Rock Identifier
Red Scoria (Lava Rock) (Scoria (Vesicular Basalt/Andesite)) — igneous
igneous

Red Scoria (Lava Rock)

Scoria (Vesicular Basalt/Andesite)

Hardness: 5-6 (Mohs scale), Color: Dark red to reddish-brown (from oxidation), Luster: Dull/Earthy, Structure: Vesicular (full of holes), Specific Gravity: 1.5 - 2.5 (relatively light and can sometimes float briefly but usually sinks).

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Physical properties

Hardness: 5-6 (Mohs scale), Color: Dark red to reddish-brown (from oxidation), Luster: Dull/Earthy, Structure: Vesicular (full of holes), Specific Gravity: 1.5 - 2.5 (relatively light and can sometimes float briefly but usually sinks).

Formation & geological history

Formed through the rapid cooling of basaltic or andesitic magma containing high concentrations of dissolved gases. As magma erupts, the gases expand and form bubbles (vesicles) which are frozen into the stone as it solidifies. The red color is caused by the oxidation of iron-rich minerals like magnetite or olivine.

Uses & applications

Commonly used in landscaping (lava rocks), gas grills for heat retention, road construction for high-friction surfacing, lightweight concrete aggregate, and filtration systems.

Geological facts

Unlike pumice, which is also a volcanic rock with many holes, scoria is more dense and has thicker bubble walls. It typically forms on the exterior of cinder cones and lava flows.

Field identification & locations

Identify by its 'sponge-like' or 'Swiss cheese' appearance and rough, jagged edges. It is found in volcanic regions such as the Cascades in the US, Iceland, Italy, and Hawaii. Collectors value it for display in terrariums or geological sets.

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