Celestite Minerals Research Articles

High rate X-ray radiation shielding ability of cement-based composites incorporating strontium sulfate (SrSO4) minerals

Abstract Exposure of radioactivity applications should be handled reliably in repositories, radiotherapy rooms, and research centers built with cement-based composites which is generally used as an engineering barrier. The design of certain materials for radioactive exposure requires special handling considering the degradation mechanism of host composite environment and barrier capability. In this study, celestite (SrSO4) minerals having favoring properties for shielding ability was used as aggregates in barrier composites. Strontium mineral-based aggregates were partially replaced with conventional concrete aggregates at different ratios. The high rate X-ray shielding ability and mechanical performance of developed composites were holistically investigated in the presence of real-case radiation. The use of celestite mineral resulted in higher performance both in mechanical and shielding capability of X-rays at a certain level. Microstructural findings also revealed that interface properties of composite paste and celestite minerals were compatible up to 30% of celestite aggregate replacement.

Utilization of low-cost celestite ore in the production of high-quality calcium-strontium aluminate refractory cement

Calcium-strontium aluminate cement (CSAC) has been successfully prepared for the first time from celestite mineral and corundum (α-Al2O3) via solid-state reaction. Various mixing compositions containing 40–70 wt% celestite and 60–30 wt% alumina have been sintered at firing temperatures between 1550 and 1650 °C with an interval of 50 °C. Among these sintered mixes, four cement specimens (CA101-1600, CA101-1650, CA201-1600 and CA201-1650) were selected as the optimal mixes for CSAC preparation based on their physico-chemical and mechanical characteristics. These cement mixes were ground to form a very fine powder with a particle size of less than 4.85 μm and a specific surface area of greater than 3629 cm2/g. Upon mixing these cement mixes with water, they consumed mixing water within a range of 19–27 wt% to form workable cementitious pastes. The initial and final setting times of these four cement mixes were in the range between 80 to 90 min and 290–379 min, respectively. An average compressive strength of approximately ~62 MPa was reached after curing of these cement cubes in a 100% humidity cabinet for 28 days. The main hydration products detected in the cement pastes were strontium aluminate hydrates such as 3SrO·Al2O3·H2O (Sr3A.H2O) and 5SrO·Al2O3·11H2O (Sr5A.11H2O) along with a minority of calcium aluminate hydrate 4CaO·3H2O·3H2O (C4A3.3H2O) and aluminium hydroxide Al(OH)3. The obtained physico-mechanical results of the four cement samples have met the international standard requirements; demonstrating the high-susceptibility of celestite mineral to be utilized as a potential feedstock in the production of CSAC on an industrial scale.

Micron-Nanometer Evaporite Mineral Compositions in the Jiangling Depression, Jianghan Basin, China, by Means of Scanning Electron Microscopy.

Scanning electron microscopy (SEM) was used to analyze and study micron-nanometer evaporite samples collected from Paleocene and Eocene drill cores in the Jiangling Depression. Accordingly, seven beds of potassium-bearing solid rocks were accurately identified. Sylvite, carnallite, syngenite, dolomite, thenardite, anhydrite, glauberite, halite, barite, celestite, and other solid salt minerals were found, and carnallite, syngenite, and thenardite were found for the first time in the Jiangling Depression. Sylvite, syngenite, and carnallite indicate that the Paleogene salt lakes in the Jiangling Depression had evolved to the sylvite stage and that prospecting for solid sylvite would be satisfactory. Micron-nanometer celestite is contained in the evaporites, from which we can infer that strontium may have been provided by deep formation water (or oil-field water). This finding is of great significance to studying the genesis of sylvite sediment in the Jiangling Depression. From the extensive development of primary glauberite beds typical of warm salt minerals in the Shashi Formation, it can be inferred that the late Paleogene paleoclimate in the Jiangling Depression of the Jianghan Basin was dry and hot. Based on the extensive distribution of micron-nanometer pyrite, siderite, iron and Fe₂O₃/FeO ratios in evaporite sediments and color analysis of mudstones, the evaporites in the study area formed in an underwater anoxic, reducing environment during sedimentation. Therefore, the evaporite sediments in the Paleocene-Eocene interval of the Jiangling Depression are proposed to have formed in a saltwater lake sedimentary environment, and the ancient lake was characterized by a deep-water salt lake sedimentary model.

