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Summary: Samples were taken from the Winsford salt mine in Cheshire, England, which exploits bedded deposits from the Triassic Period (195-225 million years ago, MYA) and from Boulby potash mine in Cleveland, England, which is Permian (225-270 MYA) and is mined for the mineral sylvite (KCl). Halobacteria and obligately halophilic eubacteria were isolated from several different sample types. The halobacteria were characterized by chemotaxonomic methods and most but not all were shown to be very similar but not identical to those halobacterial types that dominate in highly concentrated surface brines. There was a high degree of similarity between the two mine populations, but some strains were particular to each mine.

Potassium and sodium chlorides in the form of very small sylvite and halite crystals are extremely abundant in the quartz from gold ore at Muruntau2 and point to the importance of chloride-rich solutions during mineralization. Microprobe analyses show that Au, Ag, Pt and Ir are physically associated with the halides. The presence of chloride crystals in the solid quartz (not as daughter crystals in fluid inclusions) explains the much greater chlorine concentrations indicated by neutron activation analysis of whole-mineral quartz than by ion-selective electrode analysis of fluid extracts. The high chloride contents of the ore may seriously interfere with fire assays for gold.

The Dachang tin-polymetallic ore field, Guangxi, People9s Republic of China, is one of the largest in the world and contains the Changpo, Bali, and Longtaoshan tin-base metal deposits, the Dalfulou black shale-hosted cassiterite-sulfide deposit, and the Lamo Cu-Pb-Zn proximal skarn deposit. These are hosted by Devonian carbonate-rich sediments metamorphosed to hornblende hornfels facies near the underlying Yanshanian Longxianggei granite (91 Ma). Plutonic intrusion and relevant mineralization are controlled by the north-northwest-trending Longxianggei and Changpo anticlines. The conduit for distal skarn solutions was a reverse fault (F1). Tin mineralization at Changpo is genetically related to the S-type Longxianggei granite with proximal skarns precipitated near its contact and distal ores 300 to 500 m vertically away from the contact.Hydrothermal alteration is grossly zoned outward from the granite contact as follows: (a) proximal ore skarn zone (garnet and pyroxene), (b) tourmaline-silicified zone, (c) sericite (+ or - cassiterite) zone, and (d) carbonate(-sulfosalt) vein zone. Zones b to d do not occur above the Lamo deposit whereas zone a is missing directly below the large Changpo deposit but occurs lateral to it. Nearest to the granite outcrop, the Lamo Cu-Pb-Zn proximal skarn is developed with a temporal sequence of stages: (A) garnet-vesuvianite-wollastonite + or - diopside, (B) Ca amphibole-epidote-fiuorite-quartz, (C) biotite-sericite-sulfides, and (D) sulfides-carbonate-chlorite. Distal skarns have the following temporally and spatially distributed stages: (1) tourmaline-quartz-cassiterite, (2) arsenopyrite-cassiterite (+ or - other sulfides), and (3) sulfosalts-carbonate (most distal).There is a zonal pattern of both temperatures and ore fluid compositions deduced from fluid inclusions as follows: proximal skarn zone: 450 degrees to 600 degrees C, CO 2 /CH 4 35 wt percent NaCl equiv; tourmaline-silica zone: 350 degrees to 450 degrees C, CO 2 /CH 4 = 0.10 to 10.00, salinity = 12 to 30 wt percent NaCl equiv; sericite zone: 250 degrees to 350 degrees C, CO 2 /CH 4 >10, salinity 2 dominated, no CH 4 , salinity = 6 to 8 wt percent NaCl equiv.Daughter crystals include antarcticite (CaCl 2 . 6H 2 O), halite, sylvite, carbonate, MgCl 2 . 6H 2 O), and fluorite. Thermodynamic calculations based on fluid inclusion composition and measured temperature show that f (sub O 2 ) values of the ore-forming stages were very low, well below the FMQ buffer and increased from early to later stages. Tin precipitation was affected by a low oxygen fugacity of ore fluids partly resulting from the occurrence of black shale, and a decrease in temperature.

Bulk chemical analysis shows most elements enriched over average soil abundances except for Si, which is 60% of the concentration in soils. Eleven minerals were identified using pownder X-ray diffraction (XRD). Standard additions using XRD gave the following weight percent of minerals (±2σ) in combined bottom and fly ash: gypsum, 1.8±1.9; hematite, 3.7±1.7; quart, 2.3±1.0; spinel,∼3-5; halite, 0.5±0.4; calcite 3.5±1.9; rutile, 1.1±1.3 Mullite, sylvite, anhydrite, and wustite were also identified. The ash contains 18% minerals, 9% structural and adsorbed water, and 72% glass. An estimated composite glass composition is reported.

