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Editorial

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3 pages, 199 KiB

Open AccessEditorial

Editorial for Special Issue “Mineral Fibres”

by Andrea Bloise, Rosalda Punturo, Robert Kusiorowski and Dolores Pereira Gómez

Fibers 2019, 7(6), 54; https://doi.org/10.3390/fib7060054 - 13 Jun 2019

Cited by 4 | Viewed by 4388

Abstract

In the past 30 years, there has been a growing concern regarding the health risks of exposure to asbestos-containing materials (ACMs) and naturally occurring asbestos (NOA) [...] Full article

(This article belongs to the Special Issue Mineral Fibres)

Research

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15 pages, 5328 KiB

Open AccessArticle

Grinding Test on Tremolite with Fibrous and Prismatic Habit

by Oliviero Baietto, Mariangela Diano, Giovanna Zanetti and Paola Marini

Fibers 2019, 7(6), 52; https://doi.org/10.3390/fib7060052 - 1 Jun 2019

Cited by 5 | Viewed by 5693

Abstract

The main objective of this work is the evaluation of the morphology change in tremolite particles before and after a grinding process. The crushing action simulates anthropic alteration of the rock, such as excavation in rocks containing tremolite during a tunneling operation. The [...] Read more.

The main objective of this work is the evaluation of the morphology change in tremolite particles before and after a grinding process. The crushing action simulates anthropic alteration of the rock, such as excavation in rocks containing tremolite during a tunneling operation. The crystallization habit of these amphibolic minerals can exert hazardous effects on humans. The investigated amphibolic minerals are four tremolite samples, from the Piedmont and Aosta Valley regions, with different crystallization habits. The habits can be described as asbestiform (fibrous) for longer and thinner fibers and non-asbestiform (prismatic) for prismatic fragments, also known as “cleavage” fragments. In order to identify the morphological variation before and after the grinding, both a phase contrast optical microscope (PCOM) and a scanning electron microscope (SEM) were used. The identification procedure for fibrous and prismatic elements is related to a dimensional parameter (length–diameter ratio) defined by the Health and Safety Executive. The results highlight how mineral comminution leads to a rise of prismatic fragments and, therefore, to a potentially safer situation for worker and inhabitants. Full article

(This article belongs to the Special Issue Mineral Fibres)

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11 pages, 4519 KiB

Open AccessArticle

Characterization of Serpentines from Different Regions by Transmission Electron Microscopy, X-ray Diffraction, BET Specific Surface Area and Vibrational and Electronic Spectroscopy

by Miguel A. Rivero Crespo, Dolores Pereira Gómez, María V. Villa García, José M. Gallardo Amores and Vicente Sánchez Escribano

Fibers 2019, 7(5), 47; https://doi.org/10.3390/fib7050047 - 20 May 2019

Cited by 19 | Viewed by 6458

Abstract

Serpentinite powdered samples from four different regions were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), S_BET and porosity measurements, UV-Vis and Infrared Spectroscopy of the skeletal region and surface OH groups. SEM micrographs of the samples showed a prismatic morphology [...] Read more.

Serpentinite powdered samples from four different regions were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), S_BET and porosity measurements, UV-Vis and Infrared Spectroscopy of the skeletal region and surface OH groups. SEM micrographs of the samples showed a prismatic morphology when the lizardite was the predominant phase, while if antigorite phase prevailed, the particles had a globular morphology. The few fibrous-shaped particles, only observed by SEM and weakly detected by XRD on MO-9C and MO13 samples, were characteristic of the chrysotile phase. All diffraction XRD patterns showed characteristic peaks of antigorite and lizardite serpentine phases, with crystallite sizes in the range 310–250 Å and with different degrees and types of carbonation processes, one derived from the transformation of the serpentine, generating dolomite, and another by direct precipitation of calcite. The S_BET reached values between 38–24 m²∙g⁻¹ for the samples less crystalline, in agreement with the XRD patterns, while those with a higher degree of crystallinity gave values close to 8–9 m²∙g⁻¹. In the UV region all electronic spectra were dominated by the absorption edge due to O²⁻ → Si⁴⁺ charge transfer transition, with Si⁴⁺ in tetrahedral coordination, corresponding to a band gap energy of ca 4.7 eV. In the visible region, 800–350 nm, the spectra of all samples, except Donai, presented at least two weak and broad absorptions centred in the range 650–800 and 550–360 nm, associated with the presence of Fe³⁺ ions from the oxidation of structural Fe²⁺ ions in the serpentinites ((Mg_xFe²⁺_1−x)₃Si₂O₅(OH)₄). The relative intensity of the IR bands corresponding to the stretching modes of the OH’s groups indicated the prevalence of one of the two phases, antigorite or lizardite, in the serpentinites. We proposed that the different relative intensity of these bands could be considered as diagnostic to differentiate the predominance of these phases in serpentinites. Full article

