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Dykes of the Late Cretaceous to Early Tertiary (79.5 ± 3.5 to 60.7 ± 2.4 Ma) melilitic rock series of the Osecna Com- plex and the Devil’s Walls dyke swarm, including ultramafic lamprophyres – polzenites – of Scheumann (1913) occur dispersed in the entire Upper Ploucnice River basin in northern Bohemia. Polzenites and associated melilitic rocks are characterized by the mineral association of olivine + melilite ± nephe- line, hauyne, monticellite, phlogopite, calcite, perovskite, spinels and apatite. New data on their mineral and chemical compositions from original Scheumann’s localities (the Vesec, Modlibohov, Luhov types) argue against the abolition of the group of ultramafic lamprophyres and the terms ‘polzenite’ and ‘alnoite’ by the Le Maitre (2002) classification. Marginal facies and numerous flat apophyses of the lopolith-like body known as the Osecna Complex show an olivine micro-melilitolite composition (lamprophyric facies). The porphyritic texture, chemical composition and the presence of characteristic minerals such as monticellite and phlogopite point to their affinity with ultramafic lamprophyres – polze- nites of the Vesec type. Melilite-bearing olivine nephelinites to olivine melilitites (olivine + clinopyroxene + nepheline + melilite ± hauyne and spinels with apatite) form a swarm of subparallel dykes known as the Devil’s Walls. The Scheumann’s non-melilite dyke rock “wesselite”, spatially associated with polzenites and often erroneously attributed to the polzenite group, is an alkaline lamprophyre of monchiquite to camptonite composition (kaersutite + phlogopite + diopside + olivine phenocrysts in groundmass containing clinopyroxene, phlogopite, hauyne, analcime, titanian mag- netite, apatite ± glass/plagioclase). First K–Ar data show Oligocene ages (30.9 ± 1.2 to 27.8 ± 1.1 Ma) and an affinity to the common tephrite–basanite rock series.

Chemical and mineralogical characteristics and physicomechanical properties are provided for mullite-silica refractory MKRA-50 before and after service in a steel-pouring ladle. Questions of metal secondary oxidation present within a lining are considered. A mechanism of sub-compound and gaseous complex formation in steel is discovered and their effect on phase formation in a ladle lining is demonstrated. Thermochemical methods are considered for the preferred choice of refractory materials based on corundum and magnesium oxide.

A new discovery of carbonatites at Pianciano, Ficoreto and Forcinelle in the Roman Region demonstrates that Italian carbonatites are not just isolated, mantle xenoliths-bearing, primitive diatremic rocks but also evolved subtype fluor-calciocarbonatite (F ~ 10 wt%) associated with fluor ore (F ~ 30 wt%). New data constrain a multi-stage petrogenetic process, 1-orthomagmatic, 2-carbothermal, 3-hydrothermal. Petrography and geochemistry are conducive to processes of immiscibility and decarbonation, rather than assimilation and crystal fractionation. A CO2-rich, ultra-alkaline magma is inferred to produce immiscible melilite leucitite and carbonatite melts, at lithospheric mantle depths. At the crustal level and in the presence of massive CO2 exsolution, decarbonation reactions may be the dominant processes. Decarbonation consumes dolomite and produces calcite and periclase, which, in turn, react with silica to produce forsterite and Ca silicates (monticellite, melilite, andradite). Under carbothermal conditions, carbonate breakdown releases Sr, Ba and LREE; F and S become concentrated in residual fluids, allowing precipitation of fluorite and barite, as well as celestine and anhydrite. Fluor-calciocarbonatite is the best candidate to exsolve fluids able to deposit fluor ore, which has a smaller volume. At the hydrothermal stage, REE concentration and temperature dropping allow the formation of LREEF2+ and LREECO3+ ligands, which control the precipitation of interstitial LREE fluorcarbonate and silicates: (bastnäsite-(Ce), Ce(CO3)F and britholite-(Ce), (Ce,Ca)5(SiO4,PO4)3(OH,F). Vanadates such as wakefieldite-(Ce), CeVO4, vanadinite, Pb5(VO4)3Cl and coronadite Pb(Mn4+ 6 Mn3+ 2)O16 characterise the matrix. At temperatures of ≤100 °C analcime, halloysite, quartz, barren calcite, and zeolites (K-Ca) precipitate in expansion fractures, veins and dyke aureoles. © 2019 The Authors 689909 IGM SD RAS 0330-2016-0005 The HiTech AlkCarb European Union Horizon 2020 project grant-agreement number 689909 supported this research. Mineralogical studies was also partly supported by the Russian State assignment project IGM SD RAS 0330-2016-0005.

A detailed mineralogical examination of representative material from the P2-West 'kimberlite' located in the Wajrakarur Kimberlite Field (India) demonstrates that significant differences exist between these rocks and archetypal hypabyssal kimberlite. The intrusion consists of an olivine-phyric facies which has been transected by, and includes clasts of, a consanguineous phlogopite-rich pegmatitic facies. The olivine-rich parts of P2-West are relatively fresh and consist of euhedral-to-subhedral microphenocrystal olivine set in a groundmass of fine-grained anhedral monticellite, amoeboid apatite, and subhedral-to-euhedral perovskite within a partially chloritized-to-fresh phlogopite-rich mesostasis. The rock lacks the abundant olivine macrocrysts characteristic of kimberlite. Monticellite crystals are commonly partially or completely replaced by pectolite and hydrogarnet. Similar material occurs as irregular aggregates randomly scattered throughout the groundmass. The groundmass, in contrast to that of hypabyssal kimberlites, is relatively poor in spinels. Atoll spinels are absent, with the majority of spinels occurring principally as mantles upon microphenocrystal olivine. Disaggregated cumulate-like assemblages of intergrown anhedral perovskite and spinel are common. Spinel compositions are unlike those of kimberlites and their evolutionary trend is similar to that of lamproite and lamprophyre spinels. The pegmatitic facies of the intrusion are highly and pervasively altered, and characterized by the presence of large clasts, veins, and irregular aggregates consisting of large (1–5 mm) crystals of pinkish-bronze Al-poor phlogopite intergrown with and/or including: apatite; pectolite-hydrogarnet pseudomorphs after an unidentified euhedral phase; chlorite laths; barytolamprophyllite; perovskite; tausonite; diverse Sr-Ba-carbonates; and baryte. The presence of barytolamprophyllite and tausonite are typical of potassic undersaturated alkaline rocks and have never been reported from kimberlite; however, neither feldspar nor feldspathoids are present in P2-West. Micas in fresh and altered rocks are Al2O3- and BaO-poor, and exhibit compositional evolutionary trends towards tetraferriphlogopite rather than kinoshitalite. On the basis of these mineralogical data it is suggested that P2-West represents an unusual lamproite-like intrusion which has undergone extensive hydrothermal deuteric alteration and should not be considered a bona fide kimberlite.

This study concerns the chemical reactions involved and the phases formed during penetration of slags of variable compositions into porous tundish disposable lining material. The liner is mainly composed of a mixture of MgO and olivine with an organic binder. Slags of different compositions were formulated and indicated a variable composition of CaO (12–20%), SiO2 (44–55%), Al2O3 (4–16%), MgO (10–20%), MnO (9–12%) and FeO (2–3%). Experimental work indicated that when slag penetrated into pores of the refractory, the porosity was reduced depending on the penetration depth. It was observed that the lower the melting point of the slag, the higher the depth of slag penetration by capillary action. The phases of forsterite (Mg2SiO4), magnesiowustite (MgO.FeO) and monticellite (CaO.MgO.SiO2) were formed in the bulk refractory by the slag, and the chief component of the refractory responsible for the formation of those phases is the periclase.

