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Published: 10 December 2022
Last updated: 28 January 2023

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1

Pownceby, M., and P. Bourne. "Detrital chrome-spinel grains in heavy-mineral sand deposits from southeast Africa." Mineralogical Magazine 70, no. 1 (February 2006): 51–64. http://dx.doi.org/10.1180/0026461067010312.

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AbstractDetrital chrome-spinels are contaminant grains within ilmenite concentrates produced from heavy-mineral deposits along the coast of southeast Africa. The presence of even minor levels of chromia in the predominantly ilmenite-rich concentrates, downgrades their market value as potential feedstocks for the production of titania pigment. An understanding of their composition can assist in their removal from the ilmenite concentrates.Compositions from a database of close to 900 chrome-spinel analyses shows the major element components and their ranges (in wt.%) are: Cr: 0.4-45.3, Al: 0.0-31.0, Fe: 8.5-69.6 and Mg: 0.0-12.2. Minor components include Ti: 0.1-11.4 and Zn: 0.0-13.7.The chrome-spinel data fall into two compositionally distinct groups. The first group of spinels is dominated by a strong trend reflecting the mutual substitution between Al3+ and Cr3+ in the spinel structure. The second group of spinels is characterized by compositions containing abundant Fe3O4 magnetite component. The clear division between chrome-spinel compositional types indicates the grains are derived from at least two chemically dissimilar provenances.The compositional differences between the chrome-spinel groups has a positive impact on subsequent ilmenite upgrading treatments as the spinels which contain the highest magnetite component are easily removed via low-intensity magnetic separation procedures.
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2

Ahmad, S., M. A. Rhamdhani, M. I. Pownceby, and W. J. Bruckard. "Exploratory Study of Separation of Sulphidised Chrome Spinels from Reduced Ilmenite." Minerals 12, no. 10 (September 30, 2022): 1252. http://dx.doi.org/10.3390/min12101252.

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The removal of chromium-containing impurities, such as chrome spinel (ZCr2O4 where Z = Fe, Mg, Mn) from ilmenite (FeTiO3) concentrates through selective sulphidation, has been investigated by the authors. Laboratory experimental studies using sulphur added to ilmenite concentrates under Becher-type reduction conditions showed it is possible to selectively sulphidise chrome spinels from different ilmenite deposits. In this paper, processes to remove the sulphidised chrome spinels from the bulk ilmenite concentrates were investigated using flotation and magnetic separation techniques. Clustering or fusing of the reduced ilmenite (RI) and sulphidised chrome spinel grains was found to have a detrimental effect on flotation performance and made it difficult to have clear separation. A light wet grind was effective for breaking the clustering, but it caused the sulphide rim to spall off from chrome spinel surfaces, which reduces flotation efficiency. The preliminary results obtained after a magnetic separation (0.7 A) of a demetallised sulphidised RI sample show that the sulphidised chrome spinels preferentially report to the magnetic fraction. Additional magnetic separation of the non-magnetic fraction at a lower current (0.3 A) improved the recovery of sulphidised chrome spinels. The demetallisation process followed by a magnetic separation provided insights into a potential route for the removal of chrome spinels from reduced ilmenite concentrates. These two steps simulate the aeration stage of the Becher process. Further studies are required to optimise the process parameters.
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3

Pownceby, M. "Compositional and textural variation in detrital chrome-spinels from the Murray Basin, southeastern Australia." Mineralogical Magazine 69, no. 2 (April 2005): 191–204. http://dx.doi.org/10.1180/0026461056920246.

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AbstractDetrital chrome-spinels are contaminant grains within heavy-mineral concentrates found in the Murray Basin of southeastern Australia. The presence of even minor levels of chromia in the predominantly ilmenite-rich concentrates downgrades their market value as potential feedstocks for the production of titania pigment.Compositions from a database of close to 5000 chrome-spinel analyses show a broad range in chemistry. The major element components and their ranges (wt.%) are Cr: 3.10–52.06, Al: 0.46–32.50, Fe: 3.50–44.48 and Mg: 0.03–15.79. Minor components include; Ti: 0.01–6.41, Zn: 0.00–23.00 and Mn: 0.00–5.82. The broad variation in composition suggests multiple source areas for the chrome-spinels although detailed textural examination indicates that variation has also been introduced through pre- and post-deposition alteration processes.The Murray Basin chrome-spinel database has the potential to be used in interpreting and predicting the effects of various processing conditions used to separate the chrome-spinels from the ilmenite.
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4

ALEKSEEV, Aleksandr Valer’evich, and Tat’yana Andreevna SHERENDO. "Composition, structure and magnetic properties of ore chrome spinels of the Klyuchevsky massif (Middle Urals)." NEWS of the Ural State Mining University 1, no. 1 (March 23, 2020): 73–85. http://dx.doi.org/10.21440/2307-2091-2020-1-73-85.

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The overall objective was to create a geological and geophysical field test site for chromite mineralization and detailed works in order to determine and test the main search criteria for disseminated mineralization. To create a field test site, an area was selected in the southern part of the Klyuchevsky massif characterized by abundant development of disseminated mineralization in the banded dunite-clinopyroxenite complex and strong processes of superimposed metamorphism. This paper gives a piece of research on the composition of chrome spinel from disseminated ores that underwent metamorphism of different stages. The composition of chrome spinelide, the evolution of its metamorphism and the related changes in its magnetic properties are examined in detail. It was established that all chrome spinels are of a high-chromium type, to one degree or another, they were subject to secondary changes, leading to the appearance of magnetic phases. The degree and nature of the change in chrome spinels in dunites directly depends on the degree of metamorphism of the rocks. The formation of the magnetic phase begins with the formation of nuclei consisting of single magnetic dipoles, groups of 2-3 dipoles or chains of magnetic dipoles, which was first discovered by us in chrome spinel grains. Then there is an increase in the number of such phases, the appearance of optically diagnosed secondary changes in chrome spinelide. A comparison of the degree of variation of chrome spinel and its reflection in the pattern of recorded anomalies of geomagnetic fields allows us to identify some criteria for the search for disseminated chromite ores of this type.
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5

Mogessie, A., F. Purtscheller, and R. Tessadri. "Chromite and chrome spinel occurrences from metacarbonates of the Oetztal–Stubai Complex (Northern Tyrol, Austria)." Mineralogical Magazine 52, no. 365 (April 1988): 229–36. http://dx.doi.org/10.1180/minmag.1988.052.365.09.

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AbstractChromite inclusions in uvarovite-chrome garnet, chemically zoned chromite-chrome spinel and chrome spinel-olivine pairs from metacarbonates of the Oetztal-Stubai Complex (northern Tyrol, Austria) are described in terms of their textural occurrences and chemical compositions. Their genetic relationship in relation to the polymetamorphism of the region is discussed.
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6

SEREBRIANNIKOV, ALEXEI, ALLA LOGVINOVA, and NIKOLAY SOBOLEV. "Specific features of the microimpurity composition of chrome-spinel inclusions in diamonds from kimberlites of Sakha-Yakutia." Domestic geology, no. 6 (January 10, 2023): 50–63. http://dx.doi.org/10.47765/0869-7175-2022-10034.

