Description

Talc (hydrated magnesium silicate) is a soft mineral widely used in industries because of its:

High heat resistance
Chemical inertness
Lubricating property
Softness
Ability to absorb moisture and oils
Electrical insulating characteristics.

Key facts
Chemical formula: Mg₃Si₄O₁₀(OH)₂

CAS number: 14807-96-6

Molecular weight: 379.27 g/mol

Crystal system: Monoclinic or triclinic

Density: ~2.7–2.8 g/cm³

Composition and structure
Talc’s structure consists of layers of magnesium-oxygen/hydroxide sheets sandwiched between silicate tetrahedral sheets. The weak van der Waals bonding between these layers gives talc its softness and perfect basal cleavage. Pure talc is typically white to gray-green and translucent; impurities such as chlorite, dolomite, or tremolite can alter its color and properties. It is commonly formed through hydrothermal alteration of magnesium-rich rocks such as serpentine and dolomite.

Industrial and commercial uses
Talc is widely used as a filler, lubricant, and absorbent. In industry it serves in ceramics, paints, plastics, paper, roofing, and rubber as a reinforcing or matting agent. Pharmaceutical- and cosmetic-grade talc is used as a glidant, anti-caking agent, and excipient in tablets and topical powders. Its resistance to heat and chemicals also allows use in refractories and as a food-contact substance under regulatory approval.

Medical and research applications
Medically, sterile talc powder (marketed as Sclerosol or Steritalc) is approved for pleurodesis — a procedure to prevent recurrence of malignant pleural effusions by inducing adhesion between pleural membranes. Experimental research has also explored talc’s catalytic activity in organic synthesis, leveraging its layered silicate surface for mild heterogeneous catalysis.

Safety and health considerations
Pure, non-asbestiform talc is chemically inert and nonflammable, but inhalation of fine talc dust can cause respiratory irritation and, with chronic exposure, talcosis (a form of pneumoconiosis). Regulatory bodies distinguish between talc containing asbestos fibers (carcinogenic) and asbestos-free talc, which is generally regarded as non-carcinogenic though still monitored for occupational exposure.