In this study we report P-rich olivine and the tric-calcium phosphate (TCP) stanfieldite in partially molten quartzphyllites from the ritual immolation site at the Goldbichl, near Innsbruck in the Tyrol, Austria. During partial melting, foamy patches of dark glassy material formed at the surface of the rocks and also as layers within the rocks. The pyrometamorphic rocks contain mostly the mineral assemblage olivine + orthopyroxene + plagioclase + spinel + glass. During the investigation of slag samples from this prehistoric ritual immolation site, extremely P-rich, apatite-bearing micro-domains were found. In these domains phosphoran olivine was found whose P contents are approaching the maximum P contents in olivine according to the experimental investigations of Boesenberg and Hewins (Geochim Cosmochim Acta 74:1923–1941, 2010). The textures within these domains indicate strongly disequilibrium conditions. The phosphoran olivines formed due to reactions involving apatite and the mineral assemblage of the quartzphyllites, and coexist with plagioclase and a tri-calcium phosphate phase (TCP) showing stanfieldite Ca4(Mg, Fe2+, Mn2+)5(PO4)6 composition. In terms of its chemical composition, olivine shows a wide range in composition with P ranging from 0.3 to 0.54 a.p.f.u, which corresponds to maximal 23 wt.% P2O5. These are the highest P-contents in olivine reported from rocks so far. The incorporation of P correlates with decreasing Si contents according to the charge balancing scheme $$ 2{{\mathrm{P}}^{5+ }}+□{{\mathrm{M}}_{1,2 }}=2\mathrm{S}{{\mathrm{i}}^{4+ }}+{{\left( {\mathrm{M}\mathrm{g},\mathrm{Fe}} \right)}^{2+ }}{{\mathrm{M}}_{1,2 }} $$ . Therefore P can only be incorporated in combination with a vacancy on the M1,2 position. Micro-Raman spectroscopy of phosphoran olivines indicates that these olivines can easily be identified with this method due to the strong signals of the SiO4 and PO4 vibrations. The external vibrations of the M1,2 sites at low wave-numbers are more complex than for P-free olivine. This might be due to the effect of P5+ on the M1 2+ and M2 2+ positions and the formation of vacancies on these sites. Since micro-Raman investigations of the TCP phase yielded no conclusive match with a known Raman spectrum of a phosphate mineral so far, therefore it is most likely that the TCP phase is stanfieldite, whose Raman spectrum has not been obtained yet. Schematical Schreinemakers analysis in the system CaO-Al2O3-FeO-SiO2-P2O5-H2O shows that P-rich olivine (fayalite-sarcopside solid solution) can form from mineral reactions involving chlorite, apatite and quartz and show that the occurrence of P-rich Fe-olivines spans a large T-range but is restricted to domains with high aSiO2. The mineral assemblage in the P-rich micro-domains shows that the formation of phosphoran olivine is not only restricted to the interaction between bone material and rocks in slags from ritual immolation sites as suggested by Tropper et al. (Eur J Mineral 16:631–640, 2004) from the immolation site in Oetz but can form locally due to the pyrometamorphic breakdown of a P-rich accessory precursor phase such as apatite.

A sulfide-type mineral of the district of Zimapan, Hidalgo, Mexico, was chemically and mineralogically analyzed with the aim of detecting minor species with added value for their subsequent beneficiation. Apart from the usual species of the site, the X-ray diffraction analysis (XRD) detected the presence of tungsten sulfate (WS2) and the mineral species typical of a base-metal sulfide site, as well as impurities such as: orthoclase, quartz, magnesium-silicon oxide, magnesioferrite, monticellite, andradite, magnetite and calcite, the latter being the mineral matrix. The Scanning Electron Microscopy (SEM) mapping confirmed the presence of the typical elements of the mineral: W, Si, O, Mg, Ca, C, Al, K, Fe, S, Zn and Cu. The Inductively Coupled Plasma Spectroscopy (ICP) analysis indicates an average concentration of 380 g W ton”1, as well as 1.81% Zn, 3.41% S, 0.15% Cu, 2.36% Fe, 0.78% Pb, 0.04% Mn, Sb 0.05% and 0.01% Ag. This mineral is a potential source for the extraction of tungsten

Two carbonatitic mineral assemblages, calcite + wollastonite and calcite + monticellite, which are encapsulated in two diamond grains from the Rio Soriso basin in the Juina area, Mato Grosso State, Brazil, were studied utilizing the NanoSIMS technique. The assemblages were formed as the result of the decomposition of the lower-mantle assemblage calcite + CaSi-perovskite + volatile during the course of the diamond ascent under pressure conditions from 15 to less than 0.8 GPa. The oxygen and carbon isotopic compositions of the studied minerals are inhomogeneous. They fractionated during the process of the decomposition of primary minerals to very varying values: δ18O from −3.3 to +15.4 ‰ SMOW and δ13C from −2.8 to +9.3 ‰ VPDB. These values significantly extend the mantle values for these elements in both isotopically-light and isotopically-heavy areas.

Investigation of the liquidus phase relations in the forsterite–diopside–enstatite system has been made at 7 GPa and variable temperatures under anhydrous condition using a Walker-type multi-anvil high pressure apparatus. A total of 16 compositions were synthesized to facilitate study of this system. Location of the piercing point on the forsterite–diopside bounding join has been established at Fo 39 Di 61 (all compositions are in wt.%) and 1980 ± 20 °C. Electron microprobe analyses of the phases indicate that forsterite ss can incorporate about 1 to 1.5 wt.% monticellite (CaMgSiO 4 ) in solid solution. In the diopside–enstatite join, a temperature minimum occurs at Di 66 En 34 and 1975 ± 30 °C, whereas the peritectic point, where orthopyroxene ss reacts with liquid to form clinopyroxene ss , occurs at En 65 Di 35 and 2010 ± 20 °C. The maximum amount of MgSiO 3 that can be incorporated in diopside ss has been measured to be about 82 wt.%. Because of the increase in the solid solution proportion of MgSiO 3 in diopside ss compared to that at 2 and 5.1 GPa, the peritectic point in the diopside–enstatite bounding join also shifts further toward the enstatite apex. In the ternary system, the invariant point has been located at Fo 54 Di 35 Q 11 and 2010 ± 30 °C, where orthopyroxene ss + forsterite ss + liquid ↔ clinopyroxene ss + forsterite ss + liquid occurs. Our present study confirms that the primary phase field of forsterite shrinks and that of clinopyroxene expands further in comparison to that observed at 2 and 5.1 GPa. Preliminary experimental results from composition Fo 80 Di 12 Qtz 8 with 4 wt.% Al 2 O 3 indicate that garnet (Pyrope 98 Grossularite 2 ) and forsterite (with 0.31 wt.% monticellite) are the liquidus phases, followed by clinopyroxene (Al 2 O 3 contents between 3.4 to 2.7 wt.%). At 1970 °C , the average composition of the liquids obtained through electron microprobe analysis was as follows: SiO 2 49.81, MgO 34.72, CaO 7.29, and Al 2 O 3 6.75 wt.%, which is somewhat similar to a komatiitic melt. When projected onto the forsterite–diopside–enstatite plane this liquid composition plots very close to our cotectic line. Taking model mantle composition of a garnet peridotite, a shift in the compositional path of the residual mantle materials has been determined after extraction of the volume percent of the melt using the Lever rule.

SEM/EDX analysis has been applied in order to assess the mineralogical transformations occurring during high temperature treatment of several different anthracites. At 1000 °C (carbonization) loss of CO2 from carbonates, S from sulfides and OH and/or H2O from clays occurs, transforming these minerals to other inorganic phases such as lime, pyrrhotite, and (Na, Mg) K-aluminosilicates, among others. Heat treatment of the carbonized samples up to 1500, 2000, and 2500 °C resulted in: i) a decrease in oxygenated mineralogical phases, which are transformed to higher temperature silicates (grossite, anorthite, kushiroite, etc.); ii) carbide formation (SiC, TiC or Al4C3) by carbothermal reactions; iii) formation of alloys, especially a Pb–Sn alloy; and iv) formation of iron silicides (Fe2Si), iron phosphides (Fe3P), and nitrides (TiN and AlN). The new mineral phases are closely related to the mineral matter in the raw anthracite samples. Thus, samples richer in Ca–Mg phases (carbonates and phosphates) produced minerals such as monticellite, pyrope, gehlenite, grossite and kushiroite; samples richer in Al-bearing phases (boehmite and diaspore) gave rise to phases such as mullite, corundum and spinel; and Si–Al bearing phases (clay minerals) were associated with the formation of minerals such as panunzite, plagioclase and cristobalite. At the highest temperature of the process the majority of the elements vaporized, and Ti seems to be the only element in the original mineral matter that withstands treatment to 2500 °C.

Using MgO–C refractories containing 6% carbon and the slag with a basicity (CaO/SiO 2 ) of around 0.8, the melting slag resistance experiments of low carbon MgO–C refractories were carried out in induction furnace and resistance furnace, respectively. The microstructure of low carbon MgO–C refractories corroded by slag under the different conditions was analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrometer (EDAX). The results show that in induction furnace having electromagnetic field (EMF), there are MgFe 2 O 4 spinel with a little of Mn ions generated in the interfacial layer. Part of the solid solution is monticellite [CaMgSiO 4 ] containing a little MnO and FeO. While under the condition of EMF free, there is not MgFe 2 O 4 spinel in the interfacial layer and the solid solution is monticellite (CaMgSiO 4 ). At a high temperature, EMF increases the diffusion coefficient of Fe 2+/3+ ions, which displaces Mg 2+ and forms MgFe 2 O 4 with a little of Mn ions. There are MgAl 2 O 4 spinel in the penetration layers under the conditions of both EMF and EMF free. EMF speeds up corrosion of low carbon MgO–C refractories.

