation) located in the Howz-e-Dorah area (southeast Tabas, central Iran Basin) suggests a middle Tournaisian-late Viséan age for this rock unit. The Shishtu 2 Member consists of shale, sandstone, dolostone and limestone. Three palynological assemblages are recognised and mainly correlated with the miospore biozones of Northern Gondwana. A microfloristic comparison with other sections in Western Gondwana (South America) is also proposed. We identify a sedimentary hiatus between the Shishtu 1 and Shishtu 2 members. Our findings suggest that the Mush Horizon is the lowermost part of the Shishtu 2 Member, contrary to the Iranian literature where it is considered to be the uppermost part of the Shishtu 1 Member. [ABSTRACT FROM AUTHOR]

The lower–middle Permian Lucaogou (P2l) Formation is a “sandwich-type’’ combination of source rocks and reservoirs that is considered to be a potential tight oil reservoir in the Jimusar Sag (JS). We investigated the P2l Formation using a designated workflow to assess its potential as a viable tight oil reservoir play using geological, petrographical, petrophysical, and geochemical characterisation of core samples. The results showed that the P2l source rocks have a widespread distribution (up to 1500 km2), a huge thickness (up to 160 m), a relatively high abundance of organic matter (averaging 3.12 wt%), a good sapropelic quality, and a moderate thermal maturity. The reservoir consists mainly of dolomites and siltstones, predominantly characterised by secondary dissolved pores, with medium–high porosity (averaging 9.1%) and relative low permeability (averaging 0.26 mD), high abundance of brittle minerals (averaging 87.1%), and low abundance of clay minerals (averaging 11.2%) with low water sensitivity. The results demonstrate that in the JS area the P2l Formation has great potential for tight oil production with its considerable hydrocarbon expulsion quantities, good oil storage capability, and reservoir frackability potential and provide a basis for further evaluation of the tight oil potential of the P2l Formation in the wider Junggar Basin and for identifying similar plays elsewhere. [ABSTRACT FROM PUBLISHER]

This research investigates an enhanced removal rate of tar and trace pollutants (e.g. hydrogen chloride and hydrogen sulfide, H2S) in the gasification of rice straw, using an integrated in situ tar reduction and hot-gas cleaning technique. The gasification temperature was set at 900°C and equilibrium ratio (ER) was 0.30 in the gasifier. In the in situ tar reduction method, the catalyst, dolomite with an amended ratio of 0–15% was introduced to the gasifier. The integrated hot-gas cleaning system applied a multi-packed tower to remove the tar, sulfur and/or chlorine byproduct in syngas at 250°C. The packed materials composed of zeolite, calcined dolomite and activated carbon. The experimental results indicated that the tar concentration of syngas was approximately 20 g/kg. However, in catalytic gasification with 5% dolomite addition, the tar concentration reduced to 17 g/kg. The tar reduction efficiency was approximately 15% by an in situ dolomite addition. When applying the integrated hot-gas cleanup system, the tar was virtually eliminated. The total tar elimination rate was almost 100% and the cleaned syngas could be applied in other energy utilization equipment. On the other hand, the H2S and HCl concentration were 101 ppmv and 991 ppmv, respectively. After the integrated syngas cleaning system, the H2S and HCl were decreased to 7.9 ppmv and 410 ppmv with a removal efficiency of 92.1% and 58.6%, respectively. It can be concluded that combining the in situ method with the integrated syngas cleaning system can effectively reduce the amount of byproduct and enhance the syngas quality in the gasification of rice straw. [ABSTRACT FROM AUTHOR]

