mineral

Polished agate geode

Microcrystalline quartz (chalcedony), SiO₂, with possible druzy quartz and iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; cream, tan, gray, and brown concentric banding; waxy to vitreous luster; cryptocrystalline quartz with cavities lined by small crystals. Agate has no visible cleavage and typically has specific gravity around 2.6.

Identified August 24, 2026More mineral →

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At a glance

Common name: Polished agate geode
Scientific name: Microcrystalline quartz (chalcedony), SiO₂, with possible druzy quartz and iron-oxide inclusions
Category: mineral
Identified: August 24, 2026
Method: Standard

AI Estimated Value

Approximately $10–$75 for a common polished specimen; $100–$300+ if unusually large, vividly banded, or displaying attractive druzy cavities.

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 filled vesicles or cavities in volcanic rock, depositing chalcedony in successive bands and later quartz crystals in open voids. The specimen is likely Cenozoic or older, but its exact age cannot be determined from the image.

Uses & applications

Used as a decorative polished specimen, cabochon, carving material, and occasionally in jewelry; agate is also used for beads, bookends, and ornamental objects.

Geological facts

The rounded cavities and layered, flowing bands are characteristic of botryoidal or fortification agate. Dark interiors may contain druzy quartz or iron/manganese staining.

Field identification & locations

Identify by its translucent waxy banding, conchoidal fracture, and hardness sufficient to scratch glass; a steel blade should not easily scratch it. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States.