igneous
Weathered granitic cobble
Granite, composed mainly of quartz, feldspar, and mica/amphibole
AI-generated identification · may be incorrectCoarse-grained, pale gray to tan, with visible interlocking grains and dull to weakly vitreous luster; hardness about 6–7 Mohs, no consistent cleavage as a rock, and specific gravity roughly 2.6–2.7. The rounded shape and pitted surface indicate stream abrasion and weathering.
Identified More igneous →
Explore Weathered granitic cobble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Coarse-grained, pale gray to tan, with visible interlocking grains and dull to weakly vitreous luster; hardness about 6–7 Mohs, no consistent cleavage as a rock, and specific gravity roughly 2.6–2.7. The rounded shape and pitted surface indicate stream abrasion and weathering.
Formation & geological history
Slow cooling of silica-rich magma produced the crystalline granite, generally in Precambrian to younger continental plutons; the cobble was later transported and rounded in a river or gravel deposit.
Uses & applications
Used as aggregate, building stone, paving, monuments, and landscaping; this weathered specimen has little jewelry or commercial value.
Geological facts
The apparent layered or banded appearance is likely differential weathering, mineral segregation, or attached sediment rather than true sedimentary bedding.
Field identification & locations
Identify it by visible quartz and feldspar crystals, pale color, and granular texture; common in stream gravels near granitic terrains. A fresh surface or hand lens would improve identification.