Recent sedimentologic analysis of the potash-bearing Maha Sarakham Formation (Upper Cretaceous) shows that it is not of marine origin as previously thought. The main reason is the lack of evidence suggesting transgression onto the underlying redbeds of the Khok Kruat Formation, which are desert stream deposits. Similar lack of evidence also holds for the salt/red clastic contacts within the evaporites. Sedimentary features preserved in cores also point towatd the nonmarine origin. Algal lamination, palmate and swallow-tail fabrics in anhydrite (formerly gypsum) suggest shallow gypsum pan environment, while truncation and dissolution of the primary halite crystals suggest ephemeral salt pan conditions. The clastic units alternating in the formation contain features which characterize saline and dry mudflat environments, for instance, desiccation cracks, caliche, and displacive anhydrite nodules. In the potash zone, neither carnallite nor sylvite shows structures that may indicate sedimentation in a standing brine body or growing upward from the pan floor. Moreover, it is discernible at places that carnallite and sylvite were formed interstitially in the salt pan halite host, which implies their diagenetic origin. Considering the information gained so far, it is apparent that there was no restricted sea in northeastern Thailand during Late Cretaceous time. The Maha Sarakham Formation was in fact deposited in arid desert, probably deep in the continent. The new interpretation raises several quest0ons to the consensus on the formation, i.e. basin history, stratigraphic subdivision of the Khorat Group, and relationship among the formations within. It may also affect the economic aspects of the formation, i.e. continuity of the potash horizons and occurrence and migration of subsurface brines.

Prior studies of gamma-ray tools have all been focused around instruments that typically evaluate sandstone, shale, and limestone formations that are encountered in oilfield logging. For this study, a set of experiments were conducted to characterize the lateral and vertical response functions for a slim-hole gammaray sonde used in the mining industry to locate potash mineral deposits. The experiments were conducted in an indoor warehouse environment utilizing a set of large plastic tanks that were filled with light evaporite minerals (granular halite and sylvite) in differing arrangements to simulate various possible formation configurations. Measurements were taken while using a centralized slim-hole gamma ray tool in an air filled 4.5 inch plastic borehole. Sequential tests were run to establish the linearity of tool response, the radial depth of investigation, the vertical response function, and the repeatability of the measurement. Radial depth of investigation was measured using concentric radioactive rings of increasing diameter with two possible intermediary substances, air and halite. To test vertical response a column structure was built using halite as the bottom “bed” and a sylvite layer was systematically added in known quantities to acquire a response function of increasing thicknesses. Repeatability of the measurements was verified by logging several points with multiple tools of the same model for all the various experimental setups. Results were corrected for background radiation to predict the response in solid subsurface conditions without incident surface radiation seen in the experiments. The findings were also corrected for the differences between low porosity subsurface conditions and the unconsolidated granular products that were used in the simulated formation. The experimental results were surprisingly close to theoretical tool response for an oil field sonde, as well as to published specifications of major oilfield logging vendor’s tools. Consequently, gamma-ray logs collected with a slim-hole tool in shallow mineral core holes should be directly comparable to oilfield gamma-ray tools run in open-hole wellbores, once corrections for borehole size and fluid content using best practices are applied.

Single fluid inclusions (>250 μm) were extracted from 5 Permian evaporites (Zechstein). Na, K, Li, Mg, Ca; Cl, Br, and SO 4 were determined by ion chromatography. All the analyzed brines do not contain Ca but can be divided into 2 groups : NaCl-rich and MgCl 2 -rich brines. Quantitative reaction models were calculated by using the quinary system NaCl-KCl-MgCl 2 -Na 2 SO 4 -H 2 O. The composition of fluid inclusions in K3Ro can be understood by dissolution processes of polyhalite/kainite and sylvite, whereas fluid inclusions of KS go back to evaporation of brine K3Ro. The MgCl 2 -rich fluid inclusion of Na3β results from the evaporation of seawater depleted in MgSO 4 , whereas brines of K1H were formed by incongruent dissolution of carnallite at temperatures above 55°C. All the analysed brines are not in equilibrium with the neighbouring evaporite minerals indicating possible transport of brines through the salt deposit

In reply to the Critical Comment of R. K. Stoessell (this issue), limiting activity coefficients of bromide in halite ( γ NaBr ) have been calculated by least-squares fitting of Simons et al.'s (1952) bromide distribution coefficient data for the Na(Cl,Br)-NaOH-H 2 O system at 35°C. Regular and subregular solidsolution model fits give γ NaBr = 7.4 and γ NaBr = 8.8, respectively. The Br contents of halite at equilibrium with seawater at initial halite saturation, calculated from the regular and subregular fits, are 17 ppm and 14 ppm, respectively. A survey of literature data for trace bromide in halite shows a wide spread in distribution coefficients, with lower values ( D Br ≈ 0.01) reported by Bloch and Schnerb (1953), Puchelt et al. (1972), and Lutz (1975), and higher values ( D Br − ≈ 0.03) reported by Braitsch and Herrmann (1963), Kuhn (1968), Herrmann (1972), Herrmann (1980), Mccaffrey et al. (1987), valiashko et al. (1976), Valiashko and Lavrova (1976), and Fontes (pers. commun., 1990). The measurement of stoichiometric saturation states for halite (or sylvite) with trace bromide mole-fractions is not practical, given the insensitivity of the measured solubilities on the bromide mole-fractions. Distribution coefficient measurements, with proof of thermodynamic equilibrium, need to be obtained instead, to conclusively determine the thermodynamic-mixing properties of both Na(Cl,Br) and K(Cl,Br) solidsolution series at very low mole-fractions of bromide. The applicability of the stoichiometric saturation concept to the interpretation of precipitation processes is questionable, primarily because the concept requires solid-solutions to behave as one-component solids with fixed composition. Lippmann diagrams are useful in depicting stoichiometric saturation, endmember saturation, and thermodynamic equilibrium states in binary-solid-solution aqueous-solution systems. Lippmann diagrams can contribute a better understanding of these systems, regardless of the concentration of the endmember components.

