mineral

Polished agate geode

Chalcedony (microcrystalline SiO₂), commonly banded agate with drusy quartz and possible iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent gray, cream, honey-brown and rust bands; waxy to vitreous luster; cryptocrystalline quartz with curved banding, no cleavage, and conchoidal fracture. The cavity contains druzy quartz and dark iron/manganese-oxide material.

Identified August 22, 2026More mineral →

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At a glance

Common name: Polished agate geode
Scientific name: Chalcedony (microcrystalline SiO₂), commonly banded agate with drusy quartz and possible iron-oxide inclusions
Category: mineral
Identified: August 22, 2026
Method: Standard

AI Estimated Value

Approximately $15–$75 for a common polished specimen; $100–$300+ if large, unusually vivid, locality-documented, or crystal-lined.

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 gas cavities or voids in volcanic rock, depositing successive layers of chalcedony and quartz; typically Cenozoic to older volcanic-host ages depending on locality. Common sources include Brazil, Uruguay, Mexico, Madagascar, India, and the western United States.

Uses & applications

Used for cabochons, ornamental slices, carvings, bookends, and mineral collecting; agate is also used in durable decorative and precision objects.

Geological facts

Concentric banding records repeated changes in groundwater chemistry during cavity filling. “Geode” technically refers to the hollow or crystal-lined cavity, while agate describes the banded chalcedony.

Field identification & locations

Identify by translucent curved bands, waxy luster, quartz hardness, and irregular cavities lined with crystals; coloration may be enhanced by polishing or dyeing. Exact locality cannot be determined reliably from the photograph.