A local succession of interbedded dolostone, limestone and glauconitic sandstone in the central Daly Basin of the Northern Territory, dated as Early Ordovician, has for many years appeared incongruous in terms of lithology and age relative to mapped formations of the Cambrian Daly River Group. Geological mapping and stratigraphic drilling have now shown that this interval, recently named the Florina Formation and described here, unconformably overlies the karstified surface of the uppermost formation of the Daly River Group, the Oolloo Dolostone. It is the youngest formation of the Daly Basin succession, but due to the lengthy hiatus between it and the underlying units, it is not included within the Daly River Group. It comprises three intervals of carbonate rocks alternating with thicker intervals of siliciclastic rocks. The latter are viewed as forming under dominantly moderate energy, shallow marine conditions with sediments derived from a distant terrigenous source. The carbonate rocks were dominantly subtidal, too far offshore to receive significant amounts of terrigenous material but shallow enough to be above storm wave base. The Oolloo Dolostone is formally divided here into two members, the lower Briggs Member and the upper King Member. Both consist largely of dolostone, but the Briggs Member is typically well bedded, contains ooids and has a minor component of quartz sand. It accumulated mainly as ooid shoals seaward of tidal flats. The overlying King Member is massive to coarsely bedded with only traces of terrigenous sediment and was deposited in deeper water seaward of the Briggs Member. [ABSTRACT FROM AUTHOR]

The present study aims to evaluate carbon recovery and analytical precision of two methods based on dry combustion for organic carbon (OC) quantification in base metal mine tailings: (1) IC subtraction method (inorganic C(IC) measured and subtracted from total C) and (2) direct OC quantification after acid pretreatment. Results showed IC subtraction method effectively hydrolyzed a range of IC minerals [calcium carbonate (CaCO3), magnesium carbonate (MgCO3), dolomite, magnesite, calcite] with satisfactory IC (as CO2released) recovery (87–103 percent). In the direct OC quantification method, 5 M hydrochloric acid (HCl) pretreatment resulted in a satisfactory recovery (76–92 percent) of most organic compounds [ethylenediaminetetraacetic acid (EDTA), cellulose, plant litter, and charcoal], except for water-soluble OC (sucrose, 40 percent recovery). The precision of both methods declined when C levels were <5 g kg−1with RSD (Relative Standard Deviation) > 10 percent. The OC values in test samples of base metal mine tailings were comparable between the two methods. However, IC subtraction method is not applicable for tailings with low OC levels (<5 g kg−1) until the precision is substantially improved. Moreover, compared to the IC subtraction method, OC values are significantly lower in direct OC quantification method for tailings with high OC levels. [ABSTRACT FROM PUBLISHER]

Dolomitized burrows in the Mississippian (Visean) Debolt Formation of northwestern Alberta, Canada form the primary reservoir intervals in the Dunvegan gas field. Sedimentological and ichnological analyses suggest a carbonate ramp setting that includes subenvironments such as sabkhas, hypersaline lagoons, restricted subtidal lagoons, intertidal mud flats, and peloidal shoals. Dolomitization occurs primarily within oxidized muds and highly bioturbated sediments, with the primary mode being sabkha-associated precipitation. In this context, dolomitization within the burrows also appears to be mediated by sulfate-reducing bacteria. δ18O values for dolomite within burrows (mean 2.4‰) are enriched by 1.3‰ relative to calcite values (mean 1.1‰) within the burrows. This degree of fractionation is similar for dolomite and calcite that have precipitated from the same solution. It is therefore suggested that the protodolomite precipitated in equilibrium with calcite rather than by replacement of pre-existing calcite. Isotopic values of δ13C measured for dolomite associated with burrows (mean 3.4‰) and matrix (mean 3.5‰) is slightly enriched relative to measured calcite values (mean 3.2‰ for matrix; mean 3.1‰ for burrows). These isotopic trends are common for modern dolomite that has precipitated in equilibrium with seawater where concomitant sulfate reduction and organic carbon-oxidation is inferred to occur near the surface. [ABSTRACT FROM PUBLISHER]

