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The composition and distribution of alkylbenzenes, alkyltoluenes, and 2-methyl-2-(4,8,12-trimethyltridecyl)chromans (MTTC) in the aromatic hydrocarbon fraction isolated from the Lower Permian silty-clayey and salt rocks of the Upper Pechora potassium–magnesium salt basin (Yakshinskoe deposit) are presented. The studies have shown the wide distribution of alkylbenzenes and alkyltoluenes under hypersaline environment (stages of the halite and sylvite precipitation) at low organic matter maturity. The revealed differences in n-alkylbenzenes and n-alkyltoluene distributions are associated with the predominance of various biological precursors (halophilic archaea, prasinophytes, planktonic algae, etc.) during the salt deposition of the Upper Pechora Basin. Our data confirmed the predominance of hexadecylbenzene (C22) among n-alkylbenzenzenes under hypersaline environments. The presence of phytanylbenzene and phytanyltoluene was established in the rocks of the Upper Pechora salt basin. It was found that the maximum content of phytanylbenzene is correlated with elevated contents of phytane and hexadecylbenzene, which suggests their common source and allows us to consider these compounds as indicators of paleohypersalinity. The abundance of 5,7,8-trimethyl-MTTC at low concentrations of mono- and dimethyl-MTTC indicates significant input of fresh water into the evaporite basin during the deposition of the underlying rock salt horizon.

The present article reports the recovery of potassium from mica scrap using carbide lime waste and NaCl. The acid leaching of mica [4 M H2SO4 at 90 °C] can recover a maximum of 25% potassium. However, in the chlorination roasting (with CLW and NaCl) water leaching process, it was possible to recover potassium to the tune of 94% [900 °C, 50 min roasting; mica:CLW:NaCl 1:0.75:1]. The formation of water-soluble phase like sylvite (KCl) and water-insoluble phases like anorthite (CaAl2Si2O8) and nepheline (NaAlSiO4) confirms the complete breakdown of the mica crystal structure. The extraction mechanism proceeds with the formation of a transition state followed by the release of potassium as KCl. The characterisation studies using ICP-OES, XRD, FTIR and FESEM support the proposed extraction mechanism. The salt produced by the evaporation of roast-leached liquor confirms the presence of sylvite and halite only, which can be separated to get the fertiliser grade KCl.

In Gulu area, geothermal waters show a high concentration of alkali metals (Li, Rb and Cs) and some other typical pollution elements, e.g. As, Sb and Tl. They are also enriched in the geothermal deposits during the phase separation of silica sinter and residual geothermal water. A comprehensive sequential extraction was carried out on the Gulu silica sinter. The results indicated that significant Li and K amount is bound to the Fe-Mn oxide and the residual fractions of sinter while, the elements (B, Cs, Rb, As, Sb and Tl) are predominantly concentrated in the sinter crystal lattices. In addition, the elemental distribution law during phase separation of the residual geothermal water and associated evapoconcentrated deposits is also uncovered in this study. With the respect to the system of the natural silica sinters precipitated from the mother geothermal water, complex variations occur during the trace elements partition between the mother water and associated deposits under evapoconcentration. Thus, the miscellaneous minerals (Li, Rb, K, Cs and B) are also distributed in the solid phases when special minerals such as opal, borax or sylvite precipitate from the residual fluids. This confirms that the valuable minerals of K, B, Cs, Rb or Li can precipitate when the geothermal water is evapoconcentrated to a certain degree and within a very concentrative stage of density. However, these elements are remarkably depleted in the residual geothermal fluid at the stages corresponding to the precipitation of these minerals while they are highly enriched in the mother fluid during the late stages of the evapoconcentration. Thus, it can be stated for the first time that the high concentration of these elements in the residual waters at the final stages will be certainly used in the future. In contrast, the concentration of pollution elements (As, Sb and Tl) of the geothermal solids is higher in the early stage of the opal precipitation, while it is lower in the later stages. The concentration of these elements (As, Sb and Tl) in residual geothermal fluids distinctly increases and is very high at the final stages of the evapoconcentration. This scenario indicates that large quantities of toxic elements such as As, Tl and Sb may degrade the surface and ground waters resources located at or near the geothermal water by mixing process making them unsuitable for drinking or irrigation. Thus, in addition to the thermal energy provided, the geothermal area are very important prospect for exploration and extraction of the mineral resources of the elements such as K, Li, B, Rb or Cs that have very significant economic value. However, percentages of trace elements such as Li, Tl, Rb and K in the exchangeable and carbonates fractions of this sinter suggested that they could become rapidly bioavailable in the geothermal environment.

