sedimentary

Tumbled jasper or iron-rich chert

Microcrystalline quartz (SiO₂), likely colored by iron oxides

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; mustard-brown to reddish-brown, opaque, with a dull to subtly waxy luster and conchoidal fracture. The rounded surface appears tumbled or naturally water-worn, with possible iron staining and fine quartz texture.

Identified September 5, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when silica-rich fluids replaced or cemented fine sediment, while iron oxidation produced the brown-red coloration; commonly Paleozoic to younger, depending on locality. Exact age and identity require locality and testing.

Uses & applications

Used as a lapidary stone for tumbled specimens, cabochons, beads, and small carvings; not generally important as a construction stone. Common pieces are mainly decorative or educational.

Geological facts

Jasper and chert are varieties of cryptocrystalline quartz and can look nearly identical in hand specimens. A steel nail should not scratch it, while quartz or a streak plate may help confirm its hardness.

Field identification & locations

Common in gravel beds, stream deposits, volcanic terrains, and sedimentary formations worldwide, especially the western United States. Look for opaque fine grain, sharp conchoidal edges on fresh breaks, and red-brown iron-oxide coloration.