sedimentary

Sandstone (Ferruginous)

Arenite (composed primarily of SiO2 with iron oxide Fe2O3 cement)

AI-generated identification · may be incorrect

Hardness: 6-7 (Mohs/Quartz grains); Color: Brown, reddish-tan, or rusty; Luster: Dull/Earthy; Structure: Clastic, fine-to-medium grained; Specific Gravity: 2.2–2.6.

Hardness: 6-7 (Mohs/Quartz grains)
Color: Brown, reddish-tan, or rusty
Luster: Dull/Earthy

Identified March 28, 2026More sedimentary →

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Physical properties

Hardness: 6-7 (Mohs/Quartz grains); Color: Brown, reddish-tan, or rusty; Luster: Dull/Earthy; Structure: Clastic, fine-to-medium grained; Specific Gravity: 2.2–2.6.

Formation & geological history

Formed through the accumulation, compaction, and lithification of sand-sized mineral grains. This specific specimen exhibits iron-oxide staining, suggesting formation in an environment with oxygenated groundwater or subaerial weathering.

Uses & applications

Commonly used as a building stone (dimension stone), in glass manufacturing if pure silica, or as a source of aggregate for construction and road paving.

Geological facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. The reddish-brown color specifically indicates the presence of hematite or limonite acting as a cementing agent between the quartz grains.

Field identification & locations

Identify in the field by its gritty 'sandpaper' feel and visible grains. These are commonly found in riverbeds, desert dunes, and coastal environments. This specimen appears water-worn and rounded, likely sourced from a stream or glacial till.