mineral

Botryoidal chalcedony (possibly common opal)

Microcrystalline quartz, SiO₂; pale portions may include hydrated silica opal, SiO₂·nH₂O

AI-generated identification · may be incorrect

White to translucent, rounded botryoidal surfaces with a waxy to vitreous luster; quartz hardness about 6.5–7 Mohs, opal about 5.5–6.5. No visible cleavage; cryptocrystalline or amorphous structure and typically low-to-moderate specific gravity (about 2.0–2.65).

Identified August 23, 2026More mineral →

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At a glance

Common name: Botryoidal chalcedony (possibly common opal)
Scientific name: Microcrystalline quartz, SiO₂; pale portions may include hydrated silica opal, SiO₂·nH₂O
Category: mineral
Identified: August 23, 2026
Method: Standard

AI Estimated Value

About $3–$20 for a small common piece; $25–$100+ if unusually translucent, aesthetic, or confirmed as high-quality chalcedony.

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 deposits successive layers in cavities, fractures, or vesicles, commonly in volcanic rocks; specimens may range from ancient to recent depending on the host deposit.

Uses & applications

Used as a lapidary stone, cabochon, carving material, and collectible specimen; translucent colorful varieties may be sold as gemstone material.

Geological facts

The bubble-like texture is called botryoidal, meaning grape-shaped. Its appearance can resemble white chalcedony, common opal, or chalcedony coating a porous host.

Field identification & locations

Look for hardness above glass, conchoidal fracture, waxy luster, and lack of fizz in dilute acid; a loupe may reveal translucent chalcedony layers. Common sources include volcanic regions in the western United States, Mexico, Brazil, Turkey, and Australia.