Discriminant analysis of amphiboles: Additional considerations

Amphibole minerals are found throughout nature and could pose a respiratory hazard if these exist in the asbestiform growth habit. Though amphibole asbestos has not been used in commercial products as an added material for more than 30 years, these minerals could exist in other materials as trace contaminants as well as occurring in mines and earth-moving environments. It is necessary, then, that the asbestiform amphibole minerals be properly identified in order to appropriately use health-protective measures. Recent analyses of various amphibole data sets have been used to derive a discriminant function that can be used to differentiate asbestiform amphibole from non-asbestiform amphibole minerals. This paper expands on this function and examines the validity of the procedure for different size fractions of minerals. This analysis suggests that the derived function is appropriate for fibers 10 μm and longer. For fibers shorter than 10 μm, the data suggest that a broader acceptance limit may be needed. The data also suggest that current analytical procedures may require some adjustment to provide more accurate details on the widths of fibers. With additional samples, the accuracy of the discriminate function can be improved by calculating functions for each mineral.