sedimentary

Weathered mudstone or shale

Fine-grained siliciclastic sedimentary rock, composed chiefly of clay minerals and silt-sized quartz

AI-generated identification · may be incorrect

Dull, pale gray-green, earthy surface; very fine-grained with irregular fractures and possible thin layering. Typical hardness is about 2–4 Mohs; individual crystals are too small to see, and specific gravity is roughly 2.2–2.7.

Identified October 10, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed as mud and silt settled in quiet water and compacted into rock, likely over millions of years; the specimen’s exact age and setting cannot be determined from the photo.

Uses & applications

Mudstone and shale are used in cement and brick production, and sometimes as fill or landscaping material; this small weathered piece is mainly a curiosity or teaching specimen.

Geological facts

The image is consistent with weathered mudstone, but a photo cannot reliably distinguish it from other fine-grained rocks or hardened clay.

Field identification & locations

Look for a fine, uniform texture and, in shale, tendency to split into thin sheets; common in sedimentary basins worldwide. The rough, fractured shape and muted color are not diagnostic.