Mechanochemical conversion of domestic celestite mineral to SrC2O4 in the ammonium oxalate media

The main raw material used in the production of Sr metal and its compounds is SrSO4 (celestite) mineral and Turkey has valuable Sr mineral deposits. One of the important steps in the production of Sr compounds is the production of strontium oxalate compound that does not contain alkali compunds as contamination. Strontium is used as a primary raw material in the production of oxalate, superconducting material and luminescence. In this study, the in situ conversion of SrSO4 into SrC2O4.H2O by ammonium oxalate is investigated and the effect of rotation speed, ball / sample ratio and solution concentration on the conversion reaction has been determined. It was found that the conversion of SrO4 to SrC2O4.H2O was increased with the increase in mole ratio of (NH4)2C2O4 to SrSO4. The maximum conversion, above 70 %, was achieved by using (NH4)2C2O4 / SrSO4 mole ratio: 1.5, rotation speed: 500 rpm and ball / sample ratio: 13.

Low-temperature synthesis of SrCrO4 nanorod particles from strontium sulfate

Strontium chromate (SrCrO4) nanorod particles were successfully prepared at low temperature using the chemical precipitation method. In this synthesis process, sodium dichromate and celestite mineral, which is a water-insoluble mineral, were used as starting materials. The morphology and size of the particles obtained were determined by SEM-EDAX analysis. XRD analysis of the synthesized particles revealed an SrCrO4 phase and other phases. The effects of different molar ratios on SrCrO4 formation were investigated. The addition of NaCl has been found to play a significant role in the formation of strontium chromate nanorods, in particle size, particle shape and product composition.

Photocatalysis removing of NO based on modified carbon nitride: The effect of celestite mineral particles

Atmospheric NO is one of the toxic and hazardous gases. Its’ levels are continually rising in recent years. As we known, mineral particles contained in the atmosphere may affect the photocatalytic NO removal process. In this study, we found that celestite modification could greatly improve the activity (about 3.8 times) and stability of g-C3N4 for the photocatalytic NO removal. In our system, celestite particles embed in the N vacancies of g-C3N4. The synergistic effect of celestite and N vacancy is the origin of improved NO removal activity. During the light irradiation, photogenerated electrons can be captured and confined by N vacancy. Meanwhile, celestite can transfer these confined electrons to O2 and produce more ·OH, which could oxidize NO to nitrate. These findings can help us to understand the influence of mineral particles in the photocatalytic NO removal and design highly efficient NO removal phtocatalysts.

The occurrence and origin of celestite in the Abolfares region, Iran: Implications for Sr-mineralization in Zagros fold belt (ZFB)

The major celestite deposits in Zagros Fold belt are associated with coastal marine carbonate and evaporate sediments of Oligo-Miocene Asmari and Lower Miocene Ghachsaran Formations. In the Abolfares region, celestite mineralization is extended in the western limb of Bangestan anticline in the carbonates of Early Miocene (middle part of Asmari Formation), underlying by dolomitic carbonates of Burdigalian. From bottom to top three main types of mineralization can be distinguished in the study area: (1) layer texture resulting from replacement of algal limestone by celestite minerals with some parts showing idiomorphic crystals (geodes) along the walls of the cavities, (2) celestite occurrence as irregular massive shape interconnected small crystals and nodules, and (3) celestite mineralization associated with steeply dipping veins and open space fracture fillings, resulting from late-stage epigenetic processes. Highlightly, the ore-hosting carbonate rocks were deposited in an intertidal – supratidal protected setting with hypersaline conditions, in accordance with other celestite deposits of the Zagros Fold belt. The abundance of diagenetic crystallization rhythmites, carbonate and anhydrite inclusions as confirmed by Laser Raman spectroscopy analysis, high Sr/Ba values (average; 8726.1) and strong negative correlations between SO3 vs CaO (R2 = 0.98), SrO vs CaO (R2 = 0.96) with positive correlations between Ba vs SrO (R2 = 0.54) and SO3 vs SrO (R2 = 0.98) highlight the role of high Sr late-diagenetic brines in replacement of carbonates with celestite minerals. It seems that the inception of compressional folding during or soon after the deposition of the Asmari Formation in the carbonate platform at the margin of NW-trending basin in the foreland of the Zagros orogenic belt lead to the upward refluxing of penetrated high-Sr diagenetic brines and celestite mineralization.