This article provides data on cristobalite and tridymite from the Arsenatnaya active fumarole of the Tolbachik volcano, Kamchatka, Russia. The minerals occur in associations with fumarolic sylvite, sanidine, cassiterite, hematite, pseudobrookite, johillerite, tilasite, and badalovite. Fumarolic cristobalite is tetragonal (α-modification); the unit-cell parameters for one sample are: а = 4.975 (7) A, с = 6.944 (13) A, and V = 171.89 A3. There are two types of tridymite, that is, monoclinic (MC) and orthoorthorhombic (PO-10), in the Arsenatnaya fumarole. The unit-cell parameters of these tridymite modifications are: a = 18.553 (5) A, b = 5.006 (1) A, с = 25.952 (10) A, β = 117.68 (2)°, V = 2134.3 (11) A3 (MC); a = 9.941 (2) A, b = 17.165 (4) A, с = 82.362 (18) A, and V = 14053.4 (29) A3 (PO-10). Mineral assemblages of cristobalite and tridymite indicate high-temperature formation conditions of these minerals not lower 450–500°С with considerable participation of HCl and HF in process of basalt alteration by fumarolic gas. The surrounding basalt was a source of silicon. This element was probably transported in the form of SiX4, where X = F, Cl.

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.

Two types of potash ores were sampled from the Mengyejing potash deposit (the MPD) which is the only ancient potash deposit ever found in China. Geochemical analyses, including Br, K, Mg and some heavy metals, were performed on those samples. The relatively consistent Br contents (141.42 to 763.67 ppm) in both bedded potash and veined potash ores show that the potash-forming brine was likely derived from seawater. K contents and Br/Cl ratios of the veined potash ores are relatively high in contrast to bedded potash ores. The K/Br ratios of veined potash ores exhibit a positive correlation with Br contents, which is opposite to that of the bedded potash ore of the MPD and potassium-salts from the evaporation of modern seawater. The contents of heavy metals in veined potash ores are much higher than those of bedded potash ores in the MPD and potash in other evaporite basins of the world. Sr and S isotopic compositions of these two types of potash ores suggest that the brines for precipitating veined potash were formed by mixing of connate waters (seawater or/and continental freshwater) and hydrothermal fluids. The geochemical and petrological characteristics of the veined potash ores indicate that the brine for forming veined potash orebodies caused by dissolution of previous bedded potash orebodies by hydrothermal fluids. The veined potash orebodies were formed through a cooling process by which sylvite precipitated first prior to halite.

The effects of high silicon-aluminum coal ashes (Shajuzi coal ash (SJZA) and Pingshuo coal ash (PSA)) on the sintering and fusion behaviors of a potassium-rich biomass ash (cotton stalk ash (CSA)) were investigated by a horizontal tube furnace and an ash fusion temperature (AFT) analyzer. X-ray diffraction (XRD), thermogravimetry and differential scanning calorimetry (TG-DSC) techniques were applied to analyze the mineral transformations and thermal behaviors of the ash samples. As the coal ash mass ratio varied from 0 to 50%, the sintering degree of CSA/SJZA and CSA/PSA mixtures gradually mitigated. The AFTs of the two groups of mixtures all presented parabolic with respect to coal ash ratio. The potassium content in CSA was very high (K2O, 39.55%), and K-containing minerals mainly existed as low melting point (MP) matters, i.e., sylvite (KCl), arcanite (K2SO4), potassium carbonate (K2CO3), and fairchildite (K2Ca(CO3)2). The mitigation of sintering degree was ascribed to a decrease in KCl content with increasing coal ash ratio. When the coal ash ratio was less than 20%, the decrease in AFT was due to the consumption of alkaline earth metal oxide and the formation of K silicate. The conversions of low MP K salts to high MP K–Al silicates (kalsite (KAlSiO4) and nepheline (KNa3Al4Si4O16)) and the formations of other high MP minerals increased the AFTs after adding 20% coal ash. The thermogravimetric analysis showed that the endothermic peak of KCl evaporation weakened to disappear and the exothermic peaks of some reactions enhanced with rising coal ash ratio.

