# Portable Raman Spectrometer for In Situ Analysis of Asbestos and Fibrous Minerals
###### Abstract  
Asbestos inhalation is associated with fatal respiratory diseases and raises concerns from the perspective of workplace safety and environmental impacts. Asbestos and asbestos-like minerals naturally occur in rocks and may become airborne when outcrops or soils are disturbed by anthropic activities. In situ detection of these minerals is a crucial step for the risk evaluation of natural sites. We assess here whether a portable Raman spectrometer (pRS) may be used in the identification of asbestos and asbestos-like minerals at the mining front during exploitation. pRS performance was tested at three geologically different mining sites in Italy and New Caledonia and compared with a high-resolution micro-Raman spectrometer (HRS). About 80% of the overall in situ analyses at the mining front were successfully identified by pRS, even when intermixed phases or strongly disaggregated and altered samples were analyzed. Chrysotile and tremolite asbestos, asbestos-like antigorite, and balangeroite were correctly detected during surveys. The major difficulties faced during in situ pRS measurements were fluorescence emission and focussing the laser beam on non-cohesive bundles of fibers. pRS is adequate for discriminating asbestos and asbestos-like minerals in situ. pRS may support risk assessment of mining sites to better protect workers and environment. p ARTIC-R  
humans and the environment is a matter of debate [6; 7]. Recently, several environmental and health agencies worldwide (e.g., The National Institute for Occupational Safety and Health, NIOSH [8]; International Association for Engineering Geology and the Environment, IAEG Commission [9]; National Institute for Insurance against Accidents at Work, INAIL [10]; Agence Nationale de Securite Sanitaire de l'Alimentation, de l'Environnement et du Travail, ANSES [11]) focussed their attention on the assessment of the hazard of fibrous minerals which share with asbestos physicochemical properties relevant to toxicity. Several potentially hazardous asbestos-like minerals were or are currently under investigation: fibrous antigorite [12], balangeroite [13; 14], fibrous glaucophane-winchite [15; 16], fibrous ferrierite [17], and fibrous mordenite [18] have been investigated in the past years. The occurrence of fibrous, elongated mineral particles (EMP) in natural settings may have a significant impact, especially on mining and quarrying operations [6], where EPM-bearing rocks and soils are exposed and manipulated by exploitation activity (e.g., excavation, crushing, sieving, transportation, waste management), potentially increasing the risk to human exposure [19; 20; 21]. Asbestos-bearing occurrences are complex mineralogical environments, characterized by the intergrown of different mineral varieties occurring in a wide range of morphologies (e.g., [22]). Quantification of the occurrences of EMPs represents a crucial step for the risk evaluation of natural sites where fibrous minerals may occur. However, to obtain a significative quantitative analysis of EMP in rocks [23; 24; 25], an in situ screening of the presence of asbestos and asbestos-like minerals at the excavation front must be carried out. In this context, portable equipment able to distinguish potentially hazardous minerals from other non-hazardous varieties is highly envisaged. This work was designed to test the in situ performance of Raman spectroscopy in the characterization of mineralogical assemblage at the outcrop. The spectroscopic assignment of minerals by infrared spectroscopy and micro-Raman spectroscopy is today reliable on both rock specimens (rock fragments and petrographic thin sections; [26; 27; 28]) and asbestos-containing materials [29; 30]. Confocal micro-Raman has an intrinsic higher spatial resolution (up to 1 \(\upmu\)m on xyz directions with conventional benchtop setups) than micro-IR, and this makes Raman spectroscopy particularly suitable to discriminate intergrown species that are often found in serpentine and amphibes rich outcrops.