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A suite of sulphates from a locality in Lozen ore field in the Eastern Rhodopes has been characterized by chemical analyses and X-ray diffraction. Three mineral species have been identified: epsomite (MgSO4), pickeringite (MgAl2(SO4)4*22H2O) and alunogen (Al2(SO4)3*17H2O). An attempt was made to characterize the phase transformations that occur upon wetting of the studied samples. The results show that at high humidity, pickeringite dissolves, providing constituents for subsequent crystallization of epsomite and alunogen. Further on, upon drying alunogen loses some of its crystallization water and recrystallizes again to pickeringite including magnesium species from the surrounding medium. This study draws light on certain genetic aspects related to the mechanisms and sequence of deposition of sulphate mineralization under similar conditions. [ABSTRACT FROM AUTHOR]

Abstract The effect of relative humidity (RH) and light on the development of epsomite (MgSO4·7H2O) in Winsor & Newton cadmium yellow (CY) and French ultramarine (FU) artists’ oil colour paints was investigated. Tube paint samples were aged for 12 weeks at either 50% or 75% RH, under ambient light (200 ± 1 lx), elevated light (11,807 ± 328 lx), and near-dark conditions. Aged paint samples were characterised using light microscopy (LM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results indicated that ageing at 75% RH in elevated light conditions, promoted the formation of hydrated magnesium sulphate (MgSO4·6–7H2O) crystals on the surface of both paints. The formation of sodium sulphate (Na2SO4) as a degradation product of French ultramarine oil paints after ageing at 75% RH in elevated light conditions is described. The formation of magnesium sulphate crystals in the absence of elevated SO2 is a new finding. For both cadmium yellow and French ultramarine oil paints, the pigments present are a likely source of sulphur, enabling the formation of sulphate salts, i.e., cadmium sulphide (CdS) yellow, and the sulphur radical anions (S3 −) present in ultramarine pigment. Sulphur-containing impurities arising from pigment manufacture are an additional possibility. It was previously theorised that epsomite formation in water-sensitive twentieth century oil paintings resulted from exposure to the elevated atmospheric sulphur dioxide (SO2) levels of the 1950s–1970s. This study demonstrates that hydromagnesite-containing cadmium yellow and French ultramarine oil paints of any period may be vulnerable to water-soluble sulphate salts formation and that this process is promoted by exposure to light and high (75%) RH environments. The formation of sulphate salts as a degradation product is known to contribute toward the development of water sensitivity of modern oil paintings which can pose significant challenges to conservation. Therefore this study highlights the importance of minimising exposure to light and raised relative humidity for paintings containing such CY and FU oil paint passages, to help slow down these types of degradation phenomena which have implications for preservation.

Purpose. Several natural and anthropogenic factors control the hydro-geochemical behavior of groundwater. These factors influence on the quality, even the suitability of this resource for drinking. The main purpose of our study is the application of multivariate statistical methods to compile the mechanisms of mineralization acquisition in confined aquifers. Methods. The adopted method measures the chemical evolution of Ca+2, Mg+2, Na+, K+, HCO-3, Cl-, SO4-2, NO-3, NO-2, NH+4, and PO4-3 using an atomic-absorption spectrometer. The content of nitrogen and dissolved oxygen is measured using a spectrophotometer. Temperature (T°), electrical conductivity (EC), pH and dissolved oxygen are determined using a multiparameter system. Findings. The main results show that 28 water samples from the Mio-Plio-Quaternary aquifer of the Gadaïne-Ain Yaghout plain have chemical facies of chloride, sulfate-calcium and chloride-magnesium types. Originality. The originality of the study is in the demonstration that water acquires its carbonate mineralization at the supply limits. Whereas it acquires its chloride, sodium and sulfate mineralization in contact with terrigenous saliferous formations, as well as in its interaction with the salt chotts formations. The results show a significant variation in the concentrations of chemical elements, in some cases exceeding drinkability standards. Mineralization is mainly caused by the dissolution of evaporitic minerals such as gypsum, halite and epsomite. Practical implications. The practical implications of this study could be resumed in terms of the convenience of multivariate statistical evaluation of complex physical-chemical databases in identifying pollution sources and understanding temporal variations for effective groundwater quality management in semiarid regions. [ABSTRACT FROM AUTHOR]

