Olivine Form Research Articles

Acceleration of Iron-Rich Olivine CO2 Mineral Carbonation and Utilization for Simultaneous Critical Nickel and Cobalt Recovery

CO2 mineral carbonation is an important method to sequester carbon dioxide (CO2) in the form of stable mineral carbonates for permanent storage. The slow kinetics of carbonation, especially for iron-rich olivine, is the major challenge for potential application. This work proposes methods to accelerate the mineral carbonation process of different materials in the general mineral grouping of divalent metals–olivine for simultaneous nickel and cobalt recovery. It is found that nickel-olivine is facile for mineral carbonation compared to ferrous and magnesium olivine. Ferrous olivine is the most difficult form of olivine to carbonate as illustrated in both thermodynamics and experimental test results. The increase in iron content in olivine inhibits the CO2 mineral carbonation process by forming an iron-silica-rich passivation interlayer. The use of a reducing gas or reagent can enhance the mineral carbonation of olivine probably through hindering oxidation of Fe(Ⅱ). The addition of sodium nitrilotriacetate (NTA) as a metal complexing agent is much more efficient for the acceleration than usage of a reducing atmosphere. The combination of sodium bicarbonate/CO2 gas supply and NTA can enhance the diffusion of all divalent metal ions from the reacting olivine surface, thereby limiting the formation of the passivation interlayer. Meanwhile, highly selective nickel and cobalt leaching can be simultaneously achieved along with the CO2 mineral carbonation, 94% nickel, and 92% cobalt leaching as well as 47% mineral carbonation versus only 10% iron and 1% magnesium leached in 2 h. This work provides a novel direction to achieve critical metals recovery with accelerated mineral carbonation process.

Petrogenetic Study on Ultramafic Rocks from Waturapa and Surrounding Areas, South Konawe Regency, Southeast Sulawesi Province

The petrogenesis study of ultramafic igneous rocks in the South Konawe Region has been carried out by several previous researchers, however, petrogenesis of ultramafic igneous rocks in the Waturapa Region has never been carried out in detail. This study aims to determine the characteristics and petrogenesis of ultramafic igneous rocks in the Waturapa area using petrographic and geochemical analysis using the XRF method. Petrographic analysis was carried out to determine the relative abundance percentage of primary minerals in the form of olivine, clinopyroxene, orthopyroxene, and opaque minerals as well as secondary serpentine minerals which were formed later. Meanwhile, XRF geochemical analysis is used to determine the major and minor oxide content in rocks. This geochemical data is used to determine ultramafic rock types, and magma series and to interpret the tectonic setting of the research location. The results showed that the ultramafic rocks in the study area consisted of olivine websterite and lherzolite, both of which have been serpentinized which is characterized by the presence of serpentine minerals such as lizardite and chrysotile. These serpentine minerals are present as replacement minerals and fracture-filling minerals. The geochemical characteristics of the analyzed rocks showed a SiO2 content of less than 45%, high MgO content, and low K2O, TiO2, Na2O3, and P2O5 compounds. The igneous rocks in the study area are classified as ultrabasic or ultramafic rocks (peridot gabbro). Ultramafic rocks in the study area belong to the tholeiitic magma series that formed in oceanic islands or oceanic intraplate margins.

Diversity of the initial rocky planetary building materials at the edge of the solar system

AbstractAsteroids and comets are surviving members of the vast planetesimal population that was distributed across the early solar system. They appear to be a diverse set of bodies but we present evidence from comet samples that the body‐to‐body diversity of the initial rocky component mix in planetesimals may have declined with distance from the Sun. Laboratory measurements of the minor element Mn in olivine collected from Comet Wild 2 suggests that the micron‐sized rocky crystalline contents of this comet formed in numerous inner solar system environments. The results are consistent with a scenario where silicates such as olivine form at incandescent temperatures in multiple environments and then mix as they are transported to distant cold regions where silicates could accrete with ice and organics to form comets. Accreting far from silicate formation regions, many ice‐rich planetesimals are likely to have started with similar complex mixtures of diverse rocky components formed in various high‐temperature environments. This contrasts with asteroidal meteorite parent bodies whose silicates retain regional properties that give different chondrite classes their distinctive properties.

