Anthophyllite Asbestos
                This sample is from the white paint layer on the surface of
                  a cellulose fiber acoustic
                  ceiling tile. The sample is mounted in high dispersion 1.605 refractive index oil
                  and a single linear polarizing filter
                  is oriented parallel to the length of the fiber. The wavelength match here is about
                  480 nanometers. That indicates a
                  D-line refractive index for the anthophyllite of about 1.620
              
              
                Transmitted Phase Contrast with a Single Linear Polarizer Parallel to the Fiber
                Length
                
Definition/Function:
                Anthophyllite asbestos is a fibrous amphibole with the chemical composition
                (Mg, Fe)7[Si8O22](OH, F)2. It is one of the
                more hazardous forms of asbestos.
                Significance in the Environment:
                Anthophyllite had a rather limited commercial use and is encountered as an impurity in
                talc as often as it is as an
                intentionally added material. In materials with a significant talc content the amount of
                Anthophyllite can exceed 1%.
                Characteristic Features:
                Anthophyllite has refractive indices that overlap those of Tremolite and Actinolite
                asbestos but Anthophyllite always shows
                parallel extinction.
                Associated Particles:
                As an impurity it is generally found with high concentrations of talc. It was used as an
                additive in paint and ceramics,
                mastics, floor tiles, acoustic tiles, and other construction materials.
                References:
                1. Asbestos Textile Institute, HANDBOOK OF ASBESTOS TEXTILES, 3RD EDITION, 1967.
                2. Campbell, W.J., R.L. Blake, L.L. Brown, E.E. Cather, and J.J. Sjoberg, IC 8751;
                SELECTED SILICATE MINERALS AND THEIR ASBESTIFORM VARIETIES, US Dept. of the Interior,
                Bureau of Mines Information Circular, 1977
                3. Deer, W. A., R. A. Howie, and J. Zussman, AN INTRODCUTION TO THE ROCK-FORMING
                MINERALS, ISBN 0-582-30094-0, pp. 232-236, 1992
                4. Ledoux, R. L. (ed), SHORT COURSE IN MINERALOGICAL TECHNIQUES OF ASBESTOS
                DETERMINATION, Mineralogical Association of Canada, 1979. 
                5. Levadie, Benjamin (ed), DEFINITIONS FOR ASBESTOS AND OTHER HEALTH-RELATED SILICATES,
                ASTM STP 834, 1984. 
                6. Riordon, P. H. (ed), GEOLOGY OF ASBESTOS DEPOSITS, Society of Mining Engineers, 1981.
                
                7. World Health Organization, ASBESTOS AND OTHER NATURAL MINERAL FIBRES, Environmental
                Health Criteria 53, 1986.