igneous
Granite Cobble
Granite (Felsic intrusive igneous rock)
Hardness: 6-7 on Mohs scale; Color: Salt and pepper/grey with white and black flecks; Luster: Dull (weathered) to vitreous (on fresh surfaces); Crystal structure: Phaneritic (visible crystals of quartz, feldspar, and mica); Specific gravity: 2.63 to 2.75
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper/grey with white and black flecks
- Luster
- Dull (weathered) to vitreous (on fresh surfaces)
Identified More igneous →
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Physical properties
Hardness: 6-7 on Mohs scale; Color: Salt and pepper/grey with white and black flecks; Luster: Dull (weathered) to vitreous (on fresh surfaces); Crystal structure: Phaneritic (visible crystals of quartz, feldspar, and mica); Specific gravity: 2.63 to 2.75
Formation & geological history
Formed from the slow cooling of silica-rich magma deep underground (plutonic). This specific specimen has been smoothed and rounded by water erosion in a river or beach environment.
Uses & applications
Granite is used extensively in construction for countertops, floor tiles, and curbing. This specific smooth cobble is popular for decorative landscaping, rock painting, or as an aquarium stone.
Geological facts
Granite is the most common rock found in the Earth's continental crust. Over millions of years, tectonic uplift and erosion bring these deep-seated rocks to the surface.
Field identification & locations
Identify by its interlocking crystalline texture and lack of layering. Commonly found in riverbeds, glacial tills, and mountainous regions worldwide. It is very resistant to scratching with steel.
