sedimentary

Weathered sandstone or iron-rich sedimentary rock

Quartz-rich arenite, possibly ferruginous sandstone

AI-generated identification · may be incorrect

Fine- to medium-grained, tan-brown, dull to earthy luster with dark iron-oxide staining and visible bedding/fractures. Likely hardness about 6–7 for quartz grains, but the rock is porous and friable; no obvious cleavage or crystals are visible.

Identified September 13, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed from compacted and cemented sand, probably during a sedimentary basin’s burial history; brown coloration reflects oxidation of iron-bearing minerals. Exact age and formation environment cannot be determined from the photograph alone.

Uses & applications

Common sandstone is used for building stone, paving, aggregate, and landscaping; attractive pieces may be collected, but this specimen has little gem-market value.

Geological facts

The dark outer rind may represent weathering or iron-oxide cementation. A streak of white vinegar will not normally react, helping distinguish it from carbonate-rich rock.

Field identification & locations

Look for gritty texture, individual quartz grains, layered bedding, and weak acid reaction; a hand lens and hardness test are useful. Sandstones occur worldwide, especially in deserts, river channels, beaches, and sedimentary plateaus.