Soapstone
Soapstone, or steatite, is a soft, greenish-grey metamorphic rock rich in talc, with a smooth, soapy feel. It is easy to carve and holds heat well, so it has been used for vessels, carvings and stoves for thousands of years.
Soapstone, or steatite, is a soft, greenish-grey metamorphic rock rich in talc, with a smooth, soapy feel. It is easy to carve and holds heat well, so it has been used for vessels, carvings and stoves for thousands of years.
🪨 Geology Guide Specimen: Open Soapstone (Steatite) in the CRV Science Rock & Mineral ID Guide to log the specimen, compare it with the other 6 subgroups of Metamorphic, and test your eye in LithoClade.
Talc: Why Is It So Soft?
Talc is a magnesium sheet silicate whose layers are held together by very weak bonds, giving it a hardness of 1. Soapstone contains 50 to 80 percent talc, along with chlorite, carbonates and magnetite, and can be scratched with a fingernail.
Formation: How Does It Form?
Soapstone forms when hot fluids rich in water and carbon dioxide alter magnesium-rich rock such as serpentinite or peridotite, often along faults. The reaction produces talc and magnesium carbonate, which is why such rocks are called talc-carbonate rocks.
Uses: What Is Soapstone Used For?
The stone resists acid and heat and absorbs warmth slowly, so it is used for laboratory countertops, sinks, woodstoves and cookware. Peoples across North America and the Arctic carved soapstone into pots and sculptures, and Inuit artists still carve it today.
Soapstone at a Glance
| Property | Value |
|---|---|
| Type / variety | Massive Talc–Magnesite Metasomatic Steatite |
| Composition | 50–80% Talc (Mg₃Si₄O₁₀(OH)₂) + Chlorite + Magnesite/Dolomite + Magnetite |
| Geology Guide group | Metamorphic Rocks (Foliated, Granoblastic & High-P) |
| Rock Classification | Hydrothermal & Fault Zone |
| Mohs hardness | Mohs 1–2.5 (easily carved with a fingernail or wood tool) |
| Texture / habit | Massive, unfoliated to weakly felted micro-platy aggregate |
| Density | 2.70–2.85 g/cm³ |
| Lustre and cleavage | Pearly greenish-grey with an unmistakable soapy, greasy feel and high heat retention |
| Geological setting | CO₂- and H₂O-rich hydrothermal alteration of ultramafic rocks along tectonic faults |
| Diagnostic feature (Geology Guide) | Greenish-grey, heat-resistant rock with an unmistakable soapy feel that is soft enough (Mohs 1–2) to be scratched with a fingernail and carved into laboratory countertops and cookware. |
| Main mineral | Talc |
| Hardness | About 1-2.5 |