sedimentary

Ferruginous Sandstone with Quartz Inclusions

Clastic Sedimentary Rock (Iron-rich Sandstone)

AI-generated identification · may be incorrect

Hardness: 6-7 (on Mohs scale for quartz grains); Color: Reddish-brown, rust, beige; Luster: Gritty, dull to vitreous where quartz is present; Structure: Granular/Clastic; Cleavage: None (conchoidal fracture on quartz inclusions); Specific Gravity: 2.6-2.8

Hardness: 6-7 (on Mohs scale for quartz grains)
Color: Reddish-brown, rust, beige
Luster: Gritty, dull to vitreous where quartz is present

Identified March 26, 2026More sedimentary →

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Physical properties

Formation & geological history

Formed through the weathering, transport, and deposition of sand-sized grains, primarily quartz, which are then lithified. The reddish color is due to the presence of iron oxides (hematite or limonite) acting as a cement or coating. This specimen likely dates from the Paleozoic to Mesozoic era depending on the specific basin of origin.

Uses & applications

Used primarily in construction as a building stone or road aggregate. Some iron-rich sandstones are studied as low-grade iron ores. In landscaping, it is valued for its earthy, natural aesthetic.

Geological facts

The red color in these rocks is often referred to as 'red beds,' which are significant because they indicate the presence of oxygen in the atmosphere at the time of deposition. Sandstone makes up about 20% of all sedimentary rocks on Earth.

Field identification & locations

Identify in the field by its gritty texture (feels like sandpaper) and visible quartz grains embedded in a rusty matrix. Commonly found in desert environments, river basins, and coastal areas. Collectors should look for unique banding or larger inclusion crystals.