Phase relations of phlogopite and pyroxene with magnesite from 4 to 8 GPa: KCMAS–H2O and KCMAS–H2O–CO2

To constrain the melting phase relationships of phlogopite and magnesite in the presence of clino- and orthopyroxene, we performed experiments in the K2O–CaO–MgO–Al2O3–SiO2–H2O (KCMAS–H2O) and K2O–CaO–MgO–Al2O3–SiO2–H2O–CO2 (KCMAS–H2O–CO2) systems at pressures of 4–8 GPa and temperatures from 1100 to 1600 °C. We bracketed the carbonate-free solidus between 1250 and 1300 °C at 4 and 5 GPa, and between 1300 and 1350 °C at 6, 7 and 8 GPa. The carbonate-bearing solidus was bracketed between 1150 and 1200 °C at 4, 5 and 6 GPa, and between 1100 and 1150 °C at 7 and 8 GPa. Below the solidus in both systems at 4–6 GPa, phlogopite is in equilibrium with enstatite, diopside, garnet (plus magnesite in the carbonate-bearing system) and a fluid. At 7 GPa, phlogopite coexists with KK-richterite, enstatite, diopside, garnet (plus magnesite in the carbonate-bearing system) and a fluid. KK-richterite is the only stable K-bearing phase at 8 GPa and coexists with enstatite, diopside, garnet (plus magnesite in the carbonate-bearing system) and a fluid. In KCMAS–H2O, phlogopite is present to ~100 °C above the solidus. Olivine forms at the solidus and coexists with enstatite, diopside, garnet and melt. At depth in a subcontinental lithospheric mantle keel, phlogopite would be stable with orthopyroxene, clinopyroxene and magnesite to ~5 GPa along a 40 mW/m2 geotherm. A hydrous, potassic and CO2-bearing melt that intrudes the subcontinental mantle can react with olivine, enstatite and garnet, crystallizing phlogopite, magnesite and potentially liberating a hydrous fluid.

Geochemical evolution of rocks at the base of the lithospheric mantle: Evidence from study of xenoliths of deformed peridotites from kimberlite of the Udachnaya pipe