Effect of contact angle, surface tension and zeta potential on oil agglomeration of celestite

The influences of contact angle, surface tension and zeta potential on oil agglomeration recovery of celestite mineral have been investigated in the present work. Therefore, celestite mineral in methanol–water suspension was agglomerated by the use of oil (kerosene) in the presence of sodium oleate as a surfactant. The zeta potential values of celestite surfaces were measured depending on pH and sodium oleate concentration. The zeta potential values of celestite surfaces became negative even more owing to the sodium oleate adsorption. However, this phenomenon did not affect the oil agglomeration recovery at all. It was found that both increasing contact angle and surface tension raised the oil agglomeration recovery of celestite mineral. Eventually, the agglomeration degree of celestite mineral in the suspension was not lower than a particular surface tension value corresponding to the critical solution surface tension for oil agglomeration (γc-a). The γc-a values were slightly greater than the critical surface tension of wetting (γc) values.

Geology, mineralogy, and isotope (Sr, S) geochemistry of the Likak celestite deposit, SW Iran

Celestite mineralization in the Likak deposit is hosted by Early to Middle Miocene Gachsaran evaporitic formation. The celestite-bearing layers are composed of medium- to coarse-grained celestite crystals with different morphologies in a carbonate groundmass. The presence of carbonate and gypsum inclusions within celestite crystals as well as the pseudomorphic habits of some crystals suggests that celestite replaced preexisting carbonate and gypsum. The lithofacies features and faunal assemblage of the host rocks indicate subtidal–supratidal environments of deposition for country rocks. Strontium isotope analyses indicate that Sr originated from Middle Miocene seawater. Sulfur isotopic ratios indicate higher δ34S values in analyzed samples than those of Middle Miocene seawater. These higher values were probably resulted by bacterial reduction of sulfate. Based on petrographic evidences and Sr-isotope ages, it is revealed that mineralization occurred as a late-diagenetic process during deposition of Gachsaran Formation. Taking into account the available data, it can be suggested that precursors of the mineralizing fluids were probably produced by evaporation of seawater in a coastal sabkha setting. As these brines entered into underlying sediments, they leached considerable amounts of Sr from host sediments. Once these Sr-enriched fluids discharged back up into overlying beds containing gypsum and carbonate materials, celestite precipitation took place by replacement of the preexisting minerals as well as by mixing of the mineralizing fluids with sulfate-enriched brines entrapped within the beds.

Comparison of particle size distribution of celestite mineral by machine vision ΣVolume approach and mechanical sieving

A reliable and accurate measurement of particle size and particle size distribution (PSD) is central to characterization of particulate minerals. Using mineral celestite (SrSO 4) as the test material, an inexpensive machine vision approach as an alternative to standard mechanical sieving was proposed and results were compared. The machine vision approach used a user-coded ImageJ plugin that processed the digital image in a sieveless manner and automated the PSD analysis. A new approach of employing sum of volumes (ΣVolume) as weighting factor was developed and utilized in the ASABE standard PSD analysis. The plugin also evaluated 22 significant dimensions characterizing samples and 21 PSD parameters. According to Folk and Ward's classification, the PSD of ball-milled celestite was “very finely skewed” and “leptokurtic”. The PSD of celestite followed a lognormal distribution, and the plot against particle size exhibited almost a linear trend for both machine vision and mechanical sieving methods. The cumulative undersize PSD characteristics of both methods matched closely when the width-based mechanical sieving results were transformed to lengths by applying the shape factor (width/length). Based on the study, this machine vision approach can be utilized for PSD analysis of particulate minerals and similar products.

