Asbestos is a generic name used to describe a family of naturally occurring fibrous hydrated silicates divided on the basis of mineralogical features into serpentines and amphiboles. Six varieties were of commercial importance: serpentine chrysotile mg3 (si2oS) (oh)4, amphiboles: actinolite ca2(mgfe)5 (si6022) (oh)2, asbestos grunerite (amosite) (femg)7 (si6022) (oh)2,’anthhophyllite (mgfe)7 (si6022)( oh) 2, crocidolite na2fe2+3fe3+2(si6022)(oh)2, tremolite ca2mgS (si6022) (oh)2,the six varieties are deemed to be asbestos only when they have a fibrous form.