Sandstone (Quartzose)

Physical Properties

Hardness: 6-7 on Mohs scale (due to quartz grains); Color: Tan, buff, or light brown; Luster: Dull/Earthy; Crystal structure: Clastic (granular); 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 appears water-worn, suggesting a fluvial or coastal environment where it was tumbled and rounded over time.

Uses & Applications

Commonly used as a building material, in the manufacture of glass (if high purity quartz), and as a reservoir rock for oil and natural gas. Smaller pebbles are used for landscaping.

Geological Facts

Sandstone makes up about 20-25% of all sedimentary rocks on Earth. The 'Old Red Sandstone' is a famous geological formation in Britain that helped pioneers of geology understand Earth's history.

Field Identification & Locations

Identify in the field by its gritty texture (feels like sandpaper) and visible grains. Often found in riverbeds, beaches, and desert outcrops. It often shows bedding layers in larger specimens.

Identified on: 4/15/2026

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