igneous
Rounded green-gray pebble, likely altered basalt
Fine-grained mafic volcanic rock; exact identification requires examination
AI-generated identification · may be incorrectDull, mottled green-gray with tan patches and a rounded, water-worn shape. Likely dense and fine-grained, with hardness around 5–6 Mohs; crystal structure and mineral composition cannot be confirmed from the photo.
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Physical properties
Dull, mottled green-gray with tan patches and a rounded, water-worn shape. Likely dense and fine-grained, with hardness around 5–6 Mohs; crystal structure and mineral composition cannot be confirmed from the photo.
Formation & geological history
Probably formed as volcanic rock, then chemically altered and rounded by weathering or water transport. Its geological age and original setting cannot be determined from appearance alone.
Uses & applications
Primarily a natural collectible or decorative pebble; comparable rock is also used as aggregate and landscaping stone.
Geological facts
Green coloration in mafic rocks can result from alteration of iron- and magnesium-rich minerals, but color alone is not diagnostic.
Field identification & locations
Look for a fine-grained texture and test a fresh surface; basalt is generally hard and may show tiny crystals. The pebble’s exact source is unknown; common pebbles have little resale value.
