Alteration of Asbestiform Minerals Under Sub-Tropical Climate: Mineralogical Monitoring and Geochemistry
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University of New Caledonia Institute of Exact and Applied Sciences University of Parma Department of Chemistry, Life Sciences and Environmental Sustainability - Philosophy Degree in Mineralogy - ALTERATION OF ASBESTIFORM MINERALS UNDER SUB-TROPICAL CLIMATE: MINERALOGICAL MONITORING AND GEOCHEMISTRY. THE EXAMPLE OF NEW CALEDONIA. Jasmine Rita Petriglieri PhD Committee Prof. Jean-Luc Grosseau-Poussard, Referee, Université de la Rochelle, France Prof. Alessandro F. Gualtieri, Referee, Università di Modena e Reggio Emilia, Italy Prof. Bice Fubini, Inspector, Università di Torino, Italy Dr. Alessandro Cavallo, Inspector, Università degli studi di Milano-Bicocca, Italy Dr. Peggy Gunkel-Grillon, Supervisor, Université de la Nouvelle Calédonie, NC Dr. Emma Salvioli-Mariani, Co-Supervisor, Università di Parma, Italy December 15th, 2017 Contents Introduction ________________________________________________________ 1 Chapter I I. Asbestos health hazards in New Caledonia: a review. I.1. An escalating awareness in asbestos health concerns ______________________ 6 I.1.1. Asbestos health risk related to environmental exposure ______________ 6 I.1.2. The asbestos regulation in New Caledonia _________________________ 8 I.2. Geographical and geological breakdown of asbestos______________________ 12 I.2.1. Geological setting of New Caledonia ____________________________ 12 I.2.2. Occurrence of asbestiform minerals in the geological units of New Caledonia _____________________________________________________ 16 I.3. The ultrabasic units, source of Nickel ores ______________________________ 19 I.3.1. Ni-laterite ore deposits ______________________________________ 19 I.3.1.1. General processes and classification ______________________ 19 I.3.1.2. Ni deposit of New Caledonia _____________________________ 22 I.3.2. Asbestos occurrences in the ultrabasic units ______________________ 24 I.3.3. Alteration status of fibres _____________________________________ 29 I.3.4. The plan prevention of mining companies ________________________ 30 Chapter II II. Mineralogy of asbestos: sampling and methods. II.1. Mineralogical background __________________________________________ 34 II.1.1. Serpentine ________________________________________________ 34 II.1.1.1. Chrysotile ____________________________________________ 38 II.1.1.2. Polygonal Serpentine ___________________________________ 40 II.1.1.3. Antigorite ____________________________________________ 41 II.1.2. Amphiboles ________________________________________________ 45 II.1.2.1. Fibrous tremolite ______________________________________ 49 II.1.3. Crystal habits of asbestos and non-asbestiform minerals ____________ 50 II.2. General discussion of analytical methods ______________________________ 57 II.2.1. Microscopies _______________________________________________ 58 II.2.1.1. Polarized Light Microscopy ______________________________ 59 II.2.1.2. Scanning Electron Microscopy ___________________________ 66 II.2.1.3. Transmission Electron Microscopy ________________________ 68 II.2.2. X-Ray Powder Diffraction ____________________________________ 70 II.2.3. Raman Spectroscopy _________________________________________ 72 II.2.3.1. micro-Raman Spectroscopy ______________________________72 II.2.3.2. Portable Raman equipment _____________________________ 78 II.3. Sampling method _________________________________________________ 80 Chapter III III. Mineralogical study of the supergene alteration products of asbestos, and typology of associated fibres. III.1. Mineral identification ____________________________________________ 86 III.1.1. Microscopies _______________________________________________ 88 III.1.2. X-Ray Powder Diffraction _____________________________________99 III.1.3. Raman Spectroscopy ________________________________________ 103 III.1.4. Performances and limits of mineralogical monitoring ______________106 III.2. Analytical versus in situ visual identification of asbestos _________________110 III.3. The impact of alteration on analytical identification ____________________ 114 III.4. A new specific texture: the case of sample 18 _________________________ 119 Chapter IV IV. Alteration of asbestos, elements release and fibres emission. IV.1. Leaching methodologies and samples selection ___________________125 IV.1.1. Analyses of major and trace elements content ___________________ 125 IV.1.2. Batch leaching experiments ___________________________________126 IV.2. Chemical composition of asbestiform minerals ___________________128 IV.2.1. Antigorite and antigorite serpentinites__________________________ 128 IV.2.2. Chrysotile serpentinites ______________________________________133 IV.2.3. Tremolites ________________________________________________ 134 IV.3. Batch alteration of asbestos __________________________________138 IV.3.1. Metals concentrations in the supernatant _______________________138 IV.3.2. Suspended particulate matter collected on the filter _______________141 Chapter V V. Environmental risk of fibrous minerals in New Caledonia: a monitoring strategy. V.1. Preliminary characterisation of standard references ___________________ 145 V.2. Evaluation of the presence of fibrous minerals in the ore deposit soils______148 V.3. In situ identification of mineral fibres with portable Raman equipment ____ 152 Conclusion ________________________________________________________ 155 References ________________________________________________________157 Supplementary materials Annexe I _______________________________________________________ 175 Annexe II _______________________________________________________181 Annexe III ______________________________________________________185 Introduction “Asbestos” is generally defined as a commercial and regulatory term applied to a group of six minerals that has grown with a specific crystal habit and exhibits unique physical- chemical and technological proprieties such as flexibility, large surface area and heat resistance (Williams et al. 2013). The six minerals are the serpentine mineral chrysotile, also known as white asbestos, and the amphibole minerals amosite (fibrous-asbestiform variety of grunerite, also known as brown asbestos), crocidolite (fibrous-asbestiform variety of riebeckite, commercially known as blue asbestos), as well as anthophyllite, tremolite and actinolite asbestos (Directive 2003/18/EC). The start of the modern asbestos industrial age is dated at the second half of 19th century, with the exploitation of the chrysotile deposits in Northern Italy and in Canada. Ross et al. (2008) estimated that more than 95% of commercially developed asbestos ore deposits were chrysotile asbestos. Actually, many of these deposits are natural, non-occupational or non- anthropogenic, while others result from widespread use of asbestos-containing products (Gunter 2007). Nowadays, the controversial debate between the various scientific and regulatory disciplines on the definition of the term asbestos is still open (Alleman and Mossman 1997; Gualtieri 2017). To the mineralogical community, for example, the term fibre is a textural term meaning that the material looks and, more importantly, behaves as a fibre; thus, it can curve and bend under force (Gunter et al. 2007). The term fibrous refers to a (mineral) phase whose crystalline habit consists of fibres whether the phase contains separable fibres or not. On the other hand, the term asbestiform refers to a type of morphology where a mineral has longitudinal (lengthwise) parting, and thus it can be split into individual fibres. The definition used by the Occupational Safety and Health Administration (OSHA), National Institute for Occupational Safety and Health (NIOSH) and World Health Organisation (WHO) for a regulated form of asbestos is limited to those structures longer than 5 μm and a defined length-to-width aspect ratio of 3:1. The definition of the aspect- ratio, the relationship of the fibre length to its diameter, generally helps analysts in the quantification of breathable fibres from the point of view of regulation and health. The aspect-ratio criteria were never meant to define a fibre, but it were developed only as counting criteria used to determine the amount of asbestos in an industrial material, where it was known that the source of the material is a commercial asbestos product. The regulatory definition given by NIOSH has recently been integrated and published in a Bulletin entitled “Asbestos Fibers And Other Elongate Mineral Particles: State Of The Science And Roadmap For Research” (NIOSH 2011; Williams et al. 2013; Gualtieri 2017). In that contribution it is clear that all particles, including minerals in a non-asbestiform habit (e.g. acicular or prismatic fragments) may be counted as fibres when their length is 1 >5 μm and aspect ratio is ≥ 3:1 under optical microscopy. NIOSH actually classified the term fibres by replacing it with the term elongated mineral particles, a term intended to include both asbestiform and non-asbestiform mineral habits that meet the specified dimensional criteria, according to the established protocol (NIOSH 2011). Moreover, there is a growing consensus that the regulatory definition of asbestos should be expanded to include other fibrous-asbestiform minerals with asbestiform habit that have been shown to cause diseases or which are potentially toxic to human (e.g. fluoro- edenite asbestos, erionite). The inhalation of mineral fibres become causes of concern also in the case of exposition to natural deposits of asbestos. Naturally occurring asbestos (NOA)