mineral

Banded agate and chalcedony rough

Microcrystalline quartz (SiO₂), chiefly chalcedony with agate banding; some pieces may include jasper or brecciated quartz

AI-generated identification · may be incorrect

Mohs hardness 6.5–7; waxy to dull luster, translucent gray, brown, red, and cream colors, with irregular/conchoidal fracture and occasional curved bands or druzy quartz. Specific gravity is about 2.58–2.65; crystals are microscopic quartz fibers.

Identified September 7, 2026More mineral →

Explore Banded agate and chalcedony rough 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: Banded agate and chalcedony rough
Scientific name: Microcrystalline quartz (SiO₂), chiefly chalcedony with agate banding; some pieces may include jasper or brecciated quartz
Category: mineral
Identified: September 7, 2026
Method: Standard

AI Estimated Value

About $5–$30 for this type of mixed rough material; attractive banded or unusually colorful pieces may bring $20–$100+.

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 successive colored bands; associated jasper forms from iron-rich impurities. The specimens are likely Cenozoic or older volcanic-hosted material, but age requires locality data.

Uses & applications

Used for cabochons, beads, carvings, lapidary slabs, and decorative objects; crushed chalcedony is also used as silica aggregate. Rough material is mainly collected for pattern, color, and polishability.

Geological facts

Agate’s banding records repeated changes in fluid chemistry during cavity filling. Red and brown colors commonly result from iron oxides, while blue-gray areas may reflect finely fibrous chalcedony.

Field identification & locations

Identify by testing hardness against glass, observing waxy translucency, conchoidal fracture, and any concentric banding; it should not scratch easily with a steel knife. Common sources include Brazil, Uruguay, Mexico, India, Madagascar, and the western United States.