sedimentary

Agate-bearing chert (likely petrified wood or silica-rich breccia)

Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide staining and host-rock fragments

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent brown, gray, cream, and amber zones with waxy to vitreous luster. The central silica-rich area appears cryptocrystalline and displays curved/conchoidal fracture; surrounding material is angular, layered, and brecciated.

Identified September 18, 2026More sedimentary →

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At a glance

Common name: Agate-bearing chert (likely petrified wood or silica-rich breccia)
Scientific name: Microcrystalline quartz/chalcedony, SiO₂, with iron-oxide staining and host-rock fragments
Category: sedimentary
Identified: September 18, 2026
Method: Standard

AI Estimated Value

Approximately $5–$30 as a common rough specimen; $30–$150+ if attractive, demonstrably fossilized, or suitable for high-quality cutting.

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

Formed when silica-rich fluids filled cavities or fractures and crystallized as chalcedony/quartz, later incorporating or surrounding fractured host rock. Such material commonly forms in volcanic cavities or silicified sedimentary/wood-bearing deposits, generally from Phanerozoic rocks.

Uses & applications

Used as lapidary material for cabochons, carvings, polished slabs, and decorative objects; otherwise mainly collected as a specimen. Commercial value depends strongly on translucency, pattern, polishability, and whether it is confirmed petrified wood.

Geological facts

The image may show a silicified fossil or brecciated agate, but texture alone cannot securely distinguish these. Iron oxides produce the reddish-brown coloration.

Field identification & locations

Identify with a glass-scratch test, conchoidal fracture, waxy surface, and absence of obvious cleavage; hydrochloric acid should not fizz. Common sources include Brazil, Uruguay, Mexico, Madagascar, and the western United States.