The sylvite liquidus in the binary system KCl-H2O and the liquidus in the ternary system NaCl-KCl-H2O were determined by using isobaric differential thermal analysis (DTA) cooling scans at pressures up to 2 kbars. Sylvite solubilities along the three-phase curve in the binary system KCl-H2O were obtained by the intersection of sylvite-liquidus isopleths with the three-phase curve in a P-T plot. These solubility data can be represented by the equation Wt.% KCl (±0.2) = 12.19 + 0.1557T − 5.4071 × 10−5T2, where 400 ≤ T ≤ 770°C. These data are consistent with previous experimental observations. The solidus in the binary system NaCl-KCl was determined by using isobaric DTA heating scans at pressures up to 2 kbars. Using these liquidus and solidus data and other published information, a thermodynamic-PTX analysis of solid-liquid equilibria at high pressures and temperatures for the ternary system has been performed and is presented in an accompanying paper (Part V of this series). However, all experimental liquidus, solidus, and solvus data used in this analysis are summarized in this report (Part IV) and they are compared with the calculated values based on the analysis.

Mineral and fluid inclusions in seven microdiamonds (ca. 0.2 mm in diameter) from the Neogene, Samotkan' placer of the Ukrainian shield were investigated by TEM. Various types of submicron- or nanometre-sized inclusions such as olivine and orthopyroxene, Fe,Sn oxide and assemblages of mineral multi-phases were observed. In an octahedral microdiamond crystal numerous olivine and enstatite micro- and nanocrystals were observed. Their composition is close to that of other olivine and enstatite inclusions found in kimberlitic diamonds worldwide. An unusual feature of these minerals in the samples studied, however, is a relatively high NiO content: 0.50–0.80 wt.% in olivine (Fo 91.3–92.1 ) and 0.40–0.70 wt.% in enstatite (Fo 94.1–95.4 ). These peridotitic mineral associations represent the host (possibly lherzolitic mantle) in which the diamonds grew. The mean Mg# values of olivine and enstatite inclusions in Samotkan's microdiamond are, respectively, 91.43 and 94.83, which are closer to Mg#-values of these minerals in lherzolite, rather than in harzburgite assemblages (included in diamond). In addition, enstatite–clinoenstatite, K-richterite, graphite, and Fe,Sn oxide were also identified as nanoinclusions in Samotkan' diamond; the Fe,Sn oxides and magnetite were found in two microdiamonds of the transitional {111}+{110} form. The K-richterite and graphite have been attributed to epigenetic inclusions. The origin of Fe,Sn oxide is not clear. Assemblages of multi-phase, minerals were observed in four microdiamonds of variable morphology: octahedron, transitional {111}+{110} form, cube and cube-coated diamond. These phases belong to fluid-bearing inclusions and are enclosed in cavities which, as a rule, are not filled completely by the solid phases. The remainder of the volume is occupied by a fluid that for the most part has been released during sample preparation. In the majority of cases the multi-phase assemblages consist of carbonate, mica, rutile, ilmenite, apatite and sylvite. Carbonates are the most abundant phases in the fluid inclusions; they are calcium-rich carbonates, frequently with admixtures of Fe, Mg and Sr. The mica inclusions are enriched in silicon, with Si varying from ca. 6.7 to 7.0 a.p.f.u. The multi-phase mineral assemblages present in Samotkan's microdiamond are similar to fluid-bearing, microinclusions found previously in other diamond types (e.g., fibrous diamonds, the fibrous coat of coated diamonds or the internal clouds of octahedral diamonds) from kimberlites of different provinces worldwide. They represent the carbonate-, alkali-, and chlorine-rich mantle fluid composition present during crystallisation of the Samotkan's microdiamond. Judging from the composition of the multi-phase assemblages it may be assumed that the Samotkan's microdiamond grew from a carbonatitic to a slightly silicic melt, rich in alkali and volatile components.

This paper presents the results of experiments on the physicochemical conditions for the formation of picromerite in the five-component brine system K-Na-Mg-Cl-SO4-H2O and the process of isothermal evaporation-crystallization of picromerite from brines. The metastable phase fields of picromerite at 15.10 and 5°C and its stable equilibrium phase field at -5°C have been established. In addition. the phase equilibrium relationships have also been established for other salt minerals. The lower limit of formation temperature of picromerite has been deduced on the basis of experimental results. The isothermal evaporation crystallization path of the invariant assemblage (point D) of picromerite, epsomite. sylvite and halite at 25, 15, 10 and 5°C has been revealed. Furthermore, some controversial problems are approached concerning the 25°C “solar” diagram and the 25°C metastable phase diagram of this system.

Three new methods which are used for demonstrating sedimentary and diagenetic features in evaporite rocks—anhydrite, halite and sylvite—include: (a) the acetate peel technique after etching with NaCl-solution; (b) the scattered-light photomicrograph technique with thin-sections; (c) the epoxy peel technique with imprints of a vapour-etched polished slab. The examples given demonstrate that when combining these methods, it is possible to recognize all kinds of features which result from differences in crystal- and grain-size and in grain-shape, as well as by inclusions of brine or organic matter.

