sedimentary

Polished brown quartz-rich rock, possibly chert or jasper

Microcrystalline quartz (SiO₂), likely chert/jasper; exact identification is uncertain from the image

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; brown, gray, and cream mottling with a dull to waxy luster and irregular conchoidal-looking fracture. It appears fine-grained and partly polished, with no clearly visible crystal cleavage.

Identified September 16, 2026More sedimentary →

Explore Polished brown quartz-rich rock, possibly chert or jasper 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: Polished brown quartz-rich rock, possibly chert or jasper
Scientific name: Microcrystalline quartz (SiO₂), likely chert/jasper; exact identification is uncertain from the image
Category: sedimentary
Identified: September 16, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a small common polished piece; $30–$100+ if it has unusual patterning, provenance, or lapidary 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

Chert forms when silica precipitates from groundwater or replaces sediments, commonly during diagenesis; jasper is an opaque iron-rich variety. Formation ages range widely from Precambrian to recent sedimentary environments.

Uses & applications

Used for carving, cabochons, beads, tumbled stones, and occasionally ornamental stone; historically, chert was important for sharp tools and fire-starting.

Geological facts

The specimen may also be a brecciated or iron-stained jasper/chert, but the photograph does not show diagnostic banding or mineral grains clearly enough for a precise variety.

Field identification & locations

Look for a glassy or waxy surface, very fine texture, conchoidal fracture, and inability to scratch it with a steel knife; quartz-rich material can scratch glass. Common sources include sedimentary basins worldwide, especially flint and jasper localities.