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Specific features of the microimpurity composition of chrome-spinel inclusions in 323 diamond crystals from eight kimberlite pipes of two diamond-bearing regions of Yakutia were revealed by microprobe analysis. Processed data on their content of the Ni, Zn, V, Mn, and Si impurities are presented. It is shown that chrome-spinels in diamonds from the kimberlite pipes of the different regions are characterized by different contents of the impurity elements. The revealed differences in the composition of chrome spinel inclusions in the diamonds, as well as in the defect-impurity composition of the hosting diamonds, from the different, including neighboring, kimberlite pipes of Yakutia, are evidence of a local heterogeneity in the mantle composition within a certain kimberlite field. These data confirm the opinion of most researchers on heterogeneity of the mantle composition in different regions of the Yakutian diamondiferous province.
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7

Lodha, Rahul, Carmen Oprea, Tom Troczynski, and George Oprea. "Sintering Studies on Magnesia-Rich Chromium-Free Spinel-Bonded Basic Refractories." Advances in Science and Technology 70 (October 2010): 108–13. http://dx.doi.org/10.4028/www.scientific.net/ast.70.108.

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Basic bricks with Cr2O3 from chrome ore, as the spinel forming oxide, are used in the non-ferrous industry because of their corrosion resistance against fayalite-type slags, rich in FeO. Our objective in this study was to replace Cr3+ with Me4+ ions, which along with Fe3+ could maintain the spinel formation capability with MgO and perform similarly against fayalite slags in non-ferrous furnaces. Our preliminary research studies showed that Cr-free spinels in the MgO-Al2O3-FeOx-Me4+O2 systems could perform against fayalite slags similar to the complex (Mg2+, Fe2+)O·(Cr3+, Fe3+, Al3+)2O3 spinel, the main corrosion resistant component in the magnesia-chrome bricks. The incorporation of iron oxide in the MgO-Al2O3-Me4+O2 systems would contribute to reactive sintering and also in decreasing the solubility of both the ferrous and ferric ions present in the fayalite slag. Phase analysis on stoichiometric mixes showed that the use of tetravalent cation oxides like tin dioxide (SnO2) and titanium dioxide (TiO2) can induce high solubility of spinel in magnesia. In order to maintain charge balance, two trivalent cations were replaced by a tetravalent and a bivalent cation causing the additional bivalent cation to occupy the octahedral position thereby creating an inversion in position of the bivalent ions similar to the behaviour exhibited by Fe3+ occupying tetrahedral site in complex spinel phase of magnesia-chrome ceramics. Most of the magnesia-chrome refractories have ~60 wt. % MgO and hence our experimental mixes contained that amount and called “magnesia-rich” compositions, to be distinguished from the stoichiometric MgAl2O4 spinel. Our findings showed that the incorporation of nano TiO2 powders reduces the temperature of spinel formation as the diffusion path is shortened and thus activates both synthesis and sintering. Compositions containing 60 wt. % magnesia with alumina, nano TiO2 and Fe2O3 fired below 1500°C for 3 hours resulted in complete spinel formation and open porosity less than 5%.
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8

FAUPL, P., A. PAVLOPOULOS, U. KLÖTZLI, and K. PETRAKAKIS. "On the provenance of mid-Cretaceous turbidites of the Pindos zone (Greece): implications from heavy mineral distribution, detrital zircon ages and chrome spinel chemistry." Geological Magazine 143, no. 3 (April 6, 2006): 329–42. http://dx.doi.org/10.1017/s001675680600197x.

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Two heavy mineral populations characterize the siliciclastic material of the mid-Cretaceous turbidites of the Katafito Formation (‘First Flysch’) of the Pindos zone: a stable, zircon-rich group and an ophiolite-derived, chrome spinel-rich one. U/Pb and Pb/Pb dating on magmatic zircons from the stable heavy mineral group clearly illustrate the existence of Variscan magmatic complexes in the source terrain, but also provide evidence for magmatism as old as Precambrian. Based on microprobe analyses, the chrome spinel detritus was predominantly supplied from peridotites of mid-ocean ridge as well as suprasubduction zone origin. A small volcanic spinel population was mainly derived from MORB and back-arc basin basalts. The lithological variability of the mid-Cretaceous ophiolite bodies, based on spinel chemistry, is much broader than that of ophiolite complexes presently exposed in the Hellenides. The chrome spinel detritus compares closely with that from the Outer and Inner Dinarides. The source terrain of the ophiolite-derived heavy minerals was situated in a more internal palaeogeographic position than that of the Pindos zone. The zircon-rich heavy mineral group could have had either an external and/or an internal source, but the chrome spinel constantly accompanying the stable mineral detritus seems to be more indicative of an internal source terrain.
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9

Sherendo, Tatyana, Valentin Mitrofanov, Aleksey Vdovin, Petr Martyshko, Aleksey Alexeev, Dmitry Zamyatin, Vladimir Vazhenin, and Lidia Pamyatnykh. "Magnetic Clusters in Natural Ferro-Chromian Spinels." Solid State Phenomena 233-234 (July 2015): 587–90. http://dx.doi.org/10.4028/www.scientific.net/ssp.233-234.587.

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The results of investigations of natural iron-chromium spinels of variable composition Fe2+(Cr2-xFex3+)O4 of the chromite-bearing Klyuchevskoi massif (Middle Urals), which are the main carriers of the magnetization of rocks are presented. Substantial changes in the composition and in magnetic structure of accessory chrome-spinels scattered in the host rock are established, unlike the almost unaltered ore-forming chrome-spinels, under the influence of secondary geological processes. To establish the connection between the chrome-spinel changes at the microlevel and features of the geomagnetic field anomalies created by this carrier of magnetization of rocks, it is carried out a complex of investigations of Fe-Cr-spinels (thermomagnetic analysis over the temperature range (4÷1000) K; magnetic resonance (MR) spectroscopy and magnetic force microscopy (MFM) in addition to magnetomineralogical studies). As a result, in the relict areas of grains of the accessory chrome-spinels were first discovered the magnetic clusters (superparamagnetic phases) in the form of single or groups of 2 – 3 magnetic dipoles of tens nanometers in size, or in the form of chain-like structures of magnetic dipoles/single domains.
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10

BLADES, MORGAN L., JOHN FODEN, ALAN S. COLLINS, TADESSE ALEMU, and GIRMA WOLDETINSAE. "The origin of the ultramafic rocks of the Tulu Dimtu Belt, western Ethiopia – do they represent remnants of the Mozambique Ocean?" Geological Magazine 156, no. 1 (October 30, 2017): 62–82. http://dx.doi.org/10.1017/s0016756817000802.

