metamorphic
Soapstone (Steatite)
Steatite (primarily Talc: Mg3Si4O10(OH)2)
Hardness: 1.0 (Mohs scale), very soft; Color: Grey, black, or reddish-brown (as seen in image); Luster: Greasy or dull; Structure: Massively crystalline; Cleavage: Perfect (though often obscured in massive form).
- Hardness
- 1
- Color
- Grey, black, or reddish-brown (as seen in image)
- Luster
- Greasy or dull
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Physical properties
Hardness: 1.0 (Mohs scale), very soft; Color: Grey, black, or reddish-brown (as seen in image); Luster: Greasy or dull; Structure: Massively crystalline; Cleavage: Perfect (though often obscured in massive form).
Formation & geological history
Formed through the regional metamorphism of ultramafic rocks (magnesium-rich rocks) or by the hydrothermal alteration of dolostones. Often found in subduction zones where high pressure and heat transform existing minerals into talc.
Uses & applications
Extensively used for artistic carvings and ornaments due to its softness. Also used in industry for laboratory tabletops, electrical insulators, and heating components because of its high heat capacity and chemical resistance.
Geological facts
Soapstone has been used for over 3,000 years; the Ancient Egyptians carved scarabs from it, and it was a primary material for Viking cooking pots and Inuit lamps.
Field identification & locations
Identified by its distinctive 'soapy' or greasy feel and the ability to be scratched by a fingernail. It is found in mountain ranges such as the Appalachians and the Alps. Collectors should look for smoothness and heat-retention properties.
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