Talc Mines

Soapstone - Serpentine

photography — Talc from Luzenac, Ariège, France. Public Domain.

Talc (Mg₃Si₄O₁₀(OH)₂) is the softest known mineral with a hardness of 1 on the Mohs Scale, actually talc is the reference for 1. It may contain variable amounts of Fe, Al and F. Talc results from the metamorphism of magnesian minerals such as serpentine, pyroxene, amphibole, and olivine. It is often found in association with magnesite, marble and asbestos.

Talc is white, often greenish, sometimes brown or colorless. Soapstone or steatite is a coarse grayish-green rock with a high content of talc. In this form it is used for stoves, open fireplaces, ovens, sinks, and electrical switchboards, as it is heat-resistant and a good isolator. It is also used for sculptures, pots, and window sills. One of the reasons is that it is very soft and rather easy to work with. Serpentine or serpentinite is another rock with high content of talc with similar uses. Serpentine is used as a source of magnesium and asbestos, and as a decorative stone.

Talc in powdered form, often in combination with corn starch, is widely used as baby powder. As it is a thickening agent and lubricant, it is an ingredient in many cosmetic products, ceramics, paint, and roofing material.