mineral

Tumbled prehnite (probable)

Prehnite — Ca₂Al(AlSi₃O₁₀)(OH)₂

AI-generated identification · may be incorrect

Pale green, translucent, waxy-to-vitreous luster with cloudy inclusions; hardness 6–6.5 Mohs, orthorhombic crystal structure, poor cleavage, and specific gravity about 2.8–2.95. The rounded shape indicates tumbling or natural abrasion.

Identified August 11, 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; deposits range from relatively young volcanic terrains to ancient metamorphosed systems.

Uses & applications

Used mainly as a semiprecious collector gemstone and ornamental stone; rarely used industrially because attractive material is limited.

Geological facts

Prehnite is often recognized by its soft apple-green color and pearly or waxy appearance, though epidote, serpentine, jade, or green chalcedony can look similar.

Field identification & locations

Common localities include South Africa, Australia, India, China, Canada, and the United States. Look for rounded pale-green nodules with translucent edges and curved fracture; laboratory testing is needed for certainty.