igneous and sedimentary
River Pebbles (Tumbled Quartz and Basalt)
Silicon Dioxide (SiO2) for white quartz; Mafic Volcanic Rock for basalt
Hardness: 6-7 Mohs; Color: Creamy white (quartz) and dark grey/black (basalt); Luster: Sub-vitreous to dull; Structure: Microcrystalline/Aphanitic; Cleavage: None/Conchoidal
- Hardness
- 6-7 Mohs
- Color
- Creamy white (quartz) and dark grey/black (basalt)
- Luster
- Sub-vitreous to dull
Identified More igneous and sedimentary →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 Mohs; Color: Creamy white (quartz) and dark grey/black (basalt); Luster: Sub-vitreous to dull; Structure: Microcrystalline/Aphanitic; Cleavage: None/Conchoidal
Formation & geological history
Formed through cooling magma (basalt) or hydrothermal veins (quartz). These specimens have been weathered and smoothed by mechanical abrasion in a river or beach environment over thousands of years.
Uses & applications
Used in landscaping, decorative stone for gardens, massage therapy (basalt), and as tumbled stones for amateur geological collections.
Geological facts
River rocks are often shaped into 'ellipsoids' due to the uniform tumbling action of water. Basalt is the most common rock in the Earth's crust, making up most of the ocean floor.
Field identification & locations
Identify by their smooth, rounded edges and lack of sharp corners. Common in stream beds, glacial deposits, and coastlines. Collectors look for unique colors or perfectly symmetrical oval shapes.
More like this
Other igneous and sedimentary specimens
Quartz (Druzy)
Silicon Dioxide (SiO2)
mineral
Botryoidal Chalcedony
Chalcedony (SiO2)
Mineral
Greenstone (Greywacke or Nephrite Jade variant)
Metamorphosed mafic igneous or sedimentary rock (e.g., Actinolite-Chlorite Schist)
metamorphic
Quartz
Silicon Dioxide (SiO2)
Mineral
Chalcedony (Agate)
Silicon Dioxide (SiO2)
mineral
Pyrulite (Pyrite / Chalcopyrite)
Iron Sulfide (FeS2) or Copper Iron Sulfide (CuFeS2)
mineral