igneous
Rounded granite cobble
Granite, a coarse-grained felsic intrusive igneous rock, likely quartz–feldspar–mica bearing
AI-generated identification · may be incorrectSpeckled tan, gray, and dark minerals with a dull to slightly granular luster; interlocking crystals are visible. Typical granite hardness is about 6–7 Mohs; individual grains have no consistent cleavage, and specific gravity is roughly 2.6–2.7.
Identified More igneous →
Explore Rounded granite cobble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Speckled tan, gray, and dark minerals with a dull to slightly granular luster; interlocking crystals are visible. Typical granite hardness is about 6–7 Mohs; individual grains have no consistent cleavage, and specific gravity is roughly 2.6–2.7.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly billions to tens of millions of years ago. This cobble’s smooth, rounded shape likely formed through prolonged stream or beach abrasion.
Uses & applications
Granite is widely used as building and paving stone, countertops, aggregate, and decorative material; this small cobble is mainly suitable for collecting or landscaping.
Geological facts
Its mottled appearance comes from contrasting quartz, feldspar, and dark minerals such as biotite or hornblende.
Field identification & locations
Look for a hard, visibly crystalline mixture of light quartz/feldspar and darker grains; unlike sandstone, it has no cemented sand layers. Granite cobbles occur in river and glacial deposits worldwide; exact identification needs closer inspection.
