sedimentary

Tumbled brown chert or weathered sandstone pebbles

Microcrystalline quartz (chert), possibly iron-stained sandstone; SiO₂ dominant

AI-generated identification · may be incorrect

Hardness commonly 6.5–7 for chert (about 5–7 for sandstone); tan to reddish-brown, dull earthy luster, fine-grained and rounded by abrasion. No visible crystals or cleavage; density roughly 2.3–2.7 g/cm³.

Identified August 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely naturally water-worn sedimentary pebbles, with iron-oxide staining producing the brown color; chert formed by silica replacement or precipitation in sediment, while sandstone lithified from compacted sand. Ages cannot be determined from the image and may range from young river deposits to ancient bedrock.

Uses & applications

Suitable for craft projects, landscaping, lapidary work, and teaching collections; ordinary pieces have little jewelry or industrial value.

Geological facts

Chert can produce a sharp edge when freshly fractured and may spark with steel, whereas sandstone typically crumbles or shows visible sand grains. Surface rounding indicates transport in a stream, beach, or gravel deposit.

Field identification & locations

Identify chert by its waxy, very fine texture and resistance to scratching glass; sandstone feels gritty and may show individual grains. Common worldwide in riverbeds, beaches, and sedimentary terrains.