igneous
Rounded brown pebble, likely weathered basalt or iron-rich volcanic rock
Indeterminate fine-grained mafic rock; possible basalt (plagioclase–pyroxene ± iron oxides)
AI-generated identification · may be incorrectSmall, rounded, brown, and dull to weakly earthy-lustrous, with no visible crystal faces. Likely hardness about 5–6, massive texture, no obvious cleavage, and medium-to-high specific gravity; iron-oxide weathering may cause the brown color.
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Physical properties
Small, rounded, brown, and dull to weakly earthy-lustrous, with no visible crystal faces. Likely hardness about 5–6, massive texture, no obvious cleavage, and medium-to-high specific gravity; iron-oxide weathering may cause the brown color.
Formation & geological history
Probably a water- or abrasion-rounded volcanic pebble, potentially weathered basalt. Basalt forms from rapidly cooled lava, commonly in Cenozoic volcanic terrains; the photograph cannot establish its age or exact lithology.
Uses & applications
As an isolated pebble it has little commercial value, generally under $1. Similar basalt is widely used as aggregate, road stone, and construction material.
Geological facts
The smooth outline reflects transport and abrasion rather than crystal shape. Brown surfaces commonly result from oxidation of iron-bearing minerals to limonite/goethite.
Field identification & locations
The image supports only a broad identification: test for a dark gray interior under a fresh chip, lack of fizz in dilute hydrochloric acid, and magnetic response from iron oxides. Around 18.8°N, 95.8°W, sedimentary rocks and weathered volcanic clasts are plausible; a local river or beach pebble is more likely than a pristine igneous specimen.
