igneous
Granite River Cobble
Granite
Texture: Phaneritic (visible crystals); Hardness: 6-7 on Mohs scale; Color: Salt and pepper (white, grey, and black); Luster: Dull (weathered) to vitreous (on fresh surfaces); Composition: Quartz, Feldspar, and Mica.
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper (white, grey, and black)
- Luster
- Dull (weathered) to vitreous (on fresh surfaces)
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Physical properties
Texture: Phaneritic (visible crystals); Hardness: 6-7 on Mohs scale; Color: Salt and pepper (white, grey, and black); Luster: Dull (weathered) to vitreous (on fresh surfaces); Composition: Quartz, Feldspar, and Mica.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. This specific specimen has been rounded and smoothed by water transport in a river or glacial environment.
Uses & applications
Large deposits are used for construction aggregate, building stone, and countertops. Sized river rocks are used in landscaping and garden decor.
Geological facts
Granite is the most common igneous rock found on Earth's continents and makes up the bulk of the continental crust. Its name comes from the Latin 'granum', meaning a grain.
Field identification & locations
Identify by its interlocking crystalline texture and hard mineral grains that cannot be scratched by a steel knife. Commonly found in riverbeds, glacial tills, and mountainous regions.