Estimating relative permeability curves from capillary pressure data is a well-known technique and the reliability of these techniques for approximation of liquid-gas relative permeability curves had thoroughly investigated. However, there is not enough information to conclude which method is the standard one for calculating oil-water relative permeability curves. The authors utilized various capillary pressure techniques such as the Corey, Brooks-Corey, Li-Purcell, and Li-Burdine methods to calculate oil-water relative permeabilities using the measured oil-water capillary pressure data in drainage process in an oil-wet Dolomite reservoir. Despite wide popularity of Purcell and Burdine methods for calculating relative permeability, the authors used new Li-Purcell and Li-Burdine methods. The calculated results were compared to the experimental data of oil-water relative permeabilities measured in a Dolomite reservoir. The Corey and Brooks-Corey models show an acceptable and nearly exact match with the measured oil relative permeability values. However, the Li-Purcell and Li-Burdine models underestimate the values for wetting phase in most cases. It is also worth mentioning that, except Li-Purcell method, the results of all other methods for calculating nonwetting phase relative permeability are almost the same and they are in good agreement with the measured data. Results of this work reveal that calculation of oil-water relative permeability using the capillary pressure data is also a reliable technique in oil-wet systems. [ABSTRACT FROM PUBLISHER]

Magnesium oxide nanoballs with of 80–100 nm diameters were synthesized by chemical precipitation. The precursor magnesium hydroxide was prepared from dolomite ore as a raw material which was immersed in hydrochloric acid and then reacted with ammonium hydroxide without any surfactant. The effects of calcination temperature and time during the thermal decomposition of magnesium hydroxide precipitates on the crystal growth and morphology of the magnesium oxide particles were investigated by scanning electron microscopy and X-ray diffraction. The results show that the magnesium hydroxide layers collapsed on the (001) lattice surface and generated spherical grains of magnesium oxide with an increase in the calcination temperature. Magnesium hydroxide is completely decomposed to magnesium oxide after calcining at 400°C for 1 h. The crystallite size of the magnesium oxide increases with an increase in the temperature. The calcination time has no obvious effect on the size of the magnesium oxide grains. [ABSTRACT FROM AUTHOR]

Dielectric and electric behaviour of calcite and dolomite aqueous solutions were investigated using dielectric spectroscopy and electric modulus formalism. The electrode polarisation influence was observed in the low-frequency region. The influence of including grain-size (5 µm, 10 µm and 20 µm) concentration (5 × 10−5–10−2 g L−1) and temperature (295–313 K) to dielectric constant, electric modulus and conductivity was established. The Cole–Cole plot showed only one suppressed semicircle with centre below thex-axis, whose diameter changes with the grain diameter size or temperature, confirming one relaxation non-Debye process. The activation energies of conduction processes were calculated. Using the Jonscher power law, we obtained pre-factor A and exponentn. [ABSTRACT FROM PUBLISHER]

We analysed isotopic compositions of metamorphic microdiamond secondary ion mass spectrometry. Typical microdiamonds in this dolomite marble show star-shaped morphologies (S-type) consisting of single-crystal cores and polycrystalline rims. Four S-type microdiamonds and two R-type microdiamonds (single crystals with rugged surfaces) were analysed using a 5 μm diameter ion beam. S-type microdiamonds have heterogeneous carbon isotopic compositions even in a single grain. Analysis of a typical S-type microdiamond (no. xx01-1-13) revealed clear difference in δ13C between core and rim. The rim shows lighter isotopic compositions ranging from −17.2‰ to −26.9‰, whereas the core is much heavier, with δ13C ranging from −9.3‰ to −13.0‰. The δ13C values of R-type microdiamonds fall into narrow ranges from −8.3‰ to −14.9‰ for no. xx01-1-10 and from −8.3‰ to −15.3‰ for no. xx01-1-16. These δ13C values are similar to those of the S-type microdiamond cores. The R-type probably formed at the same stage as the core of the S-type, whereas rim growth at a second stage did not occur or occurred very weakly in R-type microdiamonds. These carbon isotopic data support the two-stage growth of microdiamonds in the Kokchetav ultrahigh-pressure host rock. To explain the second stage growth of S-type microdiamonds, we postulate a simple fluid infiltration of light carbon from neighbouring gneisses into the dolomite marble. [ABSTRACT FROM AUTHOR]

