igneous
Rounded gray river pebble
Likely weathered granite or granodiorite; exact identification is uncertain from the photograph
AI-generated identification · may be incorrectGray, rounded, fine- to medium-grained, with scattered pale mineral patches and a dull-to-slightly sugary luster. Likely hardness about 6–7 Mohs; quartz and feldspar would show no cleavage, while mica may show sheet-like cleavage.
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Physical properties
Gray, rounded, fine- to medium-grained, with scattered pale mineral patches and a dull-to-slightly sugary luster. Likely hardness about 6–7 Mohs; quartz and feldspar would show no cleavage, while mica may show sheet-like cleavage.
Formation & geological history
Probably an ice- or stream-transported clast eroded from crystalline bedrock, then rounded by abrasion; its crystallization could date from Paleozoic to Precambrian depending on locality.
Uses & applications
Commonly used as landscaping or decorative aggregate; an ordinary pebble has little commercial or jewelry value.
Geological facts
The rounded shape indicates transport, but the image does not resolve mineral grains well enough for a confident rock name. Pale patches may be feldspar or weathered quartz.
Field identification & locations
Look for interlocking grains, glassy quartz, blocky feldspar, and possible black mica; a streak test, hardness test, and fresh broken surface would improve identification. Similar pebbles occur in streambeds, glacial till, and gravel deposits worldwide.
