igneous
Basaltic Lava (Scoria)
Extrusive Igneous Rock / Vesicular Basalt
Hardness: 5-6 on the Mohs scale. Color: Dark brown to black. Luster: Dull to vitrified. Crystal structure: Aphanitic (fine-grained) with prominent vesicular texture (gas cavities). Specific gravity: 2.0-2.8 (often low due to porosity).
- Hardness
- 5-6 on the Mohs scale
- Color
- Dark brown to black
- Luster
- Dull to vitrified
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Physical properties
Hardness: 5-6 on the Mohs scale. Color: Dark brown to black. Luster: Dull to vitrified. Crystal structure: Aphanitic (fine-grained) with prominent vesicular texture (gas cavities). Specific gravity: 2.0-2.8 (often low due to porosity).
Formation & geological history
Formed during volcanic eruptions when gas-rich mafic lava cools rapidly at the Earth's surface, trapping gas bubbles as vesicles within the solidifying rock. Geological age ranges from recent volcanic activity to billions of years old.
Uses & applications
Used in landscaping, lightweight aggregate for concrete, barbecues (lava rocks), filtration media, and personal care (as pumice-like exfoliating stones).
Geological facts
Scoria is similar to pumice, but it is darker, has larger and more distinct vesicles, and is generally denser, meaning it usually sinks in water whereas pumice can float.
Field identification & locations
Easily identified by its dark color, rough and sharp texture, and abundant gas holes (vesicles). Found worldwide near active or extinct volcanic regions, particularly oceanic islands and continental rift zones.
