igneous
Granite Water-worn Pebble
Granite
Hardness: 6-7 Mohs; Color: Salt and pepper (mottled grey, white, and black); Luster: Dull (matte due to weathering); Crystal structure: Phaneritic (medium-grained crystalline); Specific gravity: 2.63-2.75
- Hardness
- 6-7 Mohs
- Color
- Salt and pepper (mottled grey, white, and black)
- Luster
- Dull (matte due to weathering)
Identified More igneous →
Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper (mottled grey, white, and black); Luster: Dull (matte due to weathering); Crystal structure: Phaneritic (medium-grained crystalline); Specific gravity: 2.63-2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep beneath the Earth's surface (intrusive). The rounded shape is the result of mechanical weathering and abrasion, typically in a high-energy aquatic environment like a riverbed or shoreline.
Uses & applications
Larger granite is used in construction, countertops, and monuments; as a pebble, it is used for landscaping, decorative garden paths, and as a common collectible for beachcombers.
Geological facts
Granite makes up a large portion of the Earth's continental crust. Because it is so hard and resistant to acid, it lasts for millions of years, often outlasting the softer rocks that once surrounded it.
Field identification & locations
Identify by its interlocking crystalline texture containing quartz (clear/grey), feldspar (white), and mica (black specks). This specific specimen is easily identified by its smooth, oval-ovate 'river rock' shape. Found globally in mountainous regions and glacial deposits.
