igneous
Feldspar-rich granitoid pebble
Likely granite or granodiorite, composed mainly of quartz, feldspar, and mica
AI-generated identification · may be incorrectHardness about 6–7 Mohs; tan-gray, fine-to-medium granular texture with a dull to slightly sparkling luster. Interlocking crystals are visible, with no obvious cleavage on the rounded surface; specific gravity roughly 2.6–2.8.
Identified More igneous →
Explore Feldspar-rich granitoid pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness about 6–7 Mohs; tan-gray, fine-to-medium granular texture with a dull to slightly sparkling luster. Interlocking crystals are visible, with no obvious cleavage on the rounded surface; specific gravity roughly 2.6–2.8.
Formation & geological history
A plutonic igneous rock that crystallized slowly from silica-rich magma deep underground, commonly during Precambrian to Phanerozoic continental crust formation. Its smooth, elongated shape reflects abrasion in a stream, beach, or glacial deposit.
Uses & applications
Used widely as crushed stone, aggregate, road material, building stone, and landscaping gravel; attractive pieces may be collected but are generally low value.
Geological facts
The bright specks are probably reflective quartz, feldspar, or mica grains rather than metallic gold. A hand lens would help distinguish granite from granodiorite or a weathered metamorphic rock.
Field identification & locations
Look for visible interlocking grains, abundant light feldspar/quartz, and scattered dark biotite or amphibole. Common worldwide, especially in areas exposing continental plutons; a streak test and close-grained inspection can aid identification.
