sedimentary

Tumbled chert or jasper pebble

Microcrystalline quartz (SiO₂), likely iron-stained chert/jasper

AI-generated identification · may be incorrect

Opaque tan-orange, dull to slightly waxy luster, fine-grained and rounded from abrasion; quartz hardness about 6.5–7 Mohs, with no visible cleavage and conchoidal fracture. The image is insufficient for a definitive identification; it could also be a weathered ordinary silicate pebble.

Identified August 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when silica replaces or accumulates in sediment, commonly in marine or volcanic-associated environments; jasper is its opaque, iron-rich variety. Formation ages range from Precambrian to recent, followed by weathering and transport that rounded this specimen.

Uses & applications

Used historically for tools and occasionally as ornamental stone, cabochons, beads, and lapidary pieces; this small pebble has little commercial utility.

Geological facts

Iron oxides produce the orange-brown coloration. A sharp edge should scratch glass if it is quartz-rich, while a steel knife generally will not scratch it.

Field identification & locations

Common in river gravels, beaches, glacial deposits, and areas underlain by chert-bearing formations. Confirm with a glass-scratch test, streak, and close inspection for conchoidal fracture; avoid testing valuable specimens destructively.