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AbstractThe East African Orogen contains a series of high-strain zones that formed as Gondwana amalgamated. The Tulu Dimtu shear belt is one of these N–S structures within the Barka–Tulu Dimtu zone in western Ethiopia, and contains ultramafic bodies of equivocal origin. Identifying the petrogenetic origin of these enigmatic rocks provides evidence for the geodynamic significance of these shear zones. Owing to their altered state, these ultramafic rocks’ well-preserved chrome spinels provide the only reliable evidence for their source and tectonic affiliation. Chrome spinels have high Cr2O3 (30.04–68.76 wt %), while recalculated Fe2O3 (< 2 %) and TiO2 (0.01–0.51 %) values are low. The Cr# (molar Cr3+/Cr3+ + Al2+) and Mg# (Mg2+/Mg2+ + Fe2+) have averages of 0.88 and 0.22, respectively. Based on olivine–spinel equilibria, the calculated fO2 values (FMQ +3.03) for the dunites reveal a highly oxidized environment. This spinel chemistry (high Cr# > 0.6 and low Ti) supports a supra-subduction origin, with an oxidized mantle source more refractory than depleted MORB mantle (DMM). These spinel compositions indicate that some ultramafic bodies in western Ethiopia, including those from Daleti, Tulu and Dimtu, are serpentinized peridotites emplaced as obducted ophiolite complexes. By contrast, the ultramafic rocks from the Yubdo locality have a different spinel chemistry, with strong affiliation with igneous spinels formed in Alaskan-style mafic intrusions. These collective results suggest that regardless of their origin as supra-subduction ophiolites or as Alaskan-type intrusions, these spinels were formed on a convergent-subduction margin.
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11

Li, Yang, Yong Li, Rui Li, and Dong Wang. "Research on Cr2O3-Reinforcement High Quality Magnesia-Chrome Brick." Advanced Materials Research 233-235 (May 2011): 2565–70. http://dx.doi.org/10.4028/www.scientific.net/amr.233-235.2565.

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The raw material is the fused grain magnesia-chrome and Indian concentrated chrome ore . The grain size proportion which is used in the preparation as follows: 4­-1mm 50%，≤1mm 17%,≤0.088mm 33% ,the 5 group samples are prepared by respectively adding extra 2%、4%、6%、8% fine power Cr2O3 to basic formula .Mixing and pressed under 200Mp and sintered at 1750,holding 8 hours ,the process of preparation of samples is finished .The dimension of samples is 230mm×114mm×65mm .Conclusion: the addition of fine power Cr2O3 can change the base material composition of magnesia-chrome ,form more secondry spinel and intergranular spinel ,promote direct bond between periclase and spinel .Adding quantitative fine power Cr2O3 can enhance the room properties and high temperature properties ,but as the increase of fine power Cr2O3 ,the sintering property is decreased ,the results are shown that the best content of fine power Cr2O3 should remain at about 4% .
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12

Onishchenko, S. A., and A. A. Soboleva. "Apoultramafic metasomatites of the Enganepe Uplift (the Polar Urals)." Vestnik of Geosciences 3 (2021): 11–20. http://dx.doi.org/10.19110/geov.2021.3.2.

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Ultramafic rocks of the Enganepe Uplift are transformed into serpentinites, magnesite-dolomite-talc and quartz-magnesite-dolomite metasomatites belonging to the beresite-listvenite formation. All apoultramafic rocks contain high chromium and nickel inherent in protolith. Chrome-spinel of the magmatic stage is represented by alumochromite, which, in the process of metamorphic and metasomatic transformation of rocks, has been replaced by secondary chrome-spinel (subferrialumochromite, ferrichromite) and chromium-bearing magnetite. The main nickel minerals are millerite and gersdorffite. In quartz-magnesite-dolomite rocks, nickel is party contained in Ni-Cr-chlorite.
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13

Evans, David M. "Significance of compositional zoning in cumulate chromites of the Kabanga chonoliths, Tanzania." Mineralogical Magazine 82, no. 3 (May 7, 2018): 675–96. http://dx.doi.org/10.1180/mgm.2018.87.

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ABSTRACTCompositional zoning is observed rarely in chrome-spinel grains from slowly-cooled layered intrusions because diffusion of cations continues within the spinel to low temperatures. However, in certain circumstances, such gradational zoning of both divalent and trivalent cations is observed and may be useful in deciphering the thermal history of the host intrusions. The accessory chrome-spinels of the Kabanga mafic-ultramafic chonolith intrusions of the Kibaran igneous event in north western Tanzania are notable because they have preserved gradational compositional zoning. This zoning is demonstrated to predate and be independent of later hydrous alteration of the silicate assemblage. At Kabanga, most chrome-spinel grains within olivine-rich cumulate rocks are gradationally and cryptically zoned from Fe2+-Cr3+ rich cores to more Mg2+-Al3+ rich rims (normal zoning). A few grains are zoned from Mg2+-Al3+ rich cores to more Fe2+-Cr3+ rich rims (reverse zoned). The zoning of divalent cations is proportional to that of trivalent cations with Mg2+ following Al3+ and Fe2+ following Cr3+ from core to rim. The zoning of trivalent and tetravalent cations is interpreted to be caused by either new growth from an evolving melt or peritectic reactions between evolved or contaminated melt and adjacent Al-Cr-bearing ferromagnesian minerals, which is preserved by relatively rapid initial cooling in the small chonolith intrusions. Divalent cation zoning is controlled by sub-solidus exchange of Fe2+ and Mg with adjacent ferromagnesian minerals and continues to lower temperatures, indicated to be 580 to 630°C by the spinel-olivine geothermometer. Preservation of such zoning is more likely in the smaller chonolith intrusions that typically host magmatic nickel-copper sulfide deposits and can be used as an exploration indicator when interpreting chromite compositions in regional heavy indicator mineral surveys.
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14

ASWAD, KHALID J. A., NABAZ R. H. AZIZ, and HEMIN A. KOYI. "Cr-spinel compositions in serpentinites and their implications for the petrotectonic history of the Zagros Suture Zone, Kurdistan Region, Iraq." Geological Magazine 148, no. 5-6 (July 11, 2011): 802–18. http://dx.doi.org/10.1017/s0016756811000422.

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AbstractAccessory chrome spinels are scattered throughout the serpentinite masses in two allochthonous thrust sheets belonging to the Penjween–Walash sub-zone of the northwestern Zagros Suture Zone in Kurdistan. Based on field evidence, the serpentinites are divided into two groups: (1) highly sheared serpentinites (110–80 Ma), which occupy the lower contact of the ophiolitic massifs of the Upper Allochthonous sheet (Albian–Cenomanian age), and (2) ophiolitic mélange serpentinites of mixed ages (150 and 200 Ma) occurring along thrust faults on the base of the volcano-sedimentary segment (42–32 Ma) of the Lower Allochthonous sheet. The Cr-spinels of both groups show a wide range of YCr (Cr/(Cr + Al) atomic ratio) from 0.37 to 1.0, while the XMg (Mg/(Mg + Fe2+) atomic ratio) ranges from 0.0 to 0.75. Based on the Cr-spinel compositions of the entire dataset and in conjunction with back-scattered electron imaging, from core to rim, three spinel stages have been recognized: the residual mantle stage, a Cr-rich stage and a third stage showing a very narrow magnetite rim. These three stages are represented by primary Cr-spinel, pre-serpentinization metamorphosed spinel and syn- or post-serpentinization spinel, respectively. The chemical characteristics of primary (first-stage) Cr-spinels of both serpentinite groups indicate a tectonic affinity within a fore-arc setting of peridotite protoliths. The second stage indicates that Cr-spinels have undergone subsolidus re-equilibration as a result of solid–solid reaction during pre-serpentinization cooling of the host rock. Here the primary Cr-spinel compositions have been partly or completely obscured by metamorphism. During the third stage, the Cr-spinels have undergone solid–fluid re-equilibration during syn- or post-serpentinization processes. Both the second and third stages point to diachronous metamorphic paths resulting from continuous tectonic evolution influenced by either slow or fast uplift of mantle protoliths. In the fast metamorphic paths, the primary chrome spinels are flanked by a very narrow magnetite rim. The presence of two groups of distally separated serpentinites with different emplacement ages and fore-arc tectonic affinity could indicate that the closure of the Tethys Ocean culminated in two fortuitous subduction processes.
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15

