sedimentary

Sandstone (River Pebble)

Arenite (primarily SiO2)

AI-generated identification · may be incorrect

Hardness: 6-7 Mohs; Color: Tan to light brown with darker wet patches; Luster: Dull/Earthy; Crystal structure: Granular (clastic); Cleavage: None; Specific gravity: 2.2-2.8

Hardness: 6-7 Mohs
Color: Tan to light brown with darker wet patches
Luster: Dull/Earthy

Identified March 18, 2026More sedimentary →

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Physical properties

Hardness: 6-7 Mohs; Color: Tan to light brown with darker wet patches; Luster: Dull/Earthy; Crystal structure: Granular (clastic); Cleavage: None; Specific gravity: 2.2-2.8

Formation & geological history

Formed through the accumulation, compaction, and cementation of sand-sized mineral grains or rock fragments over millions of years. This specimen shows signs of mechanical weathering and rounding from fluvial (river) transport environments.

Uses & applications

Commonly used as construction aggregate, decorative landscaping stone, and occasionally for making grindstones or building facades. Smooth pebbles are popular for home decor and zen gardens.

Geological facts

Sandstone represents about 20% of all sedimentary rocks on Earth. Its porosity makes it a primary reservoir for underground water (aquifers) and petroleum.

Field identification & locations

Identified by its gritty sandpaper-like texture and visible sand grains. It is extremely common in riverbeds, beaches, and desert environments globally. Collectors look for unique banding or fossils within the matrix.