TALC

Chemical Properties

White, apple-green, gray powder; pearly or greasy luster, greasy feel. Mohs hardness 1–1.5 (may be harder when impure), high resistance to acids, alkalies, and heat.

Uses

Chiefly as a ceramic insulator in electronic devices.

Uses

Pigment in paint, varnishes; filler for paper, rubber, soap; lubricating molds and machinery; heat insulator.

Definition

An extremely soft greenish or white mineral, a hydrous silicate of magnesium. Purified it is sold as talcum powder, and it is used as a lubricant, a filler (in paint and rubber) and an ingredient of some ceramics.

Definition

A natural hydrous magnesium silicate. Compact, massive varieties may be called steatite in distinction from the foliated varieties, which are called talc. Soapstone is an impure variety of steatite.

Definition

A white or pale-green mineralform of magnesium silicate,Mg₃Si₄O₁₀(OH)₂, crystallizing in thetriclinic system. It forms as a secondarymineral by alteration of magnesium-rich olivines, pyroxenes, andamphiboles of ultrabasic rocks. It issoaplike to touch and very soft, havinga hardness of 1 on the Mohs’scale. Massive fine-grained talc isknown as soapstone or steatite. Talcin powdered form is used as a lubricant,as a filler in paper, paints, andrubber, and in cosmetics, ceramics,and French chalk. It occurs chiey inthe USA, Russia, France, and Japan.

Hazard

Toxic by inhalation. Effects pulmonary function and causes pulmonary fibrosis. Questionable carcinogen.

Health Hazard

The fibrous talc in soapstone dust causes fibrotic pneumoconiosis; an increased incidence of cancer of the lungs and pleura has been reported.

Industrial uses

Steatites are noted for their excellent electricalproperties and low cost. They are easily formedand fired at relatively low temperatures. However,compositions containing little or no clayor plastic material present fabricating problemsbecause of a narrow firing range. Steatite partsare vacuum-tight, can be readily bonded toother materials, and can be glazed or ground tohigh-quality surfaces.