The meteorite impact that created the 32-km-wide Late Carboniferous West Clearwater structure, situated about 125 km east of the Hudson Bay arc, northern Quebec, formed a sheet of impact melt now exposed on a central ring of islands. We describe the textures and mineralogy of two xenoliths of partially metamorphosed limestone. These blocks represent recrystallized remnants of a cover of Middle Ordovician limestone, now completely eroded in the area. The fossiliferous dolomite-bearing limestone recrystallized to granoblastic calcite + periclase marble when the blocs landed in the sheet of impact-generated melt. The silica content of the marble led to the formation of a sanidinite-facies assemblage of unusual nesosilicates such as spurrite, merwinite, and monticellite. Aluminian srebrodolskite, Ca 2 (Fe 3+ ,Al) 2 O 5 , is found in material with a composition similar to “Portland cement clinker”. Phase equilibrium and stratigraphic data constrain the minimum peak conditions of metamorphism at T > 815°C, P X (CO 2 ) > 0.1. Retrograde mineral assemblages indicate that X (CO 2 ) dropped to less than 0.1 shortly after the peak of metamorphism. Portlandite and brucite formed during the late hydration of the assemblage upon cooling.

The Cambrian Snap Lake kimberlite, in the Northwest Territories, Canada, is a rare example of an economic, near-horizontal kimberlite dyke deposit with an average vertical thickness of ~2.5 m. The diamond deposit consists of hypabyssal serpentine monticellite kimberlite and contains volumetrically minor hypabyssal kimberlite breccias. The kimberlite is composed of serpentinized olivine set in the groundmass of serpentinized monticellite, serpentine, phlogopite, dolomite, spinel, apatite, rutile and ilmenite. The Snap Lake kimberlite is similar in major-element composition to Group-I kimberlite worldwide, yet has exceptionally low CaO and P 2 O 5 . The low Ca character of the kimberlite is evident in the absence of perovskite, low proportion of carbonate, and the occurrence of dolomite rather than calcite as the dominant groundmass carbonate. Three textural types of phlogopite present in the kimberlite (macrocrystic–microphenocrystic, large poikilitic groundmass phlogopite and small groundmass phlogopite) have distinct patterns of composition and zonation. Detailed studies of the zonation reveal a complex evolution of the phlogopite compositions from an early deep xenocrystal to two stages of groundmass crystallization. Superimposed on this evolution common to all kimberlites worldwide is an additional early stage of groundmass crystallization in which barian phlogopite was precipitated only in one part of the dyke. The crystallization of Ba-rich phlogopite is accompanied by Sr-rich apatite, Mn-rich ilmenite and Fe 3+ -rich rutile, and may be related to a highly localized influx of residual oxidized carbonatitic fluid. The deuteric origin of the fluid explains the Ca-poor character of the Snap Lake kimberlite and the formation of late carbonate-rich veins pervasively cross-cutting the dyke.

Kerimasi calciocarbonatite consists principally of calcite together with lesser apatite, magnetite, and monticellite. Calcite hosts fluid and S-bearing Na–K–Ca-carbonate inclusions. Carbonatite melt and fluid inclusions occur in apatite and magnetite, and silicate melt inclusions in magnetite. This study presents statistically significant compositional data for quenched S- and P-bearing, Ca-alkali-rich carbonatite melt inclusions in magnetite and apatite. Magnetite-hosted silicate melts are peralkaline with normative sodium-metasilicate. On the basis of our microthermometric results on apatite-hosted melt inclusions and forsterite–monticellite phase relationships, temperatures of the early stage of magma evolution are estimated to be 900–1,000°C. At this time three immiscible liquid phases coexisted: (1) a Ca-rich, P-, S- and alkali-bearing carbonatite melt, (2) a Mg- and Fe-rich, peralkaline silicate melt, and (3) a C–O–H–S-alkali fluid. During the development of coexisting carbonatite and silicate melts, the Si/Al and Mg/Fe ratio of the silicate melt decreased with contemporaneous increase in alkalis due to olivine fractionation, whereas the alkali content of the carbonatite melt increased with concomitant decrease in CaO resulting from calcite fractionation. Overall the peralkalinity of the bulk composition of the immiscible melts increased, resulting in a decrease in the size of the miscibility gap in the pseudoquaternary system studied. Inclusion data indicate the formation of a carbonatite magma that is extremely enriched in alkalis with a composition similar to that of Oldoinyo Lengai natrocarbonatite. In contrast to the bulk compositions of calciocarbonatite rocks, the melt inclusions investigated contain significant amount of alkalis (Na2O + K2O) that is at least 5–10 wt%. The compositions of carbonatite melt inclusions are considered as being better representatives of parental magma composition than those of any bulk rock.

Altres ajuts: FCT (SFRH / BD /11020/2002) In cases where the provenance of raw materials used in the manufacture of local archeological ceramics is of interest, a detailed study of thermal transformations of minerals may be useful. The purpose of this study was to measure mineralogical transformations of different types of clays obtained during experimental firing runs, carried out at different temperatures, with the main goal of establishing Algarve reference groups based on the composition of raw material and high-temperature mineralogy, which may be compared with ceramics in studies of provenance. Eleven samples of clay-rich raw materials from the Algarve Basin (southern Portugal) were fired to temperatures ranging from 300 to 1100°C in increments of 100°C under oxidizing conditions. These were chosen to have variable chemical and mineralogical compositions, representing the main compositional range of the clay deposits from the region. Mineralogical and geochemical characterizations of the original clays were carried out by X-ray diffraction (XRD) and X-ray fluorescence (XRF), respectively. Mineral transformations on the fired products were also studied by XRD. Three groups of clays were distinguished according to the type of neoformed high-temperature minerals: (1) non-calcareous clays; (2) clays containing calcite as the only carbonate; and (3) clays with dolomite or dolomite + calcite. Firing of non-calcareous clays produced mullite at 1100-1200°C. Gehlenite and wollastonite formed by firing calcite-rich clays above 900°C, accompanied by anorthite or larnite in samples with small or large calcite contents, respectively. Firing of dolomite-rich clays at temperatures >900°C yielded a member of the gehlenite-åkermanite group and diopside. Anorthite, enstatite, periclase, forsterite, and monticellite may also form in the firing products.

The aim of this research was to investigate the effect of the chemical composition on the mechanical properties, bioactivity, and cytocompatibility in vitro of bioceramics in the MgO-CaO-SiO(2) system. Three single-phase ceramics (merwinite, akermanite and monticellite ceramics) with different MgO contents were fabricated. The mechanical properties were tested by an electronic universal machine, while the bioactivity in vitro of the ceramics was detected by investigating the bone-like apatite-formation ability in simulated body fluid (SBF), and the cytocompatibility was evaluated through osteoblast proliferation and adhesion assay. The results showed that their mechanical properties were improved from merwinite to akermanite and monticellite ceramics with the increase of MgO contents, whereas the apatite-formation ability in SBF and cell proliferation decreased. Furthermore, osteoblasts could adhere, spread and proliferate on these ceramic wafers. Finally, the elongated appearance and minor filopodia of cells on merwinite ceramic were more obvious than the other two ceramics.

Tuffisitic kimberlites from the Wesselton Mine consist, in order of formation, of the following primary components: chloritized olivine macrocrysts and phenocrysts; magmaclasts; cryptocrystalline diopside-phlogopite-rich mantles, and a smectite–chlorite interclast matrix. Magmaclasts consist of one to several crystals of chloritized olivine set in a microcrystalline groundmass of diopside, apatite, perovskite, spinel and chloritized and fresh phlogopite, the latter commonly rimming chloritized olivines. Magmaclasts have some similarities to holocrystalline hypabyssal kimberlite but lack monticellite, carbonate, carbonate-serpentine segregations and atoll spinels. Spinels in the magmaclasts show only a limited compositional evolution relative to spinels in spatially-associated hypabyssal kimberlite. Pre-existing solids, including discrete olivine grains, magmaclasts and most xenoliths, are mantled by acicular diopside and phlogopite. The interclast matrix is now represented by mixed layer phyllosilicates (chlorite–smectites) that are poorer in alumina and iron than chlorite pseudomorphing olivine and microlitic phlogopite and diopside. The interclast chlorite–smectite is considered to represent former phlogopite which has undergone late-stage deuteric hydrothermal-like modification. The interclast matrix crystallized from the volatile-rich remnants of the magma. None of the constituents of tuffisitic kimberlites, including the chlorite or chlorite–smectites, represent material formed from externally-derived fluids. These primary textures are unique to kimberlites and only form in certain circumstances. Tuffisitic kimberlites formed by progressive crystallization and volatile exsolution-induced segregation and/or disruption within a kimberlite magma (magmaclasts, mantles, interclast matrix) during a continuum of rapidly changing conditions in a subsurface (subvolcanic) magmatic system. This continuum represents a transition from a degassing magmatic system to a magmatic-derived hydrothermal-like fluid. Rapid drops in temperature with extensive exsolution of CO 2 and incorporation of large amounts of locally-derived country rock xenoliths resulted in explosive diatreme formation and within-diatreme modification of the crystallization and deuteric replacement sequence of typical kimberlite magma resulting in a distinctive mineralogy and texture.

