Chlorite

Chlorite is a group of green, platy sheet-silicate minerals rich in magnesium, iron and aluminum. It commonly occurs alongside talc, serpentine and amphiboles in metamorphic rocks, so it often shows up in bulk analyses of talc ore and talc products. It is not asbestos, and it usually forms flakes rather than fibers.

Origin

The name comes from the Greek word for green, after the typical color of the minerals. Chlorite is a common product of low-grade metamorphism and of hydrothermal alteration of iron- and magnesium-rich minerals.

Significance in Asbestos Context

Chlorite's main importance in asbestos cases is as a marker of where a talc came from and what else it might contain. Many talc deposits formed from altered magnesium-rich rock, and chlorite, carbonates, tremolite and anthophyllite can occur in the same ore. When a lab reports the minerals in a talc product, the presence and amount of chlorite can help experts compare the product with a particular mine or ore body. Chlorite can also complicate analysis: in X-ray diffraction, its peaks can overlap with those of other minerals, and platy particles viewed on edge under a microscope can look elongated. Neither side treats chlorite as a cause of disease, but it can come up in arguments about sourcing and about whether a sample was analyzed correctly.

Example Sentence

X-ray diffraction showed the powder was mostly talc with some chlorite and dolomite, a mix the expert linked to a specific mine.

Related Terms

Talc, Cosmetic Talc, Phyllosilicates, X-Ray Diffraction (XRD), Accessory Mineral, Bulk Sample Analysis, Talc Contamination

Notes

• Keep any remaining talc product containers; lot numbers can help experts trace the source.
• Ask whether a talc test looked for asbestos by electron microscopy, not just by X-ray diffraction.