mineral

Botryoidal chalcedony (agate/quartz geode fragment)

Microcrystalline quartz, SiO₂, likely chalcedony with drusy quartz and iron-oxide staining

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent white to honey-orange/brown, waxy to slightly glassy luster, botryoidal rounded surfaces, no obvious cleavage, conchoidal fracture; quartz crystal structure. The orange-brown color is likely hematite/goethite staining.

Identified August 19, 2026More mineral →

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At a glance

Common name: Botryoidal chalcedony (agate/quartz geode fragment)
Scientific name: Microcrystalline quartz, SiO₂, likely chalcedony with drusy quartz and iron-oxide staining
Category: mineral
Identified: August 19, 2026
Method: Standard

AI Estimated Value

About $2–$15 for a small rough piece; $10–$50 if unusually attractive, well-crystallized, or verified as a locality specimen.

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 chalcedony layers and later quartz crystals. Such material is commonly Cenozoic or older depending on its host lava; the image alone cannot establish age.

Uses & applications

Used as a lapidary, cabochon, decorative, and collecting material; polished pieces may be used in jewelry. Small rough specimens have modest commercial value.

Geological facts

The grape-like surface is called botryoidal texture, produced by rounded growth fronts. It may be an exposed cavity lining or a broken fragment of an agate-like nodule.

Field identification & locations

Likely identification is chalcedony/agate rather than a specific species. Test carefully for glassy hardness: it should scratch ordinary glass, while a steel knife generally does not scratch it. In the reported Paraguay region, silica-rich agate and chalcedony are geologically plausible, especially in basalt-associated terrains, though locality confirmation requires the host rock.