Primary and pseudosecondary fluid inclusions occur in oscillatory-and sector-zoned omphacite in eclogitic veins from the Monviso ophiolitic complex in the Western Alps. The inclusions contain aqueous brines and daughter crystals of halite, sylvite, calcite, dolomite, albite, anhydrite and/or gypsum, barite, baddeleyite, rutile, sphene, Fe oxides, pyrite and monazite. This daughter mineral suite indicates high solubilites of Na, K, Ca, Mg, Fe, Zr, Ti, P, Ba, Ce, La, Th, and S species and provides direct evidence for transport of high-fieldstrenght, large-ion-lithophile, and light-rare-earth elements as dissolved species during subduction. Fluid-inclusion heterogeneities preserved within and between adjacent grains in the veins, however, suggest that the scale of fluid equilibration was small. A crack-seal geometry in some of the veins implies that fluid release in pulses rather than steady flow controlled mineral deposition and growth in the veins. From these observations, we develop a model of fluid release and entrapment in which pulses of fluid are associated in time with increments of shear and tensile failure; the rate of fluid release and the reduction in porosity both depend on the rate of plastic flow. Vein fluids may initially be derived from decreptitation of early fluid inclusions in the host eclogites, Small-scale fluid heterogeneities implied by the fluid inclusions in the veins are best interpreted in terms of limited fluid flow, and hence limited metasomatism. We conclude that element recycling into the mantle wedge during subduction will depend at least as strongly on fluid transport mechanisms as on element solubilities in the fluid phase. At Monviso, despite evidence for high trace element solubilities in saline brines, the elements were not removed from the downgoing slab prior to teaching depths of ∼40 km.

Tin-tungsten-rare earth element mineralization at Zaaiplaats is hosted by the Lease and Bobbejaankop Granites--miarolitic, alkali feldspar granites which form part of the Lebowa Granite Suite of the Bushveld Complex. Pervasive hydrothermal alteration of the granites resulted in replacement of original biotite by chlorite, sericite, carbonate and Ti oxides, development of coarse vein and patch perthite and antiperthite in alkali feldspar, and precipitation of hydrothermal minerals in miarolitic cavities. Cassiterite occurs as a cavity infill and replacement mineral in tabular, subhorizontal zones within the Lease and Bobbejaankop Granites and in shallowly plunging and branching pipe systems in the granites. Disseminated mineralization exhibits no relationship to fracture systems, and hydrothermal fluids appear to have evolved essentially in situ during crystallization to produce miarolitic cavities. Minor subvertical veins containing fluorite, calcite, quartz, and sulfides crosscut the granites and pipes.Three major types of fluid inclusions have been identified in granite quartz and hydrothermal minerals from pipes and cavities. High-salinity inclusions characterized by the presence of solid phases such as halite, sylvite, and Fe chloride occur as primary inclusions in (1) granite quartz, (2) cavity-filling quartz, fluorite, and scheelite, and (3) cassiterite from the Iota pipe. These inclusions homogenize by dissolution of solid phases in the temperature range 160 degrees to 600 degrees C. Liquid-vapor inclusions occur in (1) late quartz from cavities, (2) quartz, fluorite, and calcite from cavities in the marginal pegmatite, and (3) late quartz and calcite infill from the Iota pipe. These inclusions homogenize to the liquid phase between 88 degrees and 240 degrees C, while ice melting temperatures range from -11 degrees to -30 degrees C. H 2 O-NaCl-CO 2 inclusions occur as secondary inclusions in granite quartz and early cavity-filling quartz, and primary inclusions in quartz from the quartz-tourmaline zone of the Bobbejaankop pipe. The compositional range and homogenization behavior of these inclusions is consistent with immiscibility around 350 degrees C and 1,000 bars.The oxygen isotope composition of granite whole rocks ranges from 9.2 to 9.9 per mil. Two samples of low-grade ore (8.4 and 9.0ppm) are depleted relative to the granites, possibly reflecting higher abundances of alteration and infill chlorite, sericite, and cassiterite. The delta 18 O values of quartz from granites and the marginal pegmatite range from 7.3 to 9.4 per mil, whereas those of quartz from cavities, low-grade orebodies, pipes, and veins range from 7.8 to 13.5 per mil. Most granite and cavity samples have quartz-feldspar fractionations less than 0 per mil. Vein and pipe samples tend to have higher delta 18 O feldspar and much higher delta 18 O quartz compared to granites, with quartz-feldspar fractionations of -0.6 to 1.2 per mil.The disequilibrium quartz-feldspar fractionations observed in granites and cavities reflect pervasive hydrothermal fluid-rock interaction at subsolidus temperatures. Modeling isotopic exchange between granites and a magmatic fluid phase in isotopic equilibrium with average Bobbejaankop Granite quartz at 600 degrees C indicates that whole-rock compositions result from final exchange at temperatures less than 400 degrees C, with fluid compositions in the range 4.2 to 5.2 per mil at 300 degrees C and 0.8 to 1.8 per mil at 200 degrees C. These results are consistent with fluid compositions calculated from delta 18 O quartz and pressure-corrected fluid inclusion homogenization temperatures, and indicate that oxygen isotope variation at Zaaiplaats reflects exchange between the granite and the magmatic fluid phase at temperatures down to 200 degrees C.

