Sandstone (Water-worn Cobble)

Physical Properties

Hardness: 6-7 (on Mohs scale); Color: Tan to reddish-brown; Luster: Dull/Earthy; Structure: Granular/Clastic; Cleavage: None; Texture: Gritty like sandpaper.

Formation & Geological History

Formed through the accumulation and cementation of sand-sized mineral grains (mostly quartz) in riverbeds, beaches, or deserts. This specific specimen has been rounded and smoothed by hydraulic action in a river or coastal environment.

Uses & Applications

Commonly used in construction, as a building stone, for decorative landscaping (river rocks), and as an abrasive in industrial applications.

Geological Facts

Sandstone preserves a history of the Earth's surface, often containing ripples from ancient water currents or cross-bedding from ancient sand dunes. It is also one of the most common reservoir rocks for groundwater and oil.

Field Identification & Locations

Identify in the field by its distinctive 'sandpaper' feel and visible grain structure. Commonly found in riverbeds, along coastlines, and in sedimentary basins worldwide.

Identified on: 4/20/2026

Mode: Standard