igneous
Rounded, weathered stone (likely basaltic or andesitic river cobble)
Fine-grained mafic to intermediate volcanic rock; exact identification requires examination of a fresh surface
AI-generated identification · may be incorrectMuted tan-yellow weathering rind with dark gray-green spots; smooth, rounded surface from abrasion. Likely Mohs hardness about 5–6; fine-grained, dull to slightly earthy luster, with no obvious cleavage; density cannot be determined from the image.
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Physical properties
Muted tan-yellow weathering rind with dark gray-green spots; smooth, rounded surface from abrasion. Likely Mohs hardness about 5–6; fine-grained, dull to slightly earthy luster, with no obvious cleavage; density cannot be determined from the image.
Formation & geological history
Likely formed as volcanic rock, then chemically weathered and rounded by transport in water. Its geological age and precise formation environment cannot be determined from appearance alone.
Uses & applications
Most suitable as a decorative or collecting stone; comparable cobbles are also used in landscaping and construction aggregate.
Geological facts
The contrasting colors may reflect mineral grains or weathering products, but the image does not establish the rock’s mineral composition.
Field identification & locations
Its rounded shape suggests prolonged abrasion in a river or beach setting. Check a freshly chipped area for fine crystals and use hardness or streak tests to distinguish it from other cobble types.
