sedimentary

Rounded gray sandstone cobble

Quartz-rich sandstone (likely arkose or lithic sandstone)

AI-generated identification · may be incorrect

Fine- to medium-grained, dull gray-brown, with subtle layering and weathering cracks; likely Mohs hardness 6–7 for quartz grains, nonmetallic luster, no obvious cleavage, and moderate porosity. The rounded edges indicate prolonged transport or weathering.

Identified August 18, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand-sized grains were compacted and cemented, probably by silica, iron oxides, or carbonate. Its precise geological age and source cannot be determined from the photograph; it may be a stream, glacial, or locally weathered sedimentary clast.

Uses & applications

Common sandstone is used as building stone, paving, aggregate, and landscaping material; this specimen has little commercial or jewelry value.

Geological facts

The blocky shape and faint bedding are consistent with sandstone, but similar weathered shale, siltstone, or concrete could look comparable in a photograph.

Field identification & locations

Look for visible sand grains, gritty texture, bedding, and lack of crystal faces; a streak, hand lens, and dilute acid test can help distinguish it from carbonate rock. Sandstone occurs widely in sedimentary basins worldwide.