mineral

Pale green mineral specimen, likely prehnite or green calcite

Tentatively prehnite, Ca₂Al(AlSi₃O₁₀)(OH)₂; visual identification is uncertain from the photograph

AI-generated identification · may be incorrect

Pale mint-green, dull to pearly luster, botryoidal/granular texture, and no clearly visible crystal faces. Prehnite has Mohs hardness 6–6.5, while calcite is softer at 3 and effervesces in dilute acid.

Identified September 22, 2026More mineral →

Explore Pale green mineral specimen, likely prehnite or green calcite in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Pale green mineral specimen, likely prehnite or green calcite
Scientific name: Tentatively prehnite, Ca₂Al(AlSi₃O₁₀)(OH)₂; visual identification is uncertain from the photograph
Category: mineral
Identified: September 22, 2026
Method: Standard

AI Estimated Value

Approximately $1–$10 for an unidentified fragment; $5–$30 if confirmed as attractive prehnite, depending on size and provenance.

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

Prehnite forms in cavities and fractures of basaltic volcanic rocks through low-temperature hydrothermal alteration; calcite commonly forms in veins and cavities. Such minerals range from ancient to modern geological settings.

Uses & applications

Small specimens are primarily collector items; attractive prehnite may be cabochon-cut, while calcite is widely used industrially but this tiny piece has no practical commercial use.

Geological facts

The rounded, pale-green appearance is consistent with botryoidal prehnite, though lighting and scale prevent confident determination. A hardness and acid test would distinguish the main alternatives.

Field identification & locations

Common sources include India, Australia, South Africa, China, and the United States for prehnite; calcite is worldwide. Test an inconspicuous area: calcite scratches easily with a steel pin and fizzes in acid, whereas prehnite generally does neither.