Semyannikov, V. P., Yu I. Savchenko, V. A. Perepelitsyn, L. I. Koval'chuk, I. D. Kashcheev, and V. I. Ignat'ev. "Service tests of chrome-spinel-periclase refractories." Refractories 26, no. 1-2 (January 1985): 45–48. http://dx.doi.org/10.1007/bf01398614.

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16

Dolníček, Zdeněk, Michaela Krejčí Kotlánová, and Rostislav Koutňák. "Vliv diagenetických procesů na asociaci těžkých minerálů v pískovcích z lokality Slivotín (ždánická jednotka, flyšové pásmo Vnějších Západních Karpat, Česká republika)." Bulletin Mineralogie Petrologie 29, no. 1 (2021): 27–40. http://dx.doi.org/10.46861/bmp.29.027.

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An electron microprobe study of polished sections prepared from a sample of fine-grained sandstone from the locality Slivotín (Ždánice-Hustopeče Formation, Ždánice Unit, Flysch Belt of the Outer Western Carpathians, Czech Republic) allowed to yield in addition to data on chemical composition also the detailed information on in situ textural relationships of individual minerals. During our study, emphasis was given to accessory phases belonging to the translucent heavy mineral fraction. The detrital garnet (Alm36-82Grs2-45Prp2-22Sps0-15) was extensively dissolved and replaced by calcite cement from its margins and along the cracks. Detrital fluorapatite was dissolved in a similar way, however, dissolution episode was followed by growth of authigenic rims composed of carbonate-fluorapatite. Other observed heavy minerals (zircon, chrome spinel, TiO2 phase, monazite, tourmaline) probably remained unaltered by diagenetic processes. The chemical composition of chrome spinels varies mostly between magnesiochromite and chromite, whereas spinel is very rare. The chemical composition of garnets and chrome spinels is comparable with published data from Czech, Polish and Slovak parts of the Flysch Belt of the Western Carpathians, and indicates the primary source of detrital material in rocks of deeper parts of orogen, characterized especially by the presence of catazonal metamorphites and almost lacking volcanic rocks. Redeposition of heavy minerals from older sediments cannot also be ruled out. The pronounced diagenetic alteration of garnet, if not very scarce in the area of Flysch Belt, could help to explain the earlier observations of wide fluctuations of contents of garnet in heavy mineral concentrates.
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17

Yuan, Lin, Song Lin Chen, Xue Feng Chen, Xi Jun Liu, Jie Zeng Wang, and Xue Tao Yuan. "Spinel and Lanthanum Zirconate Composite for Cement Kiln." Applied Mechanics and Materials 66-68 (July 2011): 1179–86. http://dx.doi.org/10.4028/www.scientific.net/amm.66-68.1179.

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Researching and developing chrome-free refractory becomes a research hotspot at present because hexavalent chromium ions (Cr6+) may lead to environmental hazard. The additives lanthanum oxide (La2O3), effect on mechanism of spinel refractory react with cement clinker, several additives, such as cerium oxide (Ce2O3), titanium dioxide (TiO2), barium oxide (BaO), iron oxide (Fe2O3), are researched in this paper. It indicates that La2O3 is a suitable additive to MgO-MgAl2O4-ZrO2 brick which not only could stabilize phase transition of dicalcium silicate (C2S) in cement, but also do not impair the high-temperature-properties of spinel. The new environmentally friendly material spinel and lanthanum zirconate Composite is an excellent refractory for cement kiln which has high thermal shock resistance, good coating adherence, good corrosion resistance, higher mechanical strength, and longer service life than magnesia-chrome brick when they are used for sintering zone in cement kiln.
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18

Andronikov, A. V. "Spinel-garnet Iherzolite nodules from alkaline-ultrabasic rocks of Jetty Peninsula (East Antarctica)." Antarctic Science 2, no. 4 (December 1990): 321–30. http://dx.doi.org/10.1017/s0954102090000451.

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The petrography and mineralogy of Iherzolite nodules from an intrusive body of alkaline-ultrabasic rocks on Jetty Peninsula. The nodules are massive with a porphyritic hypidiomorphic granular texture. The main rock-forming minerals are: olivine, pyroxene, garnet and chrome spinel. The nodules are coarse granular spinel-garnet Iherzolites that are chemically similar to pyrope peridotite from Krezemze, Czechoslovakia, and pyrope-bearing peridotite from alkaline ultrabasites of Yakutia, USSR. The Al2O3 content in enstaties and Ca/(Ca + Mg) ratio in co-existing chrome diopside suggest that equilibrium conditions of the mantle mineral assemblage are: T = 875–900°C, P = 20–24 kbar, conditions typical of the spinel-pyrope facies of the upper mantle. Depths of withdrawal of the inclusions do not exceed 60–75 km. Available age determinations of the intrusive alkaline-ultrabasic rocks (145–150 Ma) suggest that alkaline-ultrabasic magmatism and withdrawal of plutonic nodules were related to rifting which resulted in the breakup of the Gondwana supercontinent in the late Mesozoic.
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19

Terfelt, Fredrik, and Birger Schmitz. "Asteroid break-ups and meteorite delivery to Earth the past 500 million years." Proceedings of the National Academy of Sciences 118, no. 24 (June 7, 2021): e2020977118. http://dx.doi.org/10.1073/pnas.2020977118.

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The meteoritic material falling on Earth is believed to derive from large break-up or cratering events in the asteroid belt. The flux of extraterrestrial material would then vary in accordance with the timing of such asteroid family-forming events. In order to validate this, we investigated marine sediments representing 15 time-windows in the Phanerozoic for content of micrometeoritic relict chrome-spinel grains (>32 μm). We compare these data with the timing of the 15 largest break-up events involving chrome-spinel–bearing asteroids (S- and V-types). Unexpectedly, our Phanerozoic time windows show a stable flux dominated by ordinary chondrites similar to today’s flux. Only in the mid-Ordovician, in connection with the break-up of the L-chondrite parent body, do we observe an anomalous micrometeorite regime with a two to three orders-of-magnitude increase in the flux of L-chondritic chrome-spinel grains to Earth. This corresponds to a one order-of-magnitude excess in the number of impact craters in the mid-Ordovician following the L-chondrite break-up, the only resolvable peak in Phanerozoic cratering rates indicative of an asteroid shower. We argue that meteorites and small (<1-km-sized) asteroids impacting Earth mainly sample a very small region of orbital space in the asteroid belt. This selectiveness has been remarkably stable over the past 500 Ma.
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Nikolaev, G. S., A. A. Ariskin, and G. S. Barmina. "Numerical modeling of the effects of major components in the melt on the chrome-spinel stability and a possible solution of the origin chromitites problem." Доклады Академии наук 487, no. 1 (July 19, 2019): 78–81. http://dx.doi.org/10.31857/s0869-5652487178-81.

