igneous
Lava Rock Substrate
Scoria (Basaltic Rock)
Hardness: 5-6 (Mohs scale); Color: Black or dark brown; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained) with vesicular (porous) texture; Specific gravity: 2.5-3.0.
- Hardness
- 5-6 (Mohs scale)
- Color
- Black or dark brown
- Luster
- Dull/Earthy
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Black or dark brown; Luster: Dull/Earthy; Crystal structure: Aphanitic (fine-grained) with vesicular (porous) texture; Specific gravity: 2.5-3.0.
Formation & geological history
Formed from gas-rich basaltic magma cooling rapidly during volcanic eruptions. The vesicles (holes) are formed by trapped gas bubbles. Found in volcanic regions worldwide.
Uses & applications
Used in aquarium hobby for biological filtration, landscaping, gas grills, and drainage in gardening.
Geological facts
The highly porous surface area of lava rock provides a vast habitat for beneficial nitrifying bacteria, which help detoxify ammonia and nitrites in fish tanks.
Field identification & locations
Identify by its light weight relative to its size and visible gas-bubble pits. Commonly found in garden centers or aquarium shops as 'black lava rock'.