The effect of relative humidity (RH) and light on the development of epsomite (MgSO4·7H2O) in Winsor & Newton cadmium yellow (CY) and French ultramarine (FU) artists' oil colour paints was investigated. Tube paint samples were aged for 12 weeks at either 50% or 75% RH, under ambient light (200 ± 1 lx), elevated light (11,807 ± 328 lx), and near-dark conditions. Aged paint samples were characterised using light microscopy (LM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Results indicated that ageing at 75% RH in elevated light conditions, promoted the formation of hydrated magnesium sulphate (MgSO4·6–7H2O) crystals on the surface of both paints. The formation of sodium sulphate (Na2SO4) as a degradation product of French ultramarine oil paints after ageing at 75% RH in elevated light conditions is described. The formation of magnesium sulphate crystals in the absence of elevated SO2 is a new finding. For both cadmium yellow and French ultramarine oil paints, the pigments present are a likely source of sulphur, enabling the formation of sulphate salts, i.e., cadmium sulphide (CdS) yellow, and the sulphur radical anions (S3−) present in ultramarine pigment. Sulphur-containing impurities arising from pigment manufacture are an additional possibility. It was previously theorised that epsomite formation in water-sensitive twentieth century oil paintings resulted from exposure to the elevated atmospheric sulphur dioxide (SO2) levels of the 1950s–1970s. This study demonstrates that hydromagnesite-containing cadmium yellow and French ultramarine oil paints of any period may be vulnerable to water-soluble sulphate salts formation and that this process is promoted by exposure to light and high (75%) RH environments. The formation of sulphate salts as a degradation product is known to contribute toward the development of water sensitivity of modern oil paintings which can pose significant challenges to conservation. Therefore this study highlights the importance of minimising exposure to light and raised relative humidity for paintings containing such CY and FU oil paint passages, to help slow down these types of degradation phenomena which have implications for preservation. [ABSTRACT FROM AUTHOR]

The cathedral of Santa María, where the Muñoz Chapel is located, is the most remarkable monument of the UNESCO Wold Heritage City of Cuenca (Spain). This emblematic chapel suffers an intense stone weathering by crystallization of a complex mixture of salts including epsomite, hexahydrite, gypsum, chlorides and phosphates. The salt dynamics is controlled by a variable indoor environment with daily and seasonal cyclicality. A methodology combining salt analysis, environmental monitoring and non-destructive stone inspection was adopted in order to understand the salt crystallization dynamics and finally, to design an adapted preventive conservation plan focused on the mitigation of the salt damages. Moreover, new parameters are designed in order to quantify the microenvironmental variability, establishing a new methodology for the analysis of indoor environments. Obtained results reveal that stone weathering is mainly due to: (1) the transformation of both CaSO 4 and MgSO 4 ·4H 2 O into CaSO 4 ·2H 2 O and MgSO 4 ·6H 2 O, respectively; and (2) the direct crystallization of MgSO 4 ·6H 2 O in the porous system. These phases crystallize as efflorescences and as subflorescences, causing granular disintegration, peeling and scaling on the stone. Several preventive measures are finally proposed, being focused on two main objectives: (1) reducing the access of salts and moisture to the monument; and (2) establishing a nonaggressive environment, keeping temperature and relative humidity constants in the range of 15−20 °C and 40–50%, respectively. This proposed climate range is defined in order to avoid both the crystallization of new salts in the porous system of the stone as well as volume changes of the present salts. This study constitutes a pilot project where to test the efficiency of these preventive measures that could be extensive to the whole cathedral complex. [ABSTRACT FROM AUTHOR]

