Types of Asbestos


Amosite (Gray Asbestos)

Asbestiform Grunerite, (Fe2+,Mg)7[Si8 O22](OH)2 Amosite asbestos was used to a lesser extent than chrysotile. Most of the amosite asbestos used in the United States was mined in South Africa. The name "amosite" derives from the "asbestos mines of South Afica".

Amosite asbestos is an amphibole. Grunerite is the mineralogically correct name used for amphiboles of the cummingtonite-grunerite series in which iron is predominant over magnesium (70% or more Fe / [Fe+Mg]).

Crystals of grunerite range in morphology from relatively thick, flat prisms to acicular, brittle grains, to very long, thin fibers and fiber bundles. The long thin fibers are moderately brittle and often bend in wide arches. Bundles of grunerite tend to separate into smaller groups of needlelike fibers. Because grunerite fibers do not normally fray or have split ends, but rather have flat or knifelike ends, the needlelike morphology may help to distinguish this amphibole from chrysotile. Forms of bundles resembling "broom tails" are also common. Small thin fragments of the mineral are common in some building materials.