gemstone

Polished banded agate (likely plume or scenic agate)

Microcrystalline quartz, mainly chalcedony (SiO₂), with iron-oxide or other mineral inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; gray, cream, and brown translucent bands or plume-like markings; waxy to vitreous luster; cryptocrystalline, with no visible cleavage. The smooth, elongated form appears polished or naturally water-worn.

Identified August 16, 2026More gemstone →

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At a glance

Common name: Polished banded agate (likely plume or scenic agate)
Scientific name: Microcrystalline quartz, mainly chalcedony (SiO₂), with iron-oxide or other mineral inclusions
Category: gemstone
Identified: August 16, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a small common polished piece; $30–$150+ for unusually attractive patterns, size, or 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

Forms when silica-rich groundwater fills cavities in volcanic rock, depositing chalcedony and quartz in successive layers over millions of years, commonly during the Cenozoic or older volcanic episodes.

Uses & applications

Used for cabochons, carvings, beads, ornaments, and lapidary collectibles; durable polished pieces are occasionally used in jewelry.

Geological facts

Agate patterns are created by changing chemistry, impurities, and growth conditions during repeated silica deposition. Internal banding is often best revealed by cutting and polishing.

Field identification & locations

Identify by its waxy polish, translucency, curved/banded patterns, and lack of obvious cleavage; common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States. A photo alone cannot confirm the exact agate variety.