This paper presents the results of study of the geochemical and mineralogical compositions of deformed peridotite xenoliths from the Eastern Udachnaya kimberlite pipe. The performed investiga� tions were mainly aimed at obtaining information on the composition and evolution of the lower layers of the lithospheric mantle in the central part of the Sibe� rian Craton. Xenoliths of deformed peridotites are present in kimberlite pipes of all old cratons and are the deepest of all mantle nodules as is evident from the PTcondi� tions of equilibrium. These rocks provide the main information on the composition and evolution of the lower layers of the lithospheric mantle; because of this, their study is of significant interest (1-7). Because of the small sizes and serpentinization (partial or com� plete) of the deformed peridotites, most of the previ� ously performed investigations concerned only the composition of individual rockforming minerals of xenoliths. There is a lack of data on the bulk composi� tion of these rocks at present, and they were obtained for partially serpentinized xenoliths (7-9). Representative collection of xenoliths of deformed peridotites from the eastern body of the Late Devo� nian Udachnaya pipe related to the Daldyn kimberlite field of the Yakutian kimberlite province, which is the largest diamond deposit in Russia, was selected for geochemical study. This body consists of two com� bined kimberlite bodies: Western Udachnaya and Eastern Udachnaya; the eastern body is unique in rela� tion to the amount deepseated rock xenoliths, their diversity, and preservation. Xenoliths are presented by a large set of facial groups and varieties, among which deformed peridotites occupy a significant place (2, 3). Samples of deepseated rocks selected for the study are uniquely fresh. These xenoliths contain no signs of secondary alterations, and the L.O.I. value in the stud� ied rocks is close to zero. The weight of the samples varies from 500 g to several kilograms. Only the central parts of xenoliths, without surfaces in the contact with kimberlite, were taken for analysis of the bulk compo� sition. Most of the xenoliths from this collection are typi� cal lherzolites composed of olivine, orthopyroxene, clinopyroxene, and garnet in various proportions. According to the content of clinopyroxene (2-4 wt %), five samples may be formally attributed to garnet harzburgites. In all samples, large (up to 1 cm) grains of rockforming minerals and the matrix composed of finegranular olivine form porphyroclastic or mosaic� porphyroclastic textures. Olivine in the studied xeno� liths is the prevailing mineral; its content varies from 60 to 85%. The concentration of the forsterite mole� cule in olivines from nodules ranges from 86.4 to 91.3 mol %. Orthopyroxene, as well as olivine, is pre� sented by relatively large grains (porphyroclasts) with a size from 2 to 10 mm and small grains (neoblasts) with a size of <0.5 mm. The amount of orthopyroxene in the studied samples varies from 5 to 18%. The study of the orthopyroxene composition demonstrates that it relates to highmagnesium varieties (En = 88.2- 92.9 mol %), however being more ironrich in compar� ison with orthopyroxenes from granular garnet peridot� ites. Orthopyroxenes contain admixtures of Al 2O3 (0.42- 0.68 wt %), Cr2O3 (0.11-0.52 wt %), and TiO2 (0.21- 0.6 wt %). The clinopyroxene content varies from 2 to 14% of rock volume. This mineral is characterized by a low concentration of the diopside component (Ca/(Ca + Mg) = 35.9-43.3 mol %) that results from high temperatures of the equilibrium of characterized associations. The concentration of garnet in rocks var� ies from 4 to 15%. Garnet grains are practically not deformed, have an isometric shape, and often form linearly elongated chains. The chemical composition of garnets corresponds to the lherzolite paragenesis

Comparison of the electronic structures of four crystalline phases ofFePO4

LiFePO4 in the olivine structure is a promising cathode material for Li ion batteries. During normal battery operation, an olivine form of FePO4 is produced. In addition to the olivine form, FePO4 is known to form in a quartzlike structure, a high pressure CrVO4-like structure, and a monoclinic structure. We report the results of a detailed density functional study of the electronic structures and total energies of these four crystalline structures of FePO4. Partial density of states analysis of the four materials finds them all to be characterized by strong hybridization between the Fe and O contributions throughout their upper valence bands, consistent with recent x-ray spectroscopy studies of olivine FePO4. Results obtained using the local density approximation for the exchange-correlation functional find the olivine structure to be more stable than the quartzlike structure by 0.1 eV, which is in good agreement with recent calorimetry experiments.

Ground‐penetrating radar sounding in mafic lava flows: Assessing attenuation and scattering losses in Mars‐analog volcanic terrains

We conducted low‐frequency (16 to 100 MHz) ground‐penetrating radar surveys on the eroded lava flows at Craters of the Moon (Idaho, USA) volcanic field to evaluate the potential of future radar‐sounding investigations on Mars to map shallow subsurface features. Radar‐sounding profiles were obtained from three locations: above a lava tube, across a volcanic rift, and over a scoria cone. Results were combined with laboratory permittivity and magnetic permeability measurements of field‐collected samples to deconvolve the electromagnetic attenuation and scattering losses from the total losses and therefore separately quantify both effects on the radar penetration depth. Our results demonstrate a constrained performance for low‐frequency sounding radars to characterize mafic, arid volcanic terrains that contain a significant amount of ferro‐oxides (∼14%), mainly in the form of olivine and magnetite. Penetration depths of 35 m were achieved at a frequency of 100 MHz, and depths of 80 m were achieved at 16 MHz, with an effective dynamic range of 60 dB. Results indicate that for frequencies below 100 MHz, the electromagnetic attenuation dominated the signal losses while above this frequency threshold the volume scattering dominated the losses. Over our frequency range, the observed electromagnetic attenuation and penetration depths were strongly dependent on the magnetic losses, ground porosities, and degree of heterogeneity rather than the sounding frequency. In light of these results, we suggest average attenuation and scattering losses measured in terms of dB/m and discuss the expected penetration depth for the Mars orbital radar‐sounding instruments SHARAD and MARSIS in mafic volcanic terrains.

