sedimentary

Ferruginous Sandstone with Concretion

Sandstone (SiO2 dominated with Fe2O3 cement)

AI-generated identification · may be incorrect

Hardness: 6-7 (quartz grains); Color: Reddish-brown, tan, or grey; Luster: Dull/Earthy; Structure: Clastic with nodular/concretionary forms; Cleavage: None; Specific Gravity: 2.2-2.8.

Hardness: 6-7 (quartz grains)
Color: Reddish-brown, tan, or grey
Luster: Dull/Earthy

Identified June 27, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (quartz grains); Color: Reddish-brown, tan, or grey; Luster: Dull/Earthy; Structure: Clastic with nodular/concretionary forms; Cleavage: None; Specific Gravity: 2.2-2.8.

Formation & geological history

Formed through the accumulation and compaction of sand grains (usually quartz) cemented by iron oxides. These iron minerals often precipitate in groundwater, sometimes forming odd shapes or concretions around a core nucleus.

Uses & applications

Primarily used in construction (decorative stone, aggregate) or as an ornamental specimen for collectors interested in pseudofossils or concretions.

Geological facts

These specimens are often mistaken for fossils, bones, or even footprints because of their strange weather-rounded shapes and iron-rich 'cast-like' appearance, leading to the nickname 'pseudofossils'.

Field identification & locations

Commonly found in sedimentary basins and riverbeds where iron-rich groundwater is present. Identify by its grainy texture, reddish 'rust' staining, and lack of internal organic bone structure.