The authors focus on the Arab reservoir of Balal oil field in the Persian Gulf. The major reservoir unit in the interested area is composed of alteration of thin dolomite with anhydrite layers. In the available 3D seismic data, these layers are not resolved and generate a composite detectable seismic response, making reservoir characterization difficult through conventional seismic attribute analysis (using single-attribute transforms). In addition to resolving the major reservoir units the main aim of this study is porosity prediction and making 3D porosity volume for detailed reservoir characterization. For this purpose first the 3D seismic volume was inverted to obtain an acoustic impedance cube using 3 different inversion algorithms. Inversion integrates log and seismic data to a full band acoustic impedance model of Earth. This process improves the vertical resolution and resolving the interested reservoir layers; it is also an important layer property, which usually has close relation with reservoir properties such as porosity, water saturation, and clay content. Among the different inversion methods applied, according to cross-validation results, acoustic impedance derived from model-based inversion has been selected as the main seismic attribute. In the next step, the acoustic impedance attribute besides other attributes extracted from seismic volume were analyzed using multiattribute regression and neural networks (probabilistic, multilayer feed forward, and radial basis function). These linear or nonlinear combinations of attributes for porosity prediction result in the improved match between the derived and predicted porosity. To estimate the reliability of the derived multiattribute transforms, cross-validation is used. Finally, multiattribute transform using stepwise regression for selection of attributes with minimum cross-validation error is selected for porosity prediction. In addition to making a 3D cube of porosity, several porosity maps from different reservoir layers were prepared. [ABSTRACT FROM PUBLISHER]

To evaluate the palaeo-environmental parameters of a portion of the Sardinia–Corsica microplate during the Messinian drop in sea level, we examined the chemistry and mineralogy of upper Tortonian–lower Messinian (late Miocene) clayey continental deposits from NW Sardinia. Differences exist between the uppermost part of the succession, which is devoid of carbonate phases, and the lower part, reflecting changes in provenance and climate. The carbonate-free samples were probably derived from quartzite of the metamorphic basement and were deposited under a climate characterized by alternating dry and relatively wet periods. The other samples were derived from basement phyllite and were deposited under a warm, dry climate that promoted the capillary rise of Ca2+ and bicarbonate from a shallow water table, and therefore, the precipitation of carbonate. This part of the succession contains both calcite and dolomite. The presence of barite indicates an important concentration of SO4 2− in the solution from which the CaMg(CO3)2 precipitated. The formation of dolomite under hypersaline conditions may be explained by bacterial degradation of organic matter, which produced CO2 and ammonia, thereby increasing the solution alkalinity. The succession formed in an oxic environment, except for a calcite-rich level that formed under relatively reducing conditions. For this level, the large amount of calcite and the lack of dolomite indicate an alkaline environment and a very low Mg2+/Ca2+ ratio in the soil solution. These observations, coupled with the reducing conditions, indicate the availability of large amounts of degraded organic matter, probably related to a period typified by a wetter climate. [ABSTRACT FROM AUTHOR]

In this study the modified procedure of the oil agglomeration process was carried out, where the emulsion of dodecylammonium hydrochloride (DDAHCl) solution and kerosene was added to the mineral suspension. The aim of this work was to research the oil agglomeration of dolomite mineral by the contact angle, zeta potential and surface free energy measurements. The relationship between the investigated parameters and the oil agglomeration as well as shear flocculation was revealed. The mechanism of oil agglomeration of hydrophilic particles in cationic-anionic surfactant system has been proposed. It was concluded that oil droplets interact rather with aggregates of particles modified by anionic surfactant than the single mineral particles as was explained for naturally hydrophobic particles. [ABSTRACT FROM PUBLISHER]

The identification of two nucleobases (adenine and hypoxanthine) by Surface-Enhanced Raman Scattering (SERS) on different mineral substrates was adopted as a test case to verify the capability of this analytical technique to detect trace amounts of organic or biological substances deposited over, or contained in, Martian regolith. Raman spectra were collected on polished samples of calcite, dolomite, magnesite, siderite, anhydrite, and gypsum, onto which traces of nucleobases were added. While spectroscopic features of the two nucleobases could not be observed in normal Raman spectrum, the addition of silver nanoparticles allowed easy identification of the vibrational bands characteristic of the two nucleobases. [ABSTRACT FROM PUBLISHER]

