gemstone

Likely tumbled yellow-green gemstone, possibly prehnite

Unconfirmed; prehnite is a hydrous calcium aluminum silicate, Ca₂Al(AlSi₃O₁₀)(OH)₂

AI-generated identification · may be incorrect

Small, polished, translucent pale yellow-green piece with a smooth rounded shape and vitreous-to-waxy luster. If prehnite, hardness is 6–6.5 Mohs and its crystals are typically orthorhombic; the photo does not show enough detail for reliable identification.

Identified October 7, 2026More gemstone →

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Physical properties

Formation & geological history

Prehnite commonly forms in low-temperature hydrothermal veins and cavities in basalt, often alongside zeolites; deposits range from ancient to geologically recent. The image cannot establish the material or its age.

Uses & applications

Tumbled prehnite is used in inexpensive jewelry and mineral collections; similar-looking stones may be sold as other gems or glass.

Geological facts

Prehnite was named for Dutch military commander Hendrik von Prehn and is known for botryoidal, grape-like aggregates.

Field identification & locations

The smooth surface suggests tumbling, but color alone is not diagnostic; inspect under magnification and test hardness or specific gravity to distinguish prehnite from glass and other pale-green minerals. Prehnite occurs in basalt cavities worldwide, including South Africa, Australia, and the United States.