The Cathedral of Saint Lawrence in Lugano, Switzerland is an important religious and historical site that contains both immovable and moveable works of art. Although the structure itself has changed, it retains many important wall paintings. In 1910, the cathedral underwent comprehensive restoration under the direction of Augusto Guidini and the painter Ernesto Rusca, including executing new paintings on undecorated surfaces, adding decorative features such as frames to some existing paintings, and retouching and filling losses to create a harmonious and coherent scheme in which all phases remained legible. By 2000, conservation issues were evident for all painted surfaces, including efflorescence, flaking paint and losses. From 2009 to 2017 another restoration project was carried out. The conservation of the wall paintings proved to be a complex process and two main aspects were important in informing decisions regarding methodology and treatments: the effects of moisture and climate, and the role of the unifying decorative scheme from the Guidini/Rusca intervention. The success of the recent project rested on prioritising the conservation needs of the paintings, considering the changes necessary to satisfy the religious and public function of the building, and wrestling with the historical, ethical, and material issues connected with the earlier intervention. [ABSTRACT FROM AUTHOR]

Athalassohaline waters that are rich in divalent ions are good analogues for the chemical environments of Mars and the ocean worlds. Sulfate salts, along with chlorides, are important in Mars regolith with Ca, Fe, Mg, and Na counterions. Certain lakes in the Pacific Northwest are saturated with MgSO4 as epsomite. Here we report on the microbial community of Basque Lake, BC, a group of playas that is saturated with MgSO4. More than 60 bacterial isolates were obtained from Basque Lake soils by enrichment culture and repetitive streak-plating using media containing 10% (~ 1.7 M) NaCl or 50% (~ 2 M) MgSO4. Most of the isolates (~ 75%) were Gram-positive, motile, and produced endospores. Isolates related to Marinococcus halophilus and Virgibacillus marismortui dominated the collection. Halomonas and Salinivibrio were Gram-negative genera found at Basque Lake. Nearly all of the Basque Lake isolates grew at 50% MgSO4, with 65% growing at 60% MgSO4. Several isolates could grow in saturated (67%) MgSO4 (aw = 0.90). All of the isolates grew at 10% NaCl with 70% growing at 20% salinity (~ 3.5 M NaCl; aw = 0.82). Basque Lake isolates grew better at basic pH than acidic pH, with 80% growing at pH 9 and 30% growing at pH 10. Only 20% of the isolates grew at pH 5. Numerical taxonomy dendrograms based on 44 phenetic characteristics showed a strong correspondence to phylogenetic trees constructed from 16S rRNA gene sequences. Pyrosequencing of 16S rRNA gene sequences from direct DNA extracts of Basque Lake soils recovered predominantly Proteobacteria (60%), Firmicutes (11%), and unclassified bacteria (27%). Microbes capable of growth under the extreme chemical conditions of Mars are a particular concern for forward planetary protection should they contaminate a spacecraft. [ABSTRACT FROM AUTHOR]

An apparatus is described for the compression of samples to ∼2 GPa at temperatures from 80 to 300 K, rapid chilling to 80 K whilst under load and subsequent recovery into liquid nitrogen after the load is released. In this way, a variety of quenchable high‐pressure phases of many materials may be preserved for examination outside the high‐pressure sample environment, with the principal benefit being the ability to obtain high‐resolution powder diffraction data for phase identification and structure solution. The use of this apparatus, in combination with a newly developed cold‐loadable low‐temperature stage for X‐ray powder diffraction (the PheniX‐FL), is illustrated using ice VI (a high‐pressure polymorph of ordinary water ice that is thermodynamically stable only above ∼0.6 GPa) as an example. A second example using synthetic epsomite (MgSO4·7H2O) reveals that, at ∼1.6 GPa and 293 K, it undergoes incongruent melting to form MgSO4·5H2O plus brine, contributing to a long‐standing debate on the nature of the high‐pressure behaviour of this and similar highly hydrated materials. The crystal structure of this new high‐pressure polymorph of MgSO4·5H2O has been determined at 85 K in space group Pna21 from the X‐ray powder diffraction pattern of a sample recovered into liquid nitrogen and is found to differ from that of the known ambient‐pressure phase of MgSO4·5H2O (pentahydrite, space group ), consisting of corner‐sharing MgO6–SO4 ion pairs rather than infinite corner‐sharing chains. [ABSTRACT FROM AUTHOR]

