Wollastonite is a white calcium silicate mineral that often forms long, needle-shaped crystals. It has been used as an asbestos substitute in brake linings, building boards, ceramics and plastics. It is not asbestos and is generally regarded as much less hazardous, but it is a mineral fiber and its use in a product does not prove the product was asbestos-free.
Origin
Wollastonite is named for the English chemist William Hyde Wollaston. It forms mainly where limestone has been heated by nearby igneous intrusions, so it is typical of skarn and other contact-metamorphic rocks, and it is mined commercially in several countries, including the United States.
Significance in Asbestos Context
As manufacturers moved away from asbestos, many turned to substitute fibers, and wollastonite was one of the common ones in friction products, fire-resistant boards and fillers. That history matters in product identification: a company may say that a brand of brake or board was reformulated with wollastonite, and the question becomes when the change happened and whether older stock containing asbestos stayed in circulation. In its review of silicate fibers in the late 1990s, IARC classified wollastonite as not classifiable as to its carcinogenicity to humans, and it is less durable in the lung than amphibole asbestos. Under a light microscope, wollastonite needles can resemble some amphibole fibers, so careful analysis is needed. Wollastonite deposits can also contain tremolite or other amphiboles, depending on the geology.
Example Sentence
The manufacturer's records showed that wollastonite replaced chrysotile in the brake pad formula in the mid-1980s, after the years the mechanic did most of his work.
Related Terms
Acicular, Skarn, Contact Metamorphism, Inosilicates, Brake Lining, Mineral Fiber, IARC Classification
Notes
- If a company says a product switched to a substitute fiber, ask for the date of the change and whether old stock was sold off.
- Keep any packaging, part numbers or receipts that show which version of a product you used.
In the research library
50 studies in our medical research library mention Wollastonite in the title or abstract. Among the most cited:
- A review of the toxicology and epidemiology of wollastoniteL.D. Maxim, E.E. McConnell, 2005 · Inhalation Toxicology · cited 24 times
- Mesothelial cell proliferation and biopersistence of wollastonite and crocidolite asbestos fibersJ.L. Macdonald, A.B. Kane, 1997 · Fundamental and Applied Toxicology · cited 18 times
- Wollastonite exposure and lung fibrosisM.S. Huuskonen, A. Tossavainen, H. Koskinen, et al, 1983 · Environmental Research · cited 17 times
- Wollastonite fibers in vitro generate reactive oxygen species able to lyse erythrocytes and activate the complement alternate pathwayM. Governa, L. Camilucci, M. Amati, et al, 1998 · Toxicological Sciences · cited 16 times
- Investigation of the biodurability of wollastonite and xonotliteB. Bellmann, H. Muhle, 1994 · Environmental Health Perspectives · cited 11 times
The journals that publish most on it: Environmental Health Perspectives (7), Environmental Research (5), Inhalation Toxicology (2).
Category: Mineralogy & Mineral Species · All Lexicon terms A–Z
This page is provided for general informational purposes and does not constitute legal advice. Every asbestos case turns on its own facts, exposure history, diagnosis, deadlines, available evidence, and applicable law. Reviewing this page does not create an attorney-client relationship. For advice about your specific situation, call 833-4-ASBESTOS for a free case review.