(This article belongs to the Special Issue Mineral Fibres)

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11 pages, 3002 KiB

Open AccessArticle

Assessment of Naturally Occurring Asbestos in the Area of Episcopia (Lucania, Southern Italy)

by Andrea Bloise, Claudia Ricchiuti, Eugenia Giorno, Ilaria Fuoco, Patrizia Zumpano, Domenico Miriello, Carmine Apollaro, Alessandra Crispini, Rosanna De Rosa and Rosalda Punturo

Fibers 2019, 7(5), 45; https://doi.org/10.3390/fib7050045 - 16 May 2019

Cited by 18 | Viewed by 6196

Abstract

Over the last few years, the risk to human health related to asbestos fiber exposure has been widely demonstrated by many studies. Serpentinites are the main rocks associated with naturally occurring asbestos (NOA). In order to investigate the presence of NOA, a mineralogical [...] Read more.

Over the last few years, the risk to human health related to asbestos fiber exposure has been widely demonstrated by many studies. Serpentinites are the main rocks associated with naturally occurring asbestos (NOA). In order to investigate the presence of NOA, a mineralogical study was conducted on eleven serpentinite samples collected nearby the village of Episcopia (Lucania, Southern Italy). Various analytical techniques such as X-ray powder diffraction (XRPD), scanning electron microscopy combined with energy dispersive spectrometry (SEM-EDS) and derivative thermogravimetry (DTG) were used to determine the occurrence of asbestos minerals and to make morphological observations. Results pointed out that all of the samples contain asbestos minerals (e.g., tremolite, actinolite and chrysotile). Moreover, it was observed that both natural processes and human activity may disturb NOA-bearing outcrops and provoke the formation of potentially inhalable airborne dust causing the release of asbestos fibers into the environment, thereby increasing the risk to human health. For this reason, our study aims to highlight the requirement of a natural asbestos survey and periodic update in the area. Full article

(This article belongs to the Special Issue Mineral Fibres)

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16 pages, 7439 KiB

Open AccessArticle

Multi-Analytical Approach for Asbestos Minerals and Their Non-Asbestiform Analogues: Inferences from Host Rock Textural Constraints

by Gaia Maria Militello, Andrea Bloise, Laura Gaggero, Gabriele Lanzafame and Rosalda Punturo

Fibers 2019, 7(5), 42; https://doi.org/10.3390/fib7050042 - 10 May 2019

Cited by 11 | Viewed by 7531

Abstract

Asbestos is a hazardous mineral, as well as a common and well-known issue worldwide. However, amphiboles equal in composition but not in morphology, as well as the fibrous antigorite and lizardite, are not classified as asbestos even if more common than other forms [...] Read more.