The origin of alkali carbonates and chlorides in the groundmass of unaltered Udachnaya-East kimberlites in Siberia is still controversial. Contrary to existing dogma that the Udachnaya-East kimberlite was either contaminated by the crustal sediments or platform brines, magmatic origin of the groundmass assemblage has been proposed on the basis of melt immiscibility textures, melt inclusion studies, and strontium and neon isotope compositions. We further tested the idea of alkali- and chlorine enrichment of the kimberlite parental melt by studying olivine-hosted melt inclusions and secondary serpentine in kimberlites from the Slave Craton, Canada (Gahcho Kue, Jericho, Aaron and Leslie pipes) and southern West Greenland (Majuagaa dyke). Host olivine phenocrysts closely resemble groundmass olivine from the Udachnaya-East kimberlite in morphology, compositions (high-Fo, low-Ca), complex zoning with cores of varying shapes and compositions and rims of constant Fo. Melt inclusions in olivine consist of several translucent and opaque daughter phases and vapour bubble(s). The daughter crystals studied in unexposed inclusions by laser Raman spectroscopy and in carefully exposed inclusions by WDS-EDS are represented by Na-K chlorides, calcite, dolomite, magnesite, Ca-Na, Ca-Na-K and Ca-Mg-Ba carbonates, bradleyite Na3Mg(CO3)(PO4), K-bearing nahpoite Na2(HPO4), apatite, phlogopite and tetraferriphlogopite, unidentified sulphates, Fe sulphides, djerfisherite, pyrochlore (Na,Ca)2Nb2O6(OH,F), monticellite, Cr-spinel and Fe-Ti oxides. High abundances of Na, K (e.g., (Na+K)/Ca = 0.15-0.85) and incompatible trace elements in the melt inclusions are confirmed by LA-ICPMS analysis of individual inclusions. Heating experiments show that melting of daughter minerals starts and completes at low temperatures (~ 100oC and 600oC, respectively), further reinforcing the similarity with the Udachnaya-East kimberlite. Serpentine minerals replacing olivine in some of the studied kimberlites demonstrate elevated abundances of chlorine (up to 3-4 wt%), especially in the early generation. Despite heterogeneous distribution of chlorine such abundances are significantly higher than in the serpentine in abyssal and ophiolitic peridotites (

Clinopyroxene and orthopyroxene are generally rare in kimberlites, and believed to originate from disintegrated mantle and crustal xenoliths. We report occurrence of inclusions of low-Ca and high-Ca pyroxenes in the olivine phenocrysts in the Udachnaya-East hypabyssal kimberlite (Yakutia, Russia), and make inferences on their relationships to the kimberlite magma. Pyroxenes are only found as either resorbed macrocrysts or small inclusions in olivine; both types are being very rare and volumetrically insignificant. All clinopyroxene and majority of orthopyroxene inclusions are hosted in the olivine cores (Fo86-92) that are compositionally similar to olivine macrocrysts. Major and trace element compositions of clinopyroxene inclusions in olivine phenocrysts and macrocrysts are similar, and resemble compositions of clinopyroxene from lherzolite xenoliths hosted in the Udachnaya-East kimberlite. Their high Na2O and Cr2O3 abundances (0.65-2.55 and 0.6-2.8 wt%, respectively) suggest deep mantle origin (>4.5 GPa). The majority of clinopyroxene inclusions have convex-upward trace element patterns that imply kimberlite-like compositions for the hypothetical equilibrium melts. Re-equilibration of clinopyroxene inclusions with the host kimberlite liquid through micro-cracks in olivine is our preferred explanation in this case, however, we cannot exclude their high-pressure crystallisation from the protokimberlite melt. Orthopyroxene inclusions show significant compositional overlap with the low-Al orthopyroxene from the Udachnaya peridotite nodules. Where such inclusions occur in olivine fragments and contact with the kimberlite groundmass, they are strongly resorbed and partially replaced by monticellite. The mantle origin of orthopyroxene and its host olivine and disequilibrium relationships with the kimberlite melt is most likely. Both clinopyroxene and orthopyroxene are completely absent in the kimberlite groundmass. We conclude that the parental melt of the Udachnaya-East kimberlite was not saturated in either clinopyroxene or orthopyroxene at low pressure. This argues against a perceived mafic-ultramafic lineage of the kimberlite primary melt, and provides further support for its essentially carbonate-chloride composition.

The matrix of volcaniclastic kimberlite (VK) from the Muskox pipe (Northern Slave Province, Nunavut, Canada) is interpreted to represent an overprint of an original clastic matrix. Muskox VK is subdivided into three different matrix mineral assemblages that reflect differences in the proportions of original primary matrix constituents, temperature of formation and nature of the altering fluids. Using whole rock X-ray fluorescence (XRF), whole rock X-ray diffraction (XRD), microprobe analyses, back-scatter electron (BSE) imaging, petrography and core logging, we find that most matrix minerals (serpentine, phlogopite, chlorite, saponite, monticellite, Fe–Ti oxides and calcite) lack either primary igneous or primary clastic textures. The mineralogy and textures are most consistent with formation through alteration overprinting of an original clastic matrix that form by retrograde reactions as the deposit cools, or, in the case of calcite, by precipitation from Ca-bearing fluids into a secondary porosity. The first mineral assemblage consists largely of serpentine, phlogopite, calcite, Fe–Ti oxides and monticellite and occurs in VK with relatively fresh framework clasts. Alteration reactions, driven by deuteric fluids derived from the juvenile constituents, promote the crystallisation of minerals that indicate relatively high temperatures of formation (> 400 °C). Lower-temperature minerals are not present because permeability was occluded before the deposit cooled to low temperatures, thus shielding the facies from further interaction with fluids. The other two matrix mineral assemblages consist largely of serpentine, phlogopite, calcite, +/− diopside, and +/− chlorite. They form in VK that contains more country rock, which may have caused the deposit to be cooler upon emplacement. Most framework components are completely altered, suggesting that larger volumes of fluids drove the alteration reactions. These fluids were likely of meteoric provenance and became heated by the volcaniclastic debris when they percolated into the VK infill. Most alteration reactions ceased at temperatures > 200 °C, as indicated by the absence or paucity of lower-temperature phases in most samples, such as saponite. Recognition that Muskox VK contains an original clastic matrix is a necessary first step for evaluating the textural configuration, which is important for reconstructing the physical processes responsible for the formation of the deposit.

The forsterite-bearing Type B (FoB) CAI SJ101 consists of three major structural units: (1) light patches of sector-zoned, poikilitic Al-rich clinopyroxene (Cpx) with numerous inclusions of small spinel grains and aggregates and subordinate amounts of Mg-rich melilite (Mel) and anorthite (An) (Sp–Cpx lithology), (2) dark sinuous bands of Al-rich clinopyroxene with large (up to ∼300 × 60 μm) poikilitically enclosed euhedral forsterite (Fo) crystals (Fo–Cpx lithology), and (3) the external Cpx–Sp–An rim overlying the entire inclusion. The two major lithologies are always separated by a transition zone of clinopyroxene poikilitically enclosing both forsterite and spinel. The patches of the Sp–Cpx lithology exhibit significant textural and mineralogical variability that is size-dependent. Small patches typically consist of Cpx and spinel with minor remnants of melilite and/or its alteration products. Large patches contain Mel–An-rich cores with either equigranular–ophitic–subophitic or ‘lacy’ textures reminiscent of those in Types B or C CAIs, respectively. All silicates poikilitically enclose numerous spinel grains of identical habit. Both melilite and anorthite gradually disappear toward the boundary with the Fo–Cpx lithology. Neither the evaporation mantle of Al-rich melilite typical of other FoBs nor the Wark–Lovering rim is present. Secondary minerals include grossular, monticellite, magnetite, and a few grains of wollastonite, andradite, and nepheline. Being a rather typical FoB mineralogically and chemically, texturally SJ101 differs from other FoBs in displaying the nearly complete segregation of forsterite from spinel which occur only in the Fo–Cpx and Sp–Cpx lithologies, respectively. The complex, convoluted internal structure of SJ101 suggests that the coarse-grained Sp–An–Mel–Cpx cores and Fo–Cpx lithology represent the precursor materials of FoBs, proto-CAIs and Fo-rich accretionary rims. While the inferred chemistry and mineralogy of the Fo-rich rims are fairly typical, the high Ak content in SJ101 melilite (78.7–82.3 mol.%) implies that the SJ101 proto-CAIs represent a new type of CAIs that has not been sampled before. This type of CAIs might have formed by remelting of spinel-rich condensates. The Group II REE pattern, slightly negative δ 29 Si and δ 25 Mg values, and nearly solar ratios of the major elements in the bulk SJ101 suggest that its precursors, proto-CAIs and Fo-rich rims, could have formed by a non-equilibrium condensation in a closed system of solar composition somewhat depleted in a super-refractory evaporation residue. The proposed formation scenario of SJ101 invokes a non-steady cooling and condensation of the nebular gas interrupted by at least two distinct melting episodes required to account for the igneous textures of the Mel–An–Cpx-rich cores (proto-CAIs) and the Fo–Cpx lithology.

