scholarly journals Raman anisotropy in serpentine minerals, with a caveat on identification

2021 ◽  
Author(s):  
Roberto Compagnoni ◽  
Roberto Cossio ◽  
Marcello Mellini
Keyword(s):  
Serpentine Minerals

scholarly journals In Situ Control of Thermal Activation Conditions by Color for Serpentines with a High Iron Content

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6731
Author(s):  
Tatiana K. Ivanova ◽  
Irina P. Kremenetskaya ◽  
Andrey I. Novikov ◽  
Valentin G. Semenov ◽  
Anatoly G. Nikolaev ◽  
...  
Keyword(s):  
Iron Content ◽  
Large Scale ◽  
Color Change ◽  
Reference Sample ◽  
Chemical Activity ◽  
High Iron Content ◽  
Color Palette ◽  
High Iron ◽  
Serpentine Minerals ◽  
Heat Treated

Serpentine heat treatment at temperatures of 650–750 °C yields magnesium–silicate reagent with high chemical activity. Precise and express control of roasting conditions in laboratory kilns and industrial aggregates is needed to derive thermally activated serpentines on a large scale. Color change in serpentines with a high iron content during roasting might be used to indicate the changes in chemical activity in the technological process. This study gives a scientific basis for the express control of roasting of such serpentines by comparing the colors of the obtained material and the reference sample. Serpentines with different chemical activity were studied by X-ray diffraction, Mössbauer spectroscopy, and optical spectroscopy. The color parameters were determined using RGB (red, green, blue), CIELAB (International Commission on Illumination 1976 L*a*b), and HSB (hue, brightness, saturation) color models. The color of heat-treated samples was found to be affected by changes in the crystallochemical characteristics of iron included in the structure of the serpentine minerals. The color characteristics given by the CIELAB model were in good coherence with the acid-neutralizing ability and optical spectra of heat-treated serpentines. Thus, in contrast to the long-term analysis by these methods, the control by color palette provides an express assessment of the quality of the resulting product.

Heat-treated serpentine-reached materials: application for sorption of heavy metals and remediation of industrially polluted peat soil

2021 ◽  
Author(s):  
Marina Slukovskaya ◽  
Irina Kremenetskaya ◽  
Andrey Novikov ◽  
Tatiana Ivanova ◽  
Svetlana Drogobuzhskaya
Keyword(s):  
Heavy Metals ◽  
Peat Soil ◽  
Initial Period ◽  
Metal Mobility ◽  
Acetate Solution ◽  
Russian Science ◽  
Serpentine Minerals ◽  
Heat Treated ◽  
Murmansk Region ◽  
Metal Fractions

<p>Serpentine minerals are widely distributed in the Earth’s crust, forming in some provinces with specific vegetation. Like clay minerals, serpentine minerals can be referred to as eco-friendly materials and can be used for the sorption of heavy metals in contaminated soil. The sorption of metals by serpentine minerals can occur by adsorption on the surface, entering into the mineral’s structure, and the precipitation of low-soluble compounds in an alkaline environment. It is possible to intensify these processes by modifying serpentines, namely by heat treatment. Our study used two types of serpentine-reached materials from mining wastes: ortho-chrysotile from overburden rocks of Khalilovsky magnesite deposit (Cht) and lizardite from host rocks of Khabozersky olivine deposit (Lt) (Russia), thermally activated in a tube furnace at 650-750 ºC.</p><p>The process of hydration occurs in the field conditions when serpentine interacts with soil solutions. Therefore, the process of nickel sorption by Cht and hydrated Cht was studied. Results indicated the formation of magnesium silicates during hydration. These chemical compounds were found to be more stable than components of initial Cht (test for leaching in 1N ammonium acetate solution, pH 4.68). Hydration of Cht reduced the activity of nickel sorption processes in the initial period of interaction. However, the nickel sorption value of hydrated Cht eventually was similar to the initial Cht when reactive phases’ contact increased up to 30 days.</p><p>In the field experiment, the topsoil (0-5 cm) of industrially polluted peat near the active Cu/Ni plant (Murmansk region, Russia) was mixed with Cht and Lt in 3:1 proportion. Initial polluted peat contained more than 500 mg/kg of exchangeable Ni and 6300 mg/kg of Cu. After eight years of the experiment in conditions of continuing aerial metal emissions, the concentration of exchangeable metal fractions in soil mixtures was lower than in peat soil by 3-5 times for Cu and by 1.3 times for Ni. Simultaneously, the concentration of immobile metal fractions (bound by organic matter, Fe/Mn (hydr)oxides, and included in other insoluble compounds) was 1.5 times higher than in peat soil. The lack of nutrients (mostly Mg and Ca) in the polluted soil causes vegetation degradation in the smelter’s impact zone. Soil mixed with heat-treated serpentine minerals led to increased plant-available Mg compounds (by 11-42 times) and Ca (by 2.6-4.4 times). These findings indicate the fixation of metal pollutants by heat-treated serpentine minerals and soil enrichment in essential elements. The use of the heat-treated serpentine-reached materials is promising for the long-term decrease of metal mobility and remediation of industrially polluted soils.</p><p>The research was conducted with the support of the Russian Science Foundation grant 19-77-00077.</p>