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Using a new model of the spinel-melt equilibrium SPINMELT-2.0, the effect of variations of fo-, fa-, en-, fs-, di-, an- and ab-components in high-Mg basaltic melts on the topology of the spinel liquidus was quantified. It has been established that enrichment of the melt in pyroxene components leads to an increase, and with plagioclase components, to a decrease in the solubility of chromite. This effect can be important during gravitational compaction of cumulates, accompanied by the extraction of intercumulus melt and its infiltration upward. In this case, one can expect a sequential re-equilibration of the infiltrating melt with cumulative piles of different composition. This suggests the possibility of transfer and new concentration of chrome-spinel at the postcumulus stage of solidification of layered intrusions. The nature of the concentration consists in the extraction of chrome-spinel into the melt enriched in pyroxene components, followed by its discharge during the reaction of this melt with a feldspar-rich matrix of proto-anorthosite layers. The realism of the proposed mechanism is evidenced by the well-known spatial association of chromite layers with anorthosites (intrusion of Ram island, Bushveld complex).
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Sobolev, N. V., and A. M. Logvinova. "Significance of Accessory Chrome Spinel in Identifying Serpentinite Paragenesis." International Geology Review 47, no. 1 (January 2005): 58–64. http://dx.doi.org/10.2747/0020-6814.47.1.58.

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22

Ghanbarnezhad, S. "New development of spinel bonded chrome-free basic brick." Journal of Chemical Engineering and Materials Science 4, no. 1 (January 31, 2013): 7–12. http://dx.doi.org/10.5897/jcems12.030.

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23

Bell, Brian R., and Ian T. Williamson. "Picritic basalts from the Palaeocene lava field of west-central Skye, Scotland: evidence for parental magma compositions." Mineralogical Magazine 58, no. 392 (September 1994): 347–56. http://dx.doi.org/10.1180/minmag.1994.058.392.01.

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AbstractMineral chemistry and whole-rock compositional data are reported for two lavas of picritic basalt from the Palaeocene lava field of west-central Skye, Scotland. Whole-rock compositions for both flows plot on Thompson's (1982) 9 kbar cotectic for olivine + plagioclase + clinopyroxene + liquid. Both flows contain highly forsteritic olivine phenocrysts (c. Fo89), which enclose early-precipitated crystals of chrome-spinel (Al2O3: c. 25 wt.%; Cr2O3: c. 36 wt.%; FeO + Fe2O3: c. 20 wt.%; MgO: c. 15 wt.%). The olivine compositions indicate equilibrium with picritic basalt magma compositions, as represented by the whole-rock compositions of both lavas. A high-pressure origin for the chrome-spinels is suspected on the basis of their textural association and aluminous composition. Compositional comparisons between the whole-rock and mineral chemistry characteristics of both flows and a picritic basalt chill facies of the temporally- and spatially-associated Rum Igneous Complex suggests that similar parental magmas were involved.
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Pekov, Igor, Fedor Sandalov, Natalia Koshlyakova, Marina Vigasina, Yury Polekhovsky, Sergey Britvin, Evgeny Sidorov, and Anna Turchkova. "Copper in Natural Oxide Spinels: The New Mineral Thermaerogenite CuAl2O4, Cuprospinel and Cu-Enriched Varieties of Other Spinel-Group Members from Fumaroles of the Tolbachik Volcano, Kamchatka, Russia." Minerals 8, no. 11 (November 1, 2018): 498. http://dx.doi.org/10.3390/min8110498.

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This paper is the first description of natural copper-rich oxide spinels. They were found in deposits of oxidizing-type fumaroles related to the Tolbachik volcano, Kamchatka, Russia. This mineralization is represented by nine species with the following maximum contents of CuO (wt.%, given in parentheses): a new mineral thermaerogenite, ideally CuAl2O4 (26.9), cuprospinel, ideally CuFe3+2O4 (28.6), gahnite (21.4), magnesioferrite (14.7), spinel (10.9), magnesiochromite (9.0), franklinite (7.9), chromite (5.9), and zincochromite (4.8). Cuprospinel, formerly known only as a phase of anthropogenic origin, turned out to be the Cu-richest natural spinel-type oxide [sample with the composition (Cu0.831Zn0.100Mg0.043Ni0.022)Σ0.996(Fe3+1.725Al0.219Mn3+0.048Ti0.008)Σ2.000O4 from Tolbachik]. Aluminum and Fe3+-dominant spinels (thermaerogenite, gahnite, spinel, cuprospinel, franklinite, and magnesioferrite) were deposited directly from hot gas as volcanic sublimates. The most probable temperature interval of their crystallization is 600–800 °C. They are associated with each other and with tenorite, hematite, orthoclase, fluorophlogopite, langbeinite, calciolangbeinite, aphthitalite, anhydrite, fluoborite, sylvite, halite, pseudobrookite, urusovite, johillerite, ericlaxmanite, tilasite, etc. Cu-bearing spinels are among the latest minerals of this assemblage: they occur in cavities and overgrow even alkaline sulfates. Cu-enriched varieties of chrome-spinels (magnesiochromite, chromite, and zincochromite) were likely formed in the course of the metasomatic replacement of a magmatic chrome-spinel in micro-xenoliths of ultrabasic rock under the influence of volcanic gases. The new mineral thermaerogenite, ideally CuAl2O4, was found in the Arsenatnaya fumarole at the Second scoria cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption. It forms octahedral crystals up to 0.02 mm typically combined in open-work clusters up to 1 mm across. Thermaerogenite is semitransparent to transparent, with a strong vitreous lustre. Its colour is brown, yellow-brown, red-brown, brown-yellow or brown-red. The mineral is brittle, with the conchoidal fracture, cleavage is none observed. D(calc.) is 4.87 g/cm3. The chemical composition of the holotype (wt.%, electron microprobe) is: CuO 25.01, ZnO 17.45, Al2O3 39.43, Cr2O3 0.27, Fe2O3 17.96, total 100.12 wt.%. The empirical formula calculated on the basis of 4 O apfu is: (Cu0.619Zn0.422)Σ1.041(Al1.523Fe3+0.443Cr0.007)Σ1.973O4. The mineral is cubic, Fd-3m, a = 8.093(9) Å, V = 530.1(10) Å3. Thermaerogenite forms a continuous isomorphous series with gahnite. The strongest lines of the powder X-ray diffraction pattern of thermaerogenite [d, Å (I, %) (hkl)] are: 2.873 (65) (220), 2.451 (100) (311), 2.033 (10) (400), 1.660 (16) (422), 1.565 (28) (511) and 1.438 (30) (440).
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Garanin, V. K., G. P. Kudryavtseva, and A. D. Khar'kiv. "CATACLASTIC CHROME-SPINEL-GARNET ULTRABASIC XENOLITHS FROM THE UDACHNAYA KIMBERLITE." International Geology Review 28, no. 3 (March 1986): 296–304. http://dx.doi.org/10.1080/00206818609466273.

