igneous
Red Scoria (Lava Rock)
Scoria (Basaltic Scoria)
Hardness: 5-6 (Mohs scale); Color: Reddish-brown to dark red; Luster: Dull/Earthy; Structure: Highly vesicular/porous; Cleavage: None; Specific Gravity: Low (often floats briefly before saturating)
- Hardness
- 5-6 (Mohs scale)
- Color
- Reddish-brown to dark red
- Luster
- Dull/Earthy
Identified More igneous →
Explore Red 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 scale); Color: Reddish-brown to dark red; Luster: Dull/Earthy; Structure: Highly vesicular/porous; Cleavage: None; Specific Gravity: Low (often floats briefly before saturating)
Formation & geological history
Formed from basaltic or andesitic magma containing high amounts of gas. As the magma erupts, gas bubbles expand and are trapped as the lava cools rapidly. The red color indicates oxidation of iron (rusting) during or after the eruption.
Uses & applications
Used in landscaping, gas grills (lava rocks), lightweight concrete aggregate, road traction (cinders), and high-temperature insulation.
Geological facts
Scoria is different from pumice in that it has larger vesicles, thicker cell walls, and is denser. It usually sinks in water, whereas pumice often floats. The red color is a result of iron in the lava oxidizing at high temperatures.
Field identification & locations
Identify by its 'Swiss cheese' appearance and lightweight feel. Commonly found in volcanic fields, cinder cones, and near basaltic lava flows. Collectors can find these easily in regions with recent volcanic activity like the Southwestern US, Iceland, or Italy.
