Cassiar Mine

The Cassiar Mine was a large chrysotile asbestos mine located in northern British Columbia, Canada, that operated from 1953 until its closure in 1992. It was one of the major sources of high-grade chrysotile (white asbestos) fiber in the world, supplying raw asbestos to manufacturers across North America and overseas. Fiber from Cassiar was known for its long, strong, and relatively pure chrysotile content, which made it commercially desirable for textiles, gaskets, and high-performance asbestos products.

Origin

The mine took its name from the Cassiar Mountains and the historic Cassiar mining district of British Columbia, where the deposit was discovered in the late 1940s. The Cassiar Asbestos Corporation developed the site and built a company town to support operations, which became one of Canada's most remote industrial communities.

Significance in Asbestos Context

Cassiar is one of the named geographic sources investigators look to when tracing the provenance of chrysotile fibers found in lung tissue, products, or workplace dust. Because Cassiar chrysotile had distinctive fiber characteristics (long fiber length, high purity, and trace mineral signatures), fiber-burden analysts and mineralogists can sometimes link exposures back to products made with Cassiar-sourced material. For patients whose work history involves chrysotile-based textiles, brake linings, gaskets, or insulation manufactured in North America between the 1950s and early 1990s, Cassiar may appear in supplier records, shipping documents, or expert reports identifying the origin of the asbestos they were exposed to. Identifying Cassiar as the fiber source can also matter because it counters the defense argument that 'pure' chrysotile is harmless. Epidemiological studies of Cassiar miners and millers themselves show elevated rates of mesothelioma and lung cancer.

Example Sentence

The industrial hygiene expert traced the gasket material used at the plant back to Cassiar Mine chrysotile, based on shipping invoices preserved in the manufacturer's archives.

Related Terms

Chrysotile, Provenance Analysis, Fiber Burden Analysis, Thetford Mines, Tremolite Contamination, Quebec Asbestos Mining

Notes

• If you worked with chrysotile asbestos products manufactured in North America between roughly 1955 and 1992, ask your legal team whether supplier records can trace the raw fiber back to Cassiar or other specific mines.
• Preserve any product packaging, purchase orders, material safety data sheets, or shipping documents from your workplace that might identify the asbestos supplier.
• Cassiar chrysotile is sometimes argued by defendants to have been 'cleaner' or lower-risk than amphibole-contaminated sources; epidemiological studies of Cassiar workers themselves contradict that claim, and your experts can address this directly.
• For mesothelioma cases involving chrysotile-only exposure, the source mine and any trace amphibole content (such as tremolite) can become a central scientific issue.