Magnesite formation by microbial activity: Evidence from a Miocene hypersaline lake

This paper provides an ancient analogue for biologically mediated magnesite in lacustrine hypersaline environments. Thin beds of massive to crudely laminated magnesitic marls occur interbedded with mudstone and evaporite facies deposited in a saline lake-mudflat sedimentary system during the Lower Miocene in the Madrid Basin, Central Spain. Exposure of this succession in a recently excavated tunnel and in collected cores offered a good opportunity to study magnesite precipitates that have been preserved in unaltered conditions by primary evaporitic minerals. Specifically, magnesite arranged as host matrix between and enclosed by displacive halite and glauberite crystals occurs closely associated with abundant microfossils embedded in sheets of organic matter, interpreted as the remains of extracellular polymeric substances (EPS). Even, many magnesite clots are seen to have resulted from the agglutination of fossilized bacterial bodies forming a biofilm. The close and pervasive association of microorganisms and magnesite is used as evidence that microbes played a fundamental role in the precipitation of this mineral. Additional traces of microorganisms and microbial activity observed in magnesite beds include the isotopic ratios in the carbonates, with the δ13C(PDB) value averaging −6.2‰, the presence of carbonaceous film-like structures and the association with patchly-distributed pyrite and celestite minerals. On the basis of the combined sedimentological, mineralogical, chemical and morphological signatures of the magnesitic deposits, it is postulated that carbonate crystals precipitated in microbial mats. Magnesite crystals together with celestite, local barite, and/or pyrite have been also observed to replace silicate and sulphate minerals. It is suggested that magnesite precipitation was biochemically coupled with the early dissolution of the associated sedimentary minerals. Microbes may have used the associated minerals as source of energy and/or of essential elements.

Mineralogy and fluid inclusions study of carbonate-hosted Mississippi valley-type Ain Allega Pb–Zn–Sr–Ba ore deposit, Northern Tunisia

The Ain Allega Pb–Zn–Sr–Ba ore deposit is located in the flysch zone on the Eastern edge of the Triassic diapir of Jebel Hamra. It is part of the extrusive Triassic evaporate formation along the Ghardimaou–Cape Serrat faults. The ore body consists of argilic–dolomite breccias surrounded by argilo–gypsum Triassic formation, which forms the hanging wall of the deposit, and rimmed by the Paleocene marls. The ore minerals show a cap-rock type mineralization with different styles particularly impregnation in dolomite, cement of breccias, replacement ore and open space filling in the dissolution cavities and fractures. Ore minerals include sphalerite, galena, marcasite and pyrite. Principal gangue minerals are composed of barite, celestite, calcite, dolomite and quartz. The ore minerals are hosted by the Triassic carbonate rocks which show hydrothermal alteration, dissolution and brecciation. X-ray – crystallographic study of barite–celestite mineral series shows that pure barite and celestite are the abundant species, whereas strontianiferous barite (85–96.5% BaSO 4) and barian–celestite (95% SrSO 4) are minor. Primary and secondary mono-phase (liquid only) fluid inclusions are common in celestite. Microthermometric analyses in two-phases (liquid and vapour) fluid inclusions suggest that gangue and ore minerals were precipitated by a low-temperature (180 °C) saline (16.37 wt.% NaCl equivalent) solution originated possibly from a basinal brine with some input from magmatic or metamorphic fluid. Based on geology, mineralogy, texture and fluid characteristics, the Ain Allega deposit is classified as a carbonate-hosted Mississippi valley-type deposit.

Hydrogeochemical factors effecting the scaling problem in Balçova geothermal field, İzmir, Turkey

Reservoir fluid compositions have been assessed from analytical data on water samples collected from thermal and cold waters in Balcova geothermal field. The results of mineral equilibrium modelling indicate that the waters, with some exceptions, are systematically supersaturated with respect to calcite, aragonite, dolomite, chalcedony and quartz, but undersaturated with respect to amorphous silica, celestite, anhydrite and gypsum and undersaturated or supersaturated with respect to barite, low-albite, K-feldspar, gibbsite and Fe(OH)3(a). Calculation of mineral saturation states and geochemical analyses of scale and field observations show that carbonate minerals (calcite, aragonite and dolomite) are most likely to be precipitated as a scale type. Besides carbonates, scale formation risk of amorphous silica, Fe(OH)3(a), anhydrite, barite and celestite minerals should be taken into account in some wells and surface equipment. Most of the waters, with some exceptions, have carbonate scaling risk at all temperatures, whereas the other scaling risks only exist over a limited temperature range. While silica, Fe(OH)3(a) and barite show a scaling tendency at low temperatures, anhydrite and celestite scaling occurs at higher temperatures.

