sedimentary
River Pebble Gravel
Hydrothermally modified Clastic Sediment (mainly Quartzite and Chert)
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
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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.
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