Seasonal desiccation of Mg 2+ –(Na + )–(Ca 2+ )–SO 4 2− –(Cl − ) saline lakes in La Mancha (Central Spain) that host microbial mats led to the precipitation of hydrated Na-Mg sulphates and gypsum. Sulphates precipitated in the submerged conditions form extensive biolaminites, whilst in marginal areas they produce thin crusts. Sedimentological, mineralogical, petrographic and high resolution textural studies reveal that the crusts were formed within the benthic microbial mats that thrive at salinities ranging from 160 to 340 g·L −1 . The minerals of the crusts are primary bloedite (Na 2 Mg(SO 4 ) 2 ·4H 2 O), epsomite (MgSO 4 ·7H 2 O), gypsum (CaSO 4 ·2H 2 O) and mirabilite (Na 2 SO 4 ·10H 2 O), as well as secondary hexahydrite (MgSO 4 ·6H 2 O) and thenardite (Na 2 SO 4 ). Primary bloedite crystals, which form the framework of surficial and submerged crusts are seen to nucleate subaqueously and grow incorporatively within the matgrounds. Displacive and incorporative epsomite grows on previous bloedite crystals and also on the ground. Mirabilite is precipitated rapidly at the brine-air interface over bloedite and epsomite. Hexahydrite and thenardite are formed due to dehydration of epsomite and mirabilite, respectively. Hydrochemical modeling with PHREEQC indicated that evaporitic biolaminites are forming from brines undersaturated with respect to bloedite, epsomite and mirabilite, which suggests that the microorganisms contribute to the heterogeneous nucleation of the sulphates in the microbial mats. Unlike carbonates, the influence of microbes on the growth and morphology of complicated double salts such as bloedite has not been documented previously and provides a new perspective on the formation of hydrated sulphate minerals that are common on Earth as well as other planets. [ABSTRACT FROM AUTHOR]

The phase stability of epsomite under a high temperature and high pressure were explored through Raman spectroscopy and electrical conductivity measurements in a diamond anvil cell up to ~623 K and ~12.8 GPa. Our results verified that the epsomite underwent a pressure-induced phase transition at ~5.1 GPa and room temperature, which was well characterized by the change in the pressure dependence of Raman vibrational modes and electrical conductivity. The dehydration process of the epsomite under high pressure was monitored by the variation in the sulfate tetrahedra and hydroxyl modes. At a representative pressure point of ~1.3 GPa, it was found the epsomite (MgSO4·7H2O) started to dehydrate at ~343 K, by forming hexahydrite (MgSO4·6H2O), and then further transformed into magnesium sulfate trihydrate (MgSO4·3H2O) and anhydrous magnesium sulfate (MgSO4) at higher temperatures of 373 and 473 K, respectively. Furthermore, the established P-T phase diagram revealed a positive relationship between the dehydration temperature and the pressure for epsomite.

An in-depth scientific survey revealed the deterioration mechanisms affecting the 'Santa Maria della Stella' church in Saluzzo, Italy, where various salt crystallization processes are strongly damaging the building materials and artworks. Rainwater seepage permeates the vault and interior, causing: (1) epsomite growth as interstitial columnar crystals (resulting in pictorial coating detachment) or superficial, powdery efflorescence; (2) formation of nesquehonite/hydromagnesite crusts on wall paintings; and (3) nitratine growth causing pigment staining and detachment. These processes involve selective Mg2+ mobilization from magnesian-lime mortars and bacterial-induced formation of nitrates from guano, with consequent precipitation of degrading salts. The study confirms how characterization of all deterioration agents is fundamental to planning a viable cultural heritage conservation and restoration programme. [ABSTRACT FROM AUTHOR]

