Sandstone (Ferruginous)

Physical Properties

Hardness: 6-7 on Mohs scale (due to quartz content); Color: Gray, tan, and reddish-brown (iron staining); Luster: Dull/Earthy; Crystal structure: Clastic (composed of grains); Cleavage: None

Formation & Geological History

Formed through the accumulation and cementation of mineral grains or rock fragments, typically in river beds, oceans, or deserts. This specific specimen shows weathering and iron leaching, common in fluvial environments.

Uses & Applications

Commonly used in construction as building stone, pavers, and as an aggregate. High-purity sandstone is used in glass making.

Geological Facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. The red/orange bands often seen in such rocks are known as Liesegang rings, caused by chemical precipitation of iron oxides.

Field Identification & Locations

Identify by its gritty, sandpaper-like texture. It occurs worldwide where sedimentary basins exist. Collectors should look for unique layering or fossils within the matrix.

Identified on: 4/22/2026

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