sedimentary

Weathered jasper or iron-stained chert pebble

Microcrystalline quartz (SiO₂), likely jasper/chert with iron-oxide staining

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; rounded brown, orange, gray, and cream surface with a dull to slightly waxy luster. Cryptocrystalline quartz has no visible cleavage and typically breaks conchoidally; the rough surface appears strongly weathered.

Identified August 28, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed when silica-rich sediment or volcanic material was replaced by microcrystalline quartz, with later iron-oxide staining and stream abrasion. Its exact geological age cannot be determined from the image; jasper and chert occur from Precambrian rocks to modern gravels.

Uses & applications

Used as a lapidary material for cabochons, beads, carvings, and decorative stone; lower-grade pieces are mainly collected as curiosities. Construction use is uncommon for individual specimens.

Geological facts

Orange-brown coloration commonly comes from hematite or limonite. A scratch test against glass and examination of a fresh edge can help distinguish it from softer iron-rich sedimentary rocks.

Field identification & locations

Common in river gravels and weathered volcanic or sedimentary terrains worldwide, including the western United States, Australia, India, and Brazil. Test hardness, inspect for a glassy conchoidal fracture, and avoid relying on color alone.