mineral

Tumbled chalcedony/quartz (possibly agate)

Microcrystalline quartz, SiO₂; likely chalcedony with iron-oxide staining and minor druzy quartz

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; translucent brown, honey, cream, and gray-white; waxy to slightly vitreous luster; cryptocrystalline quartz with no obvious cleavage and conchoidal fracture. The rounded surface indicates tumbling or natural water wear.

Identified September 17, 2026More mineral →

Explore Tumbled chalcedony/quartz (possibly agate) in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

At a glance

Common name: Tumbled chalcedony/quartz (possibly agate)
Scientific name: Microcrystalline quartz, SiO₂; likely chalcedony with iron-oxide staining and minor druzy quartz
Category: mineral
Identified: September 17, 2026
Method: Standard

AI Estimated Value

About $2–$15 as a common tumbled stone; $20–$100+ if it has exceptional translucency, patterning, druzy, or provenance.

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, precipitating chalcedony and quartz; iron oxides create the brown coloration. Precise geological age cannot be determined from the photograph; common examples range from Paleozoic to Cenozoic.

Uses & applications

Used as a lapidary stone, cabochon, carving material, and inexpensive collector specimen; attractive banding or druzy may increase jewelry value.

Geological facts

White patches may be druzy quartz, weathered crust, or attached mineral coating rather than agate banding. Chalcedony commonly fluoresces weakly under some ultraviolet wavelengths.

Field identification & locations

Identify by its glassy-to-waxy appearance, translucency, quartz hardness, lack of cleavage, and inability to scratch it with a steel knife; it should scratch glass. Common in volcanic terrains worldwide, including Brazil, Uruguay, Mexico, India, and the western United States.