sedimentary

Iron-stained sandstone (likely ferruginous sandstone)

Quartz-rich sandstone, commonly SiO₂ with iron-oxide cement (hematite/goethite)

AI-generated identification · may be incorrect

Tan to reddish-brown, earthy to dull luster, visibly granular and porous, with irregular fracture and no obvious cleavage. Typical hardness is about 6–7 for quartz grains, though the rock may crumble along cemented surfaces; specific gravity roughly 2.2–2.6.

Identified September 8, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed when sand—mostly quartz—was deposited, compacted, and cemented, with iron oxides producing the red-brown staining. The specimen is consistent with sedimentary rocks common in the Cretaceous–Tertiary formations of the southwest Arkansas/east Texas region.

Uses & applications

Used as building and paving stone, aggregate, abrasives, and occasionally decorative stone; ordinary pieces have little jewelry value.

Geological facts

The reddish coloration generally reflects hematite or hydrated iron oxides rather than abundant red minerals. A fresh broken surface and a hand lens should reveal individual sand grains and possible layering.

Field identification & locations

Likely regional material near 33.5°N, 94.0°W, where sandstone, iron-stained sediment, gravel, and clay-rich formations occur. Test with dilute hydrochloric acid: strong fizz suggests calcite-rich sandstone instead; quartz-rich sandstone usually does not fizz. Value: about $1–$10 for a common hand specimen, or $10–$30 if unusually textured or collectible.