Asbestos is a hazardous mineral, as well as a common and well-known issue worldwide. However, amphiboles equal in composition but not in morphology, as well as the fibrous antigorite and lizardite, are not classified as asbestos even if more common than other forms of the mineral. Still, their potential hazardous properties requires further exploration. The proposed multi-instrumental approach focuses on the influence of textural constraints on the subsequent origin of asbestiform products in massive rock. This aspect has a significant effect on diagnostic policies addressing environmental monitoring and the clinical perspective. Concerning minerals that are chemically and geometrically (length > 5 μm, width < 3 μm and length:diameter > 3:1) but not morphologically analogous to regulated asbestos, the debate about their potential hazardous properties is open and ongoing. Therefore, a selection of various lithotypes featuring the challenging identification of fibrous phases with critical counting dimensions was investigated; this selection consisted of two serpentinites, one metabasalt and one pyroxenite. The analytical protocol included optical microscopy (OM), scanning and transmission electron microscopy combined with energy dispersive spectrometry (SEM/EDS; TEM/EDS), micro-Raman spectroscopy and synchrotron radiation X-ray microtomography (SR X-ray μCT). The latter is an original non-destructive approach that allows the observation of the fiber arrangement in a three-dimensional space, avoiding morphological influence as a result of comminution. Full article

(This article belongs to the Special Issue Mineral Fibres)

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13 pages, 4024 KiB

Open AccessArticle

Mineralogical and Microstructural Features of Namibia Marbles: Insights about Tremolite Related to Natural Asbestos Occurrences

by Rosalda Punturo, Claudia Ricchiuti, Marzia Rizzo and Elena Marrocchino

Fibers 2019, 7(4), 31; https://doi.org/10.3390/fib7040031 - 7 Apr 2019

Cited by 7 | Viewed by 7269

Abstract

The Mg-rich marbles of Precambrian rocks of Namibia are widely exploited and marketed abroad for ornamental purposes. Karibib marbles, named after the locality where the most important quarries are located, are commercially known as “White Rhino Marble”. They formed under greenschist facies metamorphic [...] Read more.

The Mg-rich marbles of Precambrian rocks of Namibia are widely exploited and marketed abroad for ornamental purposes. Karibib marbles, named after the locality where the most important quarries are located, are commercially known as “White Rhino Marble”. They formed under greenschist facies metamorphic conditions and may be characterized by the presence of veins of tremolite. Although the quarries, whose exploited marbles contain tremolite, do not seem to be abundant, we decided to carry out a detailed mineralogical and petrographic study on Karibib marbles in order to point out the occurrence of tremolite, whose shape may vary from prismatic to acicular, even sometimes resembling the asbestiform habitus and its geometry within the rock. With this aim, we carried out optical microscopy, X-ray diffractometry, X-ray scanning electron microscopy, and micro-Raman investigations, and also imaged the 3D fabric with micro computed X-ray tomography. The study of white marbles from Namibia and their mineral phases has an important impact, since tremolite might split into thin fibers and, therefore, being potentially harmful, the presence of tremolite requires an analysis of the risks of exposure to asbestos. Full article

(This article belongs to the Special Issue Mineral Fibres)

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12 pages, 25501 KiB

Open AccessEditor’s ChoiceArticle

Assessment of Serpentine Group Minerals in Soils: A Case Study from the Village of San Severino Lucano (Basilicata, Southern Italy)

by Rosalda Punturo, Claudia Ricchiuti and Andrea Bloise

Fibers 2019, 7(2), 18; https://doi.org/10.3390/fib7020018 - 25 Feb 2019

Cited by 9 | Viewed by 6203

Abstract

Naturally occurring asbestos (NOA) is a generic term used to refer to both regulated and un-regulated fibrous minerals when encountered in natural geological deposits. These minerals represent a cause of health hazard, since they have been assessed as potential environmental pollutants that may [...] Read more.