A study on tropospheric aerosols involving Fe particles with an industrial origin is tackled here. Aerosols were collected at the largest exhausts of a major European steel metallurgy plant and around its near urban environment. A combination of bulk and individual particle analysis performed by SEM-EDX provides the chemical composition of Fe-bearing aerosols emitted within the factory process (hematite, magnetite and agglomerates of these oxides with sylvite (KCl), calcite (CaCO(3)) and graphite carbon). Fe isotopic compositions of those emissions fall within the range (0.08 per thousand

11 páginas., Silica sinters, deposited from alkali chloride waters in the El Tatio geothermal field in northern Chile (22°20'S, 68°01'W), have been characterized by XRD, SEM, TG-DTA, and FTIR. The dominant silica phase is opal-A. Minor contents of opal-A/-CT and opal-CT are also present together with halite (NaCl), sylvite (KCl), and realgar (AsS). Accessory phases include teruggite [Ca4MgAs2B12O22(OH)12·12(H2O)], sassolite (H3BO3), and detrital quartz (SiO2). FWHM values reflect the immature nature of the studied opal-A. DTA heating experiments of opal-A show cristobalite crystallization at ~1000 °C, whereas DTA cooling experiments show the β -alfacristobalite transformation at ~200 °C. The total weight loss is related to changes in the sinter microtextures, mineral phases, and organic matter contents. FTIR spectra show the effects of silica maturation as consequence of the loss of trapped and absorbed water attached to silanols.

International audience; An emerald deposit at Byrud, in southern Norway, yielded significant quantities of crystals and gem rough in the late 19th and early 20th centuries. Complex multiphase inclusions in the emeralds consist of water, gaseous methane, halite, sylvite, calcite, and a sulfide assemblage (pyrrhotite, galena, and sphalerite). This sulfide assemblage makes it easy to distinguish Byrud emeralds from those from other localities with a binocular microscope. The chemical composition of Byrud emeralds is also characteristic: They are colored mostly by vanadium (up to 1 wt.% V2O3), and contain low sodium and magnesium (0.1 wt.% oxide or less). Moreover, the relative amounts of iron, magnesium, chromium, rubidium, and cesium appear to be diagnostic. Infrared absorption spectra show that they contain little water. Emeralds from the Byrud deposit are still occasionally recovered by hobbyist collectors from the mine dumps.

It is well known that there are two patterns of potash deposition in lacustrine facies: “tear drop pattern” (the Dabsan saline lake is a typical example) and “bull's eye pattern”. Potash-forming in tear drop pattern is still continuing. The 2,678 m A. S. L. lake in the middle of the Qarhan playa in the Qaidam Basin covers an area of 210 km2, and has an average depth of 0.39 m. Its MgCl2 type surface brine is 280–340 g/l in salinity and mainly consists of Na, K, Mg and Cl. As a rule, the potash deposits occur as evaporite distributed in tear drop pattern at the northern and northeastern lakeshore zones. They mostly consist of carnallite and halite, occasionally sylvite. The deposition is very unstable and controlled principally by the varying supply of deposit materials from the Golmud River in the south. The potash deposits were formed when concentration of the surface brine reached a certain degree in the main evaporating season. Their forming process followed some crystalization paths in the phase diagram for the Na, K, Mg/Cl H2O equilibrium system. Such a sedimentary model of potash deposits in the lacustrine facies is relatively common in nature. Under the extremely arid climate, differential concentration of the nonhomogeneous potassium-rich surface brine produced the potash deposits. Qarhan Salt Lake also had the same pattern of potash depositions and so, in a sense, the Dabsan saline lake is the continuation of the Qarhan salt lake in terms of potash formation. Schmalz (1970) put forward two distributive patterns for evaporite: “tear drop pattern” and “bull's eye pattern”. These patterns exist in both marine and continental salt-bearing basins (including recent salt lakes), and are controlled by the conditions of physical geography, hydrogeology, sedimentology and climatology of each basin. In his works (Sun, 1981; 1984; 1986; 1988) on the origins of potash deposits, the author always referred to them as two models of potash formation. The “tear drop pattern” is one of the salt-forming models and also an important potash-forming model. This paper deals with the formative mechanism of the tear drop pattern potash deposition by presenting the Dabsan saline lake as an example and elucidates on the distributive characteristics and formative processes of potash deposits in the lake.

