igneous
Dark vesicular volcanic rock, likely basaltic scoria
Scoria; fine-grained basaltic rock composed mainly of pyroxene, plagioclase, and iron oxides
AI-generated identification · may be incorrectBlack to dark gray, rough and highly vesicular, with dull to slightly glassy luster; hardness about 5–6 Mohs, no obvious cleavage, and typical density around 2.0–2.7 g/cm³. The specimen appears natural and unpolished, though its small size limits certainty.
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Physical properties
Black to dark gray, rough and highly vesicular, with dull to slightly glassy luster; hardness about 5–6 Mohs, no obvious cleavage, and typical density around 2.0–2.7 g/cm³. The specimen appears natural and unpolished, though its small size limits certainty.
Formation & geological history
Forms when gas-rich basaltic lava cools rapidly, trapping bubbles in an extrusive igneous texture; commonly associated with Cenozoic volcanic eruptions and cinder cones. Exact age and locality cannot be determined from the image.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasive, drainage material, and sometimes in barbecue or horticultural applications; generally not used as a gemstone.
Geological facts
Scoria is denser and darker than pumice because basaltic magma contains more iron and magnesium. Its abundant vesicles record gas release during eruption.
Field identification & locations
Identify by its black color, rough frothy surface, and abundant holes; it is weakly magnetic if iron-rich and usually sinks in water, unlike pumice. Common around basaltic volcanoes and cinder cones.