A series of uncommon micro- and nano-inclusions has been identified in diamonds from the Rio Soriso placer deposit in Mato Grosso State, Brazil. The micro-inclusions are variable in size, from 1 to 300 µm. Usually, they are polymineralic, being formed predominantly by intergrowths of carbonates, silicates and other minerals. Carbonates are represented mostly by dolomite and occasionally by calcite. Silicates found are coesite, wollastonite-II, cuspidine and monticellite. Sulphides and ilmenite form micro-inclusions as well. Nano-inclusions are different from micro-inclusions not only in size (not exceeding 200 nm); they are usually included in micro-inclusions. Among nano-inclusions, halides (NaCl, KCl, CaCl2 and PbCl2), anhydrite, spinel, phlogopite, PbO2, TiO2 with an α-PbO2 structure, native Fe, and other phases are identified. All these minerals are of the eclogitic association: they are either associated with coesite or are included in a diamond with a light, ‘organic’ carbon isotopic composition (with δ 13C from − 14 to − 25‰ PDB). This confirms our earlier conclusion that diamonds from the Juina area may have formed as a result of subduction of the crustal material to depths of at least the lower transition zone or even the lower mantle. The pressure estimates for the investigated diamonds vary in a range from 3 to 10 GPa. An interesting assemblage of calcite + cuspidine + wollastonite + monticellite + fluid identified in one of the studied diamonds is considered as a product of a reaction of wollastonite + fluid forming cuspidine + monticellite. The presence of numerous pores, cavities and bubbles in mineral inclusions, and identification of an association of volatile-containing mineral inclusions, such as halides (NaCl, KCl, CaCl2, and PbCl2), fluorine-containing silicate cuspidine, and phlogopite emphasize the important role of volatiles, particularly chlorine and fluorine in the formation of the diamonds.

In the continuous casting of steel, the porous structure of tundish plaster with high-MgO content is commonly used. Destruction of this type of plaster is the result of silicate phases with low melting points that are created when slag containing SiO2 and CaO penetrates into pores of plaster and reacts with periclase (MgO). In this study, two new plasters are developed and their performances in contact with slag are compared with the common plaster by using crucible test. In these new plasters, part of magnesia is replaced by chromite and olivine. Experimental work indicated that basicity gap between slag and plasters is reduced. Destructive reactions between penetrated slag and these new porous plasters are inhibited and phases with high melting points are formed on the surface of primary grains, leading to less dissolution of plasters in slag. This means that the life time of tundish plaster is increased. The reason is that chromite and olivine have less tendency to react with slag rich in SiO2 and probability of formation of destructive silicate phases such as monticellite and merwinite is reduced.

Mineralogical transformations during firing of two extremely calcareous clays, one calcite and other dolomite rich, and relatively poor in silica were studied. Original clays were mineralogical and chemically characterized with X-ray diffraction (XRD) and X-ray fluorescence (XRF). Firing of both clays was carried out in the temperature range 300–1100 °C under oxidizing conditions and the mineralogical transformations were investigated with XRD, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy associated with energy dispersive X-ray spectroscopy (SEM-EDS). Important compositional differences in the neoformed phases were observed between calcite and dolomite rich clays. In the Ca-rich clay the assemblage gehlenite + wollastonite + larnite was observed. In the Mg(Ca)-rich clay the reaction products included akermanite, diopside, monticellite, forsterite, periclase and spinel. XRD and SEM-EDS showed the presence, in both clays, of a potassium–calcium sulfate in samples fired between 900 and 1100 °C.

A unique hybrid natrocarbonatite, collected from the new ash cone of the volcano Oldoinyo Lengai. Tanzania in July 2008, consists of phenocrysts of nyerereite and gregoryite together with xenocrysts of clinopyroxene, nepheline and Ti-andradite set in a groundmass of cuspidine, sodalite, ferroan manganoan monticellite, K-Fe sulphide and manganoan titanian magnetite and gregoryite. The xenocrysts were not in equilibrium with the melt which formed their current host, as clinopyroxenes and Ti-andradite are mantled by cuspidine, and nepheline by sodalite and phlogopite—potassian kinoshitalite solid solutions. A microxenolith of ijolite exhibits similar reaction phenomena. The minerals of the xenocryst suite have similar compositions to plutonic ijolites found at Oldoinyo Lengai, and are thus considered to be derived by the fragmentation of such material in a previously contaminated natrocarbonatite melt. The latter, which has cuspidine, sodalite and monticellite as primary liquidus phases, is considered to have been formed by the complete assimilation of ijolitic material in a natrocarbonatite magma at depth in the volcano conduit. The occurrence of trace amounts of cuspidine, Fe-Mn-monticellite, K-Fe sulphide and Mn-Ti-spinel in recently erupted natrocarbonatites is ascribed to similar, but less extensive, assimilation of silicate material prior to their eruption.

A series of Cr4+:CaMgSiO4 single crystals is grown using floating zone melting, and their microstructure, composition, and crystal structure are investigated. It is shown that regions with inclusions of second phases, such as forsterite, akermanite, MgO, and Ca4Mg2Si3O12, can form over the length of the sample. The composition of the single-phase regions of the single crystals varies from the stoichiometric monticellite CaMgSiO4 to the solid solution Ca(1 − x)Mg(1 + x)SiO4(x = 0.22). The Cr:(Ca0.88Mg0.12)MgSiO4 crystal is studied using X-ray diffraction. It is revealed that, in this case, the olivine-like orthorhombic crystal lattice is distorted to the monoclinic lattice with the parameters a = 6.3574(5) A, b = 4.8164(4) A, c = 11.0387(8) A, β = 90.30(1)o, Z = 4, V = 337.98 A3, and space group P21/c. In the monoclinic lattice, the M(1) position of the initial olivine structure is split into two nonequivalent positions with the center of symmetry, which are occupied only by Mg2+ cations with the average length of the Mg-O bond Rav = 2.128 A. The overstoichiometric Mg2+ cations partially replace Ca2+ cations (in the M(2) position of the orthorhombic prastructure) with the average bond length of 2.347 A in the [(Ca,Mg)-O6] octahedron. The average distance in SiO4 distorted tetrahedra is 1.541 A.

Orthorhombic magnesium-iron ludwigite-vonsenite forms a continuous isomorphic series Mg2Fe3+[BO3]O2-Fe22+ Fe[BO3]O2; its composition at the magnesioskarn and other deposits varies from magnesian to ferriferous members. In addition, they demonstrate isovalent substitution of Mn for Mg (in pinakiolite, blatterite, and others) and practically complete substitution of Ni for Mg (in bonaccordite). Ferric iron in the borates is substituted by isovalent Al and Cr. The incorporation of Ti, Sn, Sb, and V via heterovalent substitution has been studied in less detail. Our research revealed new manifestations of Ti-and Sn-bearing borates. They are magnesioludwigite and azoproite with variable Ti content, as well as by Sn-bearing aluminian borates formed via the 2Fe3+ → (Ti4+ + Mg)6+ and/or (Sn4+ + Mg)6+ substitution. The incorporation of pentavalent elements according to the scheme 3Fe3+ → (Sb5+ + 2Mg)9+ or (V5+ + 2Mg)9+ is not excluded. The highest Ti borates were found in the marbles and calciphyres of the Tazheran deposit in the Baikal region and Nalednoe, Dokuchan, and Titovskoe deposits in Yakutia, where azoproites contain more than 50 and even higher 75 mol % of the Mg2(TiMg)0.5[BO3]O2 end member. Aluminum magnesioludwigites from Yakutia and Chukotka simultaneously contain tin and titanium. Mount Brooks, Alaska, contains tin-bearing azoproite or its tin-bearing varieties. New data are reported on Sb-and V-bearing orthoborates. Calciphyres of Alaska contain monoclinic magnesiohulsite (Mg,Fe)2(SnMg)0.56+[BO3]O2, which is replaced by schoenfliesite MgSn(OH)6. The studied borate occurrences belong to hypabyssal magnesian skarns of the periclase and monticellite metasomatic PT facies at contacts of dolomites with granitoid intrusions of increasing alkalinity or leucocratic granites. Their formation was related to interaction between disequilibrium kotoite and early oxides and spinellides of various compositions, on the one hand, and, on the other hand, to the influx of Ti-and Sn-bearing hydrothermal solutions.