The present paper reports the effective utilization of marble sludge powder (MSP) for the recovery of potash values from waste mica scrap using chlorination roasting-water leaching method. Characterization studies indicated the presence of dolomite as the major mineral phase in MSP, whereas muscovite and quartz were observed in the mica sample. The acid leaching studies suggest a maximum of 22% potash recovery under conditions: 4 M H2SO4 acid, particle size of ∼100 µm, stirring speed of 600 r/min, leaching temperature of 75°C, and leaching time of 90 min. The chlorination roasting-water leaching process was adopted to achieve the lowest level of 80%–90% potash recovery. The optimum conditions for the recovery of ∼93% potash from mica (∼8.6wt% K2O) requires 900°C roasting temperature, 30 min roasting time, and 1:1:0.75 mass ratio of mica: MSP: NaCl. The roasting temperature and amount of NaCl are found to be the most important factors for the recovery process. The reaction mechanism suggests the formation of different mineral phases, including sylvite (KCl), wollastonite, kyanite, and enstatite, during roasting, which were confirmed by X-ray diffraction (XRD) analyses and scanning electron microscopy (SEM) morphologies. The MSP-blended NaCl additive is more effective for potash recovery compared with the other reported commercial roasting additives.

This review work reports the recovery of potassium from different rocks and mineral sources. The global demand for potassium is rising consistently due to the growth of agricultural production. A major portion of the world potassium production is consumed in making of fertiliser; however, other uses include those in pharmaceutical, glass, ceramic, food and detergent industries. The availability of soluble potash minerals (sylvite, kainite and carnallite) in different countries like Canada, USA, Israel and Russia makes them as major potash producers, whereas agricultural-based countries like Liberia, Somalia, Central African Republic, Thailand, Indonesia and Malaysia including India meet their potassium requirement through import only. On the contrary, the availability of huge potassium-bearing rocks/minerals (like nepheline syenite, feldspar, mica, glauconitic sandstone) in these countries containing around 4–17% K2O would be a prospective for commercial production of potassium. The potassium recovery from minerals/rocks is very complicated due to the uniform distribution of potassium throughout the crystal structure. Different physico-chemical separation methods like bioleaching, chemical leaching, flotation and roast leaching have been discussed for the successful recovery of potash values from these rocks/minerals. However, the recovery of potassium from hugely available seawater using the chemical precipitation, solvent extraction, membrane separation and ionic exchange methods is not cost-effective due to the low concentration of potassium.

Producing biochar from various agricultural and industrial biowastes through pyrolysis is recognized as an eco-friendly approach for solid waste management and remediation of contaminated soils. However, it remains debatable which type of feedstock and pyrolysis temperature could create biochar with better surface functionality and more suitable specific end use. Biochars prepared from rapeseed residue and rice straw at different pyrolysis temperatures (300 and 550 °C) were characterized using various chemical, physical, and spectroscopic techniques. Rapeseed residue and rice straw biochars produced at 550 °C had high pH (9.98 and 10.85, respectively), due to the decrease in total surface acidity with increasing temperature as demonstrated by Boehm titration data, and their high ash contents (18.70% and 24.21%, respectively). The negative charge on high-temperature biochar particles increased with pH, which was confirmed by the reduced zeta potential values (− 42.33 mV for rice straw biochar and − 31.86 mV for rapeseed residue biochar). The mineral phase of both biochars was dominated by sylvite and a small amount of dolomite and calcite, whereas quartz was only found in rice straw biochars. A pyrolysis temperature of 550 °C is suggested for producing biochars that can potentially immobilize toxic elements in the soil.

During the late Neoproterozoic, the Salt Range in Pakistan was one of the regions where the Tethys truncated and marine strata developed. The numerous transgressions and regressions that occurred during that period provided enough initial material for the development of marine evaporites. The geology of the Salt Range is characterized by the presence of dense salt layers and the existence of four regional and local scale unconformities. These thick salt deposits geologically favor potash formation. Here we coupled chloride isotope geochemistry and classical chemistry of local halite samples to assess the extent of brine evaporation that ultimately formed the salt deposits. Our results indicate that evaporites in the Salt Range area are Br-rich and precipitated from seawater under arid climate conditions. The corresponding δ37Cl values vary from –1.04‰ to 1.07‰, with an average of –0.25‰ ± 0.52‰, consistent with the isotope range values reported for other evaporites worldwide. The positive δ37Cl values we obtained indicate the addition of nonmarine Cl, possibly from reworking of older evaporites, the influx of dilute seawater, the mixing of meteoric and seawater, and the influence of gypsum-dehydration water. The negative Cl isotope compositions (δ37Cl < –1‰) indicate that brines reached the last stages of salt deposition during the late Neoproterozoic. We conclude that the Salt Range Formation could be promising for K-Mg salts.

