mineral

Raw translucent chalcedony (likely agate or common opal)

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

AI-generated identification · may be incorrect

Pale blue-gray to honey-yellow, translucent, vitreous to waxy luster, and irregular conchoidal fracture. Chalcedony has Mohs hardness 6.5–7; opal is softer at about 5.5–6.5. No visible cleavage.

Identified September 8, 2026More mineral →

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At a glance

Common name: Raw translucent chalcedony (likely agate or common opal)
Scientific name: Microcrystalline quartz, SiO₂; possibly hydrated silica opal, SiO₂·nH₂O
Category: mineral
Identified: September 8, 2026
Method: Standard

AI Estimated Value

Approximately $2–$15 as an attractive rough fragment; $20–$100 or more if it proves to be high-quality material suitable for cutting.

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

Pale blue-gray to honey-yellow, translucent, vitreous to waxy luster, and irregular conchoidal fracture. Chalcedony has Mohs hardness 6.5–7; opal is softer at about 5.5–6.5. No visible cleavage.

Formation & geological history

Silica-rich groundwater deposited gel or microcrystalline silica in cavities and fractures of volcanic rock, commonly during the Cenozoic or earlier. The yellow color may result from iron staining or natural zoning.

Uses & applications

Used for cabochons, carvings, beads, decorative stone, and lapidary practice; ordinary fragments have little industrial value.

Geological facts

The specimen’s translucent blue body with a yellow edge is consistent with chalcedony or common opal, but the photograph cannot distinguish them definitively. A refractive-index, hardness, or specific-gravity test would help.

Field identification & locations

Look for waxy luster, conchoidal fracture, translucency, and absence of cleavage; quartz will not scratch with a steel knife, while opal may. Common sources include Brazil, Uruguay, Mexico, Australia, and the western United States.