A New Ni-Rich Stevensite From the Ophiolite Complex of Othrys, Central Greece

Christidis, George E.; Mitsis, Ioannis

doi:10.1346/ccmn.2006.0540601

Cited by 30 publications

(35 citation statements)

References 41 publications

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“…Bands at 3624 cm À1 and 710 cm À1 ( Figure 5) were assigned to nNi 3 OH and dNi 3 OH, respectively, as described for kerolite and talc (Wilkins and Ito, 1967;Farmer, 1974;Gerard and Herbillon, 1983;Petit, 2005;Christidis and Mitsis, 2006). This is in agreement with the large Ni content determined by chemical analysis.…”

Section: Infrared Resultssupporting

confidence: 82%

“…nature; a dioctahedral Ni-smectite which does not exceed 0.4 Ni atoms per half unit cell was studied by Bosio et al (1975), Brindley and de Souza (1975), and Gaudin et al (2004a). Only Christidis and Mitsis (2006) found a Ni-smectite in Othrys, Greece, with >2 Ni per half unit cell. For the dioctahedral smectites, Fe 3+ is the dominant octahedral cation (1.5 Fe atoms per half unit cell).…”

Section: Discussionmentioning

confidence: 99%

“…Nickel exhibits a specific geochemical affinity for mantle-derived (mafic and ultramafic) rocks (Christidis and Mitsis, 2006). Mafic and ultramafic intrusions were responsible for the formation of the Niquelâ ndia ultrabasic massif during the Archean period (Marini et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

“…Nickel grades were observed to vary from 10 to 84% of occupancy in the octahedral sites of trioctahedral smectites in Niquelândia (Colin et al, 1990). A Ni-rich stevensite has also been reported from Othrys, Greece (Christidis and Mitsis, 2006). The complex crystal chemistry of the clay minerals in Niquelândia may be the cause of significant variability in the ores which affects the recovery rates of Ni from the hydrometallurgical process.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Mano

Caner

Petit

et al. 2014

Clays and clay miner.

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Nickel-lateritic ore is the most common source of nickel in Brazil. The Niquelândia deposit, located in State of Goias, is one of the most famous deposits due to the large amounts of nickel associated with both oxidized and mainly silicated ores. The terms oxidized and silicated ores are used to specify two different ores formed exclusively by oxides and silicate (clay) minerals, respectively. The aim of the present study was to characterize thoroughly the silicated ore to identify the Ni-bearing clay minerals and their crystal chemistry in support of developing a better mineral-processing method or optimizing the current one to improve Ni recoveries. X-ray diffraction, chemical analyses, scanning electron microscopy, and Fourier transform infrared (FTIR) spectroscopy demonstrated that nickel is associated with Ni-rich stevensite and to a lesser extent with Fe-rich montmorillonite. The crystal chemistry performed by FTIR spectroscopy revealed that Ni is present in the octahedral positions, substituting for Mg or Fe, which results in significant chemical and layer-charge heterogeneity in the samples. This heterogeneity seems to be responsible for reduction in Ni recoveries during the hydrometallurgical process.

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Section: Infrared Resultssupporting

confidence: 82%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Mano

Caner

Petit

et al. 2014

Clays and clay miner.

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“…According to DeRudder and Beck (1962), talc, the dominant material in the most intensely altered zone bordering the solution channel way, was formed by the continuing action of magnesiumbearing solutions on stevensite. Several other investigators have examined the relations among wollastonite, stevensite, montmorillonite, and talc (see, e.g., Whitney & Eberl, 1982;Christidis & Mitsis, 2006;Imai et al, 1973;Sakamoto et al, 1975;Tazaki et al, 1986;Léveillé, 2000). Talc can also be formed from alteration of tremolite materials (Ross et al, 1968).…”

Section: Characterization Of Nyco Contaminant(s)mentioning

confidence: 99%

Product Stewardship in Wollastonite Production

Maxim¹,

Niebo²,

LaRosa

et al. 2008

Inhalation Toxicology

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In July 2002, NYCO Minerals, Inc., discovered a heretofore unknown contaminant in its wollastonite ore. The contaminant was first believed to be tremolite asbestos. Immediate efforts were made to eliminate this material. Additional studies were initiated to fully characterize the contaminant and its distribution in the ore body. Subsequent study by NYCO and their consultants led to the identification of the contaminant as a transition material (TM) intermediate between tremolite and talc. In vitro dissolution rate measurements indicated that the TM dissolved much more rapidly than tremolite asbestos. This article provides background information on wollastonite mineralogy and NYCO's product stewardship program (PSP). At present, NYCO Minerals uses selective mining to control the trace levels of TM in the ore and finished product verified by periodic monitoring of workplace air and finished product.NYCO Minerals, Inc., developed a product stewardship program (PSP) to identify, manage, and control occupational risks associated with the production and use of wollastonite. This article presents a short case history of the discovery, identification, and control of what was initially considered to be a potentially

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Transformation of Magnesite to Sepiolite and Stevensite: Characteristics and Genesis (Çayirbaği, Konya, Turkey)

Yeniyol

2020

Clays and clay miner.

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Çayırbağı magnesite is one of numerous magnesite deposits occurring throughout Turkey. In this deposit, sepiolite and newly found stevensite occur locally as two daughter minerals formed from magnesite. The sepiolite and stevensite show distinctive compositions and modes of formation compared to those described in the literature. The objective of the current study was to characterize these minerals by means of mineralogic, thermal, structural, geochemical, and textural analyses and to describe their mechanisms of formation. The geology, mineralogy, and geochemistry were examined by field work followed by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential thermal (DTA), and thermogravimetric (TG) analyses. Chemical analyses were performed by means of electron microprobe (EMPA), inductively coupled plasma-optical emission spectrometry (ICP-OES), and laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). The XRD analyses showed that the d 110 of the sepiolite was at 12.64 Å and at 13 Å after air-drying and ethylene-glycol solvation, respectively. Identification of the sepiolite as sepiolite-13 Å was supported by FTIR and TG-DTA data. Chemical analyses showed an ideal composition with a structural formula of (Ca 0.05 K 0.02 )(Mg 7.79 Al 0.10 □ 0.11 )Si 12 O 30 (OH) 4 . Stevensite displayed distinctive results for XRD, FTIR, and thermal characteristics. The structural formula of stevensite was: (Ca 0.01 Na 0.20 K 0.04 )(Mg 1.90 Al 0.30 Fe 3+ 0.37 Ti 0.01 □ 0.43 )(Si 3.93 Al 0.07 )O 10 (OH) 2 , indicating a layer charge arising mainly from octahedral sheets. Field and SEM observations demonstrated that sepiolite was formed from magnesite by transformation via a dissolution-precipitation mechanism. Descending surface waters were responsible for this transformation. Thick magnesite veins were partly replaced whereas in thin veins sepiolite replaced the overall mass. Both surface waters with high Si, low Al and Fe activities, and pH values of 8-9.5 were responsible for sepiolite formation. Stevensite was formed similarly to sepiolite with respect to the mechanism and parent mineral under permanent groundwater; where both Si, Fe, Al activities and pH (>9.5) were high.

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A New Ni-Rich Stevensite From the Ophiolite Complex of Othrys, Central Greece

Cited by 30 publications

References 41 publications

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Mineralogical Characterization of Ni-Bearing Smectites from Niquelândia, Brazil

Product Stewardship in Wollastonite Production

Transformation of Magnesite to Sepiolite and Stevensite: Characteristics and Genesis (Çayirbaği, Konya, Turkey)

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