The chemical composition of aqueous fluid inclusions in crystals of halite can be accurately determined from observed melting behaviors of ice, hydrohalite, and sylvite. Some fluid inclusion melting behaviors observed in laboratory-grown halite crystals (systems NaClH 2 O, NaClKClH 2 O, NaClMgCl 2  H 2 O, and NaClCaCl 2 H 2 O) differ from predicted stable equilibrium relations. In the NaClH 2 O and NaClKClH 2 O systems, observed first melt temperatures are up to 15°C below the equilibrium eutectic temperatures of −21.2° and −22.9°C, respectively. The final melting temperature of ice, in the presence of hydrohalite, and the final melting temperature of hydrohalite are reproducible and match predicted melting temperatures. The limit of detection of sylvite daughter crystals in the NaClKClH 2 O system is approximately 5 wt% (≈ 1 molal) KCl. Final melting temperatures of sylvite match published equilibrium data to within 0.3°C. In the NaClKClH 2 O system at halite saturation, m KCl can be determined from the final sylvite dissolution temperature or from the final melting temperature of hydrohalite. Fluid inclusions in the NaClMgCl 2 H 2 O and NaClCaCl 2 H 2 O systems that form stable salt hydrates (MgCl 2 · 12H 2 O and CaCl 2 · 6H 2 O) during freezing first melt within 3°C of predicted eutectic temperatures (−37° and −52°C). However, fluid inclusions with MgCl 2 or CaCl 2 may also start melting at temperatures as low as −80°C. Such low first melt temperatures indicate the presence of metastable salt hydrates (presumably MgCl 2 · 8H 2 O, MgCl 2 · 6H 2 O or CaCl 2 · 4H 2 O). The formation of metastable phases during freezing of fluid inclusions can lead to misinterpretation of the chemical composition of fluid inclusions in natural samples. This is especially true for fluid inclusions with first melt temperatures below −37°C which may be erroneously interpreted as being rich in CaCl 2 . The final melting of ice in the presence of hydrohalite may vary by more than 15°C in fluid inclusions of different size but identical bulk composition, and occurs at lower temperatures than predicted in fluid inclusions from the NaClMgCl 2 H 2 O and NaClCaCl 2 H 2 O systems. However, the final melting temperature of ice in inclusions which fail to nucleate hydrohalite, and the final melting temperature of hydrohalite are reproducible to within ±0.1 ° C and can be used to determine MgCl 2 and CaCl 2 molalities.

A large groundwater system in the Amadeus Basin, central Australia, discharges to a chain of playa lakes 500 km long. The playas contain highly concentrated brines; these are sodium-chloride rich waters with appreciable magnesium and sulphate and very low concentrations of calcium and bicarbonate. Gypsum, glauberite, and other evaporite minerals are precipitating in the playas. The groundwaters evolve to brine by concurrent processes of dissolution, evaporative concentration, mineral precipitation, and mineralogical change. Chemical evolution is considered with reference to a concentration factor based on chloride. Ion transfer calculations demonstrate losses of magnesium and bicarbonate throughout, as a result of precipitation. Sodium, potassium, calcium, and sulphate are gained initially as a result of dissolution but lost subsequently as a result of precipitation. Larger playas in the chain, exemplified by Lake Amadeus, have dual shallow and deep groundwater flow paths whereas the smaller playas, exemplified by Spring Lake, have only shallow flow paths. Brines in the larger playas are diluted by deep groundwaters and this is reflected in the degree of saturation attained with respect to particular minerals. Thus, saturation with respect to gypsum and glauberite is attained earlier in Spring Lake than in Lake Amadeus. Saturation with respect to halite is attained in Spring Lake but not in Lake Amadeus. Both playas are undersaturated with respect to hexahydrite and sylvite although these minerals occur in efflorescent crusts in Spring Lake.

En esta investigación se determinaron las mejores condiciones de reacción para la producción de cristales de sulfato de potasio a partir de fosfoyeso y silvita en solución amoniacal. La metodología consistió en variar en un rango determinado los parámetros a estudiar: temperatura, concentración de la solución acuosa amoniacal, relación de la masa de yeso a la de solución acuosa amoniacal y tamaño de grano de fosfoyeso. En las corridas experimentales se fijaron 3 de las variables en un valor preestablecido en base a estudios anteriores y se varío la restante, tomándose muestras de la solución reaccionante cada intervalo de tiempo en el transcurso de la reacción, para evaluar bajo que parámetros de reacción se obtiene la mayor conversión. Las mejores condiciones de reacción para producir sulfato de potasio son: temperatura de 5°C; concentración de solución acuosa amoniacal 32%, siendo este un parámetro importante en la reacción, porque promueve la formación de sulfato de potasio y controla la formación de singenita; la relación masa de yeso a masa de la solución acuosa amoniacal fue 1:5 y el tamaño de grano menor de 75 mehs. El estudio de granulometría láser de los cristales dio un tamaño de partícula de 65 µm. The purpose of the work was to determine the best conditions of reaction for the production of crystals of potassium sulphate from phosphogypsum and sylvite in aqueous ammonia. The phosphogypsum used was obtained from the phosphoric acid plant of Pequiven-Morón. With this aim, a method was developed in which the variables were varied in a certain rank to study: temperature, concentration of the aqueous ammonia solution, ratio of gypsum to solvent in reactor charge and grain size of phosphogypsum. It was obtained that the best conditions of reaction for the production of potassium sulphate are: temperature of reaction 5°C; the crucial factor in the system studied is the effect of the ammonia which both promotoes the formation of potassium sulphate and also hinders its conversion to syngenite, the initial solvent composition 32% by weight ammonia in water; weight ratio of gypsum to solvent of 1:5 and size of 75 smaller grain of mehs.