The University of Georgia (GA) lime recommendation equation includes a multiplier of 1.5 to account for agricultural (ag) lime that is less reactive than reagent-grade calcium carbonate (CaCO3). Research has not been conducted with ag lime to arrive at this multiplier with GA soils typical of the coastal plain or with ag limes available in GA. These ag limes may differ in their reactivity from others tested previously. The efficiency of five dolomitic ag limes were compared to reagent-grade CaCO3 on two GA soils with different pH-buffering capacities. Reactions other than acid neutralization by lime affected pH, especially in the soil with low pH-buffering capacity. Results from the soil with high pH-buffering capacity yielded multipliers of 1.17, 1.16, 1.48, 1.34, and 1.73 for ag limes 1 through 5, respectively, with an average multiplier of 1.38. Based on these results, continued use of a multiplier of 1.5 is appropriate. [ABSTRACT FROM AUTHOR]

Wettability is an important parameter which affects the shear flocculation and oil agglomeration behaviors of minerals. The critical surface tension of wetting (γc) as a wettability parameter describes wetting characteristics of any mineral. In this study, the correlation of shear flocculation and oil agglomeration processes of dolomite with its wettability parameter is investigated. The experimental studies have indicated that these processes improved with decreasing wettability depending on the increase of oleate adsorption despite a simultaneous increase in the zeta potential of dolomite. On the other hand, the flocculation and agglomeration of dolomite decreased with decreasing surface tension and did not occur below a particular value of surface tension, corresponding to the critical surface tension of wetting (γc) and the critical solution surface tension (γc-a) values, respectively. Also, the γc-a values are slightly higher than the γc values, indicating that the agglomeration of the particles requires a lower wettability. [ABSTRACT FROM AUTHOR]

Recent observations derived from actual structures show that compared to other concretes, concretes containing high levels of carbonates (such as limestones and dolomites) tend to have longer reinforcement initiation times and also much longer durations before the occurrence of active corrosion causing obvious damage. This is provided that the structures do not suffer from poor workmanship, alkali reactions or other failure mechanisms. These findings are reviewed and a small number of additional examples given. The observations are consistent with careful laboratory experiments available in corrosion science literature. However, they are not consistent with the conventional wisdom that associates reinforcement corrosion initiation with the formation of calcium carbonate within the concrete matrix, such as caused by the influx of carbon dioxide from the environment. To cause initiation other processes, such as alkali leaching, must occur to lower the pH to around 8.5 or lower. Only this level of pH is consistent with electrochemistry fundamentals for initiation of steel corrosion. These observations have implications for achieving durable concrete structures. [ABSTRACT FROM AUTHOR]

Modern medicine utilizes a variety of Earth materials for ingestion, ranging from alum to zeolites, for palliative and curative purposes. Human consumption of Earth materials such as loess, salt, and pulverized limestone are quite common. Many antacid pills such as Tums and Rolaids have calcium carbonate or calcite as their main ingredient. The purpose for taking in these natural materials includes ameliorating nutrient deficiency, illness, and detoxification. More than 50 species of animal have been reported to ingest various types of clays, salt, and other Earth materials, typically at sites referred to as 'licks'. It has been suggested that these behaviours not only provide needed nutrients but also deal with intestinal parasites and other maladies. Minerals such as zeolites represent a popular feed additive for livestock to help with gastrointestinal problems. [ABSTRACT FROM AUTHOR]

Soil washing is one of the methods used to remediate soil contaminated with heavy metals, and when the contaminated elements have been effectively removed the washed soil can be used for agriculture. Soil washing was conducted using 0.5 mol L−1 CaCl2 solution at pH 4 as an extracting agent to remediate a paddy field soil contaminated with Cd. Dolomite powder was applied to neutralize the soil to the original pH 6.2. After CaCl2 washing, the content of Cd extractable in 0.1 mol L−1 HCl decreased from 2.4 to 0.8 mg kg−1. Subsequently, a pot experiment was carried out to evaluate the effect of soil washing on Cd concentration in polished rice (Cdpr) for three successive years. Using the washed soil, Cdpr was ≤ 0.2 mg kg−1 with and without a treatment that simulates midseason drainage, whereas it was > 0.5 mg kg−1 in the unwashed soil with the midseason drainage treatment. The reasons for low Cdpr growth in the washed soil were the low content of exchangeable Cd in the soil and the resultant high soil pH (> 7). To evaluate the effect of soil pH on Cdpr in the fourth year, we adjusted soil pH to 5 with H2SO4 before transplanting rice seedlings. The Cdpr in the washed soil with the midseason drainage treatment increased to 0.47 mg kg−1, whereas it was less than 0.2 mg kg−1 under continuous flooding. Thus, high pH or whole season flooding are important to keep Cdpr at ≤ 0.2 mg kg−1 even after soil washing. With the application of dolomite and other ordinary fertilizers, soil properties were little affected by the present soil washing procedure because the difference in rice yield between the washed and unwashed plots was not significant within each year. [ABSTRACT FROM AUTHOR]

