igneous
Granite Pebble
Granite (Plutonic Igneous Rock)
Hardness: 6-7 on Mohs scale. Color: Speckled grey, white, pink, and black. Luster: Dull to vitreous (glassy) on fresh quartz faces. Texture: Medium-grained phaneritic, rounded and smoothed by erosion (pebble/cobble form). Cleavage: None overall (granitoid texture), though individual feldspar grains show cleavage.…
- Hardness
- 6-7 on Mohs scale
- Color
- Speckled grey, white, pink, and black
- Luster
- Dull to vitreous (glassy) on fresh quartz faces
Identified More igneous →
Explore Granite Pebble in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 on Mohs scale. Color: Speckled grey, white, pink, and black. Luster: Dull to vitreous (glassy) on fresh quartz faces. Texture: Medium-grained phaneritic, rounded and smoothed by erosion (pebble/cobble form). Cleavage: None overall (granitoid texture), though individual feldspar grains show cleavage. Specific gravity: ~2.65–2.75.
Formation & geological history
Formed from the slow crystallization of felsic magma deep beneath the Earth's surface (intrusive igneous). It was subsequently exposed by uplift and erosion, and smoothed into a rounded pebble by water or glacial action.
Uses & applications
Crushed stone for road base, aggregate in concrete, landscaping gravel, ornamental stone, and mineral specimens.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Rounded granite river stones or glacial cobbles are extremely common worldwide due to granite's durability and resistance to chemical weathering.
Field identification & locations
Identified by its salt-and-pepper or pinkish speckled appearance containing visible interlocking grains of quartz (translucent glassy grey), feldspar (opaque white or pink), and dark mica/amphibole (black flecks). Found in riverbeds, beaches, glacial tills, and mountainous regions globally.
