sedimentary

Red sandstone fragment

Quartz-rich sandstone, commonly ferruginous sandstone (SiO₂-dominant with iron-oxide cement)

AI-generated identification · may be incorrect

Typically Mohs hardness 6–7 for quartz grains, reddish-brown color, dull to slightly gritty luster, and granular texture; no visible cleavage, with irregular fracture and possible bedding. The specimen appears porous and iron-stained, though its small size and lighting limit certainty.

Identified September 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Forms when sand—usually quartz-rich—is compacted and cemented, with hematite or limonite producing the red color. Sandstones range from Precambrian to modern sedimentary basins and commonly form in rivers, deserts, deltas, and shallow seas.

Uses & applications

Used as building stone, paving, aggregate, and architectural facing; attractive red varieties are collected or used decoratively. This small fragment has negligible commercial value.

Geological facts

Red coloration generally indicates oxidizing conditions during or after deposition. Sandstone’s gritty feel and visible sand grains distinguish it from dense red minerals such as jasper.

Field identification & locations

Identify by rubbing a fresh surface: individual sand grains and a gritty texture support sandstone; dilute hydrochloric acid should show little or no reaction unless carbonate cement is present. Common worldwide, especially in desert and continental basin deposits.