Silicates: Talc

Composition: Mg₆Si₈O₂₀(OH)₄; iron may replace magnesium

Crystal system: Monoclinic; foliated aggregates or finegrained masses

5.28.1
massive talc
 Darwin NT Australia

Properties:

• Greasy to silky lustre
• White to green color; sometimes brownish
• White streak
• Knife scratches easily (Mohs Hardness 1)
• Average density
• Single perfect cleavage apparent unless finegrained
• Cleaves rather than fractures
• Not ferromagnetic
• Does not react with hydrochloric acid (HCl)

Occurrence:

Talc forms by the metamorphism or hydrous alteration of magnesium-rich igneous rocks such as pyroxenites and peridotites.

5.28.2 massive talc Darwin NT Australia	5.28.3 massive talc Darwin NT Australia

5.28.4 massive talc Darwin NT Australia	5.28.5 actinolite crystals in talc

Talc is a significant industrial mineral that is used as a filler in cosmetics, paints, paper and many other manufactured materials. Attractively patterned talc-rich rocks called soapstone are used for ornaments and sculptures.

5.28.6 soapstone carving	5.28.7 soapstone carving

5.28.9
soapstone carving