sedimentary

Sandstone River Cobble

Arenite (SiO2 based)

Hardness: 6-7 Mohs; Color: Brown, tan, and grey with iron staining; Luster: Dull/Earthy; Structure: Clastic, fine-grained; Cleavage: None; Specific Gravity: 2.2-2.8

Hardness: 6-7 Mohs
Color: Brown, tan, and grey with iron staining
Luster: Dull/Earthy

Identified July 18, 2026More sedimentary →

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Physical properties

Hardness: 6-7 Mohs; Color: Brown, tan, and grey with iron staining; Luster: Dull/Earthy; Structure: Clastic, fine-grained; Cleavage: None; Specific Gravity: 2.2-2.8

Formation & geological history

Formed from the accumulation and cementation of sand-sized mineral grains or rock fragments. This specimen shows significant rounding due to fluvial (river) erosion and transport, likely over thousands of years.

Uses & applications

Commonly used in landscaping, as a building material, and in the production of glass or concrete if the quartz content is high. Often used as decorative garden stones.

Geological facts

Sandstone covers about 20% of the Earth's sedimentary rock surface. It often contains fossils and provides crucial records of ancient environments and sea levels.

Field identification & locations

Identify in the field by its gritty, sand-like texture and visible layering (bedding). Commonly found in riverbeds, beaches, and desert basins worldwide.