Abstract

The natural occurrence of asbestos (NOA) in rocks and soil has been known for many years in several areas of the world, differently from the natural presence of asbestiform minerals. In Italy, the mapping of NOA is mandatory according to the 2001 and 2003 regulations. An investigation, not yet concluded, has revealed that in Italy, NOA is represented by chrysotile and tremolite asbestos with minor amounts of actinolite asbestos and anthophyllite asbestos. A field survey conducted in the Italian Western Alps (IWA), dealing with the natural occurrence of asbestiform minerals non-asbestos classified and not regulated, started many years ago and is still ongoing. It revealed that the following kinds of asbestiform silicates are present (in decreasing order of frequency): asbestiform polygonal serpentine and asbestiform antigorite, asbestiform diopside, asbestiform carlosturanite, asbestiform forsterite, asbestiform sepiolite, asbestiform balangeroite, and asbestiform talc. The asbestiform non-silicates brugnatellite and brucite have been rarely detected. Outside the IWA, asbestiform zeolite (erionite and offretite), asbestiform sodium amphibole (fluoro-edenite), and a few other asbestiform silicates have been also detected. For some asbestiform minerals, the identification is problematic and needs the use of transmission electron microscopy combining imaging at high magnification and electron diffraction and chemical data. This investigation is particularly important to distinguish four kinds of asbestiform minerals (antigorite, polygonal serpentine, carlosturanite, and balangeroite) from chrysotile since only the last one is regulated. The issue is much more complicated by the intergrowth of different fibrous species on the submicrometer scale.

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