A Geoscience Digital Image Library

DescriptionVermiculite is a form of asbestos. Flakes of raw vermiculite concentrate are micaceous in appearance and contain interlayer water in their structure. When the flakes are heated rapidly at a temperature above 870° C, the water flashes into steam, and the flakes expand into accordionlike particles, as shown by the picture. This process is called exfoliation, or expansion, and the resulting lightweight material is chemically inert, fire resistant, and odorless. In lightweight plaster and concrete, vermiculite provides good thermal insulation. Vermiculite can absorb such liquids as fertilizers, herbicides, and insecticides, which can then be transported as free-flowing solids. Vermiculites chemical formula is (Mg,Fe,Al)3(Al,Si)4O10(OH)2·4(H2O).
PhotographerShannon Heinle. 2002-02-10.
CollectionUniversity of North Dakota Mineralogy Collection.
Key wordsvermiculite, asbestos
Tech details161 KB. Hand specimen. Fujifilm FinePix S1Pro digital camera; 60mm AF Nikon micro lens.
GeoDIL number2335