The article focuses on significant road-cut localities for mineral specimens in Saint Lawrence County, New York. The site has produced thousands of excellent specimens of calcite and dolomite for the past 40 years. Descriptions of the geology of the locality as well as the other mineral specimens collected from the area such as goethite, graphite, marcasite and quartz are provided.

Three sedimentary subenvironments, palustrine (GP), marginal lacustrine (GML) and central lacustrine (GCL), were compared regarding water chemistry and microbial activity in order to explain the differences in the carbonate mineralogical composition of the upper sediment layer in Gallocanta Lake, a shallow hypersaline environment in Northeastern Spain. Horizontal heterogeneity was considerable, salinity ranged from 5 to 116 (‰) for the GP and GCL subenvironments respectively. Sulfate, Mg 2 + , and Ca 2 + concentrations covaried among them and with salinity. The relative abundance of Mg-bearing carbonates, including high-Mg calcite, dolomite and hydrated Ca-magnesite, increased with the salinity. They were absent from the GP subenvironment, where only calcite precipitates, and maximum abundances were found in the GCL subenvironment (61%), where salinity, sulfate, and Mg 2+ concentrations were highest. Every subenvironment presented specific microecological characteristics. The microbial community of the GCL subenvironment lacked of oxygenic photosynthesis, while the microbial communities of GML and GP subenvironments were photosynthetically active. Vertical profiles of sulfide and pH at the water-sediment interface revealed clear differences between the GCL and GML subenvironments as well. Sulfide was detected below the oxic layer in the GCL subenvironment and increased with depth, but it was undetected in the GML subenvironment. The precipitation of Mg-bearing carbonates with different Mg:Ca proportions occurs at different stage along a biogeochemical gradient, where increasing salinity and sulfate content favour the anaerobic oxidation of organic carbon by dissimilatory sulfate reduction. [ABSTRACT FROM AUTHOR]

Presents information on localities in Wyoming that produce either pseudomorphs or mineral inclusions. Mistake made by W. C. Knight in reporting about pseudomorphs and hanksite; Discovery of calcite after shortite in Sweetwater County according to Ray Harris of the Wyoming Geological Survey; Location of dolomite after aragonite in east of Lovell in the Big Horn Basin.

The attrition behavior of a dolomite during fluidized-bed calcination and sulfation was investigated in a bench-scale apparatus. Operating conditions of the bed were those typical of atmospheric bubbling fluidized-bed combustion. Batchwise experiments were carried out in order to study the influence of the chemical reactions on the parallel phenomena of particle fragmentation and abrasion in the bed. To this end changes of particle size distribution and fines elutriation rates were followed throughout conversion during both sequential and simultaneous calcination and sulfation. The study was complemented by SEM/EDX analysis of polished sulfated particle cross sections in order to relate the sorbent attrition propensity to the changes of particle morphology upon sulfation. [ABSTRACT FROM AUTHOR]

