NIR–SWIR hyperspectral imaging of powder released from simulated weathering of NOA-bearing serpentinites: a pilot investigation on serpentinites from Tuscany (Italy)

Natural weathering processes, environmental cycles and anthropogenic activities (mining, excavation, road construction) involving naturally occurring asbestos (NOA) materials pose environmental and human health issues due to the potential release of pathogenic fibers. This pilot investigation focuses on the Slake Durability Test (SDT) to simulate weathering cycles and assess the long-term slaking behaviour of serpentinite samples from Elba Island and the province of Siena (Tuscany, Italy), lithologies commonly hosting asbestos minerals. The resulting rock powders from the SDT were analysed using a novel portable NIR-SWIR hyperspectral scan imaging tool, enabling rapid detection and mapping of serpentine minerals through their characteristic spectral features. To validate this results, traditional and complementary FTIR and SEM analyses were performed. This novel approach, combining laboratory engineering-geological analysis and fast NIR-SWIR hyperspectral imaging (HSI) techniques, provided new insights on the durability and the hazard potential (in terms of release index) of serpentinites, while reducing the costs and time-consuming issues of conventional laboratory methods.