igneous
Rounded river pebble, possibly iron-rich quartzite or basalt
Indeterminate from image; likely fine-grained basalt (mafic silicate rock) or ferruginous quartzite
AI-generated identification · may be incorrectDark gray-brown, smooth and water-worn, with dull to slightly waxy luster and no visible crystals or cleavage. Likely hardness about 6–7 if quartzite, or 5–6 if basalt; specific gravity approximately 2.7–3.0.
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Physical properties
Dark gray-brown, smooth and water-worn, with dull to slightly waxy luster and no visible crystals or cleavage. Likely hardness about 6–7 if quartzite, or 5–6 if basalt; specific gravity approximately 2.7–3.0.
Formation & geological history
A naturally rounded pebble shaped by stream or beach abrasion; its original rock formed either from cooling lava (basalt) or metamorphism of quartz-rich sandstone (quartzite), generally at least millions of years old.
Uses & applications
As an isolated pebble it has little commercial use, but similar material is used as aggregate, landscaping stone, pavers, and occasionally cabochons or decorative specimens.
Geological facts
The metallic-looking patches may be iron-oxide staining or reflective mineral grains rather than true metal. A magnet, streak, and hardness test would greatly improve identification.
Field identification & locations
Common in volcanic or metamorphic terrains and transported widely by rivers and glacial deposits. Check for a white streak and glass-scratching ability; strong magnetism would favor magnetite-bearing basalt.