This review analyzes various ways by which the surfaces of clay particles and related minerals can be non-covalently modified, as well as some of the analytical approaches with which these surface modifications can be measured and quantified. Among the principal methods of modification of the surface properties of clays and other metal oxide surfaces is treatment with cationic surfactants comprising long-chain alkyl groups. Using the Cassie equation, the percentage coverage by alkyl groups can be ascertained, from advancing contact angle data. Also, by measuring both advancing and retreating contact angles (e.g., with drops of water) on various surfaces, the percentage liquid coverage of such surface (or, if one wishes, the percentage contamination by the contact angle liquid) can be ascertained, using the Cassie equation. It was found that talc, treated with octadecyl amine (OA) became 100% covered with octadecyl groups when mildly heated with 1 wt.% OA. Treatment with higher concentrations did not increase the coverage, but gave the appearance as if the particles were covered with pentyl, not octadecyl groups, judging by the lowering of the apolar surface tension component of the treated talc surface. Coating of glass or mica surfaces with hexadecyl groups, via hexadecyl-quaternary ammonium groups, yielded about 42% coverage. As an improvement, coating with hexadecyl cationic surfactants yielded 82% coverage. However, when coating was done by application of pre-compressed monolayers formed on a Langmuir trough, 100% coverage (of eicosyl groups) could be achieved. Finally, if solidity of attachment, in addition to 100% coverage, is needed (as is very desirable in coatings applied to mica-covered half cylinders in Israelachvili's force balance), the compressed Langmuir trough layer approach, coupled to a further 2 hours worth of annealing at 100°C yields the most robust attachment, as shown by Wood and Sharma (Wood, J.; Sharma, R. How long is the long-range... [ABSTRACT FROM AUTHOR]

The influence of operating parameters such as sorbent properties and reaction temperature on sorbent attrition, sulfur uptake, and particle sulfation pattern during fluidized-bed desulfurization is assessed. Sulfur distribution throughout the particles is evaluated by means of a novel quantitative automated statistical procedure. With the aid of this technique, energy dispersive X-ray sulfur mappings of cross sections of sorbent particles are converted into sulfur distribution density functions, which can be directly related to the prevailing particles sulfation pattern. This procedure is applied to samples of three different sorbents (two limestones and one dolomite) sieved in three particle size ranges and batch-wise sulfated in a fluidized bed at three different temperatures. This analysis is complemented by parallel measurement of calcium conversion degree and elutriated calcium mass during the sulfation tests, as well as by visual inspection of scanning electron microscope micrographs of cross sections of spent sorbent particles discharged at the end of the tests. Experimental results show that the two limestones achieve a larger final sulfation degree than the dolomite. For one of the limestones it was found that the maximum sulfation degree was higher the smaller the particle size and the lower the bed temperature. Results of the statistical analysis on spent sorbent particles reveal that, for most samples, a core-shell sulfation pattern is established. Departure from the core-shell pattern is shown by the finest sorbent particles and by sorbent reacted at the lowest bed temperature investigated, in which a uniform sulfur distribution is achieved consistently with sulfation degree results. The influence of particle size and reaction temperature on sulfur uptake is interpreted in light of the significance of kinetic and intraparticle diffusional resistances assessed by the evaluation of particle Thiele moduli. [ABSTRACT FROM AUTHOR]

Lime and wood ash may be useful to improve acidic forest soils. A field experiment was conducted in a pine stand on a sandy podzol at Fuhrberg, Germany, which involved an application of dolomitic lime (3 t ha[sup -1]) with three replications or wood ash (4.8 t ha[sup -1]) without replications on the forest floor. During the 2 yr study period, lime affected the soil solution composition only slightly. Ash had a marked effect on solution chemistry of the mineral soil at 10 cm and the pH values dropped temporarily from 3.7 to 3.1. Nineteen months after the treatments, exchangeable calcium in the organic layer and mineral soil increased by 222 (lime addition) or 411 kg ha[sup -1] (ash addition) and exchangeable magnesium increased by 101 (lime addition) or 39 kg ha[sup -1] (ash addition). After ash addition, no marked change in heavy metal content was found below 4 cm of the organic layer. In the ash treatment, the potassium concentration of the 1-yr-old pine needles increased from 5.6 to 5.9 g kg[sup -1]. This study suggests that ash from untreated wood may be recommended for amelioration of forest soils. [ABSTRACT FROM AUTHOR]

Presents an abstract of the study `Green Dolomite From Mont Saint-Hilaire, Quebec, Canada,' by G.W. Robinson and submitted to the 23rd Rochester Mineralogical Symposium on April 19, 1996 in New York.