mineral

Tumbled white chalcedony (likely common opal or milky quartz)

Microcrystalline quartz, SiO₂; possibly hydrated silica opal, SiO₂·nH₂O

AI-generated identification · may be incorrect

White to cream, translucent, waxy-to-glassy luster with rounded tumbled surfaces and small pits. Chalcedony has Mohs hardness 6.5–7; opal is softer at 5.5–6.5, lacks visible cleavage, and is cryptocrystalline or amorphous.

Identified August 20, 2026More mineral →

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At a glance

Common name: Tumbled white chalcedony (likely common opal or milky quartz)
Scientific name: Microcrystalline quartz, SiO₂; possibly hydrated silica opal, SiO₂·nH₂O
Category: mineral
Identified: August 20, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a common tumbled piece; approximately $30–$100 if unusually large, well-polished, or demonstrably gem-quality.

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 deposited the material in cavities, veins, or volcanic vesicles; chalcedony commonly formed during the Cenozoic, while opal can form at many ages. The specimen has been cut or tumbled and polished by humans.

Uses & applications

Used as a decorative stone, cabochon, carving material, and lapidary rough; common pieces have modest jewelry and collecting value.

Geological facts

The porous-looking pits and creamy appearance are consistent with weathered or lightly polished chalcedony, though the photograph cannot distinguish it confidently from opal or even porous white quartz.

Field identification & locations

Field tests include hardness against steel or glass, conchoidal fracture, and specific gravity; opal may feel slightly lighter and show stronger translucency. Common sources include Brazil, Mexico, Australia, Turkey, and the western United States.