Soapstone (Talc Schist)

Hardness: 1-2.5 (Mohs scale), Color: Gray to greenish-gray, Luster: Pearly to greasy, Crystal structure: Monoclinic (foliated), Cleavage: Perfect basal, Specific gravity: 2.7-2.8

Formed at convergent plate boundaries where magnesium-rich rocks (like serpentinite) undergo regional metamorphism at low temperatures and pressures, involving hydrothermal fluids. Specimens can range from hundreds of millions to billions of years old.

Used in industry for heater cores, electrical insulators, and lab countertops due to its heat resistance. Also a primary material for sculpture and historically used for cookware and tailoring chalk.

Soapstone has a high heat capacity, allowing it to stay warm for hours after a fire goes out. It feels 'soapy' or greasy to the touch because of its high talc content.

Identify in the field by its distinct greasy feel and extreme softness; it can be scratched with a fingernail. Commonly found in the Appalachian Mountains, Scandinavia, and Brazil. Collectors look for pieces with minimal inclusions and high talc purity.