Infra Red Spectroscopy of the Regulated Asbestos Amphiboles

Our plain-English summary of Infra Red Spectroscopy of the Regulated Asbestos Amphiboles, by G.D. Ventura, R. Vigliaturo, R. Gieré, et al (Minerals, 2018).

The study

• Authors: G.D. Ventura, R. Vigliaturo, R. Gieré, S. Pollastri, A.F. Gualtieri, G. Iezzi
• Journal: Minerals
• Published: 2018;8(9)
• Cited by: 13 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

Vibrational spectroscopies (Fourier Transform Infra Red, FTIR, and Raman) are exceptionally valuable tools for the identification and crystal-chemical study of fibrous minerals, and asbestos amphiboles in particular. Raman spectroscopy has been widely applied in toxicological studies and thus a large corpus of reference data on regulated species is found in the literature. However, FTIR spectroscopy has been mostly used in crystal-chemical studies and very few data are found on asbestos amphiboles. This paper is intended to fill this gap. We report new FTIR data collected on a suite of well-characterized samples of the five regulated amphibole species: anthophyllite, amosite, and crocidolite, provided by the Union for International Cancer Control (UICC) Organization, and tremolite and actinolite, from two well-known occurrences. The data from these reference samples have been augmented by results from additional specimens to clarify some aspects of their spectroscopic features. We show that the FTIR spectra in both the OH-stretching region and in the lattice modes region can be effective for rapid identification of the asbestos type.

In plain English

This laboratory study recorded infrared (FTIR) spectra of the five amphibole minerals regulated as asbestos: anthophyllite, amosite, crocidolite, tremolite and actinolite. It studied mineral samples, not people or animals, and did not include chrysotile. The authors wrote that reference infrared data for these minerals were lacking. They used standard reference samples from the Union for International Cancer Control (UICC) for anthophyllite, amosite and crocidolite. The tremolite and actinolite came from two sites in Italy, and two more anthophyllite samples were added for comparison. All samples were also examined by electron microscopy. Each mineral showed its own pattern of infrared peaks. In the UICC anthophyllite, some peaks came from talc and other mineral impurities. In one part of the spectrum, tremolite and actinolite gave almost identical patterns, while anthophyllite, amosite and crocidolite each differed. The authors concluded that these spectra can serve as reference data for environmental and toxicological studies and can help identify the asbestos type quickly. They noted that data covering the full chemical range of amphiboles are still lacking.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Laboratory mineralogical study: infrared spectroscopy (FTIR) of mineral samples, with electron microscopy (FEG-ESEM and TEM) to check the samples
• Who was studied: Mineral samples listed in Table 1: UICC standard anthophyllite (Paakkila, Finland), UICC standard amosite (South Africa), UICC standard crocidolite (South Africa), tremolite from Val d'Ala (Turin, Italy) and actinolite from Valle Aurina (Bolzano, Italy). Two further anthophyllite-group samples were added for comparison: AMNH34856 from Talcville, New York State, USA, and MNHN 29_102, described in the text as from Norway. Table 1 also lists a crocidolite from Madagascar, whose pattern was compared with previously published data.
• Exposure: Not a human exposure study. The materials examined were the five regulated asbestos amphiboles: anthophyllite, amosite (grunerite asbestos), crocidolite (riebeckite asbestos), tremolite and actinolite. Chrysotile was not studied.
• Main results:
  • UICC anthophyllite: in the OH-stretching region, the sharp peak at 3676 cm-1 was assigned to talc and the broad absorption at 3690 cm-1 to clinochlore/vermiculite impurities.
  • UICC amosite: three well-resolved OH-stretching peaks at 3652, 3636 and 3618 cm-1, plus a very weak peak at 3667 cm-1. The ferrous iron content at the M(1,3) sites derived from the spectrum was 2.40 apfu, in excellent agreement with the value from Rietveld refinement.
  • UICC crocidolite: three well-resolved OH-stretching peaks at 3650, 3636 and 3618 cm-1. The ferrous iron content at M(1,3) derived from the spectrum was 2.39 apfu.
  • Tremolite from Val d'Ala: peaks at 3673, 3656 and 3643 cm-1, with a derived ferrous iron content at M(1,3) of 0.35 apfu. Actinolite from Valle Aurina: peaks at 3673, 3658 and 3643 cm-1, with a derived content of 0.91 apfu. Both values were in excellent agreement with Rietveld refinements.
  • Low-wavenumber (lattice) region: tremolite and actinolite gave almost identical patterns in region 1, while anthophyllite, amosite and crocidolite each differed. The authors suggested the patterns are characteristic of each species.
  • Region 2 peaks differed with the type of B-site cation: crocidolite (Na) had a single sharp peak at 778 cm-1, anthophyllite (Mg) a very weak band at 780 cm-1, amosite (Fe2+) a doublet at 797 to 775 cm-1, and tremolite-actinolite (Ca) a medium intense peak at 757 cm-1.
  • Electron microscopy: the UICC crocidolite fibers were 0.5 to 1.0 µm wide and 50 to 100 µm long, and this was the most defective of the samples studied.
• The authors' conclusion: The authors concluded that their FTIR data can be used as reference spectra in environmental and toxicological studies. They found that OH-stretching spectra allow relatively easy and rapid identification of the amphibole asbestos minerals, including telling tremolite-actinolite apart from anthophyllite-grunerite. They also found that lattice-mode spectra can be effective for rapid identification of the asbestos type.
• Limitations the authors state:
  • Reference data covering the full chemical diversity of the amphibole supergroup are still lacking.
  • In the UICC anthophyllite, the expected band splitting could not be seen because signals from talc and clinochlore impurities overlapped it.
  • The amorphous surface layer on the fibers could be either silica-rich material or ferrihydrite; telling the two apart would need additional higher-resolution techniques.
  • For the Talcville anthophyllite, only a single-crystal spectrum could be collected because too little material was available.

Topics

Medical terms in this study, explained in our Lexicon: Regulated Asbestos, Amphibole Group, Anthophyllite, Amosite, Crocidolite, UICC, Tremolite, Actinolite.

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