mineral

Tumbled green banded stone, likely green aventurine or serpentine

Probably quartz-rich aventurine (SiO₂) or serpentine-group silicate; exact identification requires testing

AI-generated identification · may be incorrect

Smooth tumbled surface; translucent to opaque gray-green body with a dark reddish-brown band and weak vitreous-to-waxy luster. Aventurine is Mohs 6.5–7 with quartz structure; serpentine is softer, Mohs 2.5–5.5, often waxy and massive.

Identified August 31, 2026More mineral →

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At a glance

Common name: Tumbled green banded stone, likely green aventurine or serpentine
Scientific name: Probably quartz-rich aventurine (SiO₂) or serpentine-group silicate; exact identification requires testing
Category: mineral
Identified: August 31, 2026
Method: Standard

AI Estimated Value

About $2–$10 for a common tumbled specimen; $10–$30 if unusually large, attractive, or confirmed as quality aventurine.

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

Aventurine forms when quartz crystallizes with mica or other inclusions, commonly in metamorphic veins; serpentine forms by hydration of ultramafic rocks. Geological ages vary widely by locality.

Uses & applications

Used as a decorative tumbled stone, carving material, and occasionally jewelry; common-quality pieces have modest commercial value.

Geological facts

The dark band may be iron-oxide staining or a contrasting mineral vein rather than true agate banding. A steel scratch test and streak, hardness, and specific-gravity testing can distinguish the possibilities.

Field identification & locations

Look for quartz sparkle and hardness for aventurine; a soapy feel, lower hardness, and fibrous mottling suggest serpentine. Similar material is sold from India, Brazil, China, South Africa, and the United States.