Scoria
“Dark, bubbly lava rock”
Igneous
Scoria is a dark-colored, highly vesicular (bubbly) volcanic rock that forms when gas-rich basaltic lava is ejected during eruptions. Unlike pumice, scoria is denser due to its iron-rich composition and generally sinks in water.
Composition
volcanic glass, plagioclase, pyroxene, olivine
Where Found
Stromboli (Italy), Hawaii (USA), Iceland, Canary Islands, Kamchatka (Russia)
Mohs Hardness
5-6
Fun Fact
Many cinder cone volcanoes — like Parícutin in Mexico, which famously grew in a farmer's cornfield in 1943 — are built almost entirely of scoria.
Test Your Knowledge
What is the key compositional reason scoria is denser than pumice?
Related Specimens
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