sedimentary

Red sandstone or iron-rich mudstone

Ferruginous sandstone/mudstone, composed mainly of quartz and clay minerals with hematite or goethite

AI-generated identification · may be incorrect

Dark reddish-brown, fine-grained, dull to earthy luster, weakly cemented, and apparently massive with irregular fracture; estimated hardness 3–6 Mohs and low-to-moderate density. The rounded shape suggests water abrasion or tumbling.

Identified September 2, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented silt or sand deposited in an oxidizing environment, where iron minerals produced the red color. The specimen’s geological age cannot be determined from the photograph; such rocks range from ancient to modern sedimentary formations.

Uses & applications

Commonly used as aggregate, building stone, landscaping material, and pigment source; this small rounded specimen has mainly educational or decorative value.

Geological facts

The red coloration is typically caused by microscopic hematite coating sediment grains rather than abundant metallic iron. Fine cracks and a relatively smooth exterior are consistent with weathering and transport.

Field identification & locations

Identify it by its earthy red color, fine texture, lack of visible crystals, and possible reddish streak; sandstone feels gritty, whereas mudstone feels smoother and may soften when wet. Common in arid continental basins and iron-rich sedimentary formations.