mineral

Tumbled chalcedony/agate (likely iron-stained quartz)

Microcrystalline quartz, SiO₂; chalcedony with possible agate banding and iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; translucent cream, orange, brown, and reddish colors with a waxy-to-glassy luster. It has a cryptocrystalline quartz structure, no obvious cleavage, conchoidal fracture, and typical specific gravity near 2.6; the rounded surface indicates tumbling or water wear.

Identified September 17, 2026More mineral →

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At a glance

Common name: Tumbled chalcedony/agate (likely iron-stained quartz)
Scientific name: Microcrystalline quartz, SiO₂; chalcedony with possible agate banding and iron-oxide inclusions
Category: mineral
Identified: September 17, 2026
Method: Standard

AI Estimated Value

Approximately $2–$15 for a small tumbled piece; $20–$75 if it displays attractive banding, translucency, or unusual inclusions.

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 and fractures in volcanic rocks, depositing chalcedony and quartz in layers; orange-red coloration commonly comes from hematite or limonite. The specimen’s exact geological age and locality cannot be determined from the image.

Uses & applications

Used as a decorative stone, cabochon, bead, polishing material, and collector specimen; common quality has modest value.

Geological facts

Agate is a variety of chalcedony distinguished by visible color or texture banding, though this piece may be massive chalcedony rather than clearly banded agate.

Field identification & locations

Look for translucency, waxy luster, conchoidal edges, and hardness sufficient to scratch glass; it should not fizz in dilute acid. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States.