metamorphic
Soapstone
Steatite (primarily Talc, Mg3Si4O10(OH)2)
Hardness: 1.0-2.5 on Mohs scale (can be scratched by a fingernail); Color: Gray, bluish-gray, or greenish-gray; Luster: Pearly to greasy; Crystal structure: Monoclinic; Cleavage: Perfect; Specific Gravity: 2.7-2.8.
- Hardness
- 1
- Color
- Gray, bluish-gray, or greenish-gray
- Luster
- Pearly to greasy
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Physical properties
Hardness: 1.0-2.5 on Mohs scale (can be scratched by a fingernail); Color: Gray, bluish-gray, or greenish-gray; Luster: Pearly to greasy; Crystal structure: Monoclinic; Cleavage: Perfect; Specific Gravity: 2.7-2.8.
Formation & geological history
Formed through regional or contact metamorphism of ultramafic rocks or siliceous dolostones under conditions of low to moderate temperature and pressure, often involving hydrothermal alteration.
Uses & applications
Used in industry for laboratory tabletops, electrical panels, and stove linings due to high heat resistance and chemical stability. Also used for carvings, sculptures, and kitchen countertops.
Geological facts
Soapstone is named for its soapy feel caused by high talc content. It has been used for thousands of years by indigenous cultures for cooking pots because of its incredible ability to absorb and radiate heat evenly.
Field identification & locations
Identify by its greasy or soapy feel and extreme softness; it should be easily scratched by a fingernail or penny. Found in orogenic belts such as the Appalachian Mountains, Norway, and Brazil.
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