The Majuagaa kimberlite dike in the Maniitsoq region, southern West Greenland, is 564 Ma old, 2.5 km long, and up to 2 m wide. It is well exposed and very fresh, allowing detailed petrographic and chemical investigations. Little or no serpentinization is observed, and primary petrographic characteristics and grain morphologies are preserved. The dike is diamondiferous and carries xenoliths (up to 30 cm), megacrysts and macrocrysts characteristic of kimberlite. On the bases of the paragenesis and compositions of groundmass phlogopite, geikielite and Mg–Ti-enriched spinel, the dike is classified as kimberlite, despite being carbonate-rich and the apparent absence of monticellite characteristic of many occurrences of bona fide hypabyssal kimberlite. Olivine megacrysts, macrocrysts and microcrysts are all xenocrystic, whereas microphenocrysts are xenocrystic microcrysts overgrown by equilibrium olivine. Most olivine (max. 37 wt.%) is found to be xenocrystic on the basis of Ni mass balance. The average bulk composition of the melt involved in the dike compares well with Group-1 kimberlite. Corrected for xenocrystic olivine and ilmenite, the melt has the composition of a silicocarbonatite and compares with experimental melts formed at very low degrees of partial melting of CO2-bearing lherzolite.

This paper is the second part of a study on recycling magnesite and chromite ore (in the 0–10−3 m fraction) powder, which remains as a production process waste. In this work, 90% magnesite-10% chromite composition was used as a brick composition. Compaction pressure, sintering temperature, ratio of TiO2 addition, and influence of bonding type on refractory properties were examined. In refractory brick production, one of the most important parameters that affects the properties of the product is the particle size distribution of the blend. Experiments show that using a magnesite particle size of −10−3 m and a chromite particle size of −63×10−6 m affects the properties of the product in a positive way. Experiment blends with the particle sizes selected above were used. Magnesite ore was used in experiments after calcination at 1200°C for four hours. In the experiments we mention, MgCl2 and MgSO4 solutions were used as a bonding agent, as a result of which a 6% bonding ratio of MgCl2 and MgSO4 solutions was determined as optimum. The effect of compacting pressure on the refractory properties was studied, and the optimum compacting pressure was determined as 180 MPa. For bricks prepared using calcined magnesite, the optimum sintering temperature was found to be 1750°C. The positive effect of TiO2 addition on the magnesite chrome refractory brick structure has been reported in the literature. Thus, 1, 3, 5, and 7 wt.% TiO2 ratios were used in the blend, and the refractory properties were positively affected by the 3% TiO2 addition. Taking the result of the MgCl2 and MgSO4 bonding solution into consideration, it is clear that the refractory properties of brick can be improved by using a mixture of MgCl2 and MgSO4 bonding solutions. In light of the above concept, bonding mixtures with 1:3, 1:5, and 1:10 ratios were prepared, and these bonding mixtures were studies as a bonding material. The experimental results show that the cold crushing strength (CCS) and volume density of bricks increase, whereas the porosity decreases when a 1:5 ratio of MgCl2 and MgSO4 in the bonding mixture and 3% TiO2 addition were used. Microstructural study of the produced bricks was done using scanning electron microscope (SEM). In addition to this, the phases forming the structure of brick were examined via x-ray diagrams of the material. In bricks where a mixture of a 1:5 MgCl2: MgSO4 bonding solution was used as bonding agent and 3% TiO2 was added, spinel (magnochromite (MgCr2O4)), magnesium orthotitanate (Mg2TiO4), monticellite (CaMgSiO4), and forsterite (Mg2SiO4) phases were found. The perovskite phase was not observed during the experimental study.

Hypabyssal kimberlites are similar in their mineralogy and geochemistry across the world, and thus form a distinct magma type that is produced repeatedly in time and space. This small volume magma is derived from the asthenosphere (200–?650 km), and as it nears the surface consists of olivine macrocrysts, i.e. xenocrysts (~ 25 vol.%), olivine phenocrysts (~ 25 vol.%), entrained in a Ba–Ti–Mg-rich, Al-poor carbonate-silicate liquid containing high, but unknown amounts, of dissolved CO2, CH4 and H2O. Hypabyssal kimberlites are shown to be hybrid rocks formed by mixing with, and assimilation of, mantle-derived lherzolite and harzburgite. Orthopyroxene is not stable in these magmas and its resorption leads the precipitation of primary liquidus olivine. The magma crystallizes rapidly at crustal levels to uniform holocrystalline rocks that do not contain glass. In addition to spinel, perovskite, monticellite, apatite, and phlogopite–kinoshitalite, primary carbonates are typically present as low pressure liquidus phases. Serpentines (primary polygonal serpentine and chrysotile) and carbonate commonly crystallize together from volatile-rich (CO2 + H2O) deuteric residua as a polycrystalline mesostasis or discrete segregations; the latter are not in-filled vesicles. Kimberlite magmas have a very long crystallization interval ranging from > 1200 to ~ 300 °C, and there is a continuum from the magmatic crystallization of silicate and oxide minerals to carbo-hydrothermal residua forming the calcite-serpentine mesostasis. It is concluded that there are no hypabyssal kimberlites which are representatives of the initial primary magma; all kimberlites are hybrid and contaminated magmas which have undergone crystallization in the mantle prior to crystallization of the groundmass-mesostasis assemblages.

Most chondritic materials experienced diverse styles of secondary alteration resulting in formation of hydrous and anhydrous oxygen-bearing minerals—silicates, oxides, and carbonates (phyllosilicates, magnetite, calcite, dolomite, breunnerite, ferrous olivine, hedenbergite, wollastonite, grossular, monticellite, forsterite, andradite, nepheline, sodalite) (Brearley 2003, 2005 and references therein). Petrographic, mineralogic, oxygen and short-lived isotope systematics (26Al-26Mg, 53Mn-53Cr, 129I-129Xe) suggest that alteration occurred in the presence of aqueous solutions under variable physico-chemical conditions (temperature, water:rock ratio, pH, f O2, and fluid compositions) in an asteroidal setting; it started within 1–2 m.y. after formation of the CV CAIs, was multistage, and lasted up to 15 m.y. (Krot et al. 2006 and references therein). Here we review bulk O-isotopic compositions of chondritic materials, O-isotopic compositions of secondary minerals produced during asteroidal alteration, and possible effects of fluid-assisted thermal metamorphism on O-isotopic exchange in primary, high-temperature minerals (melilite and anorthite) in the CV and CO CAIs. The implications of these data for understanding temperatures of alteration, water:rock ratios, and oxygen isotopic composition of water, that probably accreted into chondrite parent bodies in the form of ice, are discussed. The inferred or measured O-isotopic composition of the meteoritic water is close to the terrestrial fractionation line (Δ17O = ±2‰); it is very different from the inferred O-isotopic compositions of the Sun [Δ17O ~ −25‰] (Clayton 2002; Yurimoto and Kuramoto 2004; Hashizume and Chaussidon 2005; Lyons and Young 2005), suggesting significant evolution of O-isotopic composition of the gaseous reservoir in the inner protoplanetary disk over its short (~3–5 m.y.) life time.

Synthetic end-members Mg2SiO4, Fe2SiO4, Mn2SiO4, and Co2SiO4 and natural samples of forsterite-fayalite series, tephroite and monticellite, are investigated using Raman spectroscopy. The Raman spectra of the olivine-group minerals have a characteristic set of two intense lines of the Si-O asymmetric stretching band (wavenumber κ1) and Si-O symmetric stretching band (κ2). The κ1 and κ2 values of the Mg2SiO4-Ca(Mg, Fe)SiO4 series, in which the M2 site is occupied by nontransition elements, vary from 847 cm−1 to 857 cm−1 and from 815 cm−1 to 825 cm−1, respectively, and their ω (= κ1 − κ2) value is fairly constant around 32 cm−1. On the other hand, fayalite, tephroite, and other olivine-group minerals in which transition elements exist in the M2 site have a fairly constant κ1 (836-839 cm−1) value and variable κ2 (808-819 cm−1) and ω (20-32 cm−1) values. The ω value of the forsterite-fayalite series systematically increases with Mg#[= Mg/(Mg + Fe)] and is useful for determining their chemical compositions.

Ratio of slopes method (RSM) is employed for quantitative analysis of complex phases formed in continuous casting as reaction products of tundish plaster (composed of high-MgO content) and alloy steel slag contained mainly oxides of SiO2, CaO, MgO, MnO and metallic Fe. XRD results indicated that at 1600 °C, Monticellite (CaMgSiO4), Merwinite (Ca3Mg(SiO4)2) and Tephroite (Mn2SiO4) were developed by reaction of slag with MgO grains of tundish plaster, with low melting points of, respectively, 1498, 1575 and 1345 °C. For quantitative XRD analysis, CaF2 was chosen as standard material and some modifications were used for overlapping of too many peaks and lack of materials of known purity. Results of analysis indicated the range of 41–53% MgO, 13–28% Monticellite, 7–33% Merwinite and 5–13% Tephroite in three different tundish plasters. It was found that the rate of dissolution of MgO because of reaction with slag increases as the original content in plaster is increased. The data of MgO content of the best tundish plaster before and after being used in industrial application is used for some kinetic considerations. The best kinetic equation was found to be: ln m M = − H t 2 where m is the not dissolved amount of MgO from an original value of M after passage of time t and H is a constant of the specific system at the isothermal temperature of continuous casting.