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Zhang, Hui Fang, Hong Liang Huang, Li Fang Zhang, Ying Fei Sun, and Fei Zhao. "The Development of Free of Chrome of Basic Refractory Materials for Cement Kiln and its Applications in Engineering." Advanced Materials Research 578 (October 2012): 91–94. http://dx.doi.org/10.4028/www.scientific.net/amr.578.91.

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This paper introduces the domestic and international evolution of refractory for cement rotary kiln and the situation of development for basic refractory. Also it introduces the usage and advantages and disadvantages of the high alumina brick, magnesia chrome brick, dolomite brick, magnesia spinel brick, magnesia zirconia brick. Refractory for cement kiln develops towards the direction of free of chromium, and it points out the development prospect of re-bonded magnesium zirconium refractory material .
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Mukashev, N. Zh, N. Y. Kosdauletov, and B. T. Suleimen. "Comparison of Iron and Chromium Reduction from Chrome Ore Concentrates by Solid Carbon and Carbon Monoxide." Solid State Phenomena 299 (January 2020): 1152–57. http://dx.doi.org/10.4028/www.scientific.net/ssp.299.1152.

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The possibility of reduction of chromium and iron from complex oxides by gaseous carbon monoxide and solid carbon was investigated. The chromium ore concentrates of Kempirsai and Aganozero deposits used in present study had different ratio of iron and chromium content. The Reduction in CO gas atmosphere did not result in reduction of chromium and iron from spinels; however, it resulted in reduction of fines from the drying apparatus, where the particles of coke presented along with the particles of the Kempersai chromite. At the same time, iron and nickel were reduced from the silicates of the gangue minerals. In the samples mixed with solid carbon a continuous layer of carbides formed on the surface of the spinel grains. The formation of a continuous shell retarded and practically stopped the reduction process. The further development of reduction was possible after destruction of the shell that occurred as a result of smelting of the carbides and silicides mixture that constitute the shell.
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Luo, Qiong, Hua Zhi Gu, Ao Huang, and Mei Jie Zhang. "Potash Erosion Resistance of Chromium-Containing Materials." Solid State Phenomena 281 (August 2018): 144–49. http://dx.doi.org/10.4028/www.scientific.net/ssp.281.144.

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Compared with the traditional entrained flow gasifier, coal catalytic gasifier has the advantages of low reaction temperature, high production efficiency and low energy consumption, but it also has higher requirements for potash erosion resistance. Chromium-containing material is commonly used as lining material for gasification furnaces. In this paper, potash erosion resistance of chromium-containing raw materials and products were respectively researched by using powder tabletting sintering and potassium vapor erosion method. The potash erosion resistance are characterized by XRD and SEM. The study show that:(1)There are obvious potassium salt deposition on the surface of chromium-containing raw materials and products after potash erosion experiment. Potash reacts with chrome-corundum and magnesium-chrome spinel to form K2CrO4,and reacts with chromium oxide to form K2Cr2O7at 750°C. (2)Potassium vapor enters into chromium-containing products through pores and leads to crack formation and volume change, which destroy the structure and reduce high temperature volume stability of material.
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Power, Matthew R., Duncan Pirrie, Jens C. Ø. Andersen, and Paul D. Wheeler. "Testing the validity of chrome spinel chemistry as a provenance and petrogenetic indicator." Geology 28, no. 11 (November 2000): 1027–30. http://dx.doi.org/10.1130/0091-7613(2000)028<1027:ttvocs>2.3.co;2.

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Power, Matthew R., Duncan Pirrie, Jens C. Ø. Andersen, and Paul D. Wheeler. "Testing the validity of chrome spinel chemistry as a provenance and petrogenetic indicator." Geology 28, no. 11 (2000): 1027. http://dx.doi.org/10.1130/0091-7613(2000)28<1027:ttvocs>2.0.co;2.

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31

Krivilyov, Mikhail, Evgeny Kharanzhevskiy, Sergey Reshetnikov, and Lesley J. Beyers. "Thermodynamic Assessment of Chrome-Spinel Formation in Laser-Sintered Coatings with Cr2O3 Particles." Metallurgical and Materials Transactions B 47, no. 3 (February 26, 2016): 1573–82. http://dx.doi.org/10.1007/s11663-016-0616-y.

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32

Ma, Guo Dong, Yong Li, Yuan Gao, Shan Shan Hong, Ya Qin Liu, Wen Bin Xia, Zhi Ming Qian, and Jing Heng Huang. "The Reaction Mechanism between Aluminum-Magnesia-Spinel Composite Material and RH Slag." Advanced Materials Research 503-504 (April 2012): 486–89. http://dx.doi.org/10.4028/www.scientific.net/amr.503-504.486.

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Unfired specimens were made with different aluninum content (0,2%,4%,6%,8%) respectively ,using high pure magnesia , magnesia-spinel and Aluninum as the main raw material. Unfired specimens were treated under the condition:110°C×24h drying,then 300°C×6h heating treatment.The properties and microstructure of the specimens were analyzed to investigate the reaction mechanism of these speciments and RH refinery slag.The result are shown that the addition of aluninum improves cold crushing strength of specimens,reaching to 63Mpa. The specimen with aluninum content of 8% shown the best slag resistance. The reaction mechanism between aluninum-magnesia-spinel complosite material and RH slag is different from magnesite-chrome brick. The major penetration element is Ca, and the Ca elment penetrated into the matrix reacts with corundum turning out a CA2 protective layer which can stop penetrating of slag.
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Dmitrenko, G. G., A. G. Mochalov, and V. L. Bocharov. "COMPOSITIONAL VARIATIONS IN CHROME-SPINEL IN THE ALPINE-TYPE ULTRAMAFICS OF THE KORYAK HIGHLANDS." International Geology Review 29, no. 4 (April 1987): 404–11. http://dx.doi.org/10.1080/00206818709466157.

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34

Ahmad, Sazzad, M. Akbar Rhamdhani, Mark I. Pownceby, and Warren J. Bruckard. "Selective sulfidising roasting for the removal of chrome spinel impurities from weathered ilmenite ore." International Journal of Mineral Processing 146 (January 2016): 29–37. http://dx.doi.org/10.1016/j.minpro.2015.11.012.

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35

V. V., Zaykov, Saveliev D. E., and Zaykova E. V. "Nature of chrome spinel inclusions in platinum metals grains from South Urals gold placers." Zapiski RMO (Proceedings of the Russian Mineralogical Society) 147, no. 4 (2018): 27–40. http://dx.doi.org/10.30695/zrmo/2018.1475.02.

