gemstone

Polished agate (likely fire agate or carnelian-bearing agate)

Microcrystalline quartz, SiO₂; chalcedony with iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent brown, orange, cream, and gray bands or patches; vitreous to waxy luster; cryptocrystalline quartz with no visible cleavage; specific gravity about 2.6. The rounded, glossy surface indicates a polished or tumbled specimen.

Identified August 11, 2026More gemstone →

Explore Polished agate (likely fire agate or carnelian-bearing agate) 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: Polished agate (likely fire agate or carnelian-bearing agate)
Scientific name: Microcrystalline quartz, SiO₂; chalcedony with iron-oxide inclusions
Category: gemstone
Identified: August 11, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a small common polished piece; $30–$150+ if it is verified, colorful fire agate or an unusually attractive cabochon.

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 rocks, depositing chalcedony in successive layers; iron oxides create orange-red colors. Most specimens formed during ancient volcanic activity, commonly in Cenozoic to older volcanic terrains.

Uses & applications

Used for cabochons, beads, carvings, and ornamental objects; durable polished agate is also used for small decorative and industrial items.

Geological facts

The blue flashes may be surface reflections or thin chalcedony layers rather than true iridescence; confirmed fire agate typically shows intense botryoidal play-of-color beneath a polished surface.

Field identification & locations

Identify by hardness, waxy translucency, curved banding, and resistance to scratching by steel; common sources include Brazil, Uruguay, Mexico, India, and the western United States. Acid testing is unnecessary and can damage the polish.