Miocene diagenetic and epigenetic strontium mineralization in calcareous series from Cyprus and the Arabian Gulf: Metallogenic perspective on sub- and suprasalt redox-controlled base metal deposits

During the Neogene, celestite deposits evolved in the Neo-Tethys basins, in what is today called the Mediterranean Sea and the Arabian Gulf. Two evaporite deposits, in Cyprus and in Qatar have been investigated from the sedimentological and mineralogical point of view with emphasis placed on Sr, S and Ca isotopes of carbonate, gypsum and celestite. During the early Miocene shallow marine environments occurred in the Gulf region and in Cyprus both of which are abundant in syndiagenetic sulphate minerals. The calcareous environments had a strong impact on the fluid migration leading to the Sr mineralization. In the Gulf region algal biostromes favored the lateral migration of fluids but had a sealing effect so that any epigenetic mineralization based on vertical fluid flow was hampered. In contrast, the Cypriot depocentre overlying the Troodos ophiolite is dominated by patch and knoll reefs (bioherms) which provide enough porosity and permeability to be favorable for the circulation of fluids with a strong vertical component. Owing to these changes in the calcareous host series, epigenetic sulphate mineralization evolved in Cyprus during the late Miocene. This occurred as the Mediterranean Sea gradually became isolated from the open ocean and, as a precursor to the “Messinian salinity crisis” evaporitic brines circulated deep into the Meso-Cenozoic platform sediments and the underlying Troodos ophiolite where these fluids leached some base metals and sulphur for the celestite mineralization. The Red Sea Rifting was at full swing during the Late Miocene and its northern propagation into the Mediterranean Sea is assumed to have had a structural control on the positioning of the Sr deposits in Cyprus. In the Gulf area, the final closure of the Neo-Tethys and Zagros folding terminated deposition of marine calcareous rocks and alluvial-fluvial siliciclastic rocks were deposited across an unconformity. Missing circulation of highly saline brines was responsible for the absence of an epigenetic Sr mineralization of Cyprus-type in the Gulf area. Assemblages of light (e.g. zeolites) and heavy minerals (e.g. rutile, zoisite, clinopyroxene) and Ca isotope analyses support basic igneous rocks as the source for the detrital and dissolved matter in the depositional environments in Cyprus and the Arabian Gulf. The Ca isotope data imply formation of the sulphate and carbonate minerals in a marine environment without significant contributions of more radiogenic 40Ca coming from old continental crust, e.g., the Kyrenia Range or Mamonia Complex, both of which containing rocks as old as Permian. Cyprus-type (bioherm-type) and Gulf-type (biostrome-type) evaporites are potential progenitors of sediment-hosted mineral deposits (SHSCD) or base metal vein-type deposits. Syndiagenetic celestite-bearing evaporites of the Gulf-type are a model source and progenitor of base metal deposits of stratigraphically-controlled fixed or mobile reductants such as Kupferschiefer-type deposits. Is the Arabian Gulf a Kupferschiefer basin in the making? The epigenetic celestite-bearing mineralization of the Cyprus-type reflects an advanced stage of fluid migration relative to the celestite deposits along the Trucial coast but this brine mobilization failed to create a base metal deposit of its own mainly due to the absence of fixed or mobile reductants. These reductants were present in the western Mediterranean regions in Tunisia and Algeria, where evaporite-associated base metal deposits are going to be mined and in the Mesozoic through Cenozoic platform sediments in central Europe, where numerous suprasalt unconformity-related metal deposits were mined in the past.

High arsenic and boron concentrations in groundwaters related to mining activity in the Bigadiç borate deposits (Western Turkey)

