sedimentary

River Pebble Gravel

Hydrothermally modified Clastic Sediment (mainly Quartzite and Chert)

AI-generated identification · may be incorrect

Hardness: 6.5-7 Mohs; Color: Tan, cream, grey, and brown; Luster: Dull to sub-vitreous; Crystal Structure: Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.7

Hardness: 6
Color: Tan, cream, grey, and brown
Luster: Dull to sub-vitreous

Identified April 18, 2026More sedimentary →

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Physical properties

Hardness: 6.5-7 Mohs; Color: Tan, cream, grey, and brown; Luster: Dull to sub-vitreous; Crystal Structure: Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.7

Formation & geological history

Formed through the erosion of larger rock formations, transported by water over long periods. The smooth, rounded shapes are the result of constant abrasion in riverbeds or coastal environments.

Uses & applications

Primarily used in landscaping, decorative ground cover, drainage systems, and as an aggregate in concrete or pathways.

Geological facts

River pebbles represent a natural 'sorting' process where only the hardest and most durable minerals, like quartz, survive the trek downstream. They are often used in Zen gardens to represent water.

Field identification & locations

Identify by the smooth, rounded 'egg-like' texture and lack of sharp edges. Commonly found in alluvial deposits and at the base of mountains. Collectors look for unique banding or translucency.