Despite the minor amounts of gases dissolved in solutions, they can bring effects on many crystallization systems, which should be regarded as one type of “invisible” impurity. The evidence of the effect of different dissolved gases on crystallization was provided in previous work. The variation of temperature was taken into consideration in this study. CO 2 saturated solutions were prepared and air saturated solutions were used as a comparison. The results indicate that the influence of dissolved CO 2 on crystallization of epsomite is altered with the variation of temperature. At low temperature, dissolved CO 2 tends to suppress the thermodynamics and kinetic aspects of the solutions. With the increase of temperature the trend is reversed, i.e. at high temperature (>30 °C), dissolved CO 2 enhances the relating properties of the solutions. At low temperature, the decrease of the pH value could be the dominating factor. Whereas at high temperature when the dissolved CO 2 is in a supersaturated state, it starts to nucleate and grow, and partially changes into nano- or microbubbles, which can attach on crystal surfaces and disturb the crystallization process just as impurities do. [ABSTRACT FROM AUTHOR]

Pickeringite, MgAl2(SO4)4·22H2O, was observed as efflorescence at the church of Saints Peter and Paul in Largario (Switzerland). The spongy salt crusts formed directly on rusty, deeply weathered gneiss rich in mica. The building stones originate from rocks in the vicinity of the village. On outcrops, similar occurrences were discovered. Ferrous and pyritic gneiss exhibited efflorescences of gypsum, epsomite, potassium alum, and pickeringite in sheltered places. Based on these observations and the known conditions of formation, we conclude that pickeringite resulted as a secondary mineral from weathering of pyritic gneiss. Most likely, weathering happened in an environment where, among other ions, aluminium and magnesium were present, but calcium and carbonate were absent. Such conditions rarely occur. If our hypothesis was confirmed, the fact that an extremely acid, calcium- and carbonate-free weathering system evolves next to lime mortars and plasters would be very surprising. It would imply that restricted zones devoid of a buffering effect develop on a microscopic scale. [ABSTRACT FROM AUTHOR]

Five types of sulfate minerals, namely epsomite, metavoltine, sideronatrite, gypsum and jarosite were found on the core from the Ayukawa-Kita AK-1 well drilled in 1995. They were considered to be precipitated from the sulfuric acid formed by the oxidation of pyrite in the country rock. Their occurrence, powder X-ray diffraction pattern, chemical composition, solubility with water and hydrochloric acid are described in this paper. They should be easily identified as secondary products based on their occurrence, but some of them can be difficult to distinguish from some of the original rock-forming minerals by powder X-ray diffraction patterns, because of their similarities in the patterns. Therefore, it might be necessary to be familiar with secondary products of core samples for analysts. Furthermore, the first thing we have to do is to analyze and grasp the important information of core immediately after the sampling of core before they deteriorate. [ABSTRACT FROM AUTHOR]

We have grown single crystals of M 2+ SO 4 hydrates at 270 K from aqueous solutions in the ternary systems CoSO 4 –MgSO 4 –H 2 O and MnSO 4 –MgSO 4 –H 2 O. These systems exhibit broad stability fields for a triclinic undecahydrate on the Mg-rich side (i.e., Co- or Mn-bearing meridianiite solid solutions) and stability fields for monoclinic heptahydrates on the Mg-poor side (i.e., Mg-bearing solid solutions of bieberite or mallardite). The solubility curves and distribution coefficients, describing the partitioning of M 2+ ions between liquid and solid phases, have been determined by thermo-gravimetric and spectroscopic techniques. A subset of M 2+ SO 4 ·11H 2 O specimens were selected for single-crystal time-of-flight neutron diffraction analysis in order to evaluate preferential occupancy of symmetry-inequivalent coordination polyhedra in the structure. Considering the nearly identical dimensions of the first coordination shells, there is a surprising difference in the distribution of Co and Mn over the two available sites. [ABSTRACT FROM AUTHOR]

