igneous
Scoria (vesicular volcanic rock)
Scoria, typically basaltic or andesitic volcanic rock; commonly composed of plagioclase, pyroxene, and iron oxides
AI-generated identification · may be incorrectDark gray to rusty brown, glassy to dull luster, with abundant gas-bubble cavities (vesicles); hardness roughly 5–6 Mohs. The visible specimen appears dense and metallic-looking in places, but its vesicular texture is characteristic of scoria.
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Physical properties
Dark gray to rusty brown, glassy to dull luster, with abundant gas-bubble cavities (vesicles); hardness roughly 5–6 Mohs. The visible specimen appears dense and metallic-looking in places, but its vesicular texture is characteristic of scoria.
Formation & geological history
Forms when gas-rich mafic lava cools rapidly at or near the surface, trapping bubbles. It can form during eruptions of many ages; the specimen’s age and exact origin cannot be determined from the image.
Uses & applications
Used as lightweight aggregate, drainage material, landscaping stone, and abrasive; attractive pieces may be collected or used decoratively.
Geological facts
Scoria is generally denser and less frothy than pumice and often has reddish-brown surfaces from oxidized iron.
Field identification & locations
Look for irregular vesicles, a rough surface, and dark or iron-stained coloring; common near basaltic volcanoes and cinder cones worldwide. Image-based identification is consistent with scoria, though a close inspection would confirm it.
