igneous
Tumbled granite or granitic pebble
Granite; primarily quartz, feldspar, and mica (exact variety uncertain from the image)
AI-generated identification · may be incorrectCoarse-grained, rounded, mottled brown-gray specimen with a dull to slightly vitreous luster; typical hardness is about 6–7 Mohs, with no obvious cleavage at the whole-rock scale and specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, rounded, mottled brown-gray specimen with a dull to slightly vitreous luster; typical hardness is about 6–7 Mohs, with no obvious cleavage at the whole-rock scale and specific gravity around 2.6–2.7.
Formation & geological history
Granite forms when silica-rich magma cools slowly underground, allowing visible interlocking crystals to grow; most granite is Precambrian to Phanerozoic in age. This piece was likely naturally water-worn or mechanically tumbled.
Uses & applications
Used as aggregate, building and monument stone, countertops, landscaping rock, and inexpensive decorative or craft material; this small pebble has minimal gem value.
Geological facts
The pale grains are likely feldspar or quartz, while darker brown areas may be altered biotite, iron staining, or weathered feldspar. Exact identification would benefit from a fresh broken surface or magnification.
Field identification & locations
Common in glacial deposits, stream gravels, beaches, and granite outcrops worldwide; identify it by its speckled interlocking texture and resistance to scratching by a steel knife. Likely locations include granitic regions of North America, Europe, and Asia.