The new alluaudite-group mineral badalovite was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka, Russia. It is associated with hematite, tenorite, cassiterite, johillerite, nickenichite, calciojohillerite, bradaczekite, metathénardite, aphthitalite, langbeinite, calciolangbeinite, sanidine, fluorophlogopite, fluoborite, tilasite, anhydrite, pseudobrookite, sylvite, halite, lammerite, urusovite, ericlaxmanite, arsmirandite, svabite, krasheninnikovite, euchlorine, wulffite and alumoklyuchevskite. Badalovite forms oblique-angled prismatic crystals up to 1 mm × 1 mm × 5 mm, typically combined in groups or crusts up to several hundred cm2 in area. The mineral is transparent, green, grey, yellow or colourless, with vitreous lustre. It is brittle, the Mohs hardness is 3½. Cleavage was not observed, the fracture is uneven. Dcalc is 4.02 g cm–3. Badalovite is optically biaxial (–), α = 1.753(3), β = 1.757(3), γ = 1.758(3) and 2Vmeas. = 50(10)°. Chemical composition (wt.%, electron-microprobe; holotype) is: Na2O 9.23, K2O 0.19, CaO 2.04, MgO 13.78, MnO 0.31, CuO 0.12, ZnO 0.24, Al2O3 0.06, Fe2O3 12.77, TiO2 0.01, SiO2 0.06, P2O5 0.33, V2O5 0.05, As2O5 61.51, SO3 0.02, total 100.72. The empirical formula based on 12 O apfu is Na1.67Ca0.20K0.02Mg1.92Zn0.02Mn0.02Cu0.01Fe3+0.90Al0.01(As3.01P0.03Si0.01)Σ3.05O12. The simplified formula is Na2Mg2Fe3+(AsO4)3. Badalovite is monoclinic, C2/c, a = 11.9034(3), b = 12.7832(2), c = 6.66340(16) Å, β = 112.523(3)°, V = 936.59(4) Å3 and Z = 4. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 6.41(38)(020), 5.505(20)(200), 3.577(23)($\bar{1}$31), 3.523(25)(310), 3.211(46)($\bar{1}$12), 2.911(28)($\bar{2}$22, $\bar{3}$12), 2.765(100)(240, 400) and 2.618(26)($\bar{1}$32). The crystal structure was solved from single-crystal XRD data with an R1 of = 2.49%. Badalovite is isostructural with other alluaudite-group minerals. Its simplified crystal chemical formula is A(1)NaA(1)’□A(2) □A(2)’NaM(1)MgM(2)(Mg0.5Fe3+0.5)2(AsO4)3 (□ – vacancy) and the end-member formula is NaNaMg(MgFe3+)(AsO4)3. The mineral is named in honour of the outstanding mineralogist and geochemist Stepan Tigranovich Badalov (1919–2014).

The Mangka saline hot springs, in the Simao Basin in southwest China, are unique in having relatively large discharge (>10 L/s) from the red beds (relatively poor permeability) and travertine deposition from Cl-Na type hot water with high content of total dissolved solids (10 g/L). The stable hydrogen and oxygen isotopes indicate that the Mangka spring waters are meteoric in origin and the average altitude of the recharge area is estimated as 1,750 m above sea level. The high temperature of the spring water is derived from geothermal heating. The estimated geothermal reservoir temperature range is 86–91 °C and the circulation depths of the spring waters are 2,318–2,454 m. Incongruent dissolution of salt-bearing formations contributes to the mineralization of the Mangka saline hot springs, including dissolution of halite, gypsum, carbonate and sylvite. Some suitable hydrochemical factors provide beneficial conditions for travertine deposition such as a higher CO2 partial pressure of 10–1.94–10–0.9, γCa/γHCO3 (the milliequivalent ratio of Ca and HCO3) ranging from 5.76 to 6.67, and saturation indices for both calcite and aragonite over or equal to zero. There is also a favorable hydrodynamic condition for the spring water flowing down steep slopes and forming fast-flowing shallow channels with a relatively large surface area. The formation of the Mangka saline hot springs is summarized as follows: the groundwater receives recharge of infiltration from precipitation, undergoes deep circulation in the salt-bearing strata, receives heat from the geothermal heat flow, and ascends to the land surface along the permeable fault.

