sedimentary

Likely gray mudstone or shale fragment

Fine-grained siliciclastic sedimentary rock; exact composition cannot be determined from the image

AI-generated identification · may be incorrect

Dull gray-brown, fine-grained, and roughly blocky, with no visible crystals. Hardness and cleavage are uncertain; shale typically splits into thin layers, while mudstone is more massive.

Identified October 15, 2026More sedimentary →

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Physical properties

Dull gray-brown, fine-grained, and roughly blocky, with no visible crystals. Hardness and cleavage are uncertain; shale typically splits into thin layers, while mudstone is more massive.

Formation & geological history

Forms when clay- and silt-sized sediment is compacted and cemented, commonly in quiet-water settings. Its age and exact depositional environment cannot be established from the photograph.

Uses & applications

Ordinary fragments have little commercial value; mudstone and shale may be used in cement and brick manufacture or as natural building stone.

Geological facts

Mudstone and shale can look very similar in photographs; the key distinction is shale’s tendency to split along bedding planes.

Field identification & locations

Look for very fine grains and sedimentary layering; a fresh break or a simple scratch test may help distinguish it from harder crystalline rocks. Similar rocks occur in sedimentary basins worldwide.