TEM investigation of forsterite dendrites

Transmission electron microscopy (TEM) has been used to investigate dendritic forsterite systematically, in order to understand its morphology in three dimensions. TEM images of olivine dendrites are reported for the first time. Crystals have been obtained by dynamic crystallization in the CaO-MgO-Al 2 O 3 -SiO 2 (CMAS) system in a one-atmosphere vertical furnace. A fast cooling rate (1890°C/h) has been used with degrees of undercooling varying from 156 to 356 ∞C. Different microstructures were observed depending on their location in the dendritic crystal. The external part of the crystal reveals true olivine dendrite propagation, as classically observed in other materials (succinonitrile, alloys). In the inner part of the crystal, this microstructure changes to the formation of single crystalline units with well-defined crystalline faces. The shapes observed are very reproducible. These units are limited by the usual forms of olivine [(010), {021}, {110}, {120}, {101}] and also by less common forms [(001), {130}, {140}] as additional faceting. All these elementary units present the same morphology, the hopper shape that corresponds to the skeletal form of olivine. These units are linked in a peculiar spatial organization giving rise to dendrite branches. It is shown that the [101] preferential direction of growth of dendrites is a mean direction and corresponds to the juxtaposition of these elementary units. In the innermost part of dendritic crystals, a dissolution-recrystallization process of elementary units occurs and a typical textural ripening microstructure is observed. This textural ripening starts early and is coincident with the real dendritic growth (external part of the crystal). Thus, the final appearance of dendritic forsterite crystals mainly results from textural ripening. This study emphasizes that dendritic solidification is a complex phenomenon, and the various microstructures suggest that multiple mechanisms are involved during the formation of so-called dendritic crystals

High‐Temperature, High‐Pressure X‐ray Investigation of Dicalcium Silicate

Energy‐dispersive X‐ray powder diffraction experiments have been investigated at high temperature and room pressure, and at high pressure and room temperature, starting from either γ‐ or β‐Ca2SiO4. High‐temperature studies were performed up to 1980 K, using a versatile heating cell. The high‐temperature phase transformations previously described were reexamined. Volume and linear thermal expansions were measured for each Ca2SiO4 polymorph, γ, β, α′;L,α′;H, and α. Volume thermal expansion increases with increasing temperature except for α′;H, whose thermal expansion tends to decrease at elevated temperature. High‐pressure investigations were performed in the 0–15 GPa pressure range, using a diamond anvil cell, with silicon oil as the pressure‐transmitting medium. The value of the room‐pressure bulk modulus K0, assuming a second‐order BirchMurnaghan equation of state with K'0= 4, is 140(8) GPa for γ‐Ca2SiO4. The γ olivine form exhibits anisotropic compression, with the c axis as the most compressible. From such in situ high‐pressure X‐ray investigations, the γ‐→Ca2SiO4 phase transformation induced by cold compression is clearly evidenced and extends from 2 to about 5 GPa.

High pressure polymorphism of dicalcium silicate Ca2SiO4. A transmission electron microscopy study

Ca2SiO4 dicalcium silicate has been transformed at high pressure in a diamond-anvil cell (DAC) coupled with a YAG laser heater, in order to study the high-pressure modifications of this compound. Starting material was the olivine form of Ca2SiO4 (γ-polymorph). Several samples have been synthesized at loading pressures of 4.5, 10 and 15 GPa respectively, at room temperature. Other samples have been obtained at pressures ranging between 4.5 and 45 GPa and temperatures estimated to be about 2500 °C. The study of the quenched high pressure and/or high temperature phases has been performed using analytical transmission electron microscopy (ATEM) and X-ray diffraction (XRD). All the polymorphs of Ca2SiO4 usually produced with high temperatures, including α-Ca2SiO4, have been observed in the samples recovered from the high-pressure experiments. The α′-Ca2SiO4 and α-Ca2SiO4 polymorphs have been obtained at ambient conditions for the first time without stabilizing impurities. A new modification of α′-Ca2SiO4 has also been synthesized. Finally, the breakdown at high-pressure and temperature of Ca2SiO4 into CaSiO3 and CaO is reported.