Potassium is an emitter of gamma-ray radiation, consequently deposits of potash can be detected and evaluated using gamma-ray logs. A method originally designed to evaluate uranium deposits in boreholes can also be applied to potash deposits. The method equates the depth-integral of a gamma-ray log to the grade-thickness product of a potash-bearing bed or series of beds. The average grade of a bed is then determined by dividing by the overall bed thickness, which can also be obtained from the gamma-ray log. The method was tested using gamma-ray logs and potash assays from boreholes near Carlsbad, New Mexico. Introduction The radioactive isotope K-40 forms 0.01% by weight of natural potassium and emits a sufficient level of gamma rays to be detectable in the subsurface. Because potassium is one of only three geologically common elements that emit gamma rays, the best approach to the estimation of potash grade in boreholes is through the use of the gamma-ray log. The gamma-ray response to a “formation” comprised of pure potassiumbearing minerals was computed by Edmundson and Raymer (1979) and included in a tabulation by Hearst and others (2000), as shown in table 1: Table 1. Gamma-ray responses to potassium-bearing minerals. From Edmundson and Raymer (1979). Mineral Chemical composition K (wt percent) API units Sylvite KCl 52.4 747 Carnallite KMgCl3●6H2O 14.1 200 Langbeinite K2SO4Mg2(SO4)2 18.8 268 Polyhalite K2SO4Mg(SO4)(Ca(SO4))2●2H2O 13.0 185 The measured gamma-ray flux in a potash zone varies with mineral concentration. Peak gamma-ray values in 16 potash zones in wells drilled in southeastern New Mexico range from 120 to 270 API units (Lewis, 2006).

The elemental losses from ashes of common biomass fuels (rice straw, wheat straw, and wood) were determined as a function of temperature from 525 8C to below 1525 8C, within the respective melting intervals. The experimental procedure was chosen to approach equilibrium conditions in an oxidizing atmosphere for the specific ash and temperature conditions. All experiments were conducted in air and used the ashes produced initially at temperatures of 525 8C as reactants. Losses during the initial ashing at 525 8C were negligible, except for a K2O loss of 26% for wood and a Cl loss of 20% for wheat straw. Potassium losses are positively correlated with temperature for all fuel ashes. The K2O loss for wood ash commences at 900–1000 8C. Carbonate is detected in the wood ashes to about 700–800 8C and thus cannot explain the retention of K2O in the ashes to 1000 8C. Other crystalline phases detected in the wood ashes (pericline and larnite) contain little or no potassium. Petrographic examinations of high temperature, wood ash products have failed to reveal potassium bearing carbonates, sulfates, or silicates. The release of potassium, thus, appears to be unrelated to the breakdown of potassium-bearing crystalline phases. The straw ashes show restricted potassium loss compared to wood ash. The potassium content declines for both straw ashes from about 750 8C. Cristobalite appears in the straw ashes at about 700–750 8C and is replaced by tridymite in the rice straw ash from about 1100 8C. Sylvite (KCl) disappears completely above 1000 8C. The Cl content starts to decline at about 700 8C, approximately at the same temperature as potassium, suggesting that the breakdown of sylvite is responsible for the losses. The K–Cl relations demonstrate that about 50% of K (atomic basis) released from breakdown of sylvite is retained in the ash. The presence of chlorine in the ash is, therefore, best attributed to the presence of sylvite. Potassium is easily accommodated in the silicate melt formed at temperatures perhaps as low as 700–800 8C from dehydration, recrystallization, and partial melting of amorphous components. Loss of potassium persists for ashes without remaining sylvite and points to the importance of release of potassium from partial melt at temperatures within the melting interval for the fuel ashes.

The Bayan Obo REE-Nb-Fe deposit hosts the world’s largest known REE resource. The deposit consists of replacement bodies hosted in dolomite marble made up of magnetite, REE fluorocarbonates, fluorite, aegirine, amphibole, calcite and barite. Three types of fluid inclusions have been recognized: two phase aqueous liquid-apor (L-V), two to three phase CO2 (C), and three phase liquid-vapor-solid (L-V-S) inclusions. Microthermometry measurements indicate that the carbonic phase in C inclusions is nearly pure CO2. During heating experiments, hexagonal or irregular shape daughter minerals in L-V-S inclusions complete dissolution at temperatures of 420–480°C and re-crystallize again at about 400–320°C. These show that daughter minerals in multiphase inclusions in mineralizing veins were crystallized from trapped fluids, and are real daughter minerals. REE-carbonates, halite, sylvite, barite, calcite and pyroxene (?) have been identified on the basis of crystal habit (microscopic and SEM) and EDX analysis. By comparison with Raman spectra of reference REE-carbonate mineral crystals, the hexagonal or irregular shaped daughter minerals in the L-V-S inclusions might be cebaite and bastnaesite. The presence of REE-carbonates as an abundant solid in the ore-forming veins shows that the original ore-forming fluids are very rich in REE, and therefore, have the potential to produce economic REE ores at Bayan Obo.