The effect of epsomite as flame retardant for wood has been investigated and compared with a commercial boron salt. Both flame retardants have been introduced into wood samples by vacuum impregnation. Epsomite is a hydrated sulphate salt with a water solubility of 731 g L −1 at room temperature. Thanks to this high solubility it was possible to obtain elevated epsomite loadings in comparison with the borax salt. Flame retardancy was evaluated by means of the limiting oxygen index, the dripping test and the exposition to a direct flame (Bunsen test). The results showed that the addition of epsomite increases the limiting oxygen index, delays the time to ignition and the evolution of the temperatures trough the wood. [ABSTRACT FROM AUTHOR]

Objectives: To compare between the two methods of magnesium sulfate administration for duration of 12 versus 24 h after delivery in patients with severe preeclampsia.Method: The study was performed as a randomized clinical trial on 182 cases of severe preeclampsia. In one group, Mg sulfate (MgSO4) was prescribed for 12 h after delivery and, in the other group, it was prescribed for 24 h after delivery. Both groups were compared for occurrence of convulsion and other adverse effects.Results: The women of the two groups did not have significant difference according to age, BMI, parity and gravidity, gestational age at the time of delivery. Also, systolic blood pressure, diastolic blood pressure, antihypertensive use, previous diabetes and renal disorders, gestational diabetes, and proteinuria were similar in both groups before treatment. One woman had convulsion in the 12-h group and MgSO4 was continued for 24 h in this case. Blood pressure, urine volume, and laboratory indexes did not show significant differences between the two groups before and after treatment. Also, adverse effects were similar in both groups. Pain of the injection site was less in the 12-h group (p = 0.048).Conclusion: Administration of MgSO4 for a duration of 12 h after delivery should be considered somehow as effective as 24 h prescription for preventing convulsion after delivery. [ABSTRACT FROM AUTHOR]

Epsomite and hexahydrate occur in the form of efflorescence on the church walls made of pure calcium carbonate – tufa stone. A few sources of magnesium are responsible for the precipitation of Mg-salts at the block surfaces: lime mortar with Mg-rich aggregates, repair lime cement mortar, the dolostone of the rubber core, and the monastery basement composed of Mg-rich rocks. Possible sources of sulphate are: repair lime cement mortar and soil solution. The permanent presence of different solution types in the tufa pore system enabled the precipitation of salts in the following order: calcite/dolomite, gypsum, Mg-sulphate phases, syngenite and blodeite. [ABSTRACT FROM AUTHOR]

We present an ultrasonic and neutron powder diffraction study of crystalline MgSO·7HO (synthetic epsomite) and MgSO·7DO under pressure up to ~3 GPa near room temperature and up to ~2 GPa at lower temperatures. Both methods provide complementary data on the phase transitions and elasticity of magnesium sulphate heptahydrate, where protonated and deuterated counterparts exhibit very similar behaviour and properties. Under compression in the declared pressure intervals, we observed three different sequences of phase transitions: between 280 and 295 K, phase transitions occurred at approximately 1.4, 1.6, and 2.5 GPa; between 240 and 280 K, only a single phase transition occurred; below 240 K, there were no phase transformations. Overall, we have identified four new phase fields at high pressure, in addition to that of the room-pressure orthorhombic structure. Of these, we present neutron powder diffraction data obtained in situ in the three phase fields observed near room temperature. We present evidence that these high-pressure phase fields correspond to regions where MgSO·7HO decomposes to a lower hydrate by exsolving water. Upon cooling to liquid nitrogen temperatures, the ratio of shear modulus G to bulk modulus B increases and we observe elastic softening of both moduli with pressure, which may be a precursor to pressure-induced amorphization. These observations may have important consequences for modelling the interiors of icy planetary bodies in which hydrated sulphates are important rock-forming minerals, such as the large icy moons of Jupiter, influencing their internal structure, dynamics, and potential for supporting life. [ABSTRACT FROM AUTHOR]

