igneous
Scoria (Lava Rock)
Scoria (Extrusive Igneous Rock)
Hardness: 5-6 (Mohs scale), Color: Dark brown to black or reddish-brown, Luster: Dull/Earthy, Crystal Structure: Aphanitic/Vesicular (porous), Specific Gravity: 2.5-3.0 (though it can float temporarily)
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Physical properties
Hardness: 5-6 (Mohs scale), Color: Dark brown to black or reddish-brown, Luster: Dull/Earthy, Crystal Structure: Aphanitic/Vesicular (porous), Specific Gravity: 2.5-3.0 (though it can float temporarily)
Formation & geological history
Formed from gas-rich basaltic magma cooling rapidly during a volcanic eruption, which traps bubbles as the rock solidifies. Typical in Cenozoic volcanic regions.
Uses & applications
Used in landscaping, high-temperature insulation, gas grills (lava rocks), drainage systems, and as an abrasive in stone-washing jeans.
Geological facts
Scoria is different from pumice because it is denser and often has larger vesicles (holes); unlike pumice, most scoria does not float in water for long.
Field identification & locations
Look for a lightweight, dark-colored stone with many visible holes (vesicles). It is commonly found near volcanic vents and cinder cones.
