metamorphic
River Rock (likely Gneiss or Quartzite)
Metamorphic rock specimen (potentially Foliated Gneiss)
Hardness: 6-7 on Mohs scale; Color: Gray, white with green/yellow algae or moss; Luster: Dull to earthy; Structure: Foliated or massive; Specific Gravity: 2.6-2.9.
- Hardness
- 6-7 on Mohs scale
- Color
- Gray, white with green/yellow algae or moss
- Luster
- Dull to earthy
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Gray, white with green/yellow algae or moss; Luster: Dull to earthy; Structure: Foliated or massive; Specific Gravity: 2.6-2.9.
Formation & geological history
Formed through the metamorphism of pre-existing igneous or sedimentary rocks under high pressure and temperature. This specific specimen has been rounded by fluvial processes (river erosion).
Uses & applications
Commonly used in landscaping, garden decoration, drainage systems, and as aggregate in construction.
Geological facts
River rocks are geological travelers; their smooth, rounded shape is the result of tumbling for miles downstream, a process that can take hundreds or thousands of years.
Field identification & locations
Look for rounded edges and smooth textures. These are commonly found in riverbeds, glacial deposits, and as decorative stones in residential landscaping.
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