Abstract: Radiation-induced free radicals in hydrated magnesium sulfate, which are thought to be present on the surface of Europa, one of the Jovian moons, have been studied by electron spin resonance (ESR). ESR signals of both atomic hydrogen (H·) at g = 2.0023 and sulfite radical () at g = 2.0029 are observed in epsomite (MgSO4·7H2O) and in quenched samples of magnesium sulfate solutions, after gamma-ray irradiation at 77 K. Atomic hydrogen disappears at temperatures above 90 K. The sulfite radical starts to decay above 190 K in the quenched sample of 10% magnesium sulfate solution, whereas in epsomite, it is stable even at 260 K. The sulfite radical accumulates at low ambient temperatures, and is a promising candidate for estimating the age of hydrated magnesium sulfate, especially in extraterrestrial environments. [Copyright &y& Elsevier]

Cranswickite is a newly recognized mineral of composition MgSO4⋅4H2O from Calingasta, San Juan Province, Argentina (IMA2010-016). Cranswickite is monoclinic, space group C2/c,a = 11.9236(3), b = 5.1736(1), c = 12.1958(3) Å, β = 117.548(2)°, V= 667.0(1) ų, Z= 4, dobs = 1.917 g/cm³, and dcalc = 1.918 g/cm³. The mineral occurs 0 as a soft white vein filling in a metasedimentary rock. The atomic structure has been determined by direct methods and refined by Rietveld analysis of powder diffraction data. The atomic structure consists of chains of corner-sharing magnesium-containing octahedra and sulfate tetrahedra similar to the structure of pentahydrite. All the water molecules directly coordinate magnesium in the structure. The five strongest lines in the powder X-ray diffraction data are [dobs in angstroms (I) (hkl)]: 5.259 (100) (200), 3.927 (46) (112̄), 3.168 (45) (113), 4.603 (29) (111̄), 2.570 (23) (311). Infrared and Raman spectra are very similar to the spectra measured from starkeyite. The chemical composition of cranswickite is the same as starkeyite MgSO4⋅4H2O, but starkeyite has an atomic structure where two sulfate tetrahedra and two Mg(H2O)6 octahedra share corners to form a four-membered ring and not a chain as in cranswickite. The new mineral is named in honor of Lachlan M.D. Cranswick (1968-2010), an Australian crystallographer who helped to developed and maintain the Collaborative Computational Project No. 14 in Powder and Small Molecule Single Crystal Diffraction (CCP14). [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]

We present an ultrasonic study of the elastic moduli of epsomite (MgSO4·7H2O) in the temperature range 77-295 K at pressures up to 2.8 GPa. Elastic properties of epsomite MgSO4·7D2O at room temperature conditions (p=0-2.8 GPa) were also measured. The anomalies in dependencies of elastic characteristics were identified as phase transition points. Our research has shown that the elastic properties and the sequence of phase transitions for MgSO4·7H2O and MgSO4·7D2O are very similar at room temperature. The picture of transformations of the compressed epsomite significantly changes below 285 K. [ABSTRACT FROM AUTHOR]

Abstract: Short crystallisation and deliquescence cycles of mirabilite, epsomite and gypsum are identified by using an automated monitoring system on-site. It consists of digital cameras and RH/T sensors which are computer-controlled and connected to the Internet. Digital images are processed to form a time-lapse movie, so that surface alterations are easily recognised. High resolution imaging (6 mega pixels) in combination with various lenses (12–24mm zoom, 28–105mm zoom, 20mm inversed) results in a wide range of precise observation from 7 to 500mm width of image. That is essential for discriminating phase transitions of single crystals at the same time as monitoring the evolution of the efflorescence as a whole. Crystallisation-deliquescence cycles are induced by small temperature and humidity variations. Mirabilite and epsomite undergo phase changes from crystallisation to deliquescence and vice versa at about 83% RH (15–20°C). These equilibrium relative humidities are considerably reduced compared to the pure salt systems as a consequence of mixed salt solutions. Observations confirm predictions by ECOS simulation based on chemical analyses of water extracts from the site. Dehydration of mirabilite is observed when the relative humidity drops below 65% RH. Mirabilite exhibits the most pronounced and rapid phase changes in response to indoor climate variations. As an example, whisker crystals of 1–3mm length grow within one up to some days. Epsomite responds fainter and slower. Crystallisation of gypsum is distinguished by the growth of new crystals on the stone surface. They have a size of about 10μ – which is close to the image resolution – when they appear on the image. Crystallisation is associated with an increased granular disaggregation of the stone surface. Rhythmical crystallisation of gypsum appears to correlate with small relative humidity variations of ±2–5% within a band from 65 to 75% RH in the room. However, this needs to be clarified in detail. [Copyright &y& Elsevier]

