igneous
Scoria (Vesicular Basalt)
Scoria (Extrusive Mafic Igneous Rock)
Hardness: 5-6 (Mohs scale), Color: Black to dark gray, Luster: Dull/Sub-metallic, Structure: Vesicular (porous), Cleavage: None, Specific Gravity: 2.5-3.0 but often floats temporarily due to trapped air.
Identified More igneous →
Explore Scoria (Vesicular Basalt) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 (Mohs scale), Color: Black to dark gray, Luster: Dull/Sub-metallic, Structure: Vesicular (porous), Cleavage: None, Specific Gravity: 2.5-3.0 but often floats temporarily due to trapped air.
Formation & geological history
Formed from the rapid cooling of gas-rich mafic lava (basaltic) ejected from a volcano. The holes (vesicles) are created by gas bubbles that were trapped as the lava solidified. Primarily associated with Cenozoic to recent volcanic activity.
Uses & applications
Used widely in landscaping, gas grill lava rocks, drainage systems, high-temperature insulation, and as a lightweight aggregate in concrete.
Geological facts
Scoria differs from pumice because it is mafic and has thicker vesicle walls, making it denser and darker. Massive deposits often form 'cinder cones' around volcanic vents.
Field identification & locations
Identify by its dark color, heavy vesicular texture (looking like a sponge), and rough, abrasive surface. Commonly found in volcanic regions like Hawaii, Iceland, and the Western United States.
