sedimentary
River Pebbles (White Quartz and Basalt mix)
Mixed Clastic Sedimentary Assemblage (SiO2 and Mafic Volcanics)
Hardness: 6-7 (Quartz), 5-6 (Basalt). Color: White, black, brown. Luster: Dull to vitreous. Crystal structure: Cryptocrystalline to fine-grained. Cleavage: Indistinct. Specific gravity: 2.6-3.0.
- Hardness
- 6-7 (Quartz), 5-6 (Basalt)
- Color
- White, black, brown
- Luster
- Dull to vitreous
Identified More sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 (Quartz), 5-6 (Basalt). Color: White, black, brown. Luster: Dull to vitreous. Crystal structure: Cryptocrystalline to fine-grained. Cleavage: Indistinct. Specific gravity: 2.6-3.0.
Formation & geological history
Formed through the mechanical weathering and water transportation of larger rock formations. Over time, river action smooths the edges into rounded shapes through abrasion. Common in riverbeds and coastal areas.
Uses & applications
Used primarily for landscaping, decorative garden beds, aquarium substrate, and as aggregates in concrete or architectural finishes.
Geological facts
The rounded shape is a direct result of 'rounding,' a geological process where particles collide during transport in water, removing sharp edges.
Field identification & locations
Identify by the smooth, rounded 'egg-like' shape. White stones are typically quartz; darker stones are usually basalt or chert. Found globally in alluvial deposits.
More like this
Other sedimentary specimens
Sandstone or Siltstone
Arenite (if sandstone)
Sedimentary
Chert Breccia
Brecciated Chert (Microcrystalline Silica)
sedimentary
Sandstone
Arenite (primarily SiO2)
sedimentary
Sandstone Grain
Clastic Sedimentary Rock Grain (SiO2 dominated)
sedimentary
Shale or Slaty Mudstone
Argillaceous sedimentary rock
sedimentary
Sandstone
Arenite
sedimentary