igneous
Granite Water-Worn Pebble
Felsic intrusive igneous rock (Granite)
Hardness: 6-7 Mohs; Color: Speckled pink, white, gray, and black; Luster: Dull to vitreous; Crystal structure: Phaneritic (visible crystals); Specific gravity: 2.63-2.75
- Hardness
- 6-7 Mohs
- Color
- Speckled pink, white, gray, and black
- Luster
- Dull to vitreous
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Speckled pink, white, gray, and black; Luster: Dull to vitreous; Crystal structure: Phaneritic (visible crystals); Specific gravity: 2.63-2.75
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. This specific specimen has been smoothed and rounded by water transport in a river, stream, or beach environment.
Uses & applications
Large-scale granite is used for construction and countertops. Small pebbles like this are used for landscaping, decorative gravel, and as educational river-rock specimens.
Geological facts
Granite makes up much of the Earth's continental crust. The pink/orange hues are usually due to Potassium Feldspar (Orthoclase), while the clear/white parts are Quartz.
Field identification & locations
Identify in the field by its 'salt and pepper' speckled appearance and extreme hardness (cannot be scratched by a steel knife). Common in glacial till and riverbeds worldwide.
