fossil

Polished fossiliferous agate (likely fossil coral or shell in silica)

Silicified fossil in chalcedony, a microcrystalline form of quartz (SiO₂); exact fossil type is uncertain from the image

AI-generated identification · may be incorrect

Polished, curved specimen with tan, cream, and brown banding and mottled fossil-like patterns; quartz hardness 6.5–7 Mohs, vitreous to waxy luster, trigonal crystal system at the microscopic level, and no cleavage. The visible shape and surface finish make field hardness and specific gravity difficult to assess.

Identified September 28, 2026More fossil →

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At a glance

Common name: Polished fossiliferous agate (likely fossil coral or shell in silica)
Scientific name: Silicified fossil in chalcedony, a microcrystalline form of quartz (SiO₂); exact fossil type is uncertain from the image
Category: fossil
Identified: September 28, 2026
Method: Standard

AI Estimated Value

About $5–$30 USD for a small polished specimen; documented, unusually detailed fossil-agate pieces may be worth more.

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

Silica-rich groundwater can replace or fill fossil material, preserving its structure as chalcedony; agate bands form through repeated deposition. The fossil’s age and locality cannot be determined from the photograph.

Uses & applications

Primarily a collectible or lapidary piece; similar material is cut into jewelry and ornaments, while agate is also used for decorative objects and precision components.

Geological facts

Agate is composed of microscopic quartz crystals, and its fine banding records successive silica deposition. Fossil-like patterns may represent preserved or replaced biological structure.

Field identification & locations

Look for repeating natural bands and irregular fossil textures rather than uniform manufactured patterns; compare with the source locality or seller’s documentation to identify the fossil and origin. Small polished specimens of this kind commonly sell for about $5–$30 USD.