Talc (Silicate-Phyllosilicate)
Mg3Si4O10(OH)2Hardness: 1.0
Specific Gravity: 2.8
Characteristics: perfect basal cleavage; flexible fracture; resinous, silky luster and feel; translucent; often called soapstone; insoluble in most acids.
Found in schists; low temperature metamorphism of mafic rocks and dolostones.
Talc is used in ceramics, paper, paint, roofing, plastics, cosmetics; Soapstone was once used to make chemical resistant sinks and countertops for laboratories; blocks were heated on stoves and used as bed warmers.
(Primary text: Perkins, D. 2002. Mineralogy. Prentice Hall.)