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Pownceby, M. I., and M. J. Fisher-White. "Chemical variability in chrome spinel grains from magnetically fractionated ilmenite concentrates: implications for processing." Mineral Processing and Extractive Metallurgy 115, no. 4 (December 2006): 213–23. http://dx.doi.org/10.1179/174328506x128841.

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37

Fu, Wei, Xiao Rong Huang, Hong Yi Chen, Hu Jie Niu, and Meng Li Yang. "Micro-Morphology and Micro-Area Chemical Characteristics of the Nickel-Carrying Minerals in the Garnierite." Applied Mechanics and Materials 260-261 (December 2012): 896–901. http://dx.doi.org/10.4028/www.scientific.net/amm.260-261.896.

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To understand the nickel supergene enrichment mechanism in the lateritic process, we have conducted a preliminary analysis of the micro-morphology and micro-area chemical characteristics of the nickel-carrying minerals of garnierite, sampled from the Kolonodale area of Sulawesi Island in Indonesia. The SEM + EDS analysis shows that, the main nickel-carrying minerals in garnierite are serpentine and talc. The micro-morphology of the talc is fragmented and in piling structure. The micro-morphology of serpentine manifested tubular, fibrous, plate-like and other morphologies, showing the staggered and twisted, mesh-cross and sheet-interwoven structures, etc. The EPMA line scan analysis shows that the mineral types of garnierite samples are mainly of serpentine, talc, olivine and pyroxene debris, containing small amount of quartz, chrome spinel, etc. The Ni content varies a lot in the different minerals, and the nickel-carrying level sorting from high to low is: talc> secondary serpentine> iddingsite > residual serpentine> residual spinel> secondary quartz.
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Zhao, Ying, Guishi Cheng, Fei Long, Lu Liu, Changqing Dong, Xiaoqiang Wang, and Jin Zhao. "Analysis and Prediction of Corrosion of Refractory Materials by Potassium during Biomass Combustion-Thermodynamic Study." Materials 11, no. 12 (December 18, 2018): 2584. http://dx.doi.org/10.3390/ma11122584.

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As a kind of renewable resource, biomass has been used more and more widely, but the potassium contained in biomass can cause corrosion of the refractory. For a better understanding of corrosion thermodynamic mechanisms, the five components of common refractory materials (magnesium chrome spinel MgO·Cr2O3, magnesium aluminum spinel MgO·Al2O3, Al2O3, MgO, and Cr2O3) with potassium salts (K2CO3, K2SO4, and KCl) under high-temperature were studied by using the FactSageTM 7.0 software. Thermodynamic calculation results indicate that MgO is the best corrosion resistance of the five components of refractory materials. Based on the obtained results, the corrosion experiments in the laboratory were carried out (muffle furnace or high-temperature tube furnace) for corrosion reaction of KCl and MgO. The chemical compositions of the corroded samples were analyzed by X-ray diffraction (XRD). Under laboratory conditions (600–1200 °C), no corrosion products have been observed in the high-temperature corrosion experiments. The result indicates that to prevent the corrosion processes, refractories should contain as much MgO as possible.
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Dare, Sarah A. S., Julian A. Pearce, Iain McDonald, and Michael T. Styles. "Tectonic discrimination of peridotites using fO2–Cr# and Ga–Ti–FeIII systematics in chrome–spinel." Chemical Geology 261, no. 3-4 (April 2009): 199–216. http://dx.doi.org/10.1016/j.chemgeo.2008.08.002.

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Fernandes, T. R. C., and J. I. Langford. "High-resolution X-ray diffraction study of the chromite (Mg0.60Fe0.402+)(Al0.39Cr1.50Fe0.093+)O4." Powder Diffraction 13, no. 2 (June 1998): 96–99. http://dx.doi.org/10.1017/s0885715600009921.

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As part of a study by high-resolution X-ray diffraction of chrome ores from the Great Dyke, Zimbabwe, powder data are reported for a well-crystallized ferroan magnesiochromite spinel, in which some Cr had been replaced by Al. Data were obtained by using CuKα1 radiation, with an incident beam focusing monochromator to eliminate the Kα2 component. The cell parameter is a0=8.3123(2) Å, the figures of merit are M17=383 and F17=182 (0.0055, 17) and the calculated density is 4.50(5) Mgm−3. A small amount of sample broadening was observed and this was attributed to a mean crystallite size of 259(1) nm. © 1997 International Center for Diffraction Data.
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Ernowo, Ernowo, and Penny Oktaviani. "REVIEW OFCHROMITE DEPOSITS OF INDONESIA." Buletin Sumber Daya Geologi 5, no. 1 (May 31, 2010): 1–10. http://dx.doi.org/10.47599/bsdg.v5i1.250.

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Chromites (Fe,Mg)Cr O is an oxide mineral in spinel group. It is one of metallic mineral which classified in to alloy and ferro alloy metallic mineral group along with iron, nickel, titanium, manganese, cobalt, and bauxite. Chromites is the only ore mineral of metallic chromium and chromium compounds and chemicals. Because of this fact, chromites and chrome ore are used synonymously in trade literature. It is used for refractory material, because it has high heat stability. In Indonesia, chromites deposits are widely distributed in the eastern part of Indonesia, which rich in metal bearing ultramafic to mafic intrusive especially in South Kalimantan, Sulawesi, Maluku, Halmahera, Gebe, Gag, Waigeo, and Papua. These deposits are resulted from weathering of ophiolite rocks as part of the Pacific plate.
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42

Liipo, J., J. Vuollo, V. Nykänen, and T. Piirainen. "Chrome spinel compositions as evidence for an Archaean ophiolite in the Kuhmo greenstone belt in Finland." Bulletin of the Geological Society of Finland 66, no. 1 (June 1994): 3–18. http://dx.doi.org/10.17741/bgsf/66.1.001.

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43

Jantzen, Carol M., Kenneth J. Imrich, John B. Pickett, and Kevin G. Brown. "High Chrome Refractory Characterization: Part II. Accumulation of Spinel Corrosion Deposits in Radioactive Waste Glass Melters." International Journal of Applied Glass Science 6, no. 2 (January 12, 2015): 158–71. http://dx.doi.org/10.1111/ijag.12104.

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44

Chalapathi Rao, N. V., B. Lehmann, D. Mainkar, and B. K. Panwar. "Diamond-facies chrome spinel from the Tokapal kimberlite, Indrāvati basin, central India and its petrological significance." Mineralogy and Petrology 105, no. 3-4 (May 8, 2012): 121–33. http://dx.doi.org/10.1007/s00710-012-0199-5.

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45

Li, Zhi Hui, Sen Wang, Jing Li, and Feng Wu. "Effect of α-Al2O3 Micro Powder on Performance of Porous Plug Well Block." Advanced Materials Research 422 (December 2011): 561–65. http://dx.doi.org/10.4028/www.scientific.net/amr.422.561.

