igneous
Scoria (Red Lava Rock)
Scoria (Mafic volcanic rock)
Reddish-brown to dark red color, highly vesicular (pitted with gas bubbles), dull earthy luster, low density, hardness around 5 to 6 on the Mohs scale.
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Physical properties
Reddish-brown to dark red color, highly vesicular (pitted with gas bubbles), dull earthy luster, low density, hardness around 5 to 6 on the Mohs scale.
Formation & geological history
Formed during explosive volcanic eruptions from gas-rich basaltic or andesitic magma that rapidly cooled while expanding, trapping gas pockets.
Uses & applications
Widely used in landscaping, ground cover, outdoor fire pits, gas grills, lightweight concrete aggregate, and hydroponic gardening.
Geological facts
Scoria sinks in water unlike pumice because its vesicle walls are thicker and denser. The reddish hue is due to the oxidation of iron content within the rock during or after eruption.
Field identification & locations
Look for a porous, sponge-like texture with a reddish or dark brownish hue. It is lightweight compared to solid basalt and commonly found around cinder cones and volcanic fields worldwide.
