igneous
Landscape Boulder / River Rock
Granitic or Quartzite Rock
Hardness: 6-7 on Mohs scale. Color: Light gray, tan, or weathered beige. Luster: Dull to sub-vitreous. Crystal structure: Phaneritic (coarse-grained) or massive. Cleavage: None distinct due to weathering and rounded shape. Specific gravity: ~2.6-2.7.
- Hardness
- 6-7 on Mohs scale
- Color
- Light gray, tan, or weathered beige
- Luster
- Dull to sub-vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Light gray, tan, or weathered beige. Luster: Dull to sub-vitreous. Crystal structure: Phaneritic (coarse-grained) or massive. Cleavage: None distinct due to weathering and rounded shape. Specific gravity: ~2.6-2.7.
Formation & geological history
Formed via cooling of magma underground (if granite) or intense metamorphism of sandstone (if quartzite), subsequently weathered, transported by water, and rounded into smooth boulders in riverbeds or glacial environments.
Uses & applications
Commonly used in landscaping, garden decoration, dry creek beds, and construction aggregate.
Geological facts
Naturally rounded rocks like this are often smoothed by tumbling in high-energy rivers or streams over thousands or millions of years before being harvested for commercial landscaping.
Field identification & locations
Found widely in landscaping supply yards, riverbeds, and glacial drift deposits worldwide. Identified by its rounded shape, weathered surface, and hard, durable mineral composition.
