igneous
Granite Pebble
Granite
Hardness: 6-7 Mohs; Color: Mottled pink, grey, white, and black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained); Composition: Quartz, Potassium Feldspar, Plagioclase, and Mica.
- Hardness
- 6-7 Mohs
- Color
- Mottled pink, grey, white, and black
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 Mohs; Color: Mottled pink, grey, white, and black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained); Composition: Quartz, Potassium Feldspar, Plagioclase, and Mica.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface (intrusive). This specific specimen appears to be a water-worn or tumbled pebble, likely weathered out of a larger pluton and polished by fluvial or glacial action.
Uses & applications
Used extensively in construction (countertops, flooring, monuments) and as crushed stone for road base. Tumbled pebbles like this are used for landscaping, aquarium gravel, or decorative stone.
Geological facts
Granite is the most common igneous rock found on Earth's continents and makes up the core of many mountain ranges. The pink color in this specimen is caused by orthoclase feldspar.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and the presence of visible mineral grains of roughly equal size. It is extremely hard and will scratch glass easily.