The structure of the phase complex of the Na,K,Mg,Ca||SO4,Cl–H2O six-component system was studied at 50°С in the sylvite (KCl) crystallization field, and the variants how monovariant curves can appear upon the transition of the system from an n-component to an (n + 1)-component state were shown by the translation method.

The giant potash deposit on the Khorat Plateau is one of the most promising targets for exploitation of potassium salts. So far, many researches and geologic survey have been conducted on the giant potash deposits. Hence, it is necessary to make an overall review on the potash deposits. The potash deposit on the Khorat Plateau was formed during the Middle to Late Cretaceous, during which seawater was enriched in Ca2+ and depleted in SO42- compared with those of modem seawater. In addition to seawater, continental water and hydrothermal fluids could have affected the evaporite basins. The seawater was probably derived from Tethys ocean, and the brine should have evaporated to some extent before entering into the basin systems based on the evidence of absence of carbonates and unproportionate sulphate compared with chloride salts. The paleo-climate during Middle to Late Cretaceous was characterized as high temperature and extremely arid environment, which is favourable for deposition of potassium-magnesium saline minerals. The major saline minerals are of anhydrite, halite, camallite, sylvite and, tachyhydrite, with trace amounts of borates. The resources of the potash deposit on the Khorat Plateau could be approximately as much as 400×109 t of camallite and 7×109 t of sylvite. The evaporite sequences have been deformed and altered by postdepositinal processes, including tectonic movements and chemical alteration. Salt domes were formed in the postdepositional processes. Based on the analyses of geophysical surveys and drilling projects, high-quality sylvinite ores are commonly found at the flanks of those salt domes due to incongruent dissolution of camallite. The future potential prospecting areas for the high-quality sylvinite ores would be on the edges of the Khorat Plateau.

This study aims to determine the major factors controlling the qualitative characteristics of groundwater and examine the drinking and irrigation suitability in the Marathon basin, NE Attica, Greece. In this frame, a total of 25 groundwater samples were collected from irrigation wells during October 2014. The dominant ions are Cl− for anions and Ca2+ for cations in the study area. Elevated concentrations of Cl− and Na+ were observed near the coastline indicating a zone of seawater intrusion (SWI). The groundwater quality in the coastal alluvial aquifer system of the Marathon basin is affected by several factors such as water-rock/soil interaction, SWI, reverse ion exchange, and intense agricultural activities. Saturation index (SI) of carbonate (calcite, aragonite, dolomite), sulfate (gypsum, anhydrite), and halide (halite, sylvite) mineral phases were calculated using PHREEQC geochemical software. Carbonate minerals are present in the unsaturated zone (UZ), possibly increasing Ca2+, Mg2+ and HCO3– concentrations when they are dissolved, whereas sulfate and halide minerals are minor or absent in the host rock. The water suitability assessment showed that the groundwater resources are chemical or qualitatively unsuitable for drinking purposes due to the SWI regime and the NO3− pollution, whereas they are suitable for agricultural uses according to various indices (SAR, %Na, RSC, and PI). Keywords: Seawater intrusion, Reverse ion exchange, Coastal aquifer, Multivariate statistical analysis, Groundwater quality

The Khorat Plateau is one of the largest potash deposits in the world. In recent years, exploitation of potash resources accompanied by leakage of underground brines (UB) in potassium-bearing strata has threatened mining safety. However, there is little research on origin of UB in Laos. In this study, twelve samples of UB, salt springs (SS) and river waters were collected in Khammouane mining area, central Laos and analyzed for ionic and boron isotopic compositions. The results show that both of UB, dominated by K+, Mg2+, Na+ and Cl– ions, and SS, enriched in Na+ and Cl–, are chloride-type brines, while river waters abundant in Ca2+ and HC$${\text{O}}_{3}^{ - }$$ ions are carbonate-type waters. K+ (35.1–53.7 g/L) and Rb+ (12.9–16.6 mg/L) concentrations of UB are higher than the peak (25.9 g/L, 9.4 mg/L) of seawater evaporation trajectories (SET). UB is also characterized by high Mg2+ (32.7–68.0 g/L) and Br– (1795.2–2801.3 mg/L) concentrations and its lg(Cl/Br) ratios (1.9–2.1) deviate from the halite dissolution line. These comparisons indicate that the water chemistries of UB are mainly influenced by dissolution of carnallite and sylvite. High Sr2+ concentrations (31.8–58.6 mg/L) in UB might be simultaneously associated with dissolution of potash salt and Ca-bearing minerals (carbonate and anhydrite). The negative saturation indices (SI) of different salt minerals in UB suggest that salt minerals are unsaturated in UB. Meanwhile, boron (B) concentrations (396.0–426.0 mg/L) and δ11B values (+19.8–+21.0‰) of UB fall in between low B–δ11B end member (0.02 mg/L, +2.31‰) of river water and high B-δ11B end member (126.7–890.8 μg/g, +25.94–+32.94‰) of evaporitic minerals. The comparison implies that UB was influenced and mixed by two end members. Therefore, combining with major and trace ionic concentrations, isotopic compositions and lithologies of salt-bearing strata revealed by drillings in mining area, we conclude that the major solute source in UB is derived from dissolution of carnallite and sylvite. These geochemical evidences provide insights into dealing with leakage of underground brines occurred in the underground mining of potash deposits in Laos.

