gemstone

Polished agate, likely carnelian/fire agate

Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides/hydroxides

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent orange-red to brown, with a gray-brown rind and waxy to vitreous luster. The irregular bright zones may show chalcedony banding or botryoidal inclusions; no obvious cleavage. Specific gravity about 2.60–2.65.

Identified August 11, 2026More gemstone →

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At a glance

Common name: Polished agate, likely carnelian/fire agate
Scientific name: Microcrystalline quartz (chalcedony), SiO₂, colored by iron oxides/hydroxides
Category: gemstone
Identified: August 11, 2026
Method: Standard

AI Estimated Value

$10–$60 for a common polished specimen; $75–$300+ if unusually translucent, patterned, or sold as quality fire agate. Exact species and value require examining the unlit surface and internal banding.

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 successive layers of chalcedony and quartz. Iron produces the orange-red color; age depends on the host volcanic rocks, commonly Mesozoic–Cenozoic. The image could also represent iron-stained jasper/chalcedony rather than true fire agate.

Uses & applications

Used for cabochons, carvings, beads, ornaments, and collectible slices; durable enough for small decorative objects. Common pieces generally have modest value.

Geological facts

Strong backlighting reveals translucency and internal silica textures, a useful agate diagnostic. The vivid glow is optical transmission through orange chalcedony, not necessarily fluorescence.

Field identification & locations

Identify by translucent edges, conchoidal fracture, waxy luster, and fine curved or mossy internal textures; test hardness only on an inconspicuous area. Agate and chalcedony are plausible around southern Brazil, including Rio Grande do Sul, a major agate-producing region.