sedimentary

Red sandstone pebble

Quartz-rich sandstone, commonly ferruginous sandstone

AI-generated identification · may be incorrect

Usually 60–90% quartz with feldspar and iron-oxide cement; reddish-brown, dull to weakly earthy luster, fine-grained and rounded. Hardness is approximately 6–7 for individual quartz grains, but the rock may crumble along cemented surfaces; no visible cleavage.

Identified September 3, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand accumulated, compacted, and cemented in an ancient river, desert, beach, or floodplain; red color comes from hematite coating or cement. Its precise geological age cannot be determined from the photograph.

Uses & applications

Used as building and paving stone, aggregate, landscaping material, and occasionally as a natural polishing or craft stone; this rounded specimen has little commercial value.

Geological facts

The smooth shape indicates abrasion during transport by water, wind, or glacial ice. Iron-rich sandstone commonly records oxidizing terrestrial environments and is often called red bed sandstone.

Field identification & locations

Identify it by visible sand grains, rusty red color, rounded pebble shape, and uneven granular fracture; a streak test may leave a faint reddish-brown mark. Common worldwide, including red-bed regions of the southwestern United States, England, India, and Australia.