mineral

Tumbled prehnite with epidote inclusions

Prehnite, Ca₂Al₂Si₃O₁₀(OH)₂, commonly intergrown with epidote (Ca₂Al₂Fe³⁺Si₃O₁₂(OH))

AI-generated identification · may be incorrect

Pale green to yellow-green, translucent, with dark green-black epidote inclusions; vitreous to pearly luster and uneven conchoidal fracture. Hardness is 6–6.5 Mohs, typically orthorhombic, with specific gravity about 2.8–2.95.

Identified August 20, 2026More mineral →

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Physical properties

Formation & geological history

Forms in cavities and fractures of basalt and other volcanic rocks through low-temperature hydrothermal alteration, commonly alongside zeolites, quartz, and epidote. Deposits are generally Phanerozoic in age, though the specimen’s exact age cannot be determined visually.

Uses & applications

Used primarily as a lapidary stone for tumbled pieces, cabochons, carvings, and mineral specimens; it has modest jewelry value.

Geological facts

Prehnite is often described as having a distinctive soft, waxy or pearly appearance and may display attractive botryoidal masses in natural specimens.

Field identification & locations

Identify it by its pale green-yellow body, clouded translucency, rounded habit, and dark epidote inclusions; common sources include Australia, South Africa, India, China, and the United States. A typical tumbled specimen is worth about $3–$15 USD; exceptional cabochons or crystals may reach $30–$100.