This study documents the environmental impacts of borate mines in Bigadiç district, which are the largest colemanite and ulexite deposits in the world. Borate-bearing formations have affected the concentrations of some contaminants in groundwater. Groundwater quality is directly related to the borate zones in the mines as a result of water–rock interaction processes. Calcium is the dominant cation and waters are Ca–SO 4 and HCO 3 type in the mine (Tülü borate mine) from which colemanite is produced. However in the Simav and Acep Borate Mines, ulexite and colemanite minerals are produced and waters from these open pit mines are Na–HCO 3 –SO 4 types. High SO 4 concentrations (reaching 519 mg/L) might be explained by the existence of anhydrite, gypsum and celestite minerals in the borate zone. Groundwater from tuff and borate strata showed relatively low pH values (7–8) compared to surface and mine waters (>8). EC values ranged from 270 to 2850 μS/cm. Boron and As were the two important contaminants determined in the groundwaters around the Bigadiç borate mines. Arsenic is the major pollutant and it ranged from 33 to 911 μg/L in the groundwater samples. The concentrations of B in the study area ranged from 0.05 to 391 mg/L. The highest B concentrations were detected at the mine areas. The extension of the borate zones in the aquifer systems is the essential factor in the enrichment of B and As, and some major and trace elements in groundwaters are directly related to the leaching of the host rock which are mainly composed of tuffs and limestones. According to drinking water standards, all of the samples exceed the tolerance limit for As. Copper, Mn, Zn and Li values are enriched but do not exceed the drinking water standards. Sulfate, Al and Fe concentrations are above the drinking water standard for the groundwater samples.

Leaching of Celestite with Sodium Sulfide

Leaching of celestite mineral, SrSO4, with sodium sulfide, Na2S, was investigated from the point of strontium carbonate, SrCO3, production. Experiments were carried out to explain the conversion mechanism of celestite to strontium disulfide, SrS2, in Na2S solution. Effects of stirring speed, particle size, and concentration of Na2S on conversion were studied at constant temperature and solid‐to‐liquid ratio. The results showed that the rate of conversion mainly depends on Na2S concentration. It was concluded that leaching of celestite in Na2S solution for conversion to SrS2 is possible but slow.

Shear flocculation of celestite with anionic surfactants and effects of some inorganic dispersants

Shear flocculation characteristics of celestite (SrSO 4) mineral have been investigated using sodium dodecyl sulfate (SDS) and Aero 845 as anionic surfactants. The celestite suspension could be flocculated by SDS and Aero 845 in the broad pH range. However, these surfactants were slightly more effective on the celestite suspension at a pH of 7. The shear flocculation of celestite with SDS and Aero 845 increased rapidly with increasing surfactant concentration. However, it decreased at SDS concentrations higher than 45 mg/dm 3, and eventually stabilization of the suspension took place at concentration values above approximately 80 mg/dm 3. From the experiments carried out to determine the effects of stirring speed and flocculation time on the shear flocculation of celestite suspension, it was found that a stirring speed of 500 rpm and a flocculation time of 3 min were required to achieve the maximum aggregation degree of celestite particles. The effects of sodium silicate, sodium phosphate and sodium polyphosphate used as inorganic dispersants on the shear flocculation of celestite were also studied. Sodium silicate strongly prevented the shear flocculation of celestite with SDS. However, the dispersive effect of sodium silicate was low in the presence of Aero 845. In the case of sodium polyphosphate, a dispersive effect on the celestite suspension was not observed for both surfactants. On the contrary, the shear flocculation power values increased slowly in the presence of sodium polyphosphate. In addition, the similar phenomenon also took place for sodium phosphate in the presence of SDS.

Epigenetic origin of celestite deposits in the Tertiary Sivas Basin: new mineralogical and geochemical evidence

