mineral

Tumbled pale-green mineral specimen, likely calcite or prehnite

Probably calcite (CaCO₃) or prehnite (Ca₂Al₂Si₃O₁₀(OH)₂); exact identification requires testing

AI-generated identification · may be incorrect

Pale mint-green to whitish, translucent, with a dull-to-vitreous luster and granular crystalline texture. Calcite has Mohs hardness 3, rhombohedral cleavage, and fizzes in dilute hydrochloric acid; prehnite is harder (6–6.5) and does not readily fizz.

Identified September 12, 2026More mineral →

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At a glance

Common name: Tumbled pale-green mineral specimen, likely calcite or prehnite
Scientific name: Probably calcite (CaCO₃) or prehnite (Ca₂Al₂Si₃O₁₀(OH)₂); exact identification requires testing
Category: mineral
Identified: September 12, 2026
Method: Standard

AI Estimated Value

Approximately $2–$15 for a small common specimen; $20–$75 if confirmed as attractive prehnite or a rarer high-quality mineral.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Likely a hydrothermal or cavity-forming mineral from altered volcanic rock; calcite commonly forms in veins and cavities, while prehnite forms in low-temperature basalt alteration zones. Geological age is locality-dependent, commonly Mesozoic to recent.

Uses & applications

Mostly used as a collectible or lapidary specimen; calcite has major industrial uses in cement, lime, and filler, while prehnite is occasionally cut as a gemstone.

Geological facts

The rounded edges indicate tumbling or natural abrasion. Color alone is insufficient for reliable identification because pale-green calcite, prehnite, chrysoprase, and quartz can look similar.

Field identification & locations

Test hardness against a steel knife and apply dilute vinegar or hydrochloric acid to a hidden spot; effervescence strongly supports calcite. Common sources include Mexico, Brazil, India, South Africa, and the United States.