mineral

Mixed rough mineral specimens, likely calcite with prehnite/zeolite

Calcite (CaCO₃), with probable prehnite (Ca₂Al₂Si₃O₁₀(OH)₂) and/or zeolite-group minerals

AI-generated identification · may be incorrect

Identified September 7, 2026More mineral →

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At a glance

Common name: Mixed rough mineral specimens, likely calcite with prehnite/zeolite
Scientific name: Calcite (CaCO₃), with probable prehnite (Ca₂Al₂Si₃O₁₀(OH)₂) and/or zeolite-group minerals
Category: mineral
Identified: September 7, 2026
Method: Standard

AI Estimated Value

About $5–$30 for the mixed lot; attractive confirmed crystals or cabochons may sell for $10–$75 each.

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

Pale green, cream, and white translucent pieces with vitreous to pearly luster, uneven-to-cleavage surfaces, and granular or botryoidal textures. Calcite is Mohs 3 with rhombohedral cleavage; prehnite is Mohs 6–6.5 and commonly pale green. The porous brown-white piece may be a weathered zeolite or coral-like carbonate, but cannot be identified confidently from the image alone.

Formation & geological history

These are likely low-temperature hydrothermal or cavity minerals formed in volcanic-rock vesicles and fractures; calcite may also be sedimentary or vein-forming. Geological ages are locality-dependent, commonly Cenozoic to Mesozoic for such deposits.

Uses & applications

Mostly sold as inexpensive study or decorative specimens; calcite and zeolites have industrial uses, while attractive prehnite may be cut for cabochons. Not suitable for structural construction as pictured.

Geological facts

Green color alone is not diagnostic: prehnite, fluorite, apophyllite, and green calcite can look similar. A vinegar or dilute hydrochloric-acid test that effervesces identifies calcite, but may damage specimens.

Field identification & locations

Likely sources include India, Brazil, China, Mexico, and volcanic regions worldwide. Confirm with hardness, acid reaction, cleavage, and a loupe; testing individual pieces is necessary because this is a mixed lot.