igneous
Basalt River Stone
Basalt
Hardness: 6.0; Color: Dark grey to dull greenish-grey; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); Specific Gravity: 2.8 - 3.0
- Hardness
- 6
- Color
- Dark grey to dull greenish-grey
- Luster
- Dull/Earthy
Identified More igneous →
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Physical properties
Hardness: 6.0; Color: Dark grey to dull greenish-grey; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained); Specific Gravity: 2.8 - 3.0
Formation & geological history
Formed from the rapid cooling of magnesium-rich and iron-rich lava at or near the Earth's surface. Extrusive igneous rock. This specific specimen has been shaped by fluvial (river) erosion.
Uses & applications
Commonly used as aggregate in construction, road base, and for architectural uses like stone walls or decorative landscaping. Smooth ones are often used in hot stone massage therapy.
Geological facts
Basalt is the most common rock type in Earth's crust and makes up most of the ocean floor. It is also found extensively on the Moon and Mars.
Field identification & locations
Identify in the field by its heavy weight, fine-grained texture (no visible crystals), and rounded shape if found near water. Often lacks the layering found in sedimentary rocks.