Sulfide assemblages, precious metals, transition metal alloys, and associated accessory phases were characterized throughout the Skaergaard intrusion to better constrain the sulfide saturation history of the intrusion and the role of late magmatic volatiles in modifying the Skaergaard metal budget and distribution. Sulfides in and below the Middle Zone of the Layered Series of the intrusion are readily replaced by low-Ti magnetite. The ratio Σ(low-Ti magnetite mode)/Σ(sulfide mode), indicating oxidation of sulfides, reaches maximum values in the Lower Zone of the Layered Series. Sulfide assemblages below the Middle Zone are typically accompanied by minor biotite, apatite, and rare calcite as well as trace compositionally distinctive clinopyroxene and orthopyroxene. The occurrence of Ag, Au, Pt, Cu, and metal alloys outside of the Middle Zone is further evidence of the Skaergaard intrusion parental magma being S-poor. Native Ag, commonly accompanied by trace amounts of Cl, occurs both in and below the Middle Zone. Evidence of coexisting precious metal + brine assemblages exists where native metals are accompanied by sylvite ± halite and Ag is accompanied by Ag halides. Ag occurrences in the Middle Zone are of irregular morphology with trace Cl ± S ± calcite. Further evidence supportive of a metal + brine assemblage is observed where Ag + quartz is found in an apparent open clinopyroxene-hosted fluid inclusion consisting of Na, Si, Cl, Ca, K, and S. Ag is used to model the behavior of precious and transition metals in the presence of an exsolving fluid phase. Numerical modeling suggests that, in a sulfide-bearing system, residual Ag concentrations and concentrations in the exsolved fluid are most affected at the point where sulfide is lost to a separating volatile fluid phase. It is suggested that, owing to the low-S nature of the Skaergaard system, fractional crystallization and early fluid saturation produced enrichment of Ag, with other precious and transition metals, in the interstitial silicate liquid much higher than normal due to delayed sulfide saturation. As this interstitial liquid evolved, Ag was lost to an exsolved volatile phase of high salinity and migrated upward. A similar process likely occurred for Au and other elements with high affinities for Cl.

As the main resource of potash fertilizer, high grade of sylvite (KCl) is mainly separated from halite (NaCl) in soluble potash ores using flotation. An effective flotation collector determines the separation efficiency of sylvite. However, the collector adsorption mechanism is still the subject of much debate due to high ions concentration in the flotation pulp. This paper studies the hydration status of KCl, the flotation behavior of KCl and NaCl with lauric acid and the interfacial water structure of the soluble salts to provide further insights into the fundamental mechanisms at play. The contact angle measurements and laboratory micro-flotation experiments have shown that both the hydration status of KCl and the flotation soluble salts with lauric acid were dependent on the solution composition. Specifically, it was determined that the addition of Na-ions had an adverse effect on the hydrophobicity of KCl crystals. Both KCl and NaCl can be floated with lauric acid. However, flotation of NaCl is greatly enhanced with the addition of K-ions whereas the flotation of KCl is suppressed with the addition of Na-ions. Sum frequency generation (SFG) measurements have found, most strikingly, more disordered water molecules dominating the "structure maker" salt surfaces in a saturated NaCl solution. "Collins Concept" is employed to explain the specific ion binding behaviors in the flotation pulp.

