sedimentary

Yellow chert or jasper pebble

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

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; mustard-yellow to ochre, opaque, fine-grained, with a dull to waxy luster and no visible cleavage. Its rounded shape and smooth surface indicate natural water wear or tumbling.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Chert forms when microcrystalline quartz replaces silica-rich sediment or accumulates from biogenic silica; yellow coloration commonly comes from iron hydroxides. Individual formation ages vary widely, from Precambrian to recent sedimentary environments.

Uses & applications

Used as ornamental stone, cabochons, beads, tumbled stones, and occasionally as a durable aggregate or tool material. This small common pebble has modest commercial value.

Geological facts

Chert and jasper are varieties of cryptocrystalline quartz; “jasper” generally refers to opaque, impurity-rich chert. The image alone cannot distinguish confidently between natural jasper and colored quartz-rich river stone.

Field identification & locations

Identify by its very fine texture, lack of visible grains, high hardness, and inability to scratch with a steel knife; it should scratch glass. Common sources include river gravels and sedimentary formations worldwide.