Abstract: Since its abandonment 185years ago, the XII century Santa Maria de Bonaval Monastery located in Guadalajara (Spain) has suffered significant deterioration: first the roof was lost, followed by partial collapse of the walls, moisture infiltration and extensive loss of stone surfaces due to salt weathering. This case study is a clear example of the incompatibility of some building materials: in this case, the combination of sulphate-bearing mortars and magnesium-rich stone and mortars leading to extensive weathering by magnesium sulphate crystallization. Samples of plaster, bedding and core mortars, stone fragments and flakes, salt crust and powders were collected, as well stone samples from the historic quarries located close to the Monastery. Characterization by XRD (X-ray diffraction), ESEM-EDS (environmental scanning electron microscopy with energy dispersive X-ray spectroscopy) shows that the most important stone-type used in the structure, dolostone, is mainly affected by magnesium sulphate salts (epsomite, MgSO4 ·7H2O), although other salts as kalicinite (KHCO3) and mercallite (KHSO4) were also detected. The connected porosity and pore size distribution determined by mercury intrusion porosimetry and capillarity behaviour suggest that the core mortar could easily be dissolved and the stone, plaster and bedding mortars are able to transport infiltrating solutions, giving rise to the precipitation of magnesium sulphate in the mortar joints and over the surface of the stone. Due to their chemical incompatibility, the combination of sulphate and magnesium-bearing mortars and stone with high magnesium content appears to be problematic and should be avoided in future restoration work. [Copyright &y& Elsevier]

The sulfation of four types of calcitic and dolomitic lime mortars exposed to SO2 in the presence of particulate matter from diesel vehicle exhaust emissions has been investigated. The binders mineralogy and mortars texture are the main factors influencing the formation of deleterious sulfate salts. The type of binder also influences the pore size distribution and the total porosity of the mortars: for equal aggregate (quartz or dolomite), dolomitic lime mortars have smaller pores and higher porosity than calcitic ones. During the first 24 h exposure to SO2, calcitic lime mortars undergo a higher weight increase than dolomitic ones due to rapid formation of gypsum on their surface. However, at the end of the sulfation test (10 days), dolomitic mortars show a higher weight increase due to massive formation of epsomite and gypsum, which is facilitated by their higher porosity and the high reactivity of Mg phases in the porous and partially carbonated binder. Control samples (not covered with diesel particulate matter) also develop calcium and magnesium sulfates upon long term exposure to SO2. This is due to the presence of uncarbonated Ca and Mg hydroxides that promote SO2 fixation as sulfates. However, the amount and size of sulfate crystals are significantly smaller than those observed on samples covered with diesel particulate matter. These results show that diesel particulate matter enhances the sulfation of lime mortars and demonstrate that sulfation of dolomitic lime is an important mechanism for the in situ formation of highly soluble and deleterious hydrated magnesium sulfates (epsomite and hexahydrite). The use of dolomitic limes in the conservation of monuments exposed to air pollution in urban environments may therefore pose a significant risk. [ABSTRACT FROM AUTHOR]

Abstract: Pure and impurity-added (with KCl and KNO3) MgSO4·7H2O single crystals were grown by the free-evaporation method and characterized by density and DC electrical conductivity measurements. The present study indicates that the conductivity increases with temperature but does not vary systematically with impurity concentration. Activation energies were also estimated. [Copyright &y& Elsevier]