VHP Photo Glossary: Scoria

Scoria exposed in cross section of a cinder or scoria cone

Photograph by J. Lowenstern in September 1990.

Scoria

Scoria is a vesicular (bubbly) glassy lava rock of basaltic to andesitic composition ejected from a vent during explosive eruption. The bubbly nature of scoria is due to the escape of volcanic gases during eruption. Scoria is typically dark gray to black in color, mostly due to its high iron content. The surface of some scoria may have a blue iridescent color; oxidation may lead to a deep reddish-brown color.

Photo: Scoria exposed in the cross section of a cinder or scoria cone.

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