Influence of colloid synthesis techniques on barium silicates formation using silica hydrogel derived from serpentine minerals

2019 ◽  
Vol 291 ◽  
pp. 111263 ◽  
Author(s):  
Hayk A. Beglaryan ◽  
Stella A. Melikyan ◽  
Nshan H. Zulumyan ◽  
Anna M. Terzyan ◽  
Anna R. Isahakyan
Keyword(s):  
Silica Hydrogel ◽  
Synthesis Techniques ◽  
Serpentine Minerals ◽  
Colloid Synthesis

scholarly journals In Situ Oxygen Isotope Determination in Serpentine Minerals by Ion Microprobe: Reference Materials and Applications to Ultrahigh-Pressure Serpentinites

2018 ◽  
Vol 42 (4) ◽  
pp. 459-479 ◽  
Author(s):  
Maria Rosa Scicchitano ◽  
Daniela Rubatto ◽  
Jörg Hermann ◽  
Tingting Shen ◽  
José Alberto Padrón-Navarta ◽  
...  
Keyword(s):  
Oxygen Isotope ◽  
Reference Materials ◽  
Ultrahigh Pressure ◽  
Ion Microprobe ◽  
Serpentine Minerals ◽  
Isotope Determination

Effect of Milling on the Crystal Structures of Chrysotile and Other Serpentine Minerals

1975 ◽  
Vol 19 ◽  
pp. 685-694
Author(s):  
A. E. Charola ◽  
S. Z. Lewin
Keyword(s):  
Crystal Structures ◽  
Acid Treatment ◽  
Local Heating ◽  
The Other ◽  
Sharp Peak ◽  
Line Broadening ◽  
Intensity Decrease ◽  
Serpentine Minerals ◽  
Heating Effects ◽  
Integrated Intensity

The most prominent peaks of chrysotile are the 002 and 004 reflections, and in dilute mixtures of chrysotile in talc they are the only peaks that can be detected. Milling of chrysotile markedly reduces these peak heights and areas, and generates a new, sharp peak at d = 2.52 A. Milling of other serpentine minerals also results in line broadening and integrated intensity decrease of the 002 and 004 lines; a weak d = 2.52 reflection is initially present and milling causes this to increase slightly in intensity, without any detectable line broadening. The variations in relative intensities of these peaks for different size-classified fractions of the several minerals after prolonged milling confirms that the d = 2.52 A reflection is due to a phase that is different from the starting material. Investigation of specimens held at various temperatures up to 1000°C shows that the consequences of milling cannot be attributed to local heating effects. It is confirmed that chrysotile is readily attacked and dissolved by 1 M HCl, whereas the other serpentine minerals are relatively inert to this reagent. In the case of extensively milled chrysotile, the acid treatment causes the 002 and 004 peaks to weaken and eventually disappear, but the d = 2.52 A peak remains unaffected.

scholarly journals A Volcanological Paradox in a Thin-Section: Large Explosive Eruptions of High-Mg Magmas Explained Through a Vein of Silicate Glass in a Serpentinized Peridotite Xenolith (Hyblean Area, Sicily)

Geosciences ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 150
Author(s):  
Alessandra Correale ◽  
Vittorio Scribano ◽  
Antonio Paonita
Keyword(s):  
Silicate Glass ◽  
Hydrothermal Solution ◽  
Aqueous Fluid ◽  
Major Elements ◽  
Element Distribution ◽  
Explosive Eruptions ◽  
Trace Element Distribution ◽  
Serpentinized Peridotite ◽  
Serpentine Minerals ◽  
Highly Porous

