sedimentary

Sandstone (Water-worn Cobble)

Arenite (variable composition, primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 6-7 Mohs; Color: Tan, beige, or light brown; Luster: Dull or earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific gravity: 2.2-2.8

Hardness: 6-7 Mohs
Color: Tan, beige, or light brown
Luster: Dull or earthy

Identified April 7, 2026More sedimentary →

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Physical properties

Hardness: 6-7 Mohs; Color: Tan, beige, or light brown; Luster: Dull or earthy; Crystal structure: Clastic (sand-sized grains); Cleavage: None; Specific gravity: 2.2-2.8

Formation & geological history

Formed from the accumulation and cementation of sand-sized mineral particles or rock fragments. This specific specimen was likely rounded and smoothed by high-energy water action in a river or coastal environment during the Holocene era.

Uses & applications

Used primarily as decorative landscaping, construction material (crushed stone), or as simple indoor decor and paperweights.

Geological facts

Sandstone represents approximately 20-25% of all sedimentary rocks on Earth. The smooth, oval shape of this specimen is a result of fluvial erosion, a process called 'rounding' where sharp edges are knocked off by colliding with other rocks in water.

Field identification & locations

Identify in the field by its sandpaper-like texture and visible bedding planes or layers. Commonly found in riverbeds, beaches, and desert outcrops throughout the Pacific Northwest (as suggested by the Whidbey/Anacortes context).