Experimental study of element partitioning between majorite, olivine, merwinite, diopside and silicate melts at 16GPa and 2,000.DEG.C..

We have determined experimentally the partition coefficients of elements between silicate minerals and coexisting melts at 16 GPa and 2, 000°C in chondritic and CaO-rich silicate systems. Majorite garnet + melt ± olivine forms in the MgO-rich chondritic system, while in the CaO-rich system, merwinite coexists with melt ± clinopyroxene. The partition coefficients (D-values) of La, Ce, Sm, Yb, Sc, Zr, Hf and other minor or major elements for majorite garnet, merwinite, and clinopyroxene/melt pairs have been determined through EPMA analysis. D-values of a limited number of elements were also determined for the olivine/melt pair with EPMA. The D(HREE and Sc) for majorite/melt are close to unity. These values are much lower than reported values for pyrope/melt pairs at 2–3 GPa and 1, 200–1, 500°C and for pyrope megacryst/host rock matrix pairs. The pressure-induced coordination change in Al3+ at higher pressures above 10 GPa is responsible for the enormous difference in the D values as well as the contrasting temperature conditions: The coupled substitution of (VIIIM2+, IVSi4+) = (VIIIHREE3+, IVAl3+), important for accommodating HREE3+ into garnets, is severely limited because IVAl3+ is unlikely to exist in the majorite/melt system. The mechanism to reduce D(REE and Sc) with increasing pressure may also be operative between the clinopyroxene/melt pair. Systematic comparison of Onuma diagrams for VIIIM2+ and VIIIM3+ in almandine, pyrope, and majorite garnet/melt pairs clearly indicates that high enrichments of HREE in almandine and pyrope garnets are related to charge-balanced substitution and the presence of more or less polymerizing silicate melts with IVAl3+. These Onuma diagrams also suggest that the partitioning behaviors of Fe2+ and Co2+ between garnet and melt are anomalous. This may reflect the tendency for Fe2+ and Co2+ to prefer six coordinated sites in melts to cubic sites in garnets due to the crystal field effect. The D(REE and Sc) value pattern for the merwinite/Ca-rich melt pair has been found to be quite similar to those for CaTiO3/melt and CaSiO3 (perovskite)/melt pairs. This is interesting in view of the substructure of merwinite that mixed Ca2+ and O2- layers comprise a pseudo-hexagonal dense packing analogous to the perovskite structure.

Dynamic crystallization study of barred olivine chondrules

Chondrules, which comprise the bulk of most chondrites, formed very early in the solar system, and understanding their formation will elucidate early nebular processes. Barred olivine (BO) chondrules make up approximately 10% of chondrules and because of their unique dendritic textures represent a restricted set of crystal growth conditions and, thus, formation conditions. BO textures have been replicated using dynamic crystallization techniques on olivine-rich chondrule starting compositions in an attempt to determine these formation conditions. One composition was modeled after the average BO chondrule composition in L-chondrites determined by Weisberg (1987) in a survey of BO chondrules. Chondrule droplets are presumed to form by the melting of crystalline material. BO textures developed best if the crystalline precursor was melted slightly above to tens of degrees above the liquidus temperature eliminating all ready nuclei. Crystalline material (embryos) of subcritical nuclei size in the melts provide the nuclei when they reach critical nucleus size at degrees of supercooling which stabilize the plate dendritic crystal form of olivine. The plate dendrite is the basic crystal unit of the BO texture. Multiple-plate dendrites are the common texture in experimentally produced chondrules; the “classic,” single-plate-dendrite BO chondrule has not been reproduced in the experiments. While the preferred BO composition of Weisberg does produce BO textures over a broader range of melting temperatures, any composition that has olivine on the liquidus for a significant temperature interval will develop BO texture over some range of melting temperatures. The range of possible melting temperatures depends on the range of compositions available that have olivine on liquidus. The low end of the range will be near 1500°C and the upper end near 1700°C. The range of cooling rates that produced BO textures in the compositions studied is 500 to 2300°C/h.

