igneous
Red scoria (vesicular basalt)
Vesicular basalt; iron-oxide-rich mafic volcanic rock
AI-generated identification · may be incorrectUsually dark gray to reddish-brown, highly vesicular, dull to mildly glassy, with tiny cavities; hardness about 5–6 Mohs, no obvious cleavage, and specific gravity commonly 2.0–2.6. The intense red color likely reflects oxidation of iron-bearing minerals.
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Physical properties
Usually dark gray to reddish-brown, highly vesicular, dull to mildly glassy, with tiny cavities; hardness about 5–6 Mohs, no obvious cleavage, and specific gravity commonly 2.0–2.6. The intense red color likely reflects oxidation of iron-bearing minerals.
Formation & geological history
Forms when basaltic lava cools rapidly near the surface while trapped gas bubbles create vesicles; red weathering or oxidation commonly develops in subaerial volcanic settings. Most examples are Cenozoic or younger, though basalt occurs throughout geologic time.
Uses & applications
Used as lightweight aggregate, landscaping stone, drainage material, and occasionally in abrasives or decorative specimens; generally not a jewelry gemstone.
Geological facts
Scoria is denser and heavier than pumice and typically has thicker, more interconnected walls between vesicles. The pictured rounded form may be naturally weathered or human-tumbled, so exact identification from the image is limited.
Field identification & locations
Look for abundant irregular pores, rough texture, low weight, and iron-red coloration; it commonly occurs around cinder cones, lava flows, and volcanic fields worldwide, including Hawaii, Iceland, Italy, and Mexico.
