sedimentary

Likely red-brown shale or mudstone

Fine-grained sedimentary rock, probably ferruginous shale/mudstone; exact identification is uncertain from the photo

AI-generated identification · may be incorrect

Brown-red, dull, fine-grained and fractured, with pale patches that may be mineral or surface deposits. Shale often splits into thin sheets; hardness is typically low, around 2–4 Mohs, but varies with cementation.

Identified September 27, 2026More sedimentary →

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Physical properties

Formation & geological history

Likely formed as clay- and silt-sized sediment settled in quiet water, then compacted and cemented; iron compounds can give it a reddish-brown color. Such rocks may be very old, but age cannot be determined visually.

Uses & applications

Commonly used as aggregate or fill where suitable; usually collected rather than used as a decorative stone.

Geological facts

The light patches could be calcite, quartz, or weathering residue; a close-up or simple hardness/acid tests would help distinguish them.

Field identification & locations

The layered, fine-grained appearance favors shale or mudstone, but the specimen’s small size and visible surface make a firm ID difficult. These sedimentary rocks are plausible in the Volga-region setting; inspect a fresh break for fine grains and splitting layers.