High-pressure, high-temperature Raman spectroscopy of Ca 2GeO 4 (olivine form): some insights on anharmonicity

High pressure (up to 2.7 GPa) and high temperature (up to 1000 K) Raman spectra of Ca 2GeO 4 (olivine form) have been recorded. Measurements of the pressure- and temperature-induced frequency shifts of 14 modes have been performed. The classical mode Gruneisen parameter and a corresponding parameter related to temperature variation are calculated. For the high frequency modes (GeO stretching) we calculate these parameters with local tetrahedral elastic parameters. From these parameters anharmonic parameters are calculated for each Raman active mode. The effect of anharmonicity on the specific heat is calculated and compared with calorimetric data. Taking anharmonicity into account leads to a departure from the Dulong and Petit limit of the order of 2% at 1000 K and more than 6% at 2000 K, in good accord with experimental data. We propose that, eventually, such effects might be significant in the calculations of thermodynamic properties of mantle silicates like forsterite and its polymorphs.

Petrology and magnetic properties of the Chiang Khan, Thailand, meteorite

The Chiang Khan meteorite fell on 18th November, 1981 at Chiang Khan, Thailand. It consists of olivine, orthopyroxene, clinopyroxene, Fe-Ni metal, troilite, chromite, plagioclase, glass, and phosphate in order of abundance. Olivine forms barred or porphyritic chondrules, and its composition is uniform (average Fo80.2), close to the average composition of olivine in equilibrated H chondrites. Orthopyroxene and clinopyroxene also have compositions similar to those in equilibrated H chondrites. Both well-defined chondrules and their broken fragments are present in the recrystallized matrix. Microcrystalline plagioclase and clinopyroxene often occur in the groundmass of chondrules, but clear interstitial plagioclase is absent. Chemical composition of chromite plots in the field of chromites in H chondrites. Chiang Khan meteorite is thus classified as an equilibrated H 5 type chondrite. The equilibrium temperatures estimated by using mineral pairs are as follows: Opx-Cpx 800–900°C; Ol-Chromite 510°C.

High pressure-high temperature Raman spectroscopy of Ca 2GeO 4 (olivine form): Some insights on anharmonicity

High pressure-high temperature Raman spectroscopy of Ca 2GeO 4 (olivine form): Some insights on anharmonicity

Gibbs' Energy of Formation of Nickel Orthosilicate (Ni2SiO4)

A solid-state galvanic cell was used to detect the free energy of formation of $Ni_2SiO_4$ [13775-54-7], from NiO and quartz at 925-1375 K. The value for the olivine form is (-13,050 + 5.67 T) $\pm 100 J/mol$ (T in K). The free energy of formation of the spinel form was obtained from the above value and the high-pressure data for olivine spinel transition reported in the literature: (-6970 + 9.70 T) $\pm 710 J/mol$ at 900-1500 K.

The crystal chemistry of dense M 3O 4 polymorphs: High pressure Ca 2GeO 4 of K 2NiF 4 structure type

Ca 2GeO 4 of olivine form has been found to transform at 900°C and 110 kbars to K 2NiF 4 type, with a = 3.70, c = 11.88 Å, and with a corresponding density increase of 25%. The geochemical significance of this transformation is discussed, and a comparison of the molar volumes of olivines, spinels and other structure type with the volumes of their isochemical mixtures of simple oxides or fluorides is used to obtain relative molar volumes for a large number of dense M 3O 4 structure types.