Naturally occurring asbestos (NOA) is a generic term used to refer to both regulated and un-regulated fibrous minerals when encountered in natural geological deposits. These minerals represent a cause of health hazard, since they have been assessed as potential environmental pollutants that may occur both in rocks and derived soils. In the present work, we focused on the village of San Severino Lucano, located in the Basilicata region (southern Apennines); due to its geographic isolation from other main sources of asbestos, it represents an excellent example of hazardous and not occupational exposure of population. From the village and its surroundings, we collected eight serpentinite-derived soil samples and carried out Differential Scanning Calorimetry (DSC), Derivative Thermogravimetric (DTG) and Transmission Electron Microscopy with Energy Dispersive Spectrometry (TEM-EDS), in order to perform a detailed characterization of serpentine varieties and other fibrous minerals. Investigation pointed out that chrysotile and asbestos tremolite occur in all of the samples. As for the fibrous but non-asbestos classified minerals, polygonal serpentine and fibrous antigorite were detected in a few samples. Results showed that the cultivation of soils developed upon serpentinite bedrocks were rich in harmful minerals, which if dispersed in the air can be a source of environmental pollution. Full article

(This article belongs to the Special Issue Mineral Fibres)

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14 pages, 2439 KiB

Open AccessArticle

Obtaining an Artificial Aggregate from Cement-Asbestos Waste by the Melting Technique in an Arc-Resistance Furnace

by Jerzy Witek, Bronisław Psiuk, Zdzisław Naziemiec and Robert Kusiorowski

Fibers 2019, 7(2), 10; https://doi.org/10.3390/fib7020010 - 24 Jan 2019

Cited by 10 | Viewed by 5610

Abstract

Nowadays, asbestos waste still remains a serious problem. Due to the carcinogenic properties of asbestos, which are related to its fibrous structure, the exposure to asbestos mineral and asbestos-containing materials (ACM) causes dangerous health effects. This problem can be solved by recycling techniques, [...] Read more.

Nowadays, asbestos waste still remains a serious problem. Due to the carcinogenic properties of asbestos, which are related to its fibrous structure, the exposure to asbestos mineral and asbestos-containing materials (ACM) causes dangerous health effects. This problem can be solved by recycling techniques, which allow the re-use of neutralized asbestos waste, instead of disposing it in special landfills. The article presents the results of research aimed at investigating the possibility of obtaining aggregates from asbestos waste by the fusion process in the electric arc-resistance process. A mixture of ACM with selected fluxes was were melted and then cast to form a grain of aggregates. The chemical composition of the material was determined before and after the melting process. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were applied to evaluate the effects of the fusion process. The main properties of the obtained aggregate were also measured. The results confirmed that the fibrous structure of asbestos was destroyed in the obtained material, which can be successfully used for the production of artificial aggregates. Full article

(This article belongs to the Special Issue Mineral Fibres)

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Review

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13 pages, 1835 KiB

Open AccessEditor’s ChoiceReview

Mineralogical Asbestos Assessment in the Southern Apennines (Italy): A Review

by Maria Carmela Dichicco, Michele Paternoster, Giovanna Rizzo and Rosa Sinisi

Fibers 2019, 7(3), 24; https://doi.org/10.3390/fib7030024 - 19 Mar 2019

Cited by 19 | Viewed by 5213

Abstract

This paper deals with petrography and mineralogy of serpentinitic rocks occurring in the Southern Apennines (Italy) with the aim to review the already available literature data and furnish new details on asbestos minerals present in the studied area. Two sites of Southern Italy [...] Read more.

This paper deals with petrography and mineralogy of serpentinitic rocks occurring in the Southern Apennines (Italy) with the aim to review the already available literature data and furnish new details on asbestos minerals present in the studied area. Two sites of Southern Italy were taken into account: the Pollino Massif, at the Calabrian-Lucanian border, and the surroundings of the Gimigliano and Mt. Reventino areas where serpentinites of Frido Unit are mainly exposed. Textural and mineralogical features of the studied rocks point to a similar composition for both sites including asbestos minerals such as chrysotile and tremolite-actinolite series mineral phases. Only in the Pollino Massif serpentinites edenite crystals have been detected as well; they are documented here for the first time. This amphibole forms as fibrous and/or prismatic crystals in aggregates associated with serpentine, pyroxene, and calcite. Metamorphism and/or metasomatic alteration of serpentinites are the most probable processes promoting the edenite formation in the Southern Apennine ophiolitic rocks. Full article

(This article belongs to the Special Issue Mineral Fibres)

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