Talc is formed by the low-grade metamorphism of magnesium-rich silicates such as the olivines, pyroxenes and amphiboles.
Color: light green, gray, white
Streak: white
Luster: pearly
Hardness: 1
Specific gravity: 2.75
Cleavage/fracture: 1 direction
Other distinguishing properties: Talc is easily scratched with a fingernail, and has a soapy feel. Talc has a micaceous appearance and can be separated into relatively thin sheets which are flexible but not elastic. "Soapstone" is a massive, fine-grained variety of talc that is commonly used for countertops and as a medium for carving.
Klein, C., and Hurlbut, C.S., Jr., 1999, Manual of Mineralogy (after James D. Dana) [21st edition, revised]: New York, John Wiley & Sons, 682 p.
Los Angeles County Museum of Natural History, The Photo Atlas of Minerals: nhm.org/pam/
Return to the Minerals page.
