sedimentary

Tumbled brown chert or jasper pebble

Microcrystalline quartz (SiO₂), likely chert/jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque brown to honey-colored, with a waxy to dull luster and very fine-grained, cryptocrystalline structure. The rounded shape indicates natural water wear or tumbling; no visible cleavage, and a white weathered patch is present.

Identified September 4, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica-rich fluids replace or cement sediment, often from siliceous biological remains; jasper is an iron-rich opaque variety. It may range from Paleozoic to recent gravel deposits, depending on source rock.

Uses & applications

Commonly used for knapped tools, ornamental objects, cabochons, beads, and polished stones; this small specimen has modest decorative value.

Geological facts

Its quartz content makes it resistant to weathering and capable of producing a sharp conchoidal fracture. Brown coloration commonly reflects iron oxides or hydroxides.

Field identification & locations

Identify by hardness, lack of cleavage, waxy appearance, and conchoidal fracture; it should scratch glass but not be scratched by a steel knife. Common in river gravels and sedimentary terrains worldwide.