The occurrence of celestite in the evaporitic Upper Eocene-Miocene deposits of the Sivas (Ulas) Basin is documented. This paper aims to demonstrate that a group of Tertiary sediment-hosted celestite deposits are epigenetic in origin, rather than syngenetic as has been claimed by a number of previous workers. Thin section petrography, fluid inclusion data, mineral and whole rock geochemistry and isotopic compositions (87/86Sr, 180 and 34/32S) are the main tools employed. The celestite occurs as stratabound, vug-filling, nodular and lenticular types. Petrographic, microtextural (SEM), mineralogical and geochemical analyses indicate that the celestite can be classified as pure, calcareous and gypsiferous varieties. The celestite under polarizing microscope shows xenomorph, pseudomorph and acicular-radial crystal structures. Scanning electron microscope (SEM) analyses reveal abundant zonal structures in single crystals. Ore minerals associated with the celestite mineralization include pyrite (especially bravoite-melnikovite), marcasite, limonite, siderite-ankerite, gold (electrum-nabite), psilomelane, realgar-orpiment, antimony and dedritic chromite. X-ray fluorescense analyses indicate that the celestites contain 53-58 wt.% SrO, 0.05-3.70wt.% BaO, 0.02-3.40b wt.% CaO and 35-44wt.% SO 3 . Average minor element contents are: 0.4 wt.% SiO 2 , 0.9 wt.% Al 2 O 3 , 0.03 wt.% MnO, 0.3 wt.% MgO and 0.3 wt.% Na 2 O. The trace elements recognized are: Mo (1.8 ppm), Pb (18 ppm), W (0.8 ppm), As (2.3ppm), Zn (4ppm) and Cu (7ppm). The homogenization temperatures of fluid inclusions in celestite crystals vary between 210 and 390 °C. Salinity (NaCI equ.) values range from 11 to 23 wt.% NaCl. Fig. 1. A Location of the Tertiary Sivas Basin, Turkey. B Location map of the study area in the Sivas Basin. C Simplified geological map of the study area, showing the location of celestite and celestite-barite (Ba, Sr)SO 4 occurrences. The petrographic, mineralogical, geochemical and isotopic characteristics of the celestite deposits in the Sivas (Ulas) basin are compatible with an epithermalhydrothermal, rather than a sedimentary origin as it was previously proposed. A hydrothermal origin is also supported by the Sr isotope data; since the 8 7 Sr/ 8 6 Sr ratio varries between 0.70590 and 0.70718. Besides, the results of the 1 8 O and 3 4 S/ 3 2 S isotope data are in accordance with the hydrothermal origin.

Origin of Major Karst-Associated Celestite Mineralization in Karstryggen, Central East Greenland

ABSTRACT Celestite mineralization is known from an approximately 80 km(2) area of Karstryggen, on the western margin of Jameson Land in central East Greenland. The Upper Permian Karstryggen and Wegener Halv Formations, which host the celestite, contain dominantly limestones and subordinate evaporites deposited in shallow subtidal to supratidal hypersaline environments. Celestite occurs both in a lower (3-10 m thick) algally laminated limestone unit and in a thick (at least 50 m), overlying, karstified conglomerate/ breccia sequence. Celestite replaces calcite, dolomite and gypsum in the algally laminated limestone and constitutes the last diagenetically precipitated mineral phase found in these sediments. However, all other diagenetic products are of very early, near surface origin, weakening the evidence for the timing of the replacement. In the karstified limestone conglomerate/breccia sequence, mineralization occurs as a replacement of algally laminated limestone clasts, as celestite cement in the karst breccias, and as pockets, lenses and veins of celestite-filled karst fractures and caves. The SrSO4 content is locally up to 80-90% in the karstified conglomerate sequence, but 50-60% is the average grade for an estimated 25-50 x 106T of this sequence in a restricted area around Revdal. This places the Karstryggen celestite occurrence among the largest known in the world. Sr-isotopic values obtained from the celestite show a radiogenic signature for the strontium and preclude a seawater or precursor limestone source of the material. The strontium was apparently delivered by surface and/or subsurface waters derived from the adjacent Caledonian highlands. These waters passed through immediately underlying arkosic redbeds concentrating Sr through the leaching of feldspars. However, in addition to the diagenetic factors, the primary sedimentary history also appears to be important in controlling the location of mineralization. In particular, the localized (tectonically controlled) gypsum basin provided a source of sulfur, whereas early karstification enhanced porosity of the limestones and provided important permeability conduits for subsequent mineralizat on.

Relación entre los parámetros cristalinos de la celestina y su contenido en bario

26 selected samples of celestite minerals belonging to four strontium mineralizations in the eastern part of the Cordillera Betica (Murcia and Almena provinces) are studied by X-ray diffraction and chemical analysis. These samples show a continuous isomorphous series in the SrSO 4 -BaSO 4 system only in the range 0-10% BaO, with a small increase in the cell lattice parameters a, b, e , and V. The orthorrombic cell dimensions were calculated by the least squares method. In this manner we have obtained the following equations by linear regression: a = 8.353 + 7.728.10 -3 x, b = 5.352 + 9.362. 10 -4 x, c = 6.871 + 1.316. 10 -3 x y V= 307.600 + 0.1997x, were x is the BaO tenor in percentaje.