igneous
Granite Pebble
Granite (Phaneritic intrusive igneous rock)
Hardness: 6-7 Mohs; Color: Speckled pink, white, and grey; Luster: Vitreous to dull; Crystal structure: Coarse-grained (phaneritic); Cleavage: Variable based on mineral content (perfect on feldspar faces); TG: 2.63 to 2.75
- Hardness
- 6-7 Mohs
- Color
- Speckled pink, white, and grey
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Speckled pink, white, and grey; Luster: Vitreous to dull; Crystal structure: Coarse-grained (phaneritic); Cleavage: Variable based on mineral content (perfect on feldspar faces); TG: 2.63 to 2.75
Formation & geological history
Formed from the slow crystalline cooling of magma beneath the Earth's surface (plutonic). Found globally in continental crust, often dating from the Precambrian to Cenozoic eras.
Uses & applications
Used extensively in construction (curbstones, floor tiles, countertops), as crushed stone for road bases, and as architectural stone.
Geological facts
Granite makes up a large portion of the Earth's continental crust. It is often the core of mountain ranges. Famous peaks like El Capitan and Mount Rushmore are carved from granite.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible interlocking crystals of quartz, feldspar, and mica. This specific specimen appears to be a water-worn or weathered fragment common in riverbeds and gravel driveways.
