Talc is a naturally occurring mineral best known for its very low hardness and slippery, soapy feel. Chemically it is a hydrated magnesium silicate with the formula Mg3Si4O10(OH)2. Because it ranks as 1 on the Mohs scale of mineral hardness, even a fingernail can scratch it. In powdered form talc is widely called talcum powder and has been used for centuries in cosmetics, industrial products and carved objects.

Characteristics and composition

Talc typically appears as pale green, white, gray or yellow masses or flakes with a greasy luster and a translucent to opaque appearance. Its sheet-like crystal habit and easy cleavage reflect its layered silicate structure. The mineral is chemically described as a magnesium-rich phyllosilicate; its essential constituents include magnesium and silicon combined with hydroxyl groups. Talc is closely related to minerals such as pyrophyllite and is the dominant component of soapstone or steatite.

Occurrence and formation

Talc forms by metamorphism of magnesium-rich rocks in the presence of water and carbon dioxide, often where ultramafic rocks alter to serpentinite and then to talc-bearing assemblages. Typical settings include hydrothermal zones and contact metamorphic belts. Commercial deposits are mined in many countries as soapstone layers or massive talc seams.

Uses and applications

  • Cosmetics and personal care: talc is used as an absorbent and texture enhancer in powders and makeup.
  • Industrial: it functions as a filler or extender in paints, plastics, ceramics, rubber and paper to improve workability and physical properties.
  • Art and construction: soapstone (steatite), rich in talc, has been carved for centuries for stoves, sinks and sculpture.

Health, safety and notable distinctions

Talc itself is a common mineral, but some talc deposits occur near asbestos-bearing rocks and can be contaminated by asbestos minerals. Because asbestos is a known respiratory hazard, talc for cosmetic or pharmaceutical use is processed and regulated to reduce contamination. Over recent decades talc has been the subject of health studies and legal action; regulatory agencies and manufacturers have taken steps to test and certify talc supplies for safety. Consumers and industries often choose talc supplies certified for low asbestos content or select alternative fillers when appropriate.

Further reading

For origin and etymology see word origin. For mineral classification and properties consult resources on silicate minerals and clay minerals. The Mohs hardness scale is explained at Mohs scale. Chemical aspects of magnesium and silicate chemistry appear at magnesium and silicate. Information on soapstone and steatite is available at soapstone (steatite).