igneous
River Rock (Basalt or Siltstone)
Basalt (Aphanitic Igneous Rock)
Hardness: 5-7 (Mohs scale); Color: Gray to dark charcoal; Luster: Dull/Earthy; Texture: Fine-grained, smooth from water erosion; Structure: Non-crystalline visible.
- Hardness
- 5-7 (Mohs scale)
- Color
- Gray to dark charcoal
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-7 (Mohs scale); Color: Gray to dark charcoal; Luster: Dull/Earthy; Texture: Fine-grained, smooth from water erosion; Structure: Non-crystalline visible.
Formation & geological history
Formed from the rapid cooling of basaltic lava at the surface or just below it. This specific specimen has been rounded and smoothed through mechanical weathering in a river or coastal environment over thousands of years.
Uses & applications
Primarily used for decorative landscaping, garden features, or as a sentimental keepsake due to its natural heart-like shape.
Geological facts
River rocks reach their smooth, rounded shape through a process called saltation, where they tumble along the floor of a body of water, grinding against other stones.
Field identification & locations
Commonly found in riverbeds, stream channels, and beaches. Identify in the field by its smooth, water-worn texture and uniform dark gray color. This specimen is notable for its natural heart shape.
