igneous
Rounded basaltic conglomerate / breccia pebble
Basalt-rich polymict conglomerate, with plagioclase, pyroxene, and altered mafic minerals
AI-generated identification · may be incorrectDark gray-brown, fine- to medium-grained, with lighter angular to rounded mineral or rock fragments and weathered veins; typically dull to weakly vitreous, massive, with no obvious cleavage. Estimated hardness 5.5–6.5 Mohs and specific gravity about 2.8–3.1.
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Physical properties
Dark gray-brown, fine- to medium-grained, with lighter angular to rounded mineral or rock fragments and weathered veins; typically dull to weakly vitreous, massive, with no obvious cleavage. Estimated hardness 5.5–6.5 Mohs and specific gravity about 2.8–3.1.
Formation & geological history
Likely volcanic basaltic material reworked by water and cemented into conglomerate or breccia, then rounded during transport; age cannot be determined from the photograph. Such clasts commonly form in river, beach, or volcanic terrains.
Uses & applications
Used mainly as a curiosity, teaching specimen, landscaping stone, or aggregate; generally not suitable for jewelry unless polished. Typical value is modest.
Geological facts
The contrasting pale patches may be feldspar-rich basalt, quartz/calcite veins, or weathered inclusions; image-only identification cannot distinguish these confidently.
Field identification & locations
Look for a dark mafic matrix, abundant pale feldspar-like grains, possible vesicles or veins, and strong resistance to scratching by a steel tool. Common around volcanic regions and basalt-bearing river gravels.