The present communication describes a novel application of lime mud, a waste material generated in paper/pulp industries, for the recovery of potash values from mica scraps. Characterization studies of the mica scraps using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) indicate the major minerals to be muscovite and quartz while the chemical analysis confirms the presence of K2O to the tune of 7.5%. Lime mud is found to be mostly consisting of calcite and quartz as the major phases. The roast-leach studies using lime mud and NaCl as the additives have been carried out using response surface methodology to optimize the factors for maximizing the potash recovery. Under optimum conditions such as a temperature of 950 °C, a roasting period of 30 min and a ratio of mica: lime mud: NaCl – 1:0.7:0.7, around 99% of the potash value could be recovered. The results, under similar roasting conditions, are found to be comparable to the ones using CaCl2 as the additive. The formation of different phases as analysed using the characterization studies suggests that the mechanism of potash extraction may follow two routes. One of them is the direct reaction of muscovite with CaCl2 (formed due to the reaction of lime mud and NaCl) to form sylvite, anorthite, and kyanite. The other one may be an indirect route in which muscovite at high temperature along with SiO2, forms K-feldspar that further reacts with CaCl2 to give the sylvite phases. It is also noticed that a further increase in roasting temperature to 1100 °C leads to a decrease in potash recovery with the possible reasons being the formation of water-insoluble K-phases like leucite as confirmed in the SEM studies.

Newly formed titanium oxides and zircons have been identified in the salt and suprasalt of the Verkhnekamskoye Salt Deposit. These features have been associated with the hydrolysis of clay material and the release of colloidal titanium and zirconium hydroxide during diagenesis, catagenesis, and hypergenesis. This is made possible by sulfate reduction and the acidic environment, which are caused by the radiation–oxidation of Fe2+ from sylvite and carnallite. Anatase is formed both in the suprasalt and salt measures and, only in the lower part of the salt measures, in the rutile. Such a distribution can be associated both with an increase in the degree of catagenetic transformation of salt rocks with depth and with the composition of coexisting sulfate or chloride brines. A typical form of anatase crystals is pinacoid, but this is replaced by a dipyramidal structure in the carnallite zone, which is the location of the most acidic brine. Three types of twins were recorded for rutile, the formation of which is attributable to the growth of a dehydrated colloid of titanium hydroxide on a finely dispersed aggregate. The impurities V, Cr, and Zr (Al, Si, and Fe) established in the titanium oxides reflect the geochemical specialization of the aluminosilicate terrigenous material sources.

In arid areas, with rivers functioning episodically, alluvial resources are the main source of water. Considering the intensified regulation of discharge in montane catchments, supplying the intermittent rivers, in the nearest future alluvial aquifers will gain key importance for the functioning of people in arid zones. The research aimed to investigate the diversified chemistry of alluvial waters typical of large intermittent river valleys in hot arid zones as well as to analyse processes determining the water chemistry and affecting its diversity. The detailed study, carried out in October 2015, covered the Draa river valley (1100 km total length) in the region of the Mhamid Oasis. The examined water was sampled from all wells found in the study area. Concentrations of the main cations: Ca2+, Mg2+, K+, Na+, NH4 +, and Li+, anions: Cl−, SO4 2−, HCO3 −, and NO3 −, as well as trace elements: Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, and Zn, were identified. Results were analysed with statistical, hydrochemical, and geochemical modelling methods. Alluvial waters of the eastern and western part of the oasis differed in concentrations of numerous components, what resulted from the regulation of irrigation. Specific electrical conductivity showed a 3.5-fold increase, from 3800 to 13800 μS/cm, consistent with the direction of water flow in the oasis, from east to west. Even a greater rise was observed for ions: Cl− (6x), Na+ (5.5x), Mg2+ (5.0x), Ca2+, and SO4 2− (3.5x). Such a composition indicated multiionic hydrochemical type of waters dominated by Na+ and Cl−. Additionally, high Pearson correlation coefficients were recorded for Na+ and Cl− (0.98) as well as Mg2+ and Cl− (0.97). The saturation index suggested that the main water components originated from dissolving of minerals such as halite, anhydrite, sylvite, and gypsum. Groundwater chemistry in the Mhamid Oasis was determined mainly by geogenic processes, such as dissolving of evaporates, precipitation of carbonate minerals, and ion exchange.

