Crocidolite — commonly called blue asbestos — is widely regarded as the most dangerous type of asbestos. Its exceptionally thin fibers are the most strongly associated with mesothelioma of any asbestos mineral.

What Crocidolite Is

Crocidolite is an amphibole asbestos — the asbestiform variety of the mineral riebeckite, a sodium iron silicate. Its fibers are straight and extraordinarily fine — much thinner than chrysotile or amosite fibers. That thinness lets crocidolite fibers penetrate deep into the smallest airways and the pleural lining, where they are almost impossible for the lungs to clear.

Appearance and Where It Was Mined

Crocidolite has a distinctive blue to blue-gray color. The major historical sources were South Africa and the Wittenoom mine in Western Australia, whose workers and townspeople suffered a mesothelioma epidemic that became one of the most studied asbestos disasters in history.

Where Crocidolite Was Used

Crocidolite has very high tensile strength and acid resistance, so it was used where those properties mattered:

  • Asbestos-cement pressure pipe (including some “Transite”-type water and sewer pipe)
  • High-temperature and high-pressure insulation and lagging
  • Gaskets and packing for corrosive-service applications
  • Certain spray coatings and reinforced products
  • Some cigarette filters (notably the mid-1950s Kent “Micronite” filter)

Health Risk

Crocidolite is an IARC Group 1 human carcinogen and is considered the asbestos type most likely to cause mesothelioma. Its thin, biopersistent fibers reach and irritate the pleura — the mesothelial lining where mesothelioma originates — more efficiently than any other type. Even relatively brief or low-level crocidolite exposure has been linked to mesothelioma decades later.

Regulatory Status

Crocidolite has not been imported or used in the United States for many years, but products manufactured with it before the 1980s — particularly asbestos-cement pipe and older high-temperature insulation — remain in service and in the ground in many locations.

If you were diagnosed with mesothelioma, asbestosis, or another asbestos-related disease and were exposed to crocidolite-containing cement pipe, insulation, or gaskets at a jobsite or in a building, you may be entitled to compensation through asbestos trust funds and civil litigation.