sedimentary

Weathered shale or mudstone

Clastic mudrock, chiefly clay minerals, quartz, and feldspar

AI-generated identification · may be incorrect

Fine-grained, brown to gray-brown, dull to earthy luster, with pronounced fissility and thin bedding; hardness about 2–4 Mohs, typically breaking into flakes or irregular chips. Individual crystals are generally too small to see.

Identified September 18, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when clay- and silt-sized sediment accumulated in quiet water, compacted, and lithified; its exact geological age cannot be determined from the image. Surface weathering has produced the crumbly, rusty-brown appearance.

Uses & applications

Used locally as fill, aggregate, or low-grade crushed material, though it is generally unsuitable for durable construction because it absorbs water and weakens. Collecting value is usually negligible unless it contains fossils or distinctive mineralization.

Geological facts

Shale is distinguished from mudstone by its tendency to split along bedding planes; this specimen appears strongly layered but heavily weathered. It may contain microscopic fossils or organic matter not visible in the photograph.

Field identification & locations

Look for fine texture, sedimentary layering, and easy splitting; a streak is usually pale gray to brown and it does not fizz strongly with dilute acid unless carbonate-rich. Common in sedimentary basins worldwide.