igneous
Dark, vesicular volcanic rock (probable basaltic scoria)
Basaltic scoria; mainly plagioclase, clinopyroxene, olivine, and volcanic glass
AI-generated identification · may be incorrectHardness about 5–6 Mohs; dark gray to black, dull to slightly vitreous, with irregular vesicles and scattered pale mineral crystals. The rounded shape appears naturally weathered or water-worn; exact identification is limited by the image.
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Physical properties
Hardness about 5–6 Mohs; dark gray to black, dull to slightly vitreous, with irregular vesicles and scattered pale mineral crystals. The rounded shape appears naturally weathered or water-worn; exact identification is limited by the image.
Formation & geological history
An extrusive igneous rock formed when gas-rich basaltic lava cooled rapidly, trapping bubbles. It may range from geologically young volcanic material to much older weathered basalt; age cannot be determined visually.
Uses & applications
Used as lightweight aggregate, landscaping stone, abrasive, and occasionally decorative material; generally low jewelry value.
Geological facts
The pale spots may be plagioclase or altered zeolite minerals, while the porous dark matrix is typical of mafic lava. If unusually dense and metallic rather than porous, it could instead be an iron-rich meteorite or slag, requiring testing.
Field identification & locations
Common near basaltic volcanoes, cinder cones, lava fields, and volcanic beaches. Check for vesicles, a black streak, lack of metallic sheen, and weak magnetism; a streak, density, and magnet test would improve identification.
