igneous
Likely vesicular volcanic rock (scoriaceous basalt)
Vesicular basalt/scoria; chiefly plagioclase, pyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectDark gray to black, highly vesicular, with rough to locally glassy luster; typically no visible cleavage. Hardness about 5–6 Mohs, specific gravity commonly 2.4–2.9, though abundant pores make it unusually light.
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Physical properties
Dark gray to black, highly vesicular, with rough to locally glassy luster; typically no visible cleavage. Hardness about 5–6 Mohs, specific gravity commonly 2.4–2.9, though abundant pores make it unusually light.
Formation & geological history
Forms when mafic lava cools rapidly at or near the surface, trapping gas bubbles; most examples are Quaternary to modern volcanic material. The image is too unclear for a precise locality or age.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasives, and sometimes in lightweight concrete; generally little jewelry value.
Geological facts
Scoria is typically darker and denser than pumice and commonly contains rusty red oxidation around vesicles. The specimen may also be basalt with weathering or mineral coatings rather than pure scoria.
Field identification & locations
Identify by its black mafic color, abundant irregular holes, rough texture, and weak attraction to a magnet if magnetite is present; common near basaltic volcanoes, lava flows, and cinder cones. A fresh streak, density test, and close inspection of crystals would improve identification.