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In connection with broken-down mechanics of ladle porous plug well block，with tabular alundum、allitic spinel、industrial chrome oxide as the main raw material and aluminate cement and active α-Al2O3 micro powder as binder，we prepare 9 groups porous plug well block samples，for studying the species of α-Al2O3 micro powder and impact of its addition on the properties of samples．By testing room temperature flexural strength of samples、room temperature compression strength，flexural strength after sintering at 1600°C and heating for 3 hours、compression strength after burning，bulk density and apparent porosity before burning and after burning，thermal shock、high temperature bending strength and other performance indicators．The results show that，adding α-Al2O3 micro powder of multi-peak distribution in the samples，whoes granularity distributes reasonably，may have better effects of padding，and form more uniform intergranular spinel，at the same time，find that the higher the bonding strength between the grains，the higher pyknosis strength of samples，and the performance indicators are excellent．When the addition of α-Al2O3 micro powder of multi-peak distribution are 10%，compression strength of sample after burning is 132MPa，high temperature flexural strength is 14MPa，bulk density is 3.25g/cm3，and apparent porosity is 12%，also，thermal shock stability and other combination properties are the best．To meet the excellent performance that delivery needs and have higher safety factor，we may use corundum-spinel porous plug well block of longer lifespan bonding low cement．
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46

Brady, A. E., and K. R. Moore. "A mantle-derived dolomite silicocarbonatite from the southwest coast of Ireland." Mineralogical Magazine 76, no. 2 (April 2012): 357–76. http://dx.doi.org/10.1180/minmag.2012.076.2.06.

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AbstractThe magma source and evolution of a zoned breccia pipe on the southern Beara Peninsula in southwest Ireland are investigated using the geochemistry of the host mineral assemblages. The clast-poor inner zone of the pipe has a magnesium-rich silicocarbonatite whole-rock composition (14.30 wt.% MgO; 31.80 wt.% SiO2). The silicocarbonatite has retained an ultimate mantle source 13C isotopic composition after metamorphism, consistent with the presence of mantle debris. The silicocarbonatite is Cr-, Ni- and Co-rich (847 ppm, 611 ppm and 60 ppm, respectively) but REE depleted compared with volcanic dolomite carbonatites worldwide. The mineral assemblage consists of Sr-rich (0.55 wt.% SrO) ferroan dolomite, magnesite and pseudomorphs of chlorite after phlogopite, consistent with derivation from a carbonated and hydrated mantle. However, chrome spinel crystals (≤4 40.14 wt.% Cr2O3) are compositionally indistinguishable from unmetasomatized spinel macrocrysts in kimberlites. The silicocarbonatite is inferred to represent a magma produced by partial melting of metasomatized mantle at physical conditions between those in which primary dolomite carbonatite and ultramafic magmas of high-pressure origin form. The primary silicocarbonatite magma ascended and sampled mantle material in a manner similar to kimberlite, and subsequently lost volatile components due to release of metasomatic fluids and later metamorphism.
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47

Baxter, Alan T., Jonathan C. Aitchison, Jason R. Ali, Jacky Sik-Lap Chan, and Gavin Heung Ngai Chan. "Detrital chrome spinel evidence for a Neotethyan intra-oceanic island arc collision with India in the Paleocene." Journal of Asian Earth Sciences 128 (October 2016): 90–104. http://dx.doi.org/10.1016/j.jseaes.2016.06.023.

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48

Monami, Shifat J., Ashraf Uddin, and Willis E. Hames. "Multi-proxy provenance of the lower Pennsylvanian Pottsville sandstone of the northern Appalachian basin in Pennsylvania, U.S.A: Paleodrainage, sources, and detrital history." Journal of Sedimentary Research 92, no. 3 (March 31, 2022): 304–19. http://dx.doi.org/10.2110/jsr.2020.189.

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ABSTRACT The lower Pennsylvanian Pottsville Formation, in the Appalachian foreland basin, constitutes a late Paleozoic clastic wedge formed close to the Appalachian orogenic belt. In this study, we analyzed Pottsville sandstone from the western bituminous and eastern anthracite fields in Pennsylvania to evaluate the detrital history of the sediments. Petrographic modal analyses show that sandstone in the western bituminous field ranges from quartzarenite to sublitharenite, with mean composition of Qt84F1L15; sampled sandstone from the eastern anthracite field is dominated by sublitharenite to litharenite with mean composition of Qt70F2L29. Heavy-mineral assemblages from both fields are dominated by ultrastable minerals (zircon, rutile, and tourmaline), apatite, sphene, spinel, siderite, and abundant opaques. Almost all the studied sandstone samples are garnet-depleted except one from the eastern anthracite field. The chemical composition of chromium- and zinc-rich spinel in samples from both fields might suggest exhumation of an arc terrane and ophiolitic belt with ultramafic igneous rocks. Particularly, the ternary plot of Fe3+–Cr3+–Al3+ end members for the chrome spinels possibly suggest a derivation from an alpine-type peridotite complex. Laser 40Ar/39Ar analyses of detrital muscovite from eastern anthracite fields and western bituminous fields record separate ages, with the former characterized by prominent Middle to Late Ordovician Taconic and Middle Devonian Acadian ages with two discrete modes at 463 and 369 Ma, and the latter dominated by Late Ordovician Taconic, Middle Devonian Acadian, and Late Devonian Neoacadian ages with discrete modes at 445, 397, 360, and 351 Ma. The new data suggest that early Pennsylvanian sedimentation in the Appalachian foreland basin was controlled by southward, southwestward, and westward drainage systems that originated in the Appalachian orogenic belt to the east and northeast.
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Rout, Surya S., Philipp R. Heck, and Birger Schmitz. "Shock history of the fossil ungrouped achondrite Österplana 065: Raman spectroscopy and TEM of relict chrome-spinel grains." Meteoritics & Planetary Science 53, no. 5 (January 15, 2018): 973–83. http://dx.doi.org/10.1111/maps.13041.

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50

Yin, Guo Xiang, Yong Li, Jun Hong Chen, and Xin Kui Gao. "The Wear Mechanism Comparison between MgO-Based Chrome-Free Brick and MgO-Cr2O3 Brick in the Lower Part of RH Vacuum Degasser." Advanced Materials Research 476-478 (February 2012): 1991–96. http://dx.doi.org/10.4028/www.scientific.net/amr.476-478.1991.

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Abstract:
The damage and improvement mechanism of rebonded MgO-Cr2O3 brick and MgO-ZrO2 brick used in the lower part of RH vacuum degasser were studied. The results show that the main damage of rebonded MgO-Cr2O3 brick is structure spalling because of the penetration of slag. MgO-ZrO2 brick has characteristics of high direct-bonding degree, small air permeability and making the viscosity of penetrated slag increased by means of ZrO2 absorbing CaO in slag to form CaZrO3 or ZrO2 solid solution, which make the degree of slag penetration decrease and improve the structure spalling resistance. MgO-ZrO2 brick has the defect of poor thermal shock resistance in use, the incorporation of MgO-rich spinel into MgO-ZrO2 brick significantly improved both thermal shock resistance and hot modulus of rupture because of the formation of eutectoid structure of grain-refining spinel and zirconia, which also improved structure spalling resistance because air permeability was decreased to 5% of MgO-ZrO2 brick
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