mineral

Quartz-rich chalcedony (likely milky quartz/chert)

Silica, chiefly quartz and microcrystalline quartz (SiO₂); exact variety is uncertain from the photograph

AI-generated identification · may be incorrect

Tan to reddish-brown, opaque to translucent, with a dull-to-waxy luster and small sparkling quartz grains or drusy surfaces. Quartz hardness is Mohs 7; chalcedony is about 6.5–7, with no obvious cleavage and conchoidal fracture.

Identified September 21, 2026More mineral →

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At a glance

Common name: Quartz-rich chalcedony (likely milky quartz/chert)
Scientific name: Silica, chiefly quartz and microcrystalline quartz (SiO₂); exact variety is uncertain from the photograph
Category: mineral
Identified: September 21, 2026
Method: Standard

AI Estimated Value

About $2–$15 for an ordinary hand specimen; $20–$75 if it displays attractive drusy quartz, translucency, or good lapidary patterns.

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

Likely formed when silica-rich groundwater filled cavities or fractures in volcanic or sedimentary rock, later weathering into this rounded fragment. Its geological age cannot be determined visually and depends on its source locality.

Uses & applications

Common material for lapidary work, cabochons, carvings, tumbled stones, and decorative specimens; ordinary pieces have little industrial value.

Geological facts

The brown coloration may come from iron oxides or inclusions. The specimen appears natural and weathered, but its exact identity cannot be confirmed without a close fracture, translucency, and locality information.

Field identification & locations

Look for a glassy or waxy surface, conchoidal fracture, hardness sufficient to scratch ordinary glass, and lack of reaction to dilute acid. Common occurrences include silica veins, geodes, volcanic cavities, and sedimentary chert beds.