The data has been given on the possible commercial potassium content of halogen sediments from the Pogozhskaya rhythmic member within the Western part of the North Caspian depression. It has been shown that the detailed lithological and geochemical studies, with the construction of the thickness maps, allow allocating in the section the most promising intervals with the potassium mineralization, as well as the taking into account the direction of nipping of the productive intervals and, as a consequence, choosing the priority of the sites for prospecting. Chloride type of potassium mineralization is represented by carnallites and sylvinites. The latter are the main source of the potassium ore. Sulfate salt — kainite and kieserite - are allocated only within the North-Western part of the basin. It has been found that the sylvinite layer was formed as a result of entering of the solutions with lower concentration (at the level of the halite stage) to the water basin with the strong brine of carnallite-bischofite stage . It has been revealed that the sylvite from the potash intervals of the section of the pogozhskaya rhythmic member is a product of the decomposition of carnallite.

The new mineral anatolyite Na6(Ca,Na)(Mg,Fe3+)3Al(AsO4)6 was found in the Arsenatnaya fumarole, Tolbachik volcano, Kamchatka, Russia. It is associated with potassic feldspar, hematite, tenorite, cassiterite, johillerite, tilasite, ericlaxmanite, lammerite, arsmirandite, sylvite, halite, aphthitalite, langbeinite, anhydrite, wulffite, krasheninnikovite, fluoborite, pseudobrookite and fluorophlogopite. Anatolyite occurs as aggregates (up to 2 mm across) of rhombohedral–prismatic, equant or slightly elongated along [001] crystals up to 0.2 mm. The mineral is transparent, pale brownish–pinkish, with vitreous lustre. It is brittle, cleavage was not observed and the fracture is uneven. The Mohs’ hardness is ca 4½. Dcalc is 3.872 g cm–3. Anatolyite is optically uniaxial (–), ω = 1.703(4) and ε = 1.675(3). Chemical composition (wt.%, electron microprobe) is: Na2O 16.55, K2O 0.43, CaO 2.49, MgO 5.80, MnO 0.16, CuO 0.69, ZnO 0.55, Al2O3 5.01, Fe2O3 7.94, TiO2 0.18, SnO2 0.17, SiO2 0.04, P2O5 0.55, As2O5 60.75, SO3 0.03, total 101.34. The empirical formula based on 24 O apfu is (Na5.90K0.10)Σ6.00(Ca0.50Na0.13Zn0.08Mn0.03)Σ0.74(Mg1.63Fe3+1.12Al0.15Cu0.10)Σ3.00(Al0.96Ti0.03Sn0.01)Σ1.00(As5.97P0.09Si0.01)Σ6.07O24. Anatolyite is trigonal, R$\bar{3}$c, a = 13.6574(10), c = 18.2349(17) Å, V = 2945.6(4) Å3 and Z = 6. The strongest reflections of the powder XRD pattern [d,Å(I)(hkl)] are: 7.21(33)(012), 4.539(16)(113), 4.347(27)(211), 3.421(20)(220), 3.196(31)(214), 2.981(17)(223), 2.827(100)(125) and 2.589(18)(410). The crystal structure was solved from single-crystal XRD data to R = 4.77%. The structure is based on a 3D heteropolyhedral framework formed by M4O18 clusters [M1 = Al and M2 = (Mg,Fe3+)] linked with AsO4 tetrahedra. (Ca,Na) and Na cations centre A1O6 and A2O8 polyhedra in voids of the framework. Anatolyite is isostructural with yurmarinite. The new mineral is named in honour of the outstanding Russian crystallographer, mineralogist and mathematician Anatoly Kapitonovich Boldyrev (1883–1946).

Six crystalline phases (anhydrite, calcite, gehlenite, halite, quartz, and sylvite) and the amorphous phase in fly ash of municipal solid waste (MSW) were quantified using Rietveld refinement of X-ray diffraction data. Corundum was used as an internal standard for the determination of amorphous phase. Gehlenite was synthesized by the solid-phase method to obtain the pure material for calibration standard. Quantitative values of 4.8, 5.1, 12.3, 9.3, 1.3, and 7.1 mass% for anhydrite, calcite, gehlenite, halite, quartz, and sylvite, respectively, were obtained by Rietveld refinement, in agreement with those obtained using the external standard and standard addition methods. Relative standard deviations (n = 5) of each crystalline phase were 1.6–63%. Monthly variations of crystalline phases of MSW fly ash were observed over a year (2008–2009). High correlation (R = 0.8068) was observed between the concentrations of halite and sylvite, which were derived from kitchen wastes such as vegetables and seasonings. Conspicuous concentrations of calcite and quartz were each observed once at June and December, respectively. Rietveld refinement was applicable as a quantitative method for the determination of MSW fly ash composition profile.