igneous
Granite Cobble
Granite (Phaneritic igneous rock)
Hardness: 6-7 Mohs; Color: Salt and pepper (gray, white, black); Luster: Dull/Matte (eroded); Structure: Crystalline; Cleavage: None (fractures); Specific Gravity: 2.63-2.75
- Hardness
- 6-7 Mohs
- Color
- Salt and pepper (gray, white, black)
- Luster
- Dull/Matte (eroded)
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Salt and pepper (gray, white, black); Luster: Dull/Matte (eroded); Structure: Crystalline; Cleavage: None (fractures); Specific Gravity: 2.63-2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen has been rounded by fluvial or glacial transport over thousands of years.
Uses & applications
Construction, decorative gravel, river rock landscaping, and as a durable material for counter tops or monuments when in large slabs.
Geological facts
Granite is the primary component of the Earth's continental crust. Because it contains quartz and feldspar, it is extremely resistant to weathering compared to other rock types.
Field identification & locations
Identify by its 'salt and pepper' appearance of interlocking crystals. Commonly found in riverbeds, glacial moraines, and mountainous regions throughout the world.