Kimberlite magmas, as the deepest probe into Earth's mantle (>150 km), can supply unique information about volatile components (hydrogen, carbon, chlorine, sulfur) in mantle-derived melts and fluids. All known kimberlite rocks are not suitable for studies of mantle volatiles because of their pervasive postmagmatic alteration; however, this study discusses an exceptionally fresh group I kimberlites (

We present new mineral chemistry, fluid inclusion, stable carbon and oxygen, as well as Pb, Sr, and Nd isotope data of Ca-Mg-silicate-rich ejecta (skarns) and associated cognate and xenolithic nodules from the Mt. Somma-Vesuvius volcanic complex, Italy. The typically zoned skarn ejecta consist mainly of diopsidic and hedenbergitic, sometimes “fassaitic” clinopyroxene, Mg-rich and Ti-poor phlogopite, F-bearing vesuvianite, wollastonite, gehlenite, meionite, forsterite, clinohumite, anorthite and Mg-poor calcite with accessory apatite, spinell, magnetite, perovskite, baddeleyite, and various REE-, U-, Th-, Zr- and Ti-rich minerals. Four major types of fluid inclusions were observed in wollastonite, vesuvianite, gehlenite, clinopyroxene and calcite: a) primary silicate melt inclusions (THOM = 1000–1050 °C), b) CO2 ± H2S-rich fluid inclusions (THOM = 20–31.3 °C into the vapor phase), c) multiphase aqueous brine inclusions (THOM = 720–820 °C) with mainly sylvite and halite daughter minerals, and d) complex chloride-carbonate-sulfate-fluoride-silicate-bearing saline-melt inclusions (THOM = 870–890 °C). The last inclusion type shows evidence for immiscibility between several fluids (silicate melt – aqueous chloride-rich liquid – carbonate/sulfate melt?) during heating and cooling below 870 °C. There is no evidence for fluid circulation below 700 °C and participation of externally derived meteoric fluids in skarn formation. Skarns have considerably variable 206Pb/204Pb (19.047–19.202), 207Pb/204Pb (15.655–15.670), and 208Pb/204Pb (38.915–39.069) and relatively low 143Nd/144Nd (0.51211–0.51244) ratios. The carbon and oxygen isotope compositions of skarn calcites (δ13CV-PDB = −5.4 to −1.1‰; δ18OV-SMOW = 11.7 to 16.4‰) indicate formation from a 18O- and 13C-enriched fluid. The isotope composition of skarns and the presence of silicate melt inclusion-bearing wollastonite nodules suggests assimilation of carbonate wall rocks by the alkaline magma at moderate depths (< 5 km) and consequent exsolution of CO2-rich vapor and complex saline melts from the contaminated magma that reacted with the carbonate rocks to form skarns.

Gulf Coast salt diapirs have complex internal structure, which is shown by light and dark layering. The layering reflects variation in anhydrite content and is interpreted to represent highly stretched and sheared depositional bedding. Structure is dominantly vertical, consisting of repeatedly refolded isoclinal folds having vertical plunge. Geologic mapping is conducted primarily as an aid to mine planning and development; separate maps are produced to record basic structure and display the distribution of clastic stringers, sylvite stringers and lenses, crystal size, wet areas, and gas. The latter characteristics, including coarse salt crystals, are anomalous and tend to be associated (in anomalous areas and trends). Gas is a mining hazard, causing Weeks Island and Cote Blanche Island to be classified by MSHA as gassy mines having many associated regulations. Five miners died in a gas explosion at Belle Isle mine in 1979, and blasting is now normally done while the mines are unoccupied (before the morning shift goes in, for example). Water influx, particularly if derived from outside the mine, is a cause of major concern for obvious reasons; at Avery Island a crew is constantly drilling and grouting to maintain control of leaks, and Jefferson Island mine has been lost as a result of flooding when penetrated by an oil rig. Sand reduces the salability of the commercial product and also increases mining costs. The geologic maps provide structural trend information to help the mine engineers avoid undesirable or potentially dangerous areas including those in proximity to the edge of the diapir. They also cast light on the nature of salt diapirism; linear anomalous zones have routinely been interpreted (sometimes with minimal justification) as boundaries between separate salt spines. Map examples from Weeks Island are included.

Separation of water-soluble minerals by flotation is the most important present-day method of potash ore processing. It has currently come into use in the production of carnallite, that is, the raw material for the production of metallic magnesium and various fertilizers. The paper describes studies on the influence of both hydration of surfaces of alkaline halogenide crystals and that of changes in morphology of sylvite surface in saline solutions having different compositions on cationic collector sorption at saline minerals. The paper also considers the effect of cationic collector composition on the efficiency of clay-carbonate slimes protection by reagents-depressors and on floatability of sylvite and halite at different temperatures and compositions of electrolyte solutions. As a result of work, it has been suggested the optimal compositions of reagents-collectors for the separation of water-soluble minerals by flotation.

Mother liquor compositions during the solar evaporation of marine bitterns have been compared with corresponding isothermal equilibria in the NaCl-KCl-MgCl2-MgSO4-H2O system. The compositions indicate that on solar evaporation of bitterns, potassium is deposited solely in the form of kainite, and that co-deposition of free sylvite and epsomite does not take place. It is also shown that during solar evaporation, the concentration of potassium is relatively low and that of magnesium relatively high, resulting in a more efficient precipitation of potassium in solar evaporation than in the forced or isothermal evaporation of sea water or of pure salts.