Ophiolite

An ophiolite is a slab of ancient oceanic crust and the upper mantle beneath it that has been pushed up onto a continent and exposed at the Earth's surface. These rock complexes preserve the layers of the deep sea floor, including serpentinized peridotite, the rock type that most commonly hosts chrysotile asbestos and related fibrous minerals.

Origin

From the Greek ophis (snake) and lithos (stone), referring to the mottled, snake-skin appearance of serpentinite. The term was coined by French mineralogist Alexandre Brongniart in 1813 and later expanded in the 20th century, especially after plate tectonic theory revealed that ophiolites are fragments of oceanic lithosphere obducted onto continents.

Significance in Asbestos Context

Most of the world's chrysotile asbestos was mined from ophiolite belts, including the deposits at Thetford Mines and Asbestos, Quebec; the Coalinga and New Idria areas of California; the Urals; and parts of Italy, Cyprus, and Turkey. For patients, this matters because the geographic source of the asbestos in a given product can sometimes be traced back to a specific ophiolite, and ophiolites are also known to contain tremolite and other amphibole fibers as natural contaminants. That contamination is a central scientific issue in talc cases (where talc was mined from ophiolite-associated deposits) and in cases involving naturally occurring asbestos, because defendants often argue their chrysotile product was "pure" when geological evidence shows otherwise.

Example Sentence

The geologist's expert report explained that the talc used in the defendant's product was mined from an ophiolite complex known to contain tremolite and anthophyllite asbestos.

Related Terms

Chrysotile, Serpentinite, Tremolite, Naturally Occurring Asbestos, Provenance Analysis, Obduction

Notes

• If your exposure history involves talc-containing products (cosmetic powders, industrial talc, ceramics), ask whether the talc source has been linked to an ophiolite or serpentinite body. This is often key to causation evidence.
• Preserve any product labels, employment records, or shipping documents that identify the geographic origin of the asbestos or talc you were exposed to; provenance can connect your exposure to a specific mine and ophiolite.
• Ophiolite-hosted chrysotile deposits are frequently contaminated with amphibole fibers (tremolite, actinolite, anthophyllite), which is important because amphiboles are more strongly associated with mesothelioma, a point your legal team's geology expert may need to develop.