igneous
Scoria (Lava Rock)
Vesicular Basalt / Scoria
Hardness: 5-6 (Mohs); Color: Dark reddish-brown to black; Luster: Dull/Earthy; Structure: Vesicular (full of holes); Cleavage: None; Specific Gravity: 2.5-3.0 (though it feels light due to porosity).
- Hardness
- 5-6 (Mohs)
- Color
- Dark reddish-brown to black
- Luster
- Dull/Earthy
Identified More igneous →
Explore Scoria (Lava Rock) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-6 (Mohs); Color: Dark reddish-brown to black; Luster: Dull/Earthy; Structure: Vesicular (full of holes); Cleavage: None; Specific Gravity: 2.5-3.0 (though it feels light due to porosity).
Formation & geological history
Formed from the rapid cooling of basaltic or andesitic lava that contains high amounts of trapped gases. As the lava solidifies, the gas escapes, leaving behind a sponge-like honeycombed texture.
Uses & applications
Used widely in landscaping (lava rock), high-temperature insulation, gas grills, lightweight concrete aggregate, and road drainage systems.
Geological facts
Scoria is different from pumice in that scoria is denser and usually sinks in water, whereas pumice has smaller, more numerous vesicles and floats. The red color is typically due to the oxidation of iron within the lava.
Field identification & locations
Identify in the field by its distinctive 'holy' texture and dark red/black color. It is extremely common in volcanic regions like Hawaii, Iceland, and the American Southwest. Collectors look for unique shapes or inclusions of other minerals like olivine.