Ultramafic magmas (MgO ≥ 18 wt%) are generally thought to be primary mantle melts formed at temperatures in excess of 1600 °C. Volatile contents are expected to be low, and accordingly, high-Mg magmas generally do not yield large explosive eruptions. However, there are important exceptions to low explosivity that require an explanation. Here we show that hydrous (hence, potentially explosive) ultramafic magmas can also form at crustal depths at temperatures even lower than 1000 °C. Such a conclusion arose from the study of a silicate glass vein, ~1 mm in thickness, cross-cutting a mantle-derived harzburgite xenolith from the Valle Guffari nephelinite diatreme (Hyblean area, Sicily). The glass vein postdates a number of serpentine veins already existing in the host harzburgite, thus reasonably excluding that the melt infiltrated in the rock at mantle depths. The glass is highly porous at the sub-micron scale, it also bears vesicles filled by secondary minerals. The distribution of some major elements corresponds to a meimechite composition (MgO = 20.35 wt%; Na2O + K2O < 1 wt%; and TiO2 > 1 wt%). On the other hand, trace element distribution in the vein glass nearly matches the nephelinite juvenile clasts in the xenolith-bearing tuff-breccia. These data strongly support the hypothesis that an upwelling nephelinite melt (MgO = 7–9 wt%; 1100 ≤ T ≤ 1250 °C) intersected fractured serpentinites (T ≤ 500 °C) buried in the aged oceanic crust. The consequent dehydroxilization of the serpentine minerals gave rise to a supercritical aqueous fluid, bearing finely dispersed, hydrated cationic complexes such as [Mg2+(H2O)n]. The high-Mg, hydrothermal solution "flushed" into the nephelinite magma producing an ultramafic, hydrous (hence, potentially explosive), hybrid magma. This hypothesis explains the volcanological paradox of large explosive eruptions produced by ultramafic magmas.

scholarly journals Study of Microstructures of Serpentine Minerals I

1977 ◽  
Vol 13 (3) ◽  
pp. 182-203
Author(s):  
Keiji Yada ◽  
Kazuaki Iishi
Keyword(s):  
Serpentine Minerals

scholarly journals Bacterially Induced Weathering of Ultramafic Rock and Its Implications for Phytoextraction

2013 ◽  
Vol 79 (17) ◽  
pp. 5094-5103 ◽  
Author(s):  
Cristina Becerra-Castro ◽  
Petra Kidd ◽  
Melanie Kuffner ◽  
Ángeles Prieto-Fernández ◽  
Stephan Hann ◽  
...  
Keyword(s):  
Ultramafic Rock ◽  
Production Capacity ◽  
Metal Extraction ◽  
Limiting Factor ◽  
Bacterial Strains ◽  
Time Intervals ◽  
Content Type ◽  
Ultramafic Soil ◽  
Serpentine Minerals ◽  
Improve Metal

ABSTRACTThe bioavailability of metals in soil is often cited as a limiting factor of phytoextraction (or phytomining). Bacterial metabolites, such as organic acids, siderophores, or biosurfactants, have been shown to mobilize metals, and their use to improve metal extraction has been proposed. In this study, the weathering capacities of, and Ni mobilization by, bacterial strains were evaluated. Minimal medium containing ground ultramafic rock was inoculated with either of twoArthrobacterstrains: LA44 (indole acetic acid [IAA] producer) or SBA82 (siderophore producer, PO4solubilizer, and IAA producer). Trace elements and organic compounds were determined in aliquots taken at different time intervals after inoculation. Trace metal fractionation was carried out on the remaining rock at the end of the experiment. The results suggest that the strains act upon different mineral phases. LA44 is a more efficient Ni mobilizer, apparently solubilizing Ni associated with Mn oxides, and this appeared to be related to oxalate production. SBA82 also leads to release of Ni and Mn, albeit to a much lower extent. In this case, the concurrent mobilization of Fe and Si indicates preferential weathering of Fe oxides and serpentine minerals, possibly related to the siderophore production capacity of the strain. The same bacterial strains were tested in a soil-plant system: the Ni hyperaccumulatorAlyssum serpyllifoliumsubsp.malacitanumwas grown in ultramafic soil in a rhizobox system and inoculated with each bacterial strain. At harvest, biomass production and shoot Ni concentrations were higher in plants from inoculated pots than from noninoculated pots. Ni yield was significantly enhanced in plants inoculated with LA44. These results suggest that Ni-mobilizing inoculants could be useful for improving Ni uptake by hyperaccumulator plants.

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