The coarse-grained, igneous, anorthite-rich (Type C) CAIs from Allende studied ( 100 , 160 , 6-1-72 , 3529-40 , CG5 , ABC , TS26 , and 93) have diverse textures and mineralogies, suggesting complex nebular and asteroidal formation histories. CAIs 100 , 160 , 6-1-72 , and 3529-40 consist of Al,Ti-diopside (fassaite; 13–23 wt% Al 2 O 3 , 2–14 wt% TiO 2 ), Na-bearing akermanitic melilite (0.1–0.4 wt% Na 2 O; Ak 30–75 ), spinel, and fine-grained (∼5–10 μm) anorthite groundmass. Most of the fassaite and melilite grains have “lacy” textures characterized by the presence of abundant rounded and prismatic inclusions of anorthite ∼5–10 μm in size. Lacy melilite is pseudomorphed to varying degrees by grossular, monticellite, and pure forsterite or wollastonite. CAI 6-1-72 contains a relict Type B CAI-like portion composed of polycrystalline gehlenitic melilite (Ak 10–40 ), fassaite, spinel, perovskite, and platinum-group element nuggets; the Type B-like material is overgrown by lacy melilite and fassaite. Some melilite and fassaite grains in CAIs 100 and 160 are texturally similar to those in the Type B portion of 6-1-72 . CAIs ABC and TS26 contain relict chondrule fragments composed of forsteritic olivine and low-Ca pyroxene; CAI 93 is overgrown by a coarse-grained igneous rim of pigeonite, augite, and anorthitic plagioclase. These three CAIs contain very sodium-rich akermanitic melilite (0.4–0.6 wt% Na 2 O; Ak 63–74 ) and Cr-bearing Al,Ti-diopside (up to 1.6 wt% Cr 2 O 3 , 1–23 wt% Al 2 O, 0.5–7 wt% TiO 2 ). Melilite and anorthite in the Allende Type C CAI peripheries are replaced by nepheline and sodalite, which are crosscut by andradite-bearing veins; spinel is enriched in FeO. The CAI fragment CG5 is texturally and mineralogically distinct from other Allende Type Cs. It is anorthite-poor and very rich in spinel poikilitically enclosed by Na-free gehlenitic melilite (Ak 20–30 ), fassaite, and anorthite; neither melilite nor pyroxene have lacy textures; secondary minerals are absent. The Al-rich chondrules 3655b-2 and 3510-7 contain aluminum-rich and ferromagnesian portions. The Al-rich portions consist of anorthitic plagioclase, Al-rich low-Ca pyroxene, and Cr-bearing spinel; the ferromagnesium portions consist of fosteritic olivine, low-Ca pyroxene, and opaque nodules. We conclude that Type C CAIs 100 , 160 , 6-1-72 , and 3529-40 formed by melting of coarse-grained Type B-like CAIs which experienced either extensive replacement of melilite and spinel mainly by anorthite and diopside (traces of secondary Na-bearing minerals, e.g., nepheline or sodalite, might have formed as well), or addition of silica and sodium during the melting event. CG5 could have formed by melting of fine-grained spinel-melilite CAI with melilite and spinel partially replaced anorthite and diopside. CAIs ABC , 93 , and TS-26 experienced melting in the chondrule-forming regions with addition of chondrule-like material, such as forsteritic olivine, low-Ca pyroxene, and high-Ca pyroxene. Anorthite-rich chondrules formed by melting of the Al-rich (Type C CAI-like) precursors mixed with ferromagnesian, Type I chondrule-like precursors. The Allende Type C CAIs and Al-rich chondrules experienced fluid-assisted thermal metamorphism, which resulted in pseudomorphic replacement of melilite and anorthite by grossular, monticellite, and forsterite ( 100 , 160 , 6-1-72 , 3592-40 ) or by grossular, monticellite, and wollastonite ( ABC , 93 , TS-26 ). The pseudomorphic replacement was followed or accompanied by iron–alkali metasomatic alteration resulting in replacement of melilite and anorthite by nepheline and sodalite, enrichment of spinel in FeO, and precipitation of salite–hedenbergite pyroxenes, wollastonite, and andradite in fractures and pores in and around CAIs.

Mono-phase ceramics of monticellite (CaMgSiO4) were successfully synthesized by sintering sol-gel-derived monticellite powder compacts at 1,480 degrees C for 6 h. The mechanical properties and the coefficient of thermal expansion (CTE) of the monticellite ceramics were tested. In addition, the bioactivity in vitro of the monticellite ceramics was evaluated by investigating their bone-like apatite-formation ability in simulated body fluid (SBF), and the biocompatibility in vitro was detected by osteoblast adhesion and proliferation assay. The results showed that the bending strength, fracture toughness and Young's modulus of the monticellite ceramics were about 159.7 MPa, 1.63 MPa m1/2 and 51 GPa, respectively. The CTE was 10.76x10(-6) degrees C(-1) and close to that of Ti-6Al-4V alloy (10.03x10(-6) degrees C(-1)). Furthermore, the monticellite ceramics possessed bone-like apatite-formation ability in SBF and could release soluble ionic products to significantly stimulate cell growth and proliferation. In addition, osteoblasts adhered and spread well on the monticellite ceramics, which indicated good bioactivity and biocompatibility.

This study concerns the chemical reactions involved and the phases formed during penetration of slags of variable composition into porous plaster structure of tundish. Tundish plaster is mainly composed of MgO with minor amounts of SiO2 and impurities, with a grain size of less than 1 mm, inorganic or organic fibers in order to decrease density and provide porosity for insulation, plasticizers and stiffening agents and some other additions. Tundish slag analysis for different grades of steel (7176D and 1191D, according to DIN standard) at different sequences, indicated a very variable composition of CaO (11–42%), SiO2 (28–46%), Al2O3 (6–12%), MgO (11–20%), MnO (0–13%) and some minor variations of Fe, FeO and TiO2. Experimental work indicated that slag when penetrated into pores of plaster, develop the phases of Monticellite (CaO · MgO · SiO2) and Merwinite (CaO1.5 · MgO0.5 · SiO2) around MgO particles and decrease the liquidus temperature from 2,800 °C to about 1,500 °C and provide dissolution of MgO grains in steel making process. Calculation based on two kinetic equations developed for diffusion controlled dissolution, indicated that the dissolution of MgO in tundish plaster is not a diffusion controlled process and is affected by turbulent flow parameters. Phase diagram of CaO–SiO2–MgO indicates that decreasing SiO2 to below 20% and increasing CaO content to as high as possible, increases the liquidus temperature to above 2,000 °C. Sources of SiO2 in the process are the rice husk addition, which is used as an insulating material on top of the melt, and the slag flux addition. These sources should be reduced to as low a level as possible. This fact does not affect the fluidity of slag which is required for inclusion removal. Fluidity of slag comes from low melting point eutectics in CaO–Fe2O3 and CaO–FeO (about 1,200 °C) due to iron oxide on top of the steel melt.

Constraining the composition of primitive kimberlite magma is not trivial. This study reconstructs a kimberlite melt composition using vesicular, quenched kimberlite found at the contact of a thin hypabyssal dyke. We examined the 4 mm selvage of the dyke where the most elongate shapes of the smallest calcite laths suggest the strongest undercooling. The analyzed bulk compositions of several 0.09–1.1 mm 2 areas of the kimberlite free from macrocrysts were considered to be representative of the melt. The bulk analyses conducted with a new ‘‘chemical point-counting’’ technique were supplemented by modal estimates, studies of mineral compositions, and FTIR analysis of olivine phenocrysts. The melt was estimated to contain 26– 29.5 wt% SiO2, � 7 wt% of FeOT, 25.7–28.7 wt% MgO, 11.3–15 wt% CaO, 8.3–11.3 wt% CO2, and 7.6–9.4 wt% H2O. Like many other estimates of primitive kimberlite magma, the melt is too magnesian (Mg# = 0.87) to be in equilibrium with the mantle and thus cannot be primary. The observed dyke contact and the chemistry of the melt implies it is highly fluid (g =1 0 1 –10 3 Pa s at 1100–1000 � C) and depolymerized (NBO/T = 2.3–3.2), but entrains with 40–50% of olivine crystals increasing its viscosity. The olivine phenocrysts contain 190–350 ppm of water suggesting crystallization from a low SiO2 magma (aSiO2 below the olivine-orthopyroxene equilibrium) at 30–50 kb. Crystallization continued until the final emplacement at depths of few hundred meters which led to progressively more Ca- and CO2-rich residual liquids. The melt crystallised phlogopite (6–10%), monticellite (replaced by serpentine, � 10%), calcite rich in Sr, Mg and Fe (19–27%), serpentine (29–31%) and

The results of a complex study of melt inclusions in olivine phenocrysts contained in unaltered kimberlites from the Udachnaya-East pipe indicate that the inclusions were captured late during the magmatic stage, perhaps, under a pressure of

Djerfisherite, an unusual potassium- and chlorine-bearing sulphide K6Na(Fe,Ni,Cu)(24)S26Cl, is found in remarkably fresh rocks of the Udachnaya-East kimberlite pipe, including several varieties of kimberlite and a kimberlite-hosted phlogopite-spinel lherzolite xenolith. In both kimberlite breccia and monticellite kimberlite djerfisherite is a common groundmass mineral. Djerfisherite is also present as a daughter phase in olivine-hosted inclusions of trapped carbonate-chloride melt and sulphide melt. The mineral is present as irregular or rounded grains (up to 80-100 mu m) in association with magnetite and pyrrhotite in the kimberlite groundmass, and together with carbonates, Na-K-chlorides, silicates, magnetite, sulphates and Fe-Ni-sulphides in melt inclusions. Djerfisherite in the lherzolite xenolith is mainly interstitial (up to 100 mu m) and commonly rims primary mantle sulphides that show clear signs of replacement. Broad compositional variations in Fe, Ni and Cu are common in djerfisherite from different occurrences of the Udachnaya-East pipe. Textural relations, heating stage experiments with melt inclusions and compositional data, suggest a late magmatic origin of djerfisherite in the Udachnaya-East kimberlite groundmass, at shallow depths and at T

International audience; A shallow-level dioritic pluton of Upper Cretaceous age caused extensive contact metamorphism of a Mesozoic calcareous sequence at Oraviţa-Ciclova in Romania. The peak metamorphic assemblage (stage I) includes wollastonite, åkermanite-rich melilite, Ti-rich calcic garnet, and pyrrhotite. A second, subsequent paragenesis (stage II) is due to local decreases in fluid pressure and includes gehlenite, Ti-poor calcic garnet, monticellite, Al-rich diopside, magnetite, perovskite, and probably a Ca-Si mineral (kilchoanite?). An early hydrothermal stage (stage III) produced retrogression of the first two stages and a paragenesis including vesuvianite, clintonite, fukalite, katoite, and hydroxylellestadite. A second, late hydrothermal event (stage IV) resulted in the formation of clinochlore, talc, epidote, zeolites (scolecite and thomsonite-Ca), thaumasite, and tobermorite. A last, weathering, paragenesis corresponding to stage V includes allophane (C-S-H gels) and probably portlandite, unpreserved because of its transformation to aragonite, then calcite. The peak metamorphic conditions during the prograde evolution are estimated to have been 750–800 °C for a fluid pressure of up to 0.5 kbar. The main constants determined from chemical, optical, and X-ray powder analyses of these mineral species are reported here. This work documents the first occurrence of katoite and the second occurrences of perovskite, fukalite, and hydroxylellestadite in the Romanian skarns.

The four essential minerals of many potassium-rich mafic and ultramafic rocks are leucite, augite, olivine, and melilite. The bulk compositions of these simplified rocks lie within the phase volumes of forsterite–diopside–akermanite–leucite. Phase relation within the system is thus applicable to the genesis of potassium-rich mafic and ultramafic volcanic rocks. A detailed study of the system was made by Gupta (1972), who showed that all phases in this system are solid solutions. Forsterite may contain monticellite; and diopside and akermanite possibly incorporate Ca-Tschermak’s molecule and gehlenite in solid solution, respectively. Likewise, leucite may include K2O·MgO·5SiO2 and forsterite probably contains monticellite. The system is bounded by four ternary joins.

Aillikites (carbonated, melilite-free ultramafic lamprophyres grading to carbonatites) are minor components of the Gardar alkaline igneous province. They occur principally as minor intrusions and as clasts in diatremes, but more voluminous aillikitic intrusions crop out near the Ilimaussaq Complex, which they predate by a few million years. These larger intrusions were emplaced at 1160 ± 5 Ma. They are essentially carbonate-free and, consisting almost wholly of ferromagnesian silicate and oxide minerals, are mela-aillikites. Typically the mela-aillikites are fine-grained rocks composed largely of olivine, clinopyroxene, phlogopite and magnetite that crystallised in open systems, permitting loss of volatile-rich residues. The petrography is highly complex, involving at least 28 mineral species. Pyroxenitic veins were emplaced while the host-rocks were still at high temperatures and represent channels through which fluorinated silico-carbonatitic residual melts escaped, with exsolving CO 2 as propellant. Precipitation of Ca-rich minerals including monticellite, perovskite, vesuvianite, wollastonite and cuspidine was a result of dissociation of the calcium carbonate in the residual melts. Late-stage crystallisation was in a highly oxidising environment in which the ‘common minerals’ attain extreme compositions (almost pure forsterite, ferrian-diopside, highly magnesian ilmenite, Ba–Ti-rich phlogopite and Sr-rich kaersutite). Spatially associated diatremes may be vents through which CO 2 -rich gases erupted. The whole-rock compositions are considered to be well removed from those of co-existing melts: compaction and expulsion of highly mobile residual melts is inferred to have left the mela-aillikites as aberrant cumulates. The mela-aillikites are a late-Gardar manifestation of the aillikitic magmatism that occurred intermittently in the province for over 120 Ma. Repetitive formation of metasomite vein systems in the deep lithospheric mantle is postulated. These readily fusible metasomites had short residence histories, experiencing either adiabatic melting or thermal melting as a result of plume activity. The abnormally large volumes of ultramafic lamprophyre magma, from which the mela-aillikites crystallised, may denote the culmination of metasomatic processes in the closing stages of the evolution of the Gardar Province.

Minerals of olivine–melilite and olivine–monticellite rocks from the Krestovskiy massif contain primary silicate-salt, carbonate-salt, and salt melt inclusions. Silicate-salt inclusions are present in perovskite I and melilite. Thermometric experiments conducted on these inclusions at 1,230–1,250°C showed silicate–carbonate liquid immiscibility. Globules of composite carbonate-salt melt rich in alkalies, P, S, and Cl separated in silicate melt. Carbonate salt globules in some inclusions from perovskite II at 1,190–1,200°C separated into immiscible liquid phases of simpler composition. Carbonate-salt and salt inclusions occur in monticellite, melilite, and garnet and homogenize at close temperatures (980–780°C). They contain alkalies, Ca, P, SO3, Cl, and CO2. According to the ratio of these components and predominance of one of them, melt inclusions are divided into 6 types: I—hyperalkaline (CaO/(Na2O+K2O)≤1) carbonate melts; II—moderately alkaline (CaO/(Na2O+K2O)>1) carbonate melts; III—sulfate-alkaline melts; IV—phosphate-alkaline melts; V—alkali-chloridic melts, and VI—calc-carbonate melts. Joint occurrence of all the above types and their syngenetic character were established. Some inclusions demonstrated carbonate-salt immiscibility phenomena at 840–800°C. A conclusion in made that the origin of carbonate melts during the formation of intrusion rocks is related to silicate–carbonate immiscibility in parental alkali-ultrabasic magma. The separated carbonate melt had a complex alkaline composition. Under unstable conditions the melt began to decompose into simpler immiscible fractions. Different types of carbonate-salt and salt inclusions seem to reflect the composition of these spatially isolated immiscible fractions. Liquid carbonate-salt immiscibility took place in a wide temperature range from 1,200–1,190°C to 800°C. The occurrence of this kind of processes under macroconditions might, most likely, cause the appearance of different types of immiscible carbonate-salt melts and lead to the formation of different types of carbonatites: alkali-phosphatic, alkali-sulfatic, alkali-chloridic, and, most widespread, calcitic ones.

The resistance of magnesian spinellide refractories to molten slag attack is studied and effects associated with the material composition and the microstructure of test specimens are discussed. The mechanisms of corrosion wear and chemical reactions involved are considered in detail. Slags with a basicity of 1.9 – 2.1 react with periclase to yield spinel, calcium orthosilicate, and monticellite. To prevent the chemical corrosion of periclase, sintered periclase or alumina as additions to the slag are recommended for use.

Microstructural analysis of MgO—MgAl2O4 refractory bricks corroded at 1400–1450°C by calcium aluminosilicate slag reveals secondary spinel, monticellite, merwinite, and MgO as microscopic corrosion products, generally forming in this sequence as the brick is penetrated. The secondary spinel forms an incomplete layer close to (but not at) the MgO grain. Thermodynamic calculations are used to support a detailed model of the corrosion mechanism.

Lapilli and spatter of natrocarbonatite extruded from the T56B cone of Oldoinyo Lengai (Tanzania) in August 2003 are unusually rich in apatite, silicate, oxide and sulphide minerals. These minerals occur primarily within inclusions of quenched natrocarbonatite in gregoryite and fractures in nyerereite-gregoryite intergrowths. Silicates include members of the sodian cuspidine–niobian cuspidine–niocalite solid-solution series and manganoan monticellite. Oxides are represented by members of the magnesioferrite–jacobsite–magnetite solid-solution series. Sulphides occurring in decreasing order of abundance include: ferroan alabandite, manganoan ferroan sphalerite, galena and pyrrhotite